ski_dwn_it

Well these past few weeks have been a real eye opener for me.

I am gonna go against the grain and some of you might not agree with my thoughts but just hear me out. Some interesting things.

I recently put together a 406 to replace my ring leaking 350. I tuned both of them myself. When I started up the 406 I just based on past experience threw a chip together that I figured would get me out on the road with it where I could do some fine tuning.

I drove the car with impressive result for ~1 month maybe 150 miles and it felt snappy, extremely responsive etc. But I thought its gotta be just the increased power I am feeling. My WB02 was showing 14.7 at cruise as expected, since I was in closed loop. Due to the extreme compression I couldn't even think about WOT tuning. The WB was showing 11.4 AFR when the PE would kick in. I purposely added a bunch of fuel to ensure I wasn't lean.

Once I got the laptop to connect about 1.5 months after the startup and as said about 150-200 miles of cruising around, I was absolutely shocked. My Blms were 127-131 across the boards! OK I am not claiming to be some master tuner so don't get me wrong, perhaps I just got lucky. But that was better than I got my 350 with 10 chips. And you have to say to yourself, how good is good? I am more than pleased with those results.

So I go and pick up the race fuel from Corky this past week (Thursday) and get home at about 11PM. Friday rolls around and I have to pick up my other 2 kids, so no time allotted to try out the gas, Saturday we have to celebrate an early Easter since my brother is graduating med school this next weekend in St Loius. But before we go to the family dinner I siphin (sp?) out the 94 gas and fill the tank with 5 gal of race gas and take the car out on the road. Take one pass through the marked 1/4 I have and I left off about 3/4 of the way through because its just crazy too fast for the road. Take the car home and park it, and go and eat. Get home that night and burn a chip to get the AFR at WOT at about 12.8, before I go to bed for Sundays races. We leave at 8am to drive ~2 hrs to the track.

My first run ever with the car yeilds an 11.8@120 MPH w/ a 1.64-60', with a huge bog at the middle of 2nd gear. I knew right away it wasn't the tune but rather the crappy pickup problem these cars have, I returned to the pits pleased with the MPH and knew the ET would be low 11s. I put about 1gal more in and returned to the track to again have a smaller bog at the end of 1st. This time an 11.4@121 w/ 1.57 60'

Time to get more fuel. This run 11.3@114 the guy I was racig had a rag fly off his car and trip the beam for my MPH.

Upon returning with no bogs Corky says we should take my exhuast off to try it that way. we knew the exhaust was less than adequate. Off it came.

These next runs were 11.15@123 w/ 1.53 60' & 11.14@123.27 /w 1.53 60' times. Pretty decent for a car that only has 6-WOT passes under its belt. And vertually no tuning and running MAF.

This leads me to my point. I first don't think MAF hold your back one bit. I am yet to see a car with SD run substantually better after swiching over to SD from MAF. I can nearly bet that my car would not run nearly as good with SD. And if you can find one area to improve on this tune I would kiss your Azz in front of the entire grand stand at any track you prove it to me at.

I have yet to touch the MAF tables and never most likely will touch them or anything else in the tune. Here is another funny thing, perhaps my car is a freak, right...Well Corkvette1, is running the same exact times nearly, 11.2@121 with a mail order chip from way back when Famato was doing them. I read one of his chips a while back and it only had ~26* of total timing. Which is fine for a good set of heads etc. Well my chip I have has 38 total! 12 degrees difference! Still the cars run nearly the exact same times/MPH. Different cars right. So we took it one step further, we switched chip on corkys car to one that had a bunch more timing and he even advanced his timing up 5*on the base...Guess what...he ran nearly the exact same time as the time previous.

My thoughts are this....Nearly every engine with a carb runs 36 total timing, when you buy them from reputable shops they all advertise the same timing. Why? When you know they are trying to get an edge on the competition, if their engines make 15-20 more HP at a different timing, I'm sure they would have it advertised and set there. I really honestly don't think the total timing makes as big of a difference as some may make it out to be. If your getting knock yeah, but if your knock free, there is no way you are gonna pick up anyting even noticable with a change of a few degrees.

Second, the MAF. You can calculate the CFM requirments for different displacement engine and see that nearly very few N/A engines run over the 750 CFM cap on the MAF unit. Here are a few at 6500 RPM which is higher than nearly any of us should be running our engines to to make max power. And assuming 100% efficiency (don't we all wish).

406 CI Engine
Total airflow requirement:
763.6 cfm - 57.37 pounds of air.

Total air per cylinder:
95.45 cfm

383 CI Engine
Total airflow requirement:
720.34 cfm - 54.12 pounds of air.

Total air per cylinder:
90.04 cfm

350 CI Engine
Total airflow requirement:
658.28 cfm - 49.46 pounds of air.

Total air per cylinder:
82.28 cfm

I don't see a single engine here outflowing the MAF at a the realistic efficiency of ~85%. And I would bet in any case you might find that the heads or some other part of the setup is the bottleneck.

Also, you can tune the open loop of the MAF system just as easy as SD with the PE fuel tables. You need a WB to tune WOT effectively anyways, so I could care less about other parameters at WOT other than what the WB is telling me. If its lower than my desired AFR you add fuel, if its higher, you remove fuel. Why make it harder than that?

As for part throttle, who is gonna step up and say they would even notice a difference in my 127-131 BLM reading to 128 across the boards?

Maybe I am not getting something in the grand scheme of things, but I think some people make it seem like 1. you need SD to go fast, and 2 you need absolute perfect timing in every cell of the timing table.

This all may be passing right over my heads and I might not be getting all the ins and outs of this hobby, but I know i am getting the ETs.

funstick

i think your timming table needs help. but aside from that as long as the maf flow to injector flow propotion are right then yes your fuel trim will be nice and tidy,

GTA91

iTrader: (1)

Congrats, sounds like you have a runner. I can relate too though, I have a friend with a MAF Formula with a 400+ ci stroker with AFRs, a miniram, and a mystery cam along with a 700r4 and a 9" ford. He's running 30# SVO's I believe with a homemade monoblade TB and a stock MAF with a SLP CAI. It runs mid 11's on a STOCK 350 MAF tune. Whatcha think about that??? LOL I definately can believe your times after witnessing my friends car do similar things with a completely stock chip. He is thinking about going DFI later this year though. I'm curious what he will gain!

V8Astro Captain

iTrader: (1)

This is a little off topic, but are you planning to go to GateWay while you're in St.Louis? I'm in the 'burbs of St.Louis and I might be out at the track this weekend or next...

GTA91

iTrader: (1)

You're in the STL area?? I'm about 1hr away! I'd like to meet ya sometime!

ski_dwn_it

Guys,

I really don't think my timing that much effect on the car. Here is another reason why my thoughts have changed on this subject. Believe me I used to be a firm believer in each timing area needed to be perfect, and their was an optimum spark for each situation.

Corky who runs the same setup typically runs only 1* base timing. In a haste a few weeks ago at NJ raceway he made a mistake and set his base timing to 16*! He ran an 11.3 all day long off his 11.1 typical ET.....

Now that is a 15* shift in EVERY cell. i would have thought he would have been lucky to run a 12sec 1/4. Also he found out that during these same runs his back brakes that he just replaced were dragging something terrible, which surely was causing a loss in ET/MPH.

The KEY that we must differentiate here with is we are running race gas so detonation is not a real big issue, and we can get away with running that much timing. ALso our knock sensors are inactive.

I am thoughly amazed that our ETs do not change from the timing.

PS: Also not from St Loius area, my brother is graduating from med school and we are attending his grad and helping him move back home. No time for tracks presence We are here in PA.

RBob

iTrader: (1)

ski_dwn_it, congrat's on the times. You have one quick Vette there (and the A/C still works?!). Your comments about the timing are in step with what another member here has been saying: less can be better. Hopefully others will start to see the light.

For the sake of knowledge could you elaborate a little on how you set your fueling up? What I mean is that once the MAF max's out (the 255gms/sec) how did you keep the AFR in line with what you were looking for? I am always interested in tuning.

Thanks,

RBob.

ski_dwn_it

RBob,

I have read many of your posts along the way and know you know your stuff, but I will elaborate on my thoughts while tuning. As said before, these times were run on only the second chip for this setup. And corkyvette has the exact setup running a mail order chip with exact same times nearly. For the record we are NOT running the same tune. His is an 85 160 ECM and mine an 85 165 ECM. His tuned by famato, mine by myself.

I what I normally do to get the part throttle on is play with the injector constants. With both the 350 and the 406 I have been able to get VERY close to 128 with very little effort. Adjusting nothing more than injector constants. Perhaps the fact I have 24# injectors instead of some monster oversized units that are hard to control and require fine tuning at each individualized RPM is the key. My AFR hold steady at ~12.8 through the entire run, so obviously they are providing enough fuel. If they weren't I would see leaning conditions that could not be corrected with PE AFR vs RPM talbes.

Again I am not make myself out to be a know it all, just pointing out the obvious, Here is one. I have a 406 that is cranking out ~450 RWHP from the MPH I am running in a 3400 lb car. Corky and I built our car's engines exactly the same. And Sunday they ran nearly identical with two VERY different tunes. Corky is only running 38 psi on the fuel rail! Mine is up around 45! Both have the same injectors. He ran 121 MPH and mine 123.

As far as tuning WOT and say we are maxing out the maf systems 255g/sec, that only mattes if you are under closed loop, then the computer looses resolution- I am yet to do that on the street without envoking PE, where then you can tune AFR vs RPM. Unless your running a SC or Turbo I doubt very much you will be able to do that either, under cruise conditions, and are you gonna be able to tell a difference anyways? On the street now this thing can scare the bajisus out of you if not careful.

I truely believe that people confuse the 255g/sec with CFM. They are totally different! Again my 406 under 100% effieciency is only able to pull 763 CFM in at 6500 RPM. I don't have my calculator here in front of my, and I'm not sure how many g/sec are in 763 CFM. But clearly if the MAF can flow 750 CFM, then my engine is NOT being held back by running MAF. Nor is any lesser engine, especially not one running slower than 11.1@123. I just don't understand how people can not get this. It was proven once with Corkvette's MAF vette, now again with mine. What you see in my sig, is exactly what we are running, we aren't playing games and I would not want to mislead anyone.

So I guess what I want to know is how would SD make this setup go quicker? And furthermore, how does it make a 305 or 350 that is running 13s go quicker than a MAF system?

But these are the things you have to discredit.
1. My AFR is right at 12.8 +/- .1 through my entire RPM range. so obviously I have control over my fuel in WOT conditions. I'm sure I could make it 11.4 across the boards or even 13.5 if I so desired to burn though my rings.

2. My part throttle tune is 127-131 BLM adjusting nothing more than injector constants. I will admit my idle is around 140, but that is where my 350 idles best at and with no cats, I prefer to keep it there, since it cuts back on the smell of gas.

3. My engine is running well under the 763 CFM requirement @100% effiecency, and that puts me under the 750 CFM constaint.

4. Lastly I am knocking on 10s door and most likely will get it with a little better air, the DA was ~1700 Sunday. Not bad, but not optimum either.

Just for the record this in being done in a FULL trim car with power seats, windows, mirrors, everything it came from the factory with in the way of interior/exterior plus some. Not to forget the AC still 100% functional. 87_TA can verify this. Obviously I am running different wheels.

But I really would like to hear from you guys that claim you have to have SD? If you can convince me enough perhaps I will switch, but don't do it for me I think you owe it to all the people that switched over from MAF and most likely are having more problems than they realize.

Please shoot holes in my theory here. I can take the abuse

Grim Reaper

Why are you trying or insisting on restarting this stupid MAF vs SD debate? It's been argued to death and frankly, anyone who restarts it should be banned. PERIOD.

Now that I've said my part, I've always said that MAF systems can be tuned for WOT and explained a couple of years ago how you can use PE to add extra fuel once you max the MAF at 255. I've done it on a buddy's car running a 383, Miniram, AFR 195 Competion Ported with 2.05 intakes yada, yada, yada.

Oh, he too had a Fomato eprom initially. Turned out to be nothing more than a variation of the ARAP bin - imagine that?

I am quite concerned about your injector size though - even at 100% efficiecy, the most HP 24#s can handle is just under 400HP. My buddy is running 30# and we are in the low 90% DC range - too high. Also, check your fuel pump and the pressure in WOT. You might be surprised.

But dump the stupid MAF vs SD arguement and the flame bait. I really am sick of seeing it. Keep it to facts and tuning.

funstick

there are some things to consider.

Low compresion engines like mroe timming to make up for the lack of cylinder pressure.

a high compression engine will enjoy the same power with less timming and with race gas detonation isnt a factor. however you could proboaly pick up a few tenths by reworking that spark curve for more cylinder pressure as the crank passes TDC.

as for your thoughts. they are intrestting observations and i think ive been fighting the MAF battle the same way you have. only difference is i dont own a MAF car. i play with them alot but that not up for discussion here.

there are alot of advanatage to running maf

better fuel trim. why mess with a 3d table ? im not saying i dislike S/D i run it on my honda. Just if you dont need it why bother ?

the timming is interesting have you looked to see what your runnign as the maf reaches 255 grs/sec ? id bet there more spark retard there than you think.



20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0
20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0
20.0 20.0 29.9 29.9 29.9 29.9 27.1 26.0 23.9 20.0 20.0 20.0
20.0 29.9 40.1 38.0 35.9 34.1 34.1 28.1 26.0 23.9 20.0 20.0
29.9 34.8 40.1 40.1 40.1 38.0 35.9 32.0 29.9 26.0 22.1 20.0
41.1 41.1 41.1 41.1 40.1 39.0 38.0 35.2 34.1 28.1 22.9 21.1
43.9 43.9 43.9 43.9 41.8 41.1 38.0 34.1 32.0 28.8 25.0 23.9
46.1 46.1 46.1 46.1 46.1 43.9 41.1 41.1 39.0 28.8 25.0 23.9
48.2 48.2 48.2 47.1 46.1 45.0 43.9 41.1 38.0 30.9 28.1 26.0
48.2 48.2 48.2 47.1 47.1 46.1 43.9 41.8 36.9 30.9 28.1 27.1
48.2 48.2 48.2 47.1 47.1 46.1 43.9 41.1 35.9 30.9 27.1 25.0
48.2 48.2 48.2 47.1 47.1 43.9 43.9 38.0 29.9 27.1 25.0 22.9
47.1 47.1 47.1 46.1 41.8 41.1 38.0 30.9 26.0 22.9 22.9 22.9
47.1 47.1 47.1 45.0 40.1 39.0 38.0 30.9 26.0 23.9 23.9 23.9
47.1 47.1 47.1 45.0 40.1 39.0 38.0 30.9 27.1 27.1 27.1 27.1
47.1 47.1 47.1 45.0 40.1 39.0 38.0 33.0 33.0 33.0 33.0 30.9
47.1 47.1 47.1 45.0 40.1 39.0 38.0 35.2 35.2 35.2 35.2 35.2

the lv8 208 column could use some work id be willing to bet that with the optimized cylinder pressure that youd pick up some et for sure.

the other thing to think about is the maf itself. how is it behaving and repsonding to air flow ? are you maxing it out ? hard to say. unless youve hit 5.10 volts i doubt youve really maxed it. i think people often mistake the LV8 for the maf reading. its pretty easy to hit and lv8 of 255 but watch the maf voltage. redoing the last maf table will also help. BSing the injector constant will allow you to do that. the ecm is only spitting out what the MAF tables tell it.

87400tpi

Well the major ,major thing with tuning the s/a, it is not the total amount but where in the rpm range it comes in.Your are right,anyone can max the timing to 36 or whatever and see no gains.That is because most efi engines only need a certain amount of total to get max power.After that it's overkill,then your pistons are prime candidates for meltdown.I suggest taking the total timing up bits at a time.When you see no improvements (in performance) at that point you have your total.That's really shorthand for getting total but we know how it's done(36 total seem a bit much for efi).

You have overlooked the rate of the total s/a.I have heard of race only setups gaining 1/2 sec or more just by bringing in the total s/a in by 2800-3200rpm.That means have your total in sooner in the rpm range.The stock bin s/a tables is sick.They always need some attention.But why don't you put your total s/a at 31d and bring it in @3600 rpm.Make sure to have 31d from 3600 rpm to redline.Burn it into a chip,take it to the track.Compare your chip to the method I described.Be carefull with this,it's not for the faint of heart.

Now I'll address the sd issue.I have felt an increase in throttle response and total power by switching to SD.Not to mention now it sound like I have a turbo.I have a k&n on the tb and it is loud.I can hear the air getting sucked into the engine.Now I see why GM makes "silencer boxes" for the air intake assembly.But I can admit running a filter on my throttle body has the least restrictions.It's like having no filter,almost.There is alot more tunability with th 730,more tables .The fact of the matter is the L98 gained 5hp when GM switched to SD.There is an increase in power.

Here is some downsides to SD ....Maf calculates the VE curve by itself.So when you switch cams or intakes maf requires little changes.Maf will calculate your ve curve automatically vs map that will need some manual reshaping/tweaking of the VE.Maf is alot less work,in terms of tuning.But you are dead right that maf can flow enough.I've seen too many cars running 11s w/ maf.That shatters some "mythes" of the maf system.Bot to tell you the truth I'm not sure if i like sd or maf better.I started with the 870?(85 ecm) then repinned for the 165.I've have SD for about 8 months now.

p.s. arnt ugonna make someone mad with that "final thought" ,cough,cough

ski_dwn_it

Glen91,

I am not trying to start a flame fest. I think we can all debate here on the forum and be civil about it. Why should someone get banned for disagreeing or asking a valid question that runs through all our minds? And its suggested to all the new comers to switch over to SD at the even breath they mention MAF?

The board here you have to admit is VERY pro SD, which is fine by me. Their is no doubt that SD can be tuned to run just as well as MAF, but it requires the tuner to be much more dedicated and plan on spending much more time than the MAF system would require. But actually you hear exactly the opposite. If I was a newcomer and did not know better, I would think the MAF system was a nightmare, inadequate to run even close to the 12s. Yet the opposite is very true. The MAF is a sinch in my book. I only think its fair to mention this aspect to people considering the swap.

I guess I am just speaking from the other side of the fence and offering my .02 on the subject. Its s DIY board so asking questions and picking others brains is the way knowledge is shared. Debating back and forth over a subject like this allows others to sift through the opinions and find the truth, and frankly I would rather read stuff like that and seek out the knowledge.

I think the subject is VERY valid to the boards and could bring about some interesting opinions, perhaps I am overlooking. I am trying to be my car into the 10s consistantly, and if someone can point out a fact that I believe in, I would switch over in a minute. But when I search a little deeper into the subject the items you normally hear getting the fingers pointed at are not all that concrete, ie 255 g/sec.

And although the subject of tuning beyond 255 g/sec has been discussed before, there are MANY MANY people under the impression that there is NO WAY you can effectively tune the WOT runs of a MAF system exceeding those values.

400, The selection of my title had no implication at all towards one person. Sorry to offend anyone if it was implied. I respect everyones opinion here and think there are some VERY bright people that I'm sure I learned a great deal from over the past two years.

RBob

iTrader: (1)

No trying to shoot holes in your theory as I am going to keep this an amiable discussion. (for all: no flames wars please).

ski_dwn_it, my current knowledge w/MAF is only by what the code does and others experience with it. I must admit I am quite surprised with the times you are turning, nice. So my curiosity has been piqued to say the least.

Just for info: SCFM = gms/sec * 1.787

SCFM being standard(sealevel, 68deg f, 36 % humidity).

750 CFM = 420 gms/sec

By what you have found it sounds as though you have a decent combination of fueling parts (MAF, inj, plenum, . . .) that it works out well. What I am trying to say is that the pieces for the combo fits together. No one piece is overbearing. You have also stated exactly why car makers like MAF: easy to tune which makes it cheaper for them.

I like this statement:

>>On the street now this thing can scare the bajisus out of you if not careful.

I'll bet!

The only recommendation that I would have before a switch to SD would be to place a vacuum gauge on the manifold (or a MAP sensor & datalog it) while you make a pass. This will show the resistance of the intake tract. I tell folks the same when they ask if they need a bigger TB.

>>As far as tuning WOT and say we are maxing out the maf systems 255g/sec, that only matters if you are under closed loop, then the computer looses resolution.

I don't believe this to be true. The ECM still uses the MAF value when in PE mode. PE mode changes the desired AFR by a percentage. The BPW is calculated from both gms/sec and the AFR (among other terms).

However, being able to change the PE AFR % you are able to dial in the proper BPW for the desired AFR. As I mentioned above it also sounds like you have the correct combo of parts that even the part throttle transition to PE works out. (These are the areas that con-MAF people talk about).

RBob.

P.S. Please let us know when the 10.xx sec slip happens.

Grumpy

There is little to actually debate, it's a matter of posting data.
If you go back 4-5 years ago and read everything to date, you'd realise that there is alot of time, that went into sorting thru the MAF, vs SD debate. There have been guys that have run both on the same engine and documented the results.

Basing one's opinions on the results from one car from first hand knowledge will often lead to less then accurate information.

And drivibility is a big deal with some folks (ie me). While you might be pleased as punch with yours, to some other folks, it might just leave something to be desired.

I'm happy that your happy, don't get me wrong. But, the statements you've made aren't universally true, nor do they reflect alot of actual research into what is really going on in the ecm.

ski_dwn_it

Grumpy I actually have gone back and seen some of the data you speak of. However none of it concludes to me that the SD is any better. I seen where guys will run say a 13.1 with MAF and a 13.08 with SD?? I see no difference.

As far as the driveability of the car its as good as the car when it was new. Just alot more power. Put it this way, right now when I just hit the gas about 1/8 more than it is at a cruise type scenerio, with the converter locked, it instantly spins the tires. If the slicks are on the car when you do the same, if they don't squack, it sounds like it rips the underside of the car apart it hits so hard.

A big key here is having a WB on board to be able to sort through any tune. Believe me I played and played with my 350 to get it tuned, but most of the tuning was never realized anywhere, at the track or the street. Don't get me wrong there are improvements, but you yourself have said, when good, good enough.

You say that some of the things I pointed out aren't universally relevant, in what way?

The basics of it are if you are able to achieve a desired AFR, and ignite that charge at a desired advance you will get the max power. I have also looked at many dyno graphs of AFR and don't see any that make major shifts like one second at 11.8 next rpm 12.7, next rpm 11.2 etc. But rather they are gradual shifts that can easily be accounted for.

How many chips have you done for your car? With experience like yours, I'm sure you have it nailed down within 3-5 chips, can you really tell me that there are any huge improvements beyond those? I have a feeling that the other 90 are just experimenting seeing how things interact. Again don't get me wrong, that is all fine and dandy.

You yourself pointed out to me that the new cars run both systems, MAF then SD as a backup. OK. Why if SD can give such better control, which is what the emmision people are asking for, do they have SD as the backup system, and not the primary?

My guess would be that they would have 10X the people complaining about hesitation, poor performance, etc. Now in the hands of someone like yourself with experience, the system is able to be tweaked and perform most likely flawless. Sd is a system that is great under ideal conditions that can be tuned to perform, but taken to a different elevation, it less than adaptable. I tune here at ~2300 Ft, sometimes I take my car to Jersey where its below sea level, or on the button. I think you would have trouble doing that with a SD car.

Here is what my plans are to do in the near future. Suggested to my by Ralph at the corvetteforum. Another 350 SR engine running the 160ecm at 11.7 sec 1/4.

I am going to fix a vacuum guage to my plenum and see what kind of vacuum if any I am pulling at WOT. If there is a vaccum then I have a restriction, from there up to the front of the car. Could it be the TB or the MAF or the intake itself?

Grim Reaper

Actually, elevation is where SD has a distinct advantage. The Spark Tables can be distinctly tuned for various elevations and keep the optimum tune. You don't have this ability with MAF.

I suggest that you work more with SD so you learn the advantages and disadvantages of MAF and SD, rather than limit yourself to just one system.

ski_dwn_it

How does the altitude effect your fuel curves?

Grim Reaper

Simple, the VE Table. Lower elevation, higher Kpa - more fuel. Higher elevation, lower Kpa - less fuel.

You set the VE Table by a combination of driving around and recording BLM/INTs for tuning and, if you are lucky enough, a WB O2 sensor. Nice part, if I want to "fine tune" a specific elevation you can without affecting anything else.

Conversely, you can do a "global" correction via PE if you feel the VE Table is correct, but you still need more (or less fuel), for a given RPM.

Again, you really need to work with both to fully understand them.

Grim Reaper

Sometimes a picture is worth a thousand words. Here is a graphical representation of my VE Table. Part of the table is below, but not totally displayed when you show both.

TRAXION

MAF cars go fast. SD cars go fast. I've seen MAF thirdgens in the 10's. I've seen SD thirdgens in the 10's. It's all good.

Is SD better than MAF. Yes. There is absolutely no doubt. SD has no intake tract restriction, it's easier to duct, it has better spark routines, it has better fueling routines, etc. Yes, SD is better than MAF. Now - with that said - notice that I did NOT say that MAF cars are slow or bad or inferior. On the contrary - I've seen MAF cars in the 10's. It's all relative Both can run fast. But, there is no disputing the technical advantage that SD has over MAF with regard to the 165 vs 730 debate. I am NOT talking down MAF by any means. MAF cars are easy to tune because you basically ignore part throttle fueling. You just force power enrichment early and tune off the PE tables. Very easy. Doesn't take a genius to tune MAF. Speed Density takes a lot more time to nail down all the curves ... definitely takes more tuning time to get the payoff. However, if you are REALLY concerned about part throttle tuning than SD gives you the means to have a radical car that runs awesome everywhere under WOT. As an example - take your car up a nice long steep hill WITHOUT power enrichment enabled. Ouch. Yea, I know, how often are we driving up steep hills? But, you see my point.

Your car sounds like a total beast! Very sweet and big congrats!

Tim

87_TA

Well I would like to touch on this subject a little and dont mind doing it again..
Its nice to see somebody go so fast with MAF ,wtg ski- and yes I seen it nice run!!! even got a pic.
Well as far as the spark tables go in yours and corkys case ski ,you are both running very effecient combos that make the most of their burn and need less timing to do so.
On a not soo effecient combo it will make the most of timing advance - much like you will see a larger gain using nitrous on a stock engine as opposed to one thats already effecient.
As far as making you do the switch,well it would be hard to convince you but here is how I see it..
Both systems can make you have the same pulse width at wot and same timing, so therefore the power is going to be there for both MAF and SD but one can do so with little more adjustability
at wot. but not a big deal..
Now as far as the restriction of the MAF you have proven you can run very,very fast with it but here is my view.
Try breathing with a straw in your mouth you can live and live well but you would be alot more athletic without it.
Your MAF may not be killing you but I would bet its worth 15HP to get rid of it. HMMM 10 sec et..
Now also on your car its les of a restriction because your setup is straight through desight to the TB to nose of car which lessens the reastricion for you and hurts the Transams and such.
Make a adapter harness to run SD with out messing up your harness and give it a shot. you can probable do it under 80 dollars and some time.
Great time!!! keep it up.

ski_dwn_it

trax, how can you say its a restiction from what I posted on CFM requirements?

Also everyone is dodging the obvious items that need to be disproved in my one post.

You say you don't have to be a genius to tune MAF. That actually is the exact opposite that everyone says is the main reason to switch over to SD. Because SD is soo much easier and clearer.

Lastly, you mention long hill drives. Clearly you didn't realize where I live. You can't drive a mile without climbing a MAJOR hill or decending down another. Coming from my parents I go from ~800ft to 2500 ft over about 4 miles of road. That is actually where I took my logs from when I got the 127-131 blms. I really did not follow what you were trying to say. The driveability of our cars is really quite nice, I know you would disagree without being around it, but I would not hesitate to drive it to the nearest track which is 2.5 hrs away. The absolute only reason I don't is the slicks. I see testing of cars where they are required to drive X miles then race, they must pass the drive before being permitted to race. I would volunteer in a second for that. My car at the track never exceeds 185*.

If anyone replies in the next several days, I am not dodging any replies, I am gonna be leaving for the weekend. Have a safe holiday, and the discussion is fun.

:cheers:

ski_dwn_it

87_TA,

Thanks for the pic, I got it last night.

It sure was fun Sunday. I will have to look into the harness you describe, it would interesting to see what a difference it would make on a larger cube engine. The comparisons I saw were that of smaller slower low 13s cars. Not sure if that is a good arena to be comparing in. Its gotta be something that is pushing the limits of the system, and we very well may be. Who knows maybe we could be running 10 all day with another system that is why I asked the questions I did.

Secondly, maybe I did not make my first statement of the post real clear, the entire reasoning behind the post was to bring to light the fact that I don't think cars are as sensitive to tune as I once thought. For instance, we are both running the same heads/setup with the same compression. Corky is running 26-28* of timing. I am running 36*. Kinda wierd that we would not see a huge difference in ET/MPH.

Also corky have made a huge swing in timing on his car alone, from the past week of +15* on the base to ~1* base this week, yet his car runs the same ETs/MPH for the two timing. That is a significant shift. SOmething I would have suspected would have caused a huge drop in ET.

Weird stuff.

Grumpy

I'll be brief,
Your now saying you blind to differences, OK. We could stop there.

Other then some STSs in general I consider GM calibrations at best tolerable.

MAFs are designed to work best with a fixed AFR other then when in PE. Look at the tables closely.

Several dozen for the MAF not including start up routines, but hundreds on the ecm bench seeing how things really work.

Guess you missed the post about why they went MAF with the OBDII systems.
On a cold start, just as you leave crank and enter run, the MAP system have a period of time where they are running at 400-600 rpm with MAPs in the 100-70 K/Pa area of the table for VE. With the wild oscillations of the MAP, they have to run that area of the table rich. The larger the plenum the worse the case.
On the other hand, with a MAF system at that same condition it's reading air flow, so can be spot on AFR wise.
Cold Start Emissions are absolutely critical, and are something that can't be traded off with something else in some other area.
The EPA and CAFE numbers are the only motivations for MAFs.
If Motec, Bosch, F.A.S.T., Accel, and Holley could go faster with a MAF, don't you think they'd be using them?. Never mind the rarifided realm of F1.

When I have said good is good enough?.
Good is only good enough when CORRECT.
Count how many times you've read CORRECT in Caps in my postings.

We'll ignore the physics of the situation with what even the minor restriction of a MAF does to rod loads at high RPM..

;Map: 20 25 30 35 40 45 50 55 60 65 70 80 90 100 ; RPM:

FCB 108, 108, 108, 108, 108, 114, 115, 116, 118, 118, 118, 110, 100, 100 ; 400
FCB 108, 108, 108, 108, 108, 113, 114, 115, 118, 118, 118, 118, 118, 118 ; 600
FCB 59, 102, 102, 108, 108, 113, 114, 116, 118, 118, 118, 118, 118, 118 ; 800
FCB 25, 25, 51, 108, 110, 116, 117, 119, 135, 140, 140, 140, 140, 140 ; 1000
FCB 25, 25, 40, 100, 118, 124, 127, 135, 145, 151, 154, 160, 165, 175 ; 1200
FCB 0, 0, 40, 100, 123, 133, 135, 141, 145, 151, 161, 180, 185, 185 ; 1400
FCB 0, 0, 40, 115, 135, 135, 138, 143, 148, 157, 166, 180, 185, 190 ; 1600
FCB 0, 0, 40, 120, 138, 138, 141, 145, 148, 165, 175, 185, 190, 195 ; 1800
FCB 0, 0, 40, 133, 141, 143, 145, 148, 148, 167, 177, 187, 192, 195 ; 2000
FCB 0, 0, 40, 133, 143, 147, 148, 148, 149, 170, 180, 190, 195, 195 ; 2200
FCB 0, 0, 40, 133, 144, 147, 148, 150, 152, 173, 183, 193, 195, 195 ; 2400
FCB 0, 0, 40, 133, 145, 147, 150, 150, 152, 175, 185, 195, 195, 195 ; 2800
FCB 0, 0, 40, 133, 145, 148, 150, 150, 153, 180, 185, 195, 195, 195 ; 3200
FCB 0, 0, 40, 134, 147, 150, 152, 150, 154, 180, 185, 195, 195, 195 ; 3600
FCB 0, 0, 40, 134, 147, 150, 152, 153, 156, 174, 185, 195, 195, 195 ; 4000
FCB 51, 51, 51, 136, 147, 152, 154, 154, 156, 174, 185, 195, 195, 195 ; 4400
FCB 51, 51, 51, 138, 147, 152, 154, 159, 159, 174, 195, 195, 195, 195 ; 4800

Tell me you honestly think you can approach this with a MAF. That a 14x17 table. 238 points vs 54. And this is just the 1 bar area, I have a whole nother bunch of corrections for over 1 bar.
You just can't do that with a MAF.
Notice the over run conditions, while often ignored, on some cars they can made a day and night difference.

Not to mention what can be done with the spark.

Combine the two and you can truely get the AFR and timing CORRECT across the board.

Altitude ain't a concern for a MAP car when done right.
Trouble is most folks get it backwards with BARO corrections.
Using a carb type correct for venturis ain't what you need to do with EFI.

TRAXION

Oh - I think you misunderstood. I never said anything about your car. I just made a general statement. It is a restriction in certain circumstances. It is not a restriction in other circumstances. I do believe that the MAF is not a restriction with regard to most setups that guys here will be running ... as long as they understand that you have to fully modify a MAF to get the 750cfm (it only flows ~550cfm in stock form). Furthermore, the only other thing that is being ignored with regard to the calculations above is initial air demands. When you first crack the throttle and go from fully closed to fully open the air demands are greater than the static air demands from your calculations ... at least that's what Vizard explains.

Specifically which points (so I know the ones that you are thinking about)?

I'm talking about plug-n-play here. I've never downtalked MAF systems to which you are mentioning. Speed Density is easier to tune with regard to logic. You have this MAP and this RPM and it corresponds to once point on the VE Table. That is easy. But, then you have to realize that you have over 250 cells in those VE tables to tune! That is a lot of work if you want to get it right. Most MAF guys can leave most of the MAF Tables as they are and just run. The other MAF guys can usually get away with tuning only the first MAF table which is only 9 points. MAF guys know that they will hit the 255 limit very early. Thus, forcing PE early and tuning from the PE tables makes the tuning process even easier. SD guys can tune their entire part throttle curve if they wanted because there is no limit. There are +'s and -'s to both systems. They both can go fast. Also - for clarification - when I say genius I am not talking about how smart someone is. I am talking about what needs to be done to get the fueling close.

I am guessing that your setup has gobs of torque at lower RPMs and high LV8 to climb hills without hitting the 255 limit of the ECM. That's the only explanation I can come up with. Were you accelerating up the hills?

I just want to make it VERY clear that I am in absolutely no way saying that MAF is bad and that people should swap over to SD because MAF is bad and cannot perform. On the contrary - as I've illustrated many many many times - I personally know that both MAF and SD can go fast and that is what we are all about. What I am saying is that if you compare point for point for point for point then SD will win. I am not talking about speed and 1/4 mile time! The code in the binary for the $8D is better. GM has better routines in the SD code. That is a fact. Also, I have to admit that I really like the fact that SD systems don't have an expensive MAF or MAF burnoff relay to replace when they go bad. I also really like the logic of tuning VE curves and the extra space left over in the 256k PROM as compared to the 128k PROM (not that it matters). With that said - I dislike the amount of time that you have to put into a SD calibration to get it close when MAF systems can get there so much quicker! But, with tools like Joe Georger's VEMaster it is now A LOT easier to tune those VE curves.

I honestly think that everyone should drop this whole SD vs MAF thing. Both systems can go fast. I've said that too many times to mention but no matter how much I say it this conversation continually comes back to the board and people just don't listen. Everyone should accept that they both can go fast and that they are both viable solutions. It seems to always be the hardcore proponents of both MAF and SD that bring this conversation back to light.

.... and, again I want to say that your car is totally BAD and it's really nice to have a MAF guy running that quick. Maybe your boot is the final kick on this dead horse. Because now you've illustrated what I have already mentioned many times - they BOTH can go fast.

Tim

TRAXION

BTW, what size throttle body are you running? Is it the stock 48mm unit?

Also - I do have to admit that I am totally surprised that you are running 123mph with the 24 SVOs. Your Duty Cycle has to be 100% unless you are running really high pressures. I had 24# SVOs and I was at 93% DC with my 350.

Tim

Grim Reaper

My feelings exactly - it's been beaten to death and usually argued by people that have only worked with just one of the systems. I still say you need to work with both to understand the advantages and disadvantages of each.

In fact, we've gotten all the parts (ECM, sensors) to convert my buddy's 383 car from MAF to SD. But I do not recommended converting immediately - I recommend waiting for the MAF unit to die because it is cheaper to convert to SD than to buy a new MAF.

Grim Reaper

This is what I want to discuss also. My buddy's 383 is running 90+% on his 30#SVOs and looking at 36#s.

Ski, what is your pulse width at 6,000 rpm?

87400tpi

[/quote]MAF cars are easy to tune because you basically ignore part throttle fueling. You just force power enrichment early and tune off the PE tables.[/quote]
That's not how I tuned my maf system.I could set my p.e. /throttle% table to 90 to keep from engaging pe.Then tune to 128s everywhere.I can tune a maf system to perfection.But I never ignored part throttle tuning.I have honed my own unique methods though.Thats besides the point though.It's nice to see the moderators speaking positive about maf.I feel like it's a great system.There is alot more than forcing pe.I have logged many many hours learning maf.

But,I will say ski_down_it you might just break into high tens with little more than a switch to SD.I love maf but I can tell you my 406 loves to breathe now w/o that air intake tract.It's not just the maf it's the whole inake tract that restricts air to the engine.The way I see it is there is a formula for the restricton(more or less).The faster you run,the greater restriction of any air cleaner/air intake.SD will allow you to run faster IF you take the time to FINE tune it.There is no denying that the basic spark/fuel tables in SD is more precise.I kind of view maf as a good system to learn on(not to mention auto ve calcs).Then when you get your legs move to the advanced ecm.It's kind of like my little brothers.I made them start on the original 8 bin nintendo to learn how to play games. then they stepped up to the 32bit? super nes,then the n64.So the 730 is not the holy grail of engine management.The new gm pcms are light years ahead of this 80 tech.That proves there is no debate.I think what ski_down_it is trying to say is there is a lack of help/talk of tuning maf.He's here to say YES maf can run damn fast.I have tried in the past to share my methods but was silenced.Imagine when some guy just bought the stuff to burn and tune his maf car.He makes post for help but gets a lack of help and suggestions to go to SD.He might be discouraged,thats not what any of us want.That seems to be the heart of the maf debate.Let's work to change that.There seems to be alot of maf people in need out there.Keep in mind there is WAY more maf than sd third genners,maf 85-90 SD91-92.This will become diy-proms core subscribers IF the movement gets elevated.They cant all switch to sd,most will be lucky/happy to tune their maf system.There will be hordes of maf tuners,I can see it now.


One more thing,nobody addressed my response about the s/a rate.All this talk of maf nobody cares about lowly spark advance.

Grumpy

One more thing,nobody addressed my response about the s/a rate.All this talk of maf nobody cares about lowly spark advance. [/QUOTE]

I don't see a guestion in there.
If one looks at a number of calibrations, the majority of the advance is in by peak torque, then some dither a few extra degrees in by peak HP.

He'll probably slow down going to MAP.
Judging from what's going on, he might be short on injector, and the restriction of the MAF is what is allowing his car to run so well.

You didn't mention how to get the DFCO on a MAF to duplicate my VE tables. Or how in overrun to get them to run rich.

Or comment that all the racing ecms forgo the MAF setup.

Can you go fast with a MAF?, sure, there are 10 sec GNs doing it all the time, and a few 9 sec ones.

And other then the what is it 89s, you'll have to chug along with the sloow ALDL, and that is not a good thing anyway you slice it.

87400tpi

????The s/a tables gm created migh work for you but I found better gas milage,better drivability,more power with tuning the s/a pe & non-pe.I have conversed many times with glenn about the importance of s/a tuning.I still dont get you gespone,your saying the total s/a is in by peak torque??for what??Gm does not have a calibration for a bad boy 406ci730ecm.My peak torque is nowhere near the stock cal.You must have misread what I said b/c there was no "guestion".So your saying there is no need to adjust the advance rate????plz explain

Grumpy

Geesh,
Spark advance is critical.

For any given engine you will want most of your spark timing in by peak torque. If a 502 that might be at 2,600 RPM, or a 302 at 3,800 RPM. When ever it occurs in your combination.

Are you trying to discuss something, or just relaying what you've found.

For a street engine you want to run the least amount of timing consistant with max performance. Not the greatest amount. There is a serious difference between the two. WAY too often guys get caught up in the more the better timing situation, and then bump up the fuel. That can add up to masking the knock sensor, and then knock the corners off of the pistons.

Might grab a copy of Tuning Tips from DIY-EFI.org.

Grumpy

Remember my comments the other day about MAF/MAPs and on start up how it takes some time for the engine to pump the manifold down into actually be in a vacuum?. This is from my car, with a larger then stock plenum.

Here's a data log showing that.
Takes well over .5 sec., and when dialing with the EPA that matters.

Run Mph Rpm KPa Tps CtsF MatF
00 0 0 91 0 63 63
00 0 0 90 0 63 63
00 0 0 87 0 63 63
00 0 0 86 0 63 63
00 0 0 84 0 63 63
00 0 0 76 0 63 63
00 0 750 73 0 63 63
Run Mph Rpm KPa Tps CtsF MatF
01 0 825 78 0 63 62
01 0 850 78 0 63 62
01 0 925 77 0 63 62
01 0 950 73 0 63 62
01 0 975 71 0 63 62
01 0 1025 67 0 63 62
01 0 1025 61 0 63 62
01 0 1075 57 0 63 62
01 0 1050 54 0 63 62
01 0 1100 53 0 63 62
01 0 1075 53 0 63 62
01 0 1075 52 0 63 62
01 0 1100 52 0 63 62

And the WB blips very rich intially.
Here in black and white is why the latter cars for the time being are primarily MAF based. With a MAF there is no pumping down of the manifold, it's just reading the actual airflow.

87400tpi

ok??????been tuning for years


still no response to tuning the ADVANCE RATE......

87400tpi

ok then stock bin s/a good enough

hmm my engine is far from stock....

That is a very rude statement,aparently you did,nt read that I've been tuning efi for years.I'm just trying to share my experiences,that is all.

Grumpy

No that's not what I said or implied. I've tired twice now to explain it to you, but you seem to not want to grasp what I've said. And rather then ask a guestion, you make an erroneous statement.

So.

You wanted comments then cop some sort of attitude when someone responds.
It would seem only obvious that timing is engine specific.

Craig Moates

Good fken Lord,

How is it that MAF vs MAP can excite any level of response at all? It's just a different approach to the same end...

Give it up guys, one way can be just as good as the other given certain assumptions.

I think most of us realize and understand the difference between the two, let's just enjoy the inherent benefit of either/or...

Ah well, enough traffic cop role. I'm gonna try less timing and see what it does to me on a 236/242 .560/.570 10.5:1 383. Maybe I can get away with 89 octane on iron heads. Gotta see about knock sensing with that solid roller setup...

Actually just arm-wrestling oil spatter in the PCV vent right now. Easy enough. All else is good looks like. Gonna break this 700R4 I swear.

-Craig

ski_dwn_it

Grumpy,

I have a few comments that I would like to clear up about your assessment of my setup, and others have alluded to.

First how can you say I am short on injector and the MAF is resticting the flow of air to allow me to get away with the smaller injectors? When:

1. The car holds a steady 12.8 AFR through the entire 1/4, monitored on the WB02.

2. My pressure is around 45psi, and Corky running the same exact setup, set his PSI that say at 38 psi and ripped off a 11.2@121. There are two totally different PSI readings, and in either case, corky making himself more suseptable because of the lower psi, if the injectors were running short on fuel the car/s would have fallen flat on their faces.

You guys are very smart, but sometimes I fail to see the logic behind your comments. I mean either you have gas or you don't, no gas, no go or should I say no gas no desired AFR. Prior to burning the other chip I was running grossly rich. So obviously there is much more injector left.

I wish to *** my scanner would not have crapped out on my for what ever reason or I would post the MAF, IPW, etc on here for you all to see.

I mean its crazy, I have been in cars that run short on fuel and at those speeds/tq they physically throw you forward. This thing pulls like there is no tomorrow.

And again I will say the part throttle tune is 127-131 across the boards. Abosolutely not a hair of hesitation anywhere. And I really DO NOT believe that I am running short on ET from the MAF system.

PLease explain to me how you have achieve & maintain a given AFR if you are short on injector, all while running near 10sec ETs??? Are you telling me I have a mid 10s car, because that is what it would take to do what I think your saying.

funstick

im not diving into the maf vs sd argument. with that said here my 2cents.

BOTH systems are capable of controling spark and fuel. Maf has advanatges and so does sd

what hasent been discused so far is the MAF tables themselves. the $6 $32b $32 code in the #6 table is hiding resolution. over 1/2 the table is filled with 255 grs/sec

my thought on this is that GM imposed a flow limitation and based there Fueling calcs from that.

so if you lower the injector constant and rescale the maf tables accordingly youll gain back the loss thats there. the ecm can read it. the maf puts it out.

this whole argument is silly. provided the MAF iself isnt posing a restriction then there no argument. only when you being to draw vacum between the TB and the MAF due you actualy loose power.

as for Connecting rod loading. carbs impose a restrition and the down stroke of the crank moving form TDC create 100x the load any vacum might impose. then again the vacum might actually make it easier to move the piston down from TDC as there is little to no AIR underneath the rings.

this will also help limit crankcase windage and blowby. opening the gap on the secondary compresion ring could have the same effect.

the real issue is that if your able to achive the A/F ratios you need and the timming you need then neither system is better.

The maf outdoes SD where you would have to run alpha-N due to little to no engine vacum.

Sd outdoes maf in apllications where a large maf would cuase a loss of low flow resolution to the point where the ECM could not longer clean up the fuel trim.

its apples and oranges. 2 ECMS that do the same thing.

for the record.

1227165 is 160 and 8192 buad
1227730 is 8192 buad

they both log at the same speed no gains there.

if the debate does end in a constructive manner ill be grateful. it would be nice to see people actually talke about MAF and the advatageous it can offer a radically cammed car. but then again we also need to look into way to improve the code to mak that larger less restrictive sensor work.

im all ears. lets have a real discusion instead of a pissing match

ski_dwn_it

funstick,

EXACTLY! THere is absolutely NO discussion in depth on MAF anymore. If you read my posts you will see, that in my one I even say that more people that start out tuning and instantly switch to SD probably are having more touble than they know.

Therefore I am sorta pushing the issue, since you can't deny the times I have run, and I will soon have a video posted to prove the times are valid.

Its really not meant to be a pissing match, just people sharing their points of view on the subject. Lets keep that all in mind.

Grim Reaper

Can you please answer this question?

ski_dwn_it

I don't know since as I stated in my other posts, We shift these things at about 5200 RPM. 5600 MAX. There is no need to go any higher. That is one of the biggest mistakes people make when draggin. Its actually better to short shift rather than over shift.

Also my scanner for whatever reason did not save the runs that day. Kinda pissed me off, but OH well. I will let you all know what the max pulse width is when I get it out again.

Not avoiding your question, I am curious as well. But not too concerned for I am able to effectively maintain my AFR. Yeah I know where your coming from I put my engine etc into a calculator and it said I needed ~40 lb/hr injectors. I say they are WAY overrated

Grim Reaper

As you just mentioned, the RPM you shift has a major function. A Superram shifting at 5,200-5,600 rpm will have more time to fuel the engine than an injector in a Miniram making peak HP @ 6,500 rpm. The faster you spin it, the less time you have fuel it. But once you hit 100% DC, you cannot add any more fuel (except through fuel pressure, which can lead to other problems unless you've upgraded your fuel delivery system).

The "rule of thumb" is just that, a "rule of thumb" to give you an approximation based on estimates of your HP and the actual efficiency of your engine.

Determining the Injector PW vs the time to complete 1 revoltion is the only effective way to measure your %DC. I know one guy that @ 6,000 rpm was showing a PW of 12 ms for his injectors. Of course, this is impossible as an engine will complete 1 rev @ 6,000 rpm in 10 ms. But it did indicate that he needed more injector to get his "safety margin" %DC.

Similarly, my buddy with the 383 Miniram AFR (and yes MAF) and 30# injectors are running 93% DC at 6,000 rpm. I don't have a scan @ 6,500 rpm (his estimated peak HP), but it is my feeling he is probably very close to 100% DC.

What was more amazing was his fuel pressure drop in WOT when he installed his Fuel Pressure guage. He is now in the process of upgrading his entire fuel delivery system. As I recall, he had installed a new fuel pump with more capacity, but it didn't last too long (I've notice this problem with others that are running high DC).

ski_dwn_it

Interesting points, but don't you think if I was at 100% duty, I would not have any control over fuel ? When the exact opposite is true. Before the car ran at 11.4, till I burned the second chip. It held pretty constant throughout too at the fat condition.

Also you have to remember I have the stock fuel pump. I have been running it with my 350 and never saw a drop in FP.

My first two runs were slower due to the gas level being low and moving away from the pickup. I would defintately notice any reduction in fuel delivery. You just can't image how hard this thing pulls, even at 120+ MPH. It litterally pins you against the seat. The one time it did run out of fuel, it literally threw me forward to the point my belts caught and then it took off again. In the video you can see the front held high, then bad dip, then it pull the front up again for the rest of the run.

You very well might be right, with the fact that the RPMs are relatively low, but my take on that is 95% of the people out there have 1. Too steep of gears 2. Rev their engines way further than they need to.

Then when they have item 1. it just compound item 2 even more. Everyone is RPM crazy, I will take the low RPMs, less stress on the engine components, and quicker ETs.

I have seen people revving the stock l98s to 6500 thinking they were doing good. When realistically you should be shifting at about 4300-4500 MAX. The one guy picked up several .1s switching tp lower shift points.

I have well over a grand just in lifter, cam, springs, valves, retainers. To go 6500+ in RPM you better be ready to spend about 5x that amount. Again you have to ask yourself is something else the bottleneck for air flow? If it is and then the better components aren't gonna make much difference. This is just a blanket statement, and realize no one is saying that, just want to point it out for the high revvers.

I have a guy at work here that said I should be without a doubt revving my engine to 7200+, because he does in his stock mustang. I should entertain myself and tell him to show me how hard his car pulls up there with a ride. But I don't want to get crud under my nails again, helping him pick up the pieces of his engine off the road when he does it.

Corky and I are running very different timing maps ~10* difference, and also running about 8 lbs difference on the fuel pressure, on the same size injectors, Yet our ETs and MPH are nearly identical. Corky doesn't have a WB, so I can't speak for his AFR. Mine holds damn near steady though the RPM ranges.

He has a voltmeter that he monitors off the o2 sensor. He usually is pretty good about tuning it with that as for different heat contitions I have seen him pick up some ET, so he does have a method to his madness. But I watched him set his pressure and it was mid 30s when he was done.

Kinda crazy, well I have to get on the road to St Lui. Have a nice easter everyone!

Talk to you all when I get back.

87400tpi

I have stated SD is more advanced.But there is a major lack of maf talk here.People like me get major flack for reporting what has worked for them.I have people telling me to read tuning 101.When I'm just sharing what I have learned by experience.Keep in mind I've got a little over 3 years in the game.

Glenn,your buddy might just need a bigger fuel line from the tank to the rails.I have seen drops in pressure caused by lack of flow.It's just like electricity current flow.Have you addressed the size of the fuel lines?Or the fuel rails have resriction,maybe.

In a way I wish I had my maf setup still.Maf has alot more upsides than downsides.SD is about even,there is more downsides than maf.But SD does not virtually auto adjust to any ve curve.That is where maf shines.If do things to effect my ve, maf will require little changes.SD might require reworking the fuel tables.I realize that when you take the time to retune the fuel tables SD will be more precise,in the end.But nobody can seem to find the code to correct mph after gear change for maf(last time I checked).The little amounts of maf proved to be fatal,for me.I'de rather repin for SD than pay for a $100+ for a new maf.Unless the maf was covered in gold.BUT the talk of some person saying 255 in the maf tables=total flow of maf=limit to around 400hp for maf.The maf tables "gr/sec"bin column is a calculation NOT any indication of actual air flow that can be contorted to a hp limit for the maf system.That is just ludicris,as ski_down_it has demonstrated.I could find that post about the 255gr/sec+?=max airflow/hp.There is alot of maf mythes.I ask can a maf car go faster than 12 sec.I got tore to shreds more or less,the general responses was I could run fast but at a great loss. Basically they said why waste my time,that is stupid to even try.Now ski is knocking on 10s door,the mood has shifted on maf.Hmmm

87_TA

Glenn I thought you were running a mini-ram now? I see that your VE drops off pretty hard after 4000 like a long runner car would.

Yeah ski,I too would check that duty cycle. even at 5500 I think it would be real close unless your inj. flow more that labeled.
My Seimen dekas 30lbs Would reach about 89% in my old 350
@ 6000.

Well I have seen alot but you need to remember that your 406 w/ super ram is gonna pull peak alot lower,And the awsome amout of torque will allow you to short shift, and not be affected as much as a mini rammed 350 that pulls peak around 5700 and much less torque .
That guy has to run more gear to get to peak HP by the end of third to maximize his time and make up for the torque thats not down low.

Shift a stock mustang @ 7200 lol ,i hope its atleast a 4.6 ,cause 5.0's die after 5300.

87400tpi

I was thinking with all the torque I have down low, 3:42s might be a hair too much for a 700r4 and a 406ci.It seems like all that tq need to be exploited.Besides the fact my car tops off at only 150-160mph with 3:42s.T56 would be nice but I like what Nick Fusco is doing w/ his 700R4.

Grim Reaper

I do. The heads are ported Al ZZ3 heads but the cam is still stock. I am doing comparisons on "low end TQ" between the MR and heads (but stock cam) vs TPI. I can say that at low rpms, the MR actually feels as if it has more low end TQ than the old TPI setup. I'm sure the heads help.

After, I plan to swap the cam and monitor the difference between the different setups (ie. VE Tables)

On SD, I have noticed a STRONG correlation between the VE Table and TQ. Actually, the table I posted before shows peak VE at 4,000 - 4,400 rpm. This is probably where my peak TQ is now with the current setup. Swap the cam (I am thinking either Crane 214/220 or Comp Cams 218/224), and I will probably see peak TQ (and VE Table) peak around 4,400-4,800 rpm.

While if you look below at my optimized TPI setup, I have peak VE occuring between 3,200-3,600 - probably quite close to peak TQ. What is more interesting is the upper VE table on the two tables. Also, I only tuned the VE Table to 4,800 rpm. There was no point to tuning past 4,800 rpm as it didn't produce any power there. But if I had continued tuning past 4,800 rpm, I would expect the VE Table to drop even further.

Grim Reaper

To save people from scrolling all the way back through the post, here is my the VE Tables for a Miniram, ported Al ZZ3 heads and stock cam to compare it the TPI VE Table.

Grim Reaper

He's looking at everything. He is considering a cam change in the future and wants to make sure that he has the system to handle it.