These are the test results of the MAF test along with the dyno sheets. I think this pretty much explains all we need to know, contray to the new excuses flying around.

http://forums.corvetteforum.com/zerothread?id=566897

 

:hail: :hail: :hail: :hail:

Now all the nay-sayers can eat a butt.

 

I'm going to make a bold statement here. I think you have proved that you are at the threshold of being static. When you added that 2.5% fuel you got a little spike of torque (where it actually added fuel), but the rest of the curve is IDENTICAL (where injectors were / approaching static). Sorry, but less than 1% gain is in the noise, the dyno has some amount of error tolerance. The fact that when you added more fuel the power stayed the same only further supports this, because you weren't actually adding any fuel.

Still very impressive. But if it was my car, i would be seriously looking at more injector, or at least would have tried more fuel pressure to increase global fueling to see if those gains could be extended. Couldn't hurt.

As for the vacuum thing, i'm sure you've read the comments from Trax and others about vacuum being a tricky thing to check. Just because you can't measure vacuum doesn't mean it wouldn't go faster, you haven't proved anything to the eggheads with this test. Engines are complex systems. If each cylinder is stealing each others air, overall VE would drop and MAP would stay high. You'd never even see the restriction.

 

I agree Ed. Adding fuel globally should have changed the entire RPM range, good or bad. I'd say those 24# units (if that's what you're still running) are out of headroom.

Can you watch injector duty cycle on these ECU's? (sorry, I don't have a scanner yet for these older ones) If you can, watch their injector cycle. I'd bet they are at or very near max.

The very flat curve you show is very suspect also, especially with the jump you saw at low RPMs where you could actually add fuel with the small injectors. If you continue that jump throughout the curve by using larger injectors, it should give you some nice bulk into the midrange. Bumping pressure would work too, but could effect spray pattern in a negative way and put undue stress on other parts in the fuel system at these levels.

 

Nice work ski_dwn_it!

Thats Funny!

I would almost swear that in my TPIS insider hints book that they did most all their dyno testing using the MAF system and were making more than 450 HP with certain set ups years ago.

 

Guys with the injectors....

You may very well be right and I am not 100% opposed to maybe trying some bigger ones at some point, but I still am stuck on the point that the thing is making more and more power all the way through the RPMs! Therefore it HAS to be getting enough fuel for 1 and air for another.

Trust me, I have seen MANY MANY engines that are running out of fuel at the strip, or on a dyno, they fall flat on their faces....they sure as hell don't keep making more power.

As for the *new* theory that was drempt up overnight in a hurry for todays results on the MAF...to keep a little doubt in the air...

Lets think about this for a second.

Your saying the runner next to another is going to pull air from the other on right? Yes that is very possible and could happen, when looking at 1 engine cycle. But if that was happening and the MAF was a restriction in the sense of limiting power, then I hardly doubt that the power would continue to rise! And the torque would remain at only ~60-100 ft/lb less than 3400 RPM! Comeon! As the RPMs increase the "stealing" of air would increase and the power would eventually reach a point at which it again like the fuel would fall on its face.

The bottom like is I am making 430+RWHP and 500+ft/lbs of torque with this setup....I will go along with the fact that maybe its 450hp setups (doubtful), but I think any rational thinking individual will agree with my that UNLESS your making those kinds of numbers, then your pointing the finger at the worng thing if your blaming the injectors or the MAF. There is absolutely NO agueing that point.

A 12sec car making 320RWHP/330 ft/lb sure as hell isn't pushing the limits of MAF or 24# injectors and not many cars here are even at that range, let alone 100hp and 200ft/lbs more!

That is plain and logical thinking...something I think some of us miss. You can throw all the formulas etc you want on the table. They don't mean diddly squat in comparison to real world results.

 

??? I was trying to help by relaying some information and you are turning this into a thing where people are trying to find fault with the MAF. I just don't get it. This is no 'drempt up' theory. I openly admit to never having thought of things in this manner. I thought that others might also like to hear of this too ... especially you since you were going to be running some tests. Man - what a way to take some helpful comments and turn them around

I really really am hating it how both you and kvu are perpetuating this story of ...

"The MAF meter has had stigmatizm that you could not make over 450 crank HP on a motor without some power adder"

I have been telling people for years that MAF can make big power. I have told you and many others ... I have witnessed MAF cars in the 10's. I have books on flow theory out the yingyang and cfm rating of a ported MAF flows enough to support this.

Tim

 

Trax,

You might realize it, I realize it....the problem I see is that there are a TON of others that don't think it can.

Perhaps I was a little harsh, for that I appologize. :cheers:

I really could careless to be honest with you what someone else runs on their car. Please don't take this wrong in what I am saying, but the majority of people here/on the corvette forum and I'm sure other boards have than stigmatism opinion.

At times I has speak harsh, but always try to maintain a level of respect, I admit that was maybe a little to far, but as I said I already appologized. But just yesterday in the tech section I commented to a guy explaining what I was doing ET/MPH wise....he was convinced that starting out with MAF in a mild engine was wrong from the start. Nect thing you know the post was closed! There were three of us all conversing in a constructive manner and bam, closed! WTF?? And that was a response that came from another member involved in the coversation, and rightfully so IMHO. Jeeepers it just gets frustrating, and why you might ask? Well its pretty cut and dry in my case....I am running well and making decent power. I have my car and am quite pleased with it, the only reason I even comment on others guys setups is I love to see people succeed. I openly post everything there is to see about my setup for others to see/copy ask questions about etc. I don't keep anything to my chest. Likewise I want to help people with there setups, when I see a guy with a 300 RWHP car (which believe me is nothing to sneeze at) saying or having other tell them they have a restriction on their car ie MAF. You can bet you bottom dollar I am gonna speak up.

I don't want to be thought of as a leader in the tuning world or even the fastest yahoo that frequented the boards here or on the vette forum. I come here and I go there because I LOVE this stuff more than myself I think

I am just an opinion with some clout I guess....nothing more, nothing less.

:cheers:

 

The argument for injectors has no merit unless you post A/F ratios shown from a dyno run. By adding the fuel down low and seeing that bump, it is just a best guess at what is going on with that combination... that it needs more fuel. Do you have any A/F readouts from recent runs?

Also, you state that a car can't make more HP without more fuel... Have you ever heard of running lean? How about a lean out button on drag cars??? Those cars lean out on purpose on the top end because it can make more HP at higher RPMs to be lean.

The thing we're trying to say about your car concerning the injectors may not change your max HP or TQ readings, but judging from the jump your global change made to only one area of the dyno graph, you could fatten up a lot of the low end and middle with more headroom to work with. You proved it by making a global change, jumping in low end, while the rest of the curve didn't make a twitch. Even without having your higher HP numbers, people with dyno experience on any fuel injected car can see those signs... whether a 150 HP NA Honduh, or a 1000 WHP Supra.

It's a very impressive combination, nobody is arguing that fact. We're just suggesting ways we think you could improve. I have yet to see anyone of any stature put down a MAF car. If they have put it down, then they don't know what they're talking about and probably don't deserve that higher stature.

 

I don't understand why you lash out so much. All anybody is trying to do here is help.

As for the stealing air only mattering for 1 cycle, i disagree and i'll attempt to explain the model i am seeing in my head. We'll assume an accelerating engine somewhere in the power band, but pretend it was operating ideally, then a restriction is introduced far upstream.

Imagine cylinder 1 pulls, with the new restriction, it's easier for it to pull air from the entire plenum / runner volume than new air through the TB. Here's the important part though. Air is still entering the TB. So plenum pressure will stay relatively higher than it is at the head side of the intake runner.

Now 8 pulls Initially, the pressure at the head side of the port is on the low side because it was just robbed by 1. But it pulls, and as with #1 some of the air is coming from the runners.

And so on. Every time a cylinder hits, the pressure at the head end of the intake is lower than at the plenum end. So at the start of every intake stroke the cylinder is not getting maximum filling. Keep in mind that the intake is not a hydraulic system where pressure on one end equals pressure on the other end.

There is some evidence of this in the dyno graphs too. Superrams are a tuned runner intake. You'd expect to see a peak on the torque curve somewhere in that midrange where the resonance hit. Instead it looks like the curve from a miniram engine. I'd explain that as the runners starting from a low pressure state, which would kill / alter the resonance. Basic SHM.

I know it's tough to visualize. As for it being a "new theory" i guess you missed that one of the reponses in your other thread came from a fella who has experience with big inch / power engines and has OBSERVED this phenomena on a running engine with many ports on the intake to verify. A vacuum guage on the plenum would not show what we are talking about. Hell, a vacuum guage ported into the head end of the intake wouldn't show it. You'd need a very fast very accurate pressure transducer to detect these momentary drops in pressure.


I don't care if you believe me or not, no skin off my back. I'm just trying to help. If you really think your car is maxed out, then keep on trucking. If you're looking for that little bit extra, i think we might have given you some areas to look into.



BTW, hate to bring this back up, but your method of tuning does lack resolution for altitude and temperature. So if you were dialed in at sea level at 12.8:1 on a 50' day but the dyno was at 1500' and 70' you weren't at 12.8:1 anymore. I'm not trying to start a fight here either, but i think it's imprtant to point out since i see you proclaiming that your method has plenty of resolution / no draw backs. BTW, this is where maxing the MAF matters. A valid MAF reading will account for temperature and airflow (pressure). Once you max it you're tuning for an assumed condition (X airflow at Y RPM) that isn't constant with temp and altitude. But i digress.

 

True about the MAF readings Ed... If the max voltage is reached at, say, 4500 RPMs on the MAF, then the ECU is tuning blindly from there up until redline. It's not to say that the engine isn't going to make more power at higher RPM's then it did at 4500 when the MAF maxed out, but it theoretically could make more HP at those RPMs if the ECU could *see* what's actually going into the engine.

The only way to know for sure is to run a scanner, mapping out the MAF readings. A low tech method is to hook up a volt meter to the MAF leads during the run and watch it through the run.

The way to get past this limitation is fairly easy hardware-wise by either substituting a smaller sampling tube, or getting a larger MAF meter. Either way changes the sampling tube to overall MAF diameter ratio to slow the transfer voltage down as air velocity increases past the stock MAF's capabilities. The MAF software changes, on the other hand, would reguire you to rebuild the MAF tables to properly run the new MAF.

 

bnoon,

I understand exactly what you are saying with regards to the injectors.

I wanted an AFR reading more than I wanted those numbers, I can tell you that right now. I was highly disappointed and almost didn't even run the car when I saw they didn't have enough provisions to hold the sensor in my exhuast pipe.

We tried several times to get those AFR numbers, had guys there with vid cameras and everything with the RPM from the computer in the background showing RPM for playback and tuning purposes.
But in each case the sensor would go flying out. The back of the car was up against a wall and there were papers and all kinds of stuff flying around, it looked like a tornado from the exhaust pressure. It gave us all an appreciation what it takes for an exahust to perform at high RPMs with an engine like this.

That is the reason I can't run my own WB at the present moment. I have the sensor provisions in the 2 1/2 inch duel exhaust and when I drop it at the track, I gain .3 and 2 MPH.

But when its in there I can tell you that the AFR with the first dyno reading is 12.8 across the boards.....how much that number changes when I drop the exhaust I don't know. Another thing, we pull plugs and look at them. They are tan color, not white and no specs of any kind on them. In the collective knowledge I have with myself and others that have had a hand in this car, their is overwhelming opinion that I am not running lean. No knock counts ANYWHERE.

Here is the other kicker.......Here is Corkvette1s dyno graph of his car. His and mine were identically built down to the last bolt. We took great care, same machinist balanced his assembly down to under 1/2 gram the whole nine yards. We assembled it together and have the same injectors. He had his car on the carisle dyno with poop tires and spun on the dyno roller a few times. Here is his AFR running the 24# injectors. He has been running this setup for over 2 yrs now with no problems.



That doesn't look like a car that is having problems with getting enough fuel, and probably why he is down on power, but that is mostly probably because the car was slipping the rollers.

I made a post about 1 month ago and it pertains to what you are saying about making AFR changes and not seeing any difference in power. I made the statement and still stand by it. That these cars are NOT as touchy as people make them out to be. Let me explain further. Corky is running the same exact chip that dyno was made with(a mail order formato chip to boot, I have not had time to sit down and do one for him). If in fact I am running lean, let assume my afr is 13.3. Corkys is in the 11 most of the run. He and I both ran at Keystone about 1 month ago within .05 sec of one another. My MPH was 2 higher, but his converter is non-lockup and mine a lock. He has his FP regulator cranked all the way down to 34-36 PSI. I know people think I am lying to them, so that is why the next time I am at a track with him we will film the gage before he goes out to run, right before he does his burnout.

My big hangup is these engines have to be running at about their max potential, efficiency the whole nine yards. I think that it would be possible to put out these kinds of numbers with an ill equiped injector car if it had potential to make MUCH MUCH more power. ie a 600 RW car that is running lean or out of fuel.

Torque to me is what says I am fine in those dynos, when you have a car that can start at 500 tq and only drop to 400 through the entire RPM range, that is pretty convincing......and its not an engine like the before mentioned 600rwhp, at least I don't think it is

However I see what you are saying, and how do you explain Corky's AFR? And like I said before, when I have my WB and exhaust on, I can move that AFR to anywhere I like to. I am going to video, as soon as we get the exhaust back on and have some decent weather my car on the highway with the WB connected. I am going to take it from ~12.8 to in a much richer state. If it won't move down, which is where it came from when I started the tune for it after I got it together with the first chip, then YES, you are exactly Right, and I will be the first to jump up and down, just as I was 100% honestly hoping the MAF was pulling a vacuum on the dyno run last night. Hey that is easy HP in my book. I feel the engine is at its max right now, at least with the accesories etc on it, ie water pump/AC/power steering all that good stuff.

I would love to have that thing be able to run in the 10s in all kinda of weather.

Hope you see that I am not being an ignorant stubborn person. THis allows others to see the thought process etc that needs to go into a setup. This is how we ALL learn/benefit.

Thanks for your input its appreciated and taken into consideration.

 

It depends on where those readings were taken in the exhaust stream. My last car I had to run at less than 12 because their O2 was at the tail pipe after the cat... Stoich is just a guessing game unless you have the dyno runs back to back and compare one run to the next to not only read the O2, but compare power levels too. Depending on where the O2 sensors are located in the exhaust stream, your car can read anywhere from high 11's up to mid 13's and still be optimal for the particular set up.

The point is, until you see all of the information together on the same page, comparing dyno runs of the same car between runs made minutes apart after a few changes, you aren't going to know for sure. I notice his A/F ratio starts to lean out about the same RPM that your HP and TQ start to decline as well... maybe he's out of fuel too...

 

I hear what you are saying, and believe me I can convince myself in either way. I just wanted to show some proof that big power can be made from these components. I the 2 years or more that I have been here nearly religiously everyday, mind you not always posting, but browsing. I have never seen a car that came close to this kind of power with a SR. Sure I'm sure there is, so spare us all the list of names, but someone that did their own tuning and engine work etc. Again I am not trying to be pioneer and could really care less about the nestalga.

I set out to reach a goal and am there, now a 10sec run with be icing on the cake.

I regard everyones opinion as valuable and file away all suggestions that you or anyone else offers. Sometime I may argue the point a little just to bring about conversation. And I think everyone would agree that it makes for some interesting reading, and most of all gets people thinking. I don't know all there is to know, I am a 28 yr old that paid attention and was able to build and tune a good running setup.

So remember behind those arguing words there are reasons other than to be a jerk........sometime I will admit my Dego temper gets the best of me But in the end we should all

 

He has 3" duel exhaust with no cats, so I would say that those dyno AFR ratios with a WB02 are pretty accurate. That is the first time I have heard that a WB is not accurate. Stock 02, I would agree 100%.

Comparing his car is a VERY valid example. His car runs the same exact times as mine and MPHers nearly the exact same, weights the same is the same. Running the same exact injectors laying down the same kind of power. Why would be be down the in the 11 and 10s. with AFR if his injectors were static. Actually let me clarify something.....He very well might be static where he is at, but that leaves me with a lot of room to move around. I drove my car, actually got the 12.8 AFR in about 15* weather here this early spring, snow everywhere but the roads, I took the car for a ride this past week 70* and my AFR was exactly the same +/- .1, so I am confident that there is little enough change that the AFR isn't going to chance 2 points with a weather change unless he parks his on the north pole and I part mine on the sun. I would say they will vary a little, but not 2 points.

 

No no no, I wasn't saying that two identically set up cars could have that much variance. I was saying two completely different cars could have that much variance in O2 readings, using the same O2 sensor, just by being in different places of the exhaust. Read close to the tail pipe, the O2's are higher because of a cat, the mufflers, and the cooler temperature back there. Read at the header, the O2's will read less oxygen...

The whole point of this part of the discussion stems from the global fuel change you made, which did not make a global dyno change. Go back again, make that same global change, then make a larger global change for even more fuel... I'll bet the upper RPM never waivers... Good sign they're pumping their little hearts out to the max.

 

I just got home and read this thread. First off, I'd like to tell ski you have a nice running engine. I will argue with you however the formula thing. Its just phsysics. I have a ton of experience with formulas, and also with real world results. Enough experience that if I post a formula, you can bet money I have seen it be accurate. I have not argued that you can not make power with a maf setup. I happen to own a maf car, and will eventually have a legit 10 sec pump gas maf car. My only point in posting in this thread in the first place was to try to be informative, not to try to discredit anyone. I have never measured a maf, but its crossectional area (CA) probably isnt big enough to produce that much hp without introducing some kind of restriction. It is obvious that you are making 450+hp, but my only point would be without a maf sensor, its power would probably rise. It is posible to make more power than what a given CA at the inlet will mathmatically work out to, the formula is to find out what, if anything is a restriction.Anyone into NASCAR at all? they have engines that for the sake of argument make 800 hp, but at some tracks use a restrictor plate to keep speeds down. The plate is something in the neighborhood of 4 3/4 inch holes or something. The CA of those holes would work out to alot less than what they make with the plate on, the engine just has to pull harder. Ski, Im not trying to argue with you here, but to try to explain what i think. Ski, if you are interested, pm me, and I would be happy to discuss a few things with you, or to maybe test a maf on a flowbench, just to see what it actually is capable of flowing.
Bob

 

Jesse,

Thanks for the thoughtful reply. Now I'll get to what I really wanted to say

VERY NICE NUMBERS! Your car is an awesome example of what MAF cars can do. Personally, I appreciate all the data that you are posting. I have been doing my best to explain things 'in your favor' and I hope that beast's power keeps growing!

Sweet!

Tim

 

ski i want you to email me. id like to flow your maf.

 

Funstick....

Hasn't anyone every flowed a stock ported MAF off one of these?

The only thing I ever did to mine was take the screens out with a pair of pliers. Then taped the tube thingy off in the middle with tape to protect the wires. Then cut all the heat sink fins off as flush to the bottom as possible. If anyone has every done it, you know it gets very messy, with nicking the plastic etc. I thought mine looked pretty ****ty actually, some of the fins are actually still above the plastic radius to be honest.

I will take some pictures of it after this weekend. I have to go to a friends wedding I am in. HWT wrestling buddy from PSU I wrestled with while going to college. Definately gonna loose some brain cells this weekend

Corky is running the same exact one, unless the 85 vettes had a little bit different design, but from what I know they are all pretty much the same through those years, right?

I have been doing some thinking and when I get back if I remember where I live I want to do some to verify if the injectors are static or not. I double checked my FP tonight and its right at 43. I am going to:

1. with the romulator, increase the fuel by about 15% across the boards then run the car through the end of 2nd gear, as anything before that it will break the street tires loose too much for my liking on the street. If the AFR stays the same, then I will concede, and have a beer knowing I can make even more power.

2. I will then, before having the beer, take a moment to raise the pressure to about 52 psi and take it through the run again. If it changes to a lower AFR, then we know for sure the inj are too small, then I will commence with a beer.

If they both reduce the AFR as I suspect they will, then its back to the drawing boards.

Sound feasible? To me it does and I think it will prove what we need know. The only difference is the exhaust will be hooked up and I know it chokes the car down about 3 mph at the track. That could make a false rich reading, but if a baseline run is made it should be OK when talking relative readings. Same air pretty much, etc etc.

 

Jesse,
I'm not sure what you mean here. If you raise the fuel pressure from 43 to 52, I would have thought your injector flow would increase by just on 10%, and so your AFR would decrease by 9%. So why would a decrease in AFR with increase in injector flow mean "we know for sure the inj are too small?"

John

 

John,

As I raise the FP the values for AFR ie 14.7;12.8;11.7 is what I meant will decrease.

The reason I want to do the second test is to make sure something is not goofy in the WB setup I have. I am positive it works fine, but just a check will not hurt.

If I infact see those AFR numbers decrease (approach) a richer state ie 12.2 then I know for sure the injectors are too small, since an increase in pe% chg to AFR vs RPM did not make a difference. If in fact the PE chg doesn't, but I know I pulled those values out of the basement when I started, so I suspect the injectors will flow more than people expect them too. But I am willing to perform the experiments, since I too thought that was funny the upper HP numbers were not effected by the % increase in fuel.

 

Ski, that does sound like a plan. If you're able to do it on the dyno next time, you'll be able to see what changes it'll actually make. Really, if the A/F ratio doesn't change by doing it with software, then you know for sure already. Confirming it with fuel pressure would make it known without a doubt.

Here's a nice little online flow calculator...

 

bnoon,

Exactly.

That is a nice site. What do you think of this with respect to the MAF. We can all agree that the MAF flows ~750 CFM in a ported state.

Assuming 100% efficiency and 70* air a 406 at 6500 RPM only requires 763.6 CFM of air. So that means I am well below the flow requirements of that MAF meter. Since 1. I am not even near 6500 RPM and my efficiency is I doubt 100%. This most likely explains the reason most guys that run these engines at the track are running 750 CFM carbs. I just had a guy in the pits next to me with almost the exact same setup as mine with a carb though. That was what he was running as a carb and he was only cranking at 8.0X @150+ In a small rail type car. He said my engine probably is putting out more than his when he saw my times, and I told him the weight of the car ~3350. He took down all the internal components and said he is very interested in my cam etc.

Here is that page:
http://www.smokemup.com/auto_math/airflow.php