Ratty Vette

I've got a 383 mini-ram, 245 deg 580 lift, 30lb inj, runing 6E w/guted maf that hits the 255 wall by 5k. O2 drops out by 5300, added fuel to PE, scaled back Maf vs RPM to not max till 6400 but still can't get enough fuel, rail press holds at 47psi. Comand fuel is like 10:1, time for some 42lb injectors or time for SD?

Orr89RocZ

iTrader: (20)

whats the injector cycle duty?

is the cam a roller cam either solid or hydraulic? how much power do you expect outof this combination?

30 lb injectors i would think could feed that thing, but if your up over 400whp maybe its not enough injector. I know i have seen some high hp cars with 30 lb injectors tho. Also, seen some 400+whp 383's using 36 lbr's so maybe you dont have enough injector. depends on your cycle duty.

ttypecamaro

iTrader: (2)

I was able to squeeze a little more out of my brother's MAF system by leaving the "injector constant" stock, and multiplying the MAF tables by the quotient of: [stock injector flow rate]/[actual injector flow rate]

in his case it was: 19pph/25pph = .76

The ecm thinks the injectors are smaller than they really are so it calculates a longer pulse width. Then it thinks its getting less air than it really is, so the final pulse width calculation is decreased, making it correct again. This works because the MAF itself does not max out at 255gms/sec, the ecm does. The MAF can read accurately a little more than 255gms/sec.

With injectors much larger than stock, you will lose MAF resolution at low rpm, so you can also just pick a number like .75 to multiply (both) your actual injector flow rate and your MAF tables.

example for 30pph injectors:
30 x .75 = 22.5 (enter this in the .bin as your injector constant)
then multiply all the numbers in the MAF tables by .75, now you will have room at the very top to tune the last MAF table to your engine.

its cheating, but it seems to work.

Ratty Vette

Cam is hyd roller, Hp before last redo dyno at 420, injector duty is in question, target hp is 450. When I looked up a std injector lb per hour vs hp it's short, yes 36 lb would seem in order. I main concern is fuel control with the maf maxing out

Ratty Vette

ttypecamro

I like the idea of under reporting inj size, problem is I know, I'm close to maxing out duty cycle as it is and I need fuel control to at least to 6400 or better.

Orr89RocZ

iTrader: (20)

yeah with that cam i'd go bigger on injectors but i guess you have to watch low rpm stuf with big injectors

DSmith

What will this do to the duty cycle of the injectors? Will the datalog show the correct value for this?

ttypecamaro

iTrader: (2)

yes. the actual duty cycle will be the same as the calculated duty cycle (which is what is displayed in the datastream). The only difference is how its calculated... getting around the memory limitations of the 1227165.

Ratty Vette

Orr89RocZ
This a local Club member car's (thank god a stick this time, 6E apyp) that got parked in my drive because I got another insane, same cam, but a auto 6E arap to idle in gear w/AC on. That was a rough tune, 30 deg of timing at idle 1000 rpm in gear and all that.

>>>>>>>>>>>>>>>>>>Side Bar<<<<<<<<<<<<<<<<<
The apyp has a much better idle control vs arap "auto" with tooo big of cam & the "Expanded 6E.xdf" by Jhon Phillips (on this site) the diff's between the to bin's are well seen. Havn't had a chance to copy them (idle prams) over to a auto bin, but will soon as I can.

I did a few of these tunes just to see where my own current build was going to have problems, I have a littel smaller cam with the vortech HSR, needs to be redrill for gen 1 (has a higher port, uses a 1206 gasket, the reg gen1 HSR won't cover the top of the Broix ports), 200cc Broix heads, 11:1 comp.

As I'm looking over all the data log's I see now a lot where doing a lean-out to some deg in the upper rpms. All were maxing out the maf w/ported super rams before 6000, but this mini-ram is the bitch in keeping fuel @ wot.

So, have I max the 6E MAF 165, the injectors, yes need bigger and or go to a SD system. I did some work with the Holden 5D bin for the 808/082 160buad with useing the same 165, but with no spark knock control and 11:1 it's not much of an option. So is a "SD" 730 AUJP or sim, seem to be up next, unless I missed something.

Orr89RocZ

iTrader: (20)

i know the SD will handle that. i know of bigger 406 motors running on the 730ecm

i was always curious to see how much motor the 6E can handle, as i may be doing a 383 now with a 236/242 hydro-roller cam. if it cant handle it, i'll go with a smaller cam or keep a 350-355. i dont want to convert to SD just yet

Ratty Vette

Orr89RocZ
A few weeks back, I got to meet some of the GOD'S of Tuner's \ Hackers Moates & Mansur at the PRI show in Orlando, both super guys. And to spend some time with them and ran some idea's on their simulater, to cool to beleave. We did the maf VS rpm scale-back and yes it looked doable. But in real world it didn't get us home to a product. Even my logs of cams with 230 deg @ 50 w/ mini-ram showed some lean-out at 6k, but they also didn't spend much time up there between shifts, dwell time seems to affect the lean-out. Which may be fine for a TPI but bad for a mini-ram and big cam.

The cam spec you posted looks like the gm cam I have and I'm also not looking forward to the rework of VE tables with the 730 and rewire, but I'm afaid it's going to be in the near future.

RednGold86Z

iTrader: (1)

You *could* make a larger tube for the MAF, then recal the scalars and tables.

Orr89RocZ

iTrader: (20)

i thought it was said the stock MAF can read alittle more than 255 g/s but the ECM cant go any higher? so how would a larger MAF help?

Ratty Vette

Moates had a the same type of idea of by-passing some air around the maf when I got to chat with him in Orlando, but it still comes back to fuel control and what the engine fuel needs are a given prm, really no diff in "max maf VS rpm" kinda same, same but still dosn't give use fuel control in the volume where it's needed and when.

The other thing we noted is a VL declay factor vs maf gain and dwell time at a given RPM, if the ecm dosn't see a gaining maf, it thinks VL is no longer in PE to some degree and starts lessening PW, even though rpm is still gaining.

I not bashing the maf, but I seem to be running out options with some 383s' even going with bigger injectors and still maintaning fuel control in the upper rpm range.

That's why I'm revisting the Holden 808/165 or the 730, I beleave the later 808 $5A may be some thing to take another look at? The only big item needed for a work around is the KS

RednGold86Z

iTrader: (1)

The ECU doesn't REALLLLYYY know the grams per second. It only takes some inputs and makes some outputs.

If you lie to the current software, i.e. fudge the injector flowrate, and have a larger MAF tube, it will work, with minor changes to the scalars and MAF tables.

For example, assume the MAF tables were linear (which they're not, but just for example). Double the AREA of the MAF tube. Cut the flowrate number in half (i.e. if you have 30's, tell it that it has 15's). The voltage from the MAF will be half of "normal" but the PW will double, so that it balances out in the end.
So, when the MAF says 255, it really gets 510, but reports as 255 in the software. The ECU thinks it has 15s, so gives double the PW as if it was told that it has 30s.

So, as long as the larger MAF area is proportionally countered with a proportionally smaller injector constant, it should take minimal fiddling with the MAF table to get'r done.

But, yes, you'll loose some resolution. Who cares.

tequilaboy

Another approach along the lines of the re-scaled MAF idea that has been suggested, would be to use a late model digital MAF that could measure flow in the vicinity of 450-500 gm/sec.

Then convert the high frequency digital MAF output to low frequency with a turbo buick style MAF translator.

Run a $32B bin with the MAF switch set to digital instead of analog, and re-pin the ecm for the digital MAF input. I forget the exact pin change on the ecm, but I've found it on this forum before, so with a little digging it can be found easily enough. Edit: Looks like pin B6 can be used for the digital MAF input according to info obtained from this thread (assuming VATS is disabled):

https://www.thirdgen.org/forums/dfi-...730-749-a.html

Rescale the MAF tables and/or scalors to take advantage of the increased flow measurement potential (say divide everything by 2 so that 255 gm/sec indicated is really 510 gm/sec actual airflow) and also reduce the injector flow rate or stoich target proportionately to the changed MAF scaling to achieve appropriate fueling.

I've been toying with this idea, since I prefer the packaging flexibility of the newer digital MAFs, and also the availability and low cost of the digital MAFs make it attractive. The only real downside is the cost of the translator, but maybe a simpler signal interface like a Dakota Digital SGI-5 used for vss recalibration could handle the frequency conversion.

In my case, I'd like to try and put a 3.5" LS1 MAF on my supercharger inlet, or maybe a 3" impala MAF on the supercharger discharge, but the inlet side may be a cleaner installation.

For the OP, As I posted on another forum, I would try raising the fuel pressure as a first step to increase the fueling with your current injectors, since this is basically a free mod.

ttypecamaro

iTrader: (2)

That seems like a great solution for when the ecm AND the stock MAF are maxed out (in much higher than stock airflow applications), but may be unnessecary for airflow levels just over the 255gms/sec limit.

Orr89RocZ

iTrader: (20)

what kinda of combination of parts will max out the stock MAF at 255gms/second? the bigger mass air tube doesnt look too bad to do

Ratty Vette

The more, I think about your under reporting inj size. The more I think I'll give it a go at it, to see how far we can get with it.

_________________________________________________________________


In respond the "big tube maf" I'am afaid that we be still dealing with the same thing as the "scale back" of the RPM vs MAF in that, there is a PW gain & decay factor (not AE connected) build in to the 6E, which I noted on my data logs and which Mansur (the org decompler) confirmed. The only way I see this working is if we can edit the 6E around this, anyone game? I just don't see us handling this at the input level.

BTW, I would like to thank everyone that has inputed on this and I will update on the out come, no matter what.

Bigger injs' on order!! Should have them installed on the test mule by the 5th for our next "test & tune"

If anyone is central FL and would to come out to our next x-cross, check us out @ www.Floridacorvetteracing.com Reg is full for the 5th, but there are always a few be no shows, e-mail me @ Xerox.3@Netzero.com and I'll get you on the back-up Reg list.

PS, we don't do parking lots, we do 1 mile run-ways!

Happy New Year, Chris

tequilaboy

I just took a look into a couple of my old maxed MAF datalogs from a $32B based bin.

The max BPW that I see is 12.89 ms. Even though the target AFR is still going richer, the BPW is limited and flat at 12.89 ms. The target AFR in PE is going as low as 9.06:1 above 5200 rpm with around +40% enrichment.

Its not clear to me where this limit is actually coming from. I will continue to dig into it. I don't notice any decay. Its flat as a pancake.

ttypecamaro

iTrader: (2)

60000/RPM is the theoretical static injector pulse width in milliseconds. Seems like your injectors are going static around 4650 rpm.

tequilaboy

And good point.

With the 12.89 pw, the injector duty cycle does reach 100% at 4650 rpm so they were indeed static above 4650 rpm.

The 12.89 pw limitation occurs as early as 2600 rpm and remains flat. I would still like to understand where the limitation is coming from.

In my case, an increased pw wouldn't have helped at higher rpm even if it were possible. It would just go static at an even a lower rpm with no effect at higher rpm, since they were already static above 4650.

It is likely that the OP's injectors are going static as well, so I think his only alternative for additional fuel is larger injectors or increased fuel pressue, which he is already addressing.

It will be interesting to see if he can fine tune the fuel delivery as desired for high rpm. I would think that an elevated PE vs rpm table after MAF saturation rpm would be sufficient, but I agree it is rather crude.

PE vs tps tuning may become more critical to get it right for heavy throttle at higher rpm.

I've since installed 42.5 lb. lucas injectors in my car (maybe overkill).

pandin

I have data logged pulse widths as high as 13.72 on a bua stock chip at 3900 rpm 178 gr/sec. Was also flat 12.3 to 11.8 2600 rpm to 5200 rpm

ttypecamaro

iTrader: (2)

so your injectors are at 89% duty cycle and your peak torque is right around 3900rpm

Guest

You should be able to tune it with the MAF maxed out via the PE v RPM table. Sounds like the injectors are the issue at this point.

Ratty Vette

This is the same thing we are seeing, I see you are useing the 32b which I had wondered about if this was limited to the 6E

Ratty Vette

This BUA is a is for a 86? I 'm trying to do a sort-out with the BPW and Maf vs rpm.

The other thing about the decay factor is seen with maf gain vs time, in that when we did tests with the scaled back "max maf vs rpm" table while we gained some control over fueling. We still couldn't keep WOT fueling near what was needed as there is a "ramp-up" with PW vs time which Moates also noted. So the faster the maf gain, the more VL and PW, but there is a dclay to this built in, once the maf maxs out, the ecm starts a lean out because the maf is no lomger riseing. Remembering there is no map to tell it the engine is still in PE.

Ratty Vette

42's in another club member's Sam's 383, same, same build but with a Super Ram, test mule in the chassie shop. Sam's ran at test & tune on the 5th, still running a lean-out as we saw before with his car, We are going to try a under report of inj size to see if we can move this problem somewhat.

Orr89RocZ

iTrader: (20)

What rpms you guys looking to turn? doesnt that WOT PE vs rpm table only go to 6400 rpms? those big cams will want to turn that high and much higher.

good heads, great intake, and a mid 230's duration roller will peak 6500rpms in a 383.

Guest

These are the AFR's recorded by my LM-1 wideband during the last dyno run I made. Sorry that I dont have a file with the RPM's and MAF tied into it, but I wasnt able to get the LM-1 data logged with the ECM data at the time.
12.01
11.79
11.94
11.54
11.79
11.91
11.94
11.8
11.72
11.85
11.83
11.79
11.86
11.8
12.04
12.23
12.22
12.04
12.22
12.26
11.8
11.98
11.79
12.14
12.01
11.94
12
12.19
12.2
12.16
12.35
12.2
12.26
12.23
12.29
12.2
12.3
12.33
12.35
12.11

This is the dyno chart:


The MAF hit 221 gm/s at 3925RPM at WOT (thats when the pedal was dropped) and the RPM's went up about 500 in no time and the MAF maxed itself from there on out. The dyno wideband recorded it leaner than whats above, but not a lot. Reading from a different location anyway. I had just changed the cam before this run, made about a 10 minute drive and brute force crunched that data into a tune and this is what I got. Actually had a rich spike (into the mid 11's) on a full pass at the track, but nothing leaner than 12.5

SD is the easy way out, if you dont run into any of the hitches people have with them (not going into PE is common, but fixable). It eliminates any maxed sensor 'issues' you may have.

Ratty Vette

The shift target for the mini ram (Paul's car) is 7000 rpm. Sam's car is a super ram & heavly ported, shift target 6700 rpm and yes I know thats a real push for it (too long of runners). These are more track cars than street, btw. Both are running the 245 deg cam.

We didn't really see this lean-out till we started to make over 400hp, I was hopeing we could control fuel till at least 6400, "in that" for the short time from 6400 to their shift points, even though I may have gone a littel rich at the 6400 mark to carry them through.

Grim Reaper

You can still go over 6400 rpm using the WOT PE table on the $6E MAF system. You need to use your WB and tune the highest level (6400) to make sure you have adequate fuel in the 6400+ rpm area. Typically, the problem is "too much fuel", not "lack of fuel" using this method. But it will work adequately until you have an engine that makes peak HP in the high 7K rpm area. It won't be "perfect" but for the average guy it will be more than adequate. But if you are fighting for every 1/100th of second, then this will probably not work for you.

Also, SD also has tuning issues beyond 6400 rpm. So, if you are need to tune in the 8,000+ rpm area or need to fight for every 1/100th of a second, then you really need to look at a DFI system.

Orr89RocZ

iTrader: (20)

thanks thats exactly what i was thinking. I've talked to Rbob about it too and he said pretty much the same thing. i'm looking to peak power at 64-6500 and only rev to 6600 so i should be fine

Grim Reaper

I used that method on a friend's engine that made peak power at 7,200 rpm. And frankly, we found very little variation in our desired AF ratio (12.8:1) from 6,400 - 7,200 rpm. As well, there really isn't that much of an HP difference if your AF ratio is varying +/- .2 (from an average of 12.8). Again, only if you were racing and every 1/100th of a second is important would this be an issue.

Ratty Vette

Question, was this in single fire mode or double?

RBob

iTrader: (1)

Glenn, I don't understand this. Why would SD have tuning issues above 6400 RPM? And what does DFI bring to the table to alleviate this tuning issue?

RBob.

tequilaboy

I think I have a better understanding of the issue now.

Now that I've got some data running with 42 # injectors and +40% PE above 5200 rpm, I'm seeing the BPW begin to decrease from a peak value of about 8 ms as rpm continues to rise above 5200 rpm. With this tuning the PE is no longer increasing with rpm. This is my problem.

To counter this, I plan to keep increasing PE roughly proportionately to rpm. This should work up to 6400 rpm.

Something like +40 @5200, +44 @5600, +48 @ 6000, +50 @6400.

The increasing PE% will help to offset the increasing rpm (and increasing airflow) and maintain (or increase) the BPW.

Above 6400 rpm, since there is no (normal) way to further increase PE, the BPW will begin to decay since the DRP period is decreasing (rpm increasing), the PE % is fixed and can't continue to rise without extrapolation and the airflow is already maxed.

If the real airflow is still increasing above 6400 rpm, some lean-out will be inevitable as the bpw is reduced due to the falling DRP period.

I'm not concerned about running over 6400 rpm for my car, but it could be a continuing problem for the OP without another method to add fuel.

Ratty Vette

We think we have found the problem, TPI's ran in double fire mode (twice per revolution) from factory, problem is this seems to be good only untill about 4400 rpm, the factory tpi max'ed hp at 4000 rpm, so no problem.

But when we went further in rpm, we ended up here at this point, a very bad lean-out and no matter what, we didn't seem to be able to keep fuel up. This was because of injector duty in "double fire" too much time is wasted opening and closing the injector, see www.dynamicefi.com/InjectorDriving.html

The good news is apparently all we needed to do turn off the double fire in the Flags / Switches. Sam will be testing this on his 383 this week, I will update on our findings.

Orr89RocZ

iTrader: (20)

good find! definately keep us updated!!

RednGold86Z

iTrader: (1)

It'll only help a smidge, like 2-4%. It'll also possibly idle with a strange mis or gurgle on 2 or 3 cylinders that are getting a full shot on an open valve.

Ratty Vette

UPDATE, Sam as reported in on the "single fire mode" as pig rich @ 6375RPM, with NO PROBLEM WITH IDLE, then again these 383's idle @ 1000 rpm in gear. Sam, is e-mailing his data logs tonight, so we can see were the PW went to with the single fire mode vs double fire.

Stay tuned for updates!

Ratty Vette

Query,

Has anyone seen data logging with rpm above 6375 with the 6E/165. Sam's rpm stops at 6375 with tuner pro logging, but I still see maf and O2 moving around after that.

Orr89RocZ

iTrader: (20)

6400 is technically where no more fuel can be added based on the PE tables, so many the computer doesnt output any more values after that during the log, which would suck cuz i plan to watch my car till 6600 atleast.

Ratty Vette

I beleave, Sam ran his car to rev limit 7000, rpm stop at 6375, but maf and O2 still there reporting after, we can still see whats going on to some point. Good news is you can kinda see his peak HP and after his maf droping and O2 going rich +900mv before he hits the rev limit.

If we get time this weekend I'll grab my G-teck which runs its rpm off the alt nosie and see if we can't look at this from another angle for tuning. I don't see a real problem in hitting a good max hp even though we can't nail it down a "X" rpm, after all carbs do it all the time. We just need to target our max hp AF by commanding "X" at 6400.

Orr89RocZ

iTrader: (20)

have you ever put this car on the dyno to play with high rpms, and see what power it makes?

RBob

iTrader: (1)

The raw DRP count is in the ALDL data stream for $6E. Bytes 12 & 13. These are RPM unlimited and are also used for the rev-limiter.

RBob.

Ratty Vette

Sam's 383 last dyno was 430, before last refresh were he did some more porting to base and runners.

We got a chance today for some further logging, the good news is, that we have backed upped Sam's first log, and that we all the fuel we need and more with the 42's and switching to single fire mode.

We are currenty pulling fuel from the PE vs RPM, that is "pulling it back up" from command 11.5 to 12.5 to get the O2 down from 900 to more like 800mv.

Chris

Ratty Vette

Thanks RBob, didn't think to look there, even though we saw the rev limiter working @ 7000, with the G-tech.

Chris

Orr89RocZ

iTrader: (20)

Good deal, thats great to see that you have all the fuel you need now. I feel more confident in my combo now

RednGold86Z

iTrader: (1)

So it's using 42's now?? THAT's why it's rich enough. Not the single fire mode. Single fire mode is only good for about .6 ms, which is 2-4% depending on RPM for static injection. 42's are plenty for all but the most radical or huge N/A engines.