Tuning a high CR engine

[quaddriver]

Thats the hex value, not the actual spark advance. I don't refer to them as cells, but yes, there are quite a few. Using a scan tool and recording the engine data while I drive, its pretty easy to go through and modify the values based on KR and BLM/INT.

That tool is winbin, there are others but I had that one handy for posting some example pics for the tables. The range you see for the numbers is just a part of the whole thing which is shown as the chart. Most of the arrays are smaller increments til 1200, for tuning idle.

Hex would make it worse! x80 = 128 decimal! there must be a conversion that is not happening on the display....

and here is the kicker, that is a speed density system, on a MAF system it automatically works, all you have to do is add spark or fuel at higher hpms to take advantage of hard motor mods

[RacerX11]

Take the raw hex value and scale it by 90/256.

Marty

[SappySE107]

I didnt hit the "scale" button. MAF is easier to tune from what I hear. Anyway, MAP does work with engine mods, including the topic of this thread which is high compression. 12:1 has been ran on MAP.

[quaddriver]

I didnt hit the "scale" button. MAF is easier to tune from what I hear. Anyway, MAP does work with engine mods, including the topic of this thread which is high compression. 12:1 has been ran on MAP.

yes maf is WAY easier, its almost plug an play, u only have to tune if you want to exceed the norm. On my one truck (ford - yes, the evil trinity) I switched ecms and injector harnesses from S/d to MAF (ford actually makes a plug -n-play kit) to take advantage of stuff I did. the MAF gen3's should be a cake walk....

but to get back on topic...Id like to see a 12:1 660 any gen on a dyno pull at 6500..I betcha she eats herself (stipulation: not carbed, efi)

[GPXSS]

but to get back on topic...Id like to see a 12:1 660 any gen on a dyno pull at 6500..I betcha she eats herself (stipulation: not carbed, efi)

Ask and ye shall receive!
This is the printout of 3 runs that day.. most bottom end torque was produced by bumping up to a 62mmTB AND slight VE tuning.. spark at this point is completely stock. Compression was at least 12.1:1
Top end dropped off because I pulled out too much fuel.. but that was changed after the dyno run and should have been equal to if not a little higher than the other 2 runs.

[SappySE107]

Been done, to 6800 (made no power after 6 though). Still runs. I dunno if the owner will actually share it but I can find out. It still needs more tuning, since some things were changed that were causing problems since the last time I saw it.

[SappySE107]

ok, or chris can share his as well:P

[brian89gp]

Want to expand on this a little? I know in the $DF mask that there isn't a BLM cutoff till at least over 4800 and thats only because it requires a MAP/TPS reading that throws it into PE to get it spinning that fast. OBD2 might be able to detect misfires but I am pretty sure that the 727/730 on these engines could care less.

Im not sure what ur asking me...here is a *representative* sample of a breakdown of the data area in the ECM: (I hope to god this formats, else its gonna look like major shit)

What I meant was expand on this "BLM cutoff". From what I have been able to figure out the BLM plays a part in fueling at all times. It is changeable in closed loop and when you hit PE it will lock it at the current value or 128, whichever is higher. I just don't understand what you mean by this BLM cutoff.

[quaddriver]

What I meant was expand on this "BLM cutoff". From what I have been able to figure out the BLM plays a part in fueling at all times. It is changeable in closed loop and when you hit PE it will lock it at the current value or 128, whichever is higher. I just don't understand what you mean by this BLM cutoff.

ahh ok I gotcha...the BLM table is broken up into chunks based on RPM 'slices' and MAF/MAP slices, but is used for the entire range of either 1500-1800rpm on up as the same cell (well same group of cells based on MAx input) - meaning it no longer has the granularity

[brian89gp]

I see, it looses resolution above a certain RPM point cause they all get lumped together. You should try tuning a 60v6 ECM with only 1 cruise BLM cell

[quaddriver]

I see, it looses resolution above a certain RPM point cause they all get lumped together. You should try tuning a 60v6 ECM with only 1 cruise BLM cell

problem is the BLM strategy tries to maintain 14.7:1....at high rpm when motorvating you want it well overfueled...

[SappySE107]

That is what the PE fuel table is for.

[gpse3400]

Been done, to 6800 (made no power after 6 though). Still runs. I dunno if the owner will actually share it but I can find out. It still needs more tuning, since some things were changed that were causing problems since the last time I saw it.

I'm not the owner but I've assisted in the basic H.O. construction of a VIN J 3100 in an '88 Cutlass FWD. We even have a TDC transaxle installed just to make this the car work better. At the dyno I made an audio recording. After listening to the tape a number of times, driving in the car listening to the upper rpm, looking at the SHARP drop off in HP on the dyno sheet, and coversing with some sources I revere as credible, I came to the conclusion the valves were bouncing at idle and floating at upper RPM. Going back and doing some math I realise that 80 lbs seat pressure on a roller cam lifting over .500 is totally incorrect, not to mention the low open pressure. All part of the learning experiance, but still Ben got the idle program done and it always started. With the change in valve springs the engine now idles pretty nice to the point where you cant even feel it most times 128 and 128 on the dot. With better idle comes better power with a valve spring change. It feels to rev higher. We made peak power at roughly 5800 RPM. From 4800-6500 the HP was pretty flat. Torque peak was at 4800 RPM. This was all with incorrect valve springs. I therefore helped my friend out with Stiffer valve springs, and even after doing the math we can still go stronger. This is good for now. At 6600 the HP dropped like a rock, not a graudual thing most people see, it's like someone was trying to cover the intake. From what I know the engine is running a hair lean on the bottom end, and on top is rich. After the springs change I'd say it's still lean on the bottom but it might be ok on top, but without another wide band we won't really know.... As far as durability is concerned...We live in NewYork on LongIsland. We regular the Big Apple 3 times a week, and have well over 20,000 miles on this engine and when the scan tool shows no detonation on high test, it's hard not to want to rev it to 7000 often. Enough said about that. Ok maybe 3 more things, spark plugs are burning nicely, the compression tests are good, and it isn't taking on oil. You wanna talk about durability, try driving a pos Grand Prix Turbo with a closed shut wastegate. That computer will give you like 5 seconds of 25 psi fun before it kicks in....Beat a newer GTP pretty good with my wreck malfunctioning like that And the driveline is still in order. I feel pretty safe about the parts in these engines, as long as there is no detonation, and revolution past that conrod 7000 rpm mark. I have a 3400 version that will soon be in service.

[3100 MPFI]

What? Nobody has anything else to say? I am the owner of said car with high compression, and I can't thank Ben enough for tuning it. My compression is just over 12:1 (with the stock cam, it would be closer to 13:1). With all of the work that Ben has done tuning, GPSE3400 and Brian P has done with helping me out and building it, and Ben and GPXSS's suggestions, and answering any questions when I could not find an answer of my own, I have a car that drives civilized, has a lot of power, and I can confidently rev to 7,000 RPM and not have to worry about it blowing up, or dying off losing power.

There was a time when I though that Ben would not be able to get the chip tuned, and I would have to convert my car to OBD2 just to even get it to run. I also though that I would have to change out my cam thinking that mine was a little TOO extreme. Once I fixed the vacuum problems, and got it breathing a little better, Bens chip suddenly started working the way it was suppose too. Now, once I get it back together (took the engine out to fix the tranny), I am planning a trip to Ben's to get him to do the fine tuning of it (seeing that I have done a lot of work to the engine since the last time that I was there, I want it checked over again).

I have every confidence in Ben's tuning and knowledge with these engines. If it was not for him, and GPSE3400, and Brian P, and GPXSS, I would have succumbed to the evils of the 3800 series II SC swap a long time ago.

I am extremly pleased with my high compression 3100 that does not knock, or ping, and pulls to just under 7,000 RPM without breaking a sweat.

[z284pwr]

This is a rather interesting topic indeed....
I've got a question, Taylor, how difficult is it to get yoru car started? I don't have nearly the compression and have a great pain in getting it started when its warm.

Oh ya, I don't suppose you or anyone else would be willing to post up your *.bin file or the maps? I'm interested in seeing how the timing in particular looks, I just dynoed my car, with rather poor results for being a brand new motor. Its gotta have something with the tuning I'm guessing. The Haltech has a different way of doing the Fuel than the GM tuning utlities, but timing is relatively the same....well, it a way, Haltech uses a Negative and Positive KPa reading for pressure, and from what I've seen the GM only uses Positive Pressures?