I'm doing a retrofit of a 87 TPI to a 50's vehicle. What is it about the 94-95 PCM/harness from an LT1 that would keep me from adapting it to the 87 unit? It seems that with the Flash ROM it would be a lot easier to reprogram.

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It's a whole different ECM and a whole different harness. Swapping EPROM's is not really all that hard

 

I thought about using a 92-93 LT1 computer with my TPI, but I forgot about the optispark, so that was out.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

Iv'e thought about this also considering the late model lt1's are sequental computers. I remember some where seeing a optispark eliminator that only needed a crank or cam trigger. Cant remember where I saw it. Can any one else shed some light? This might be a untapped sorce if we can use the lt1 comp and maf on our cars, and use some sort of crank trigger like dfi does when you dont use a comp cont dist.

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87z 383,afr 190's, crane hyd roller(224/230-.509/.528,112 sep),Ported and polished mini ram, 24lb inj, 3.42 gears, strange 12 bolt, tremec 5spd, , 1,3/4" slp headers.(stock 305 hypercrap chip), other stealth goodies.
Runs 14's all day long.

 

Electra motive sells a crank trigger to replace the optispark.
SEFI isn't really a big deal thou it does help with really big injectors at idle.

There is just so much time to shot the fuel so you wind up using at least 85% DC, and with the intake valve only open 25% of the time fuel is just spraying against the walls of the runners anyway.

Only my 231 with 40lb/hr injectors have idle PWs of 3.2, so even batch fire I could handle it. Some of the nasties are running 72s. But, that is getting to really big HP numbers.

While atta glance the individual spark and fuel timing corrections look neat, it's just a little over kill for the home guy.

Not many guys have resolved how to use all they have at their disposal anywho.
IMO

 

Your looking at a sequential setup with a performance bias. Im looking at it because it has the ability to trim each individual cylinder instead of a blanket approach like batch fire. I am not a efi genius like alot of people are on here. And I know everyone wants to work with batchfire because thats what they have , but I get pissed off when I see a mustrag at the track running 11's and the ecm has never been touched. I have seen plenty of them. They were sequential eec4's, just like the lt1's that run like a bat out of hell with little mods and no computer work. I think adapting the late lt1 setup on our cars, if it is cheap enough, would be well worth it.

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87z 383,afr 190's, crane hyd roller(224/230-.509/.528,112 sep),Ported and polished mini ram, 24lb inj, 3.42 gears, strange 12 bolt, tremec 5spd, , 1,3/4" slp headers.(stock 305 hypercrap chip), other stealth goodies.
Runs 14's all day long.

 

An just how are you going to figure out the right correction per cylinder?.
Running 8 WB O2s gets real expensive.
There is almost an infinite number of combos., and to trial and error that would take forever.

Fords have fallen into a odd combination of tuning mods.
1st because the ecms are so hard to work with they've had to do a work around.
Meaning come up with mechanical answers to software problems. ie they can buy MAFs that are calibraated to run with a specific size of injector. So rather the $200 worth of software, they get to buy injectors and a MAF.
No thanks, I'll take the GM set up in a heart beat.
Of course you can wire up a ford ecm to run your gm efi.

 

I believe the answer to your question is egt sensors.

 

yeah, don't "professional" racers use pyrometers in each header primary tube to balance cylinder-to-cylinder A/F distribution?

 

EGT is for finding the thermal limits of the various cylinders and in a racing application that is important.
For street you'll want to be AFR correct.
EGTs are most meaningful at WOT.
AFRs are univerally important

 

Anyone with real racing experience knows the character of the small block chevy. It is beneficial to be able to control individual cylinders for economy and performance. The two siamesed exhaust ports on the small block create different traits than the outer banks. And the ability to tune them seperatly with fuel injection is not that hard for someone that can read plug cuts and knows how egt's work. And no egt's are not used only for wot. Its a shame not everyone can be an engineer but they can't. Its also a shame people have to try to argue when they feel inferior and are un open to new ideas. I think i have talked myself into using the lt1 system on my car just because people say it wont be any better. I know it can be, or chevrolet would still be using the crotch fire method.

 

So any one that comments back to anything you say is agruing?.
Geesh,
Might look a little closer for where the inferiority is..

That nonsense aside.
If all your going to be changing is fuel, then watching fuel on the exhuast is what would seem most important, that just seems logical to me. If you were worrying about distribution of fuel like with a wet manifold, and were tampering with manifold design the EGT would be a larger issue. Since this forum is EFI related and the original thread was about that, is what I'm addressing.

EGT is primarily used to avoid hitting the thermal limits of the engine, ie things don't last long with a EGT of 2000dF.

Watching fuel, is best done watching fuel.

EGTs can wonder with a constant AFR.

It's only been the last few years where there has been alot of WB usage, and like anything new, there are some tuners stuck with EGT cause that has been what has worked for them, and hence why change.

There is just so much resolution to testing that the none laboratory tuner can do.

 

I just wanted to throw my .02 and say that 87Z-ya is quite a *****. Everyone here was just trying to help, and grumpy went over the basics of limited gains vs. vast increase in complexity in using the sequential set-up. I think you said it all when you said "I am not a efi genius", thats obvious, otherwise you'd realize that the reason mustangs/LT1s run teh times they do has nothing to do with SEFI and everything to do with the rest of the combination. In the case of the mustang it's super lightweight and propensity to hook up will let completly stock long block SE car run low 12s. In the LT1 case, give anybody 10.5:1 compression, a mild EFI cam and some good flowing aluminum heads and see if they can't get it to do miracles with a balanced chassis.
If you want to make it work, fine, do it. If you want to tinker with correcting fuel for each individual cylinder, have fun. Consider this though...people who do consider themsleves EFI geniuses say to hell with SEFI in applications when it would matter a lot, like in max effort forced induction cars running mini-ram and other manifold designs that have a tendency to run lean in the back cylinders because of air piling up there. For them extra fuel would be great for those cylinders, but thinking of figuring it out makes them itch. And they have alot more to gain from it than you.
...ed

 

Hey Ed, Your one of those keyboard tough guys huh? My point was that if someone would like to try to tune a lt1 setup why should they be shut down? It has much more potential than the batch fire setup, and people are afraid of it. A light stock mustang? A 93 gt weighs in at 3400. Lx is 200 less. Is that less than a third gen? Which lt1 had a mild cam? It is a balance of parts and the sefi helps balance these cars......*****. Cant we all get along, we all just wanna go fast?

[This message has been edited by 87Z-ya (edited November 27, 2000).]

[This message has been edited by 87Z-ya (edited November 27, 2000).]

 

Just trying to save you the grief of disappointment. Your under the assumption that the SEFI is some sort of cure all when it's not. You also, went on to say that with individual cyl tayloring was an advantage. SEFI only helps slightly at low PWs. At anything over 12% duty cycle the advantage is lost. As far a tayloring ind cylinders, with out really being able to split hairs, in testing, how are you going to be accurate in tuning?.
There is a point of deminishing returns.
I've played with both, and have some idea of how things work.
If you want to go off and do it, fine, just was trying to save you time and energy.
Just also be sure to be sitting down when you start figuring the costs.

 

No i'm not a keyboard tough guy, i was just pointing out that you were being a *****. If say the 3 of us were in a bar (you, me and grumpy) and you were talking about the idea of using SEFI and grumpy outlined why it isn't worth it, and you started spazzing about how LT1s and mustangs go fast easy and they have SEFI, i'd still call you a *****. Then we'd calm you down and slowly go over it all again.
As to what you said, yes a mustang is light compared to a thirdgen. And near stock mustangs that run really fast have been lightened even more. I used the SE (stock eliminator) example cuz it perfectly illustrates the point of how they go fast.
And as for the LT1s, ummm, all of 'em had mild cams. In case you didn't know, all SBCs have cams, and LT1s are no different. With ~207/213' duration, the LT1 cam qualifies as a mild performace EFI cam. Coupled with 10.5:1 compression and good flowing aluminum heads and of course it makes power. SEFI has little (make that nothing) to do with it. Did i blaspheme and say it did nothing, yup, cuz a 93 F body LT1 made 275 HP, with batch-fire, EXACTLY the same number as in 94 with SEFI.
Anyhow, noone is trying to stop you from your project, it's a neat idea. But considering how little you obviously know, you're gonna sure have some fun.
...ed

 

Guys,

Ease up. Let it go. I want to keep this post alive but if there is another negative post I will have to lock it. I'm pretty forgiving in terms of what I allow here. I'd like to keep it that way.

Tim