In the process of deciding a path for my motor build, my 88 IROC-Z Camaro with the L98 350TPI is due for a new motor. Trying to figure out how to squeeze every bit of power out that the stock computer will allow. I am wanting to use my block so the car remains "matching numbers". I have seen in a few places that aftermarket manufacturers make a big deal out of their products being stock computer friendly or modified computer friendly, what systems does our computer control and what are the limitations of the stock computer to adapt to different parts. Cams are where I started to notice that verbage, but id like to know if I stroked my bottom end to a 383 with a comp cams "stock friendly" cam, cleaned up my stock heads(hot tank, valve job, ect.) and put my stock TPI intake setup on top, would the computer be able to compensate for it all? my limited understanding of our systems is that it pretty much reads oxygen in and O2 out to adjust the fuel/air mixture in the combustion chamber. That's why I don't understand how a cam swap can affect it that much. I did try searching for the answers prior to posting this, but my boolian logic must be a bit rusty.

 

Stock ECM can be tuned to run almost anything ( within reason ) depending on the quality of the tuner

"Computer friendly" relates to the LSA / overlap of the cam.
Recommended LSA for EFI is 112+ , a good tuner can get 110 to run
The more overlap on the cam ( lumpy ) , the more raw fuel goes out the exh at idle ;as you note the ECM reads the O2 in the exh to control the fuel so the excess fuel
in the exh ( more fuel / less O2 ) screws with the ECM making it think the engine is lean so it dumps even more fuel in
Eyes watering at idle is a common comment on here


Works but as the TPI was designed for a 305 you would be leaving Hp on the table

 

ok, im starting to get a fuzzy picture on this, thank you for your time, I know that the stock tpi set up would leave a lot of potential to be had out of a 383 setup, but as always budget constraints leave me with few other options for the time being. perhaps start with this setup and switch to another such as a stealthram or something later. I still would think however that an essentially "de-tuned" 383 with the stock TPI intake would show better numbers and performance than a bone stock L98 350 rebuild(such as a long block from ATK with my intake on it). now as far as tuning goes, as long as that LSA on the cam is one of the "comp friendly" ones, would I be fine to go the 383 route without a tune?

 

The First question that needs to be answered is ;

1. What is your Budget?

Second,

2. What will you be doing with the car? Driving it everyday? Cruising on the weekends? Hitting the dragstrip every weekend? Road Racing?


Then you can Start to put together a list of parts that will work together to meet the goals of 1 and 2.

 

roughly 3 grand at a stretch, and I'm looking for a street drivable road course car, weekend cruiser with a bad attitude I would be excited if the 383 half step were possible, get me going at least till I can get the funds for a different intake setup and computer tune. doesn't the tune effect the transmission as well?

 

I don't know what a 383 half step is?

No the tune does not affect the transmission. Your 700R4 is controled by the TV cable.

My suggestion,
Rebuild your shortblock. Speedpro hyperutectic pistons. Reuse stock crank and rods after machine shop checks them. Vortec heads, vortec tpi base, slp runners comp 08-502-8 cam. Good headers and catback.

Get a tune.

This will give you what you want and stay in your budget.

 

I agree with what Johnny is saying too. Look into the vortec route. VERY good bang for the buck.

Also, I think that "numbers matching" kinda goes out the window once you stroke the cubes out to 383. It's a collector/originality thing. To a collector, the cubes are just as important. Now having it rebuilt and cleaned up to .030, I could overlook. "Basically" still stock, but a 383. Nah, do as little as possible, or store it and buy another block to stroke.

 

Once you deck the block, you loose the numbers matching feature anyway.

 

what I meant by the half step was stroke the bottom end, freshen up my heads and put my stock TPI setup on there.

what are my options as far as a tune goes? is it an off the shelf thing or what?

 

Do you have part numbers and or a build sheet for this route?

 

Dude, we have some 355cu in SoCal that will smoke the combo you're trying to build. You are going about the wrong way. Stop, think and listen to these people for a minute. You dont need to build a 383 for what you want to do.

 

Ok so walk me through the 350 or 355 route, punch the block out .30 over, use my crank and rods if they are in good shape (maybe lighten the rods), new pistons(what kind of compression ratio increase are we talking with the machine work on the block?) Comp Cams PN222009D (262/264dur .450/.480lift) will put a cam lifters and replace most of the inners of the stock heads, hot tank and replace the rest of the components in the heads with new stock pieces, I've already ported and polished the intake, runners and plenum, upgrade my injectors and call it a day.

I can afford realistically to go this route.

I push for the stock computer settings only because of where I am in Nevada I'm not sure how available a reputable shop with a dyno, tuner, and tech will be.

 

So, your saying whats the max you can run with a Stock Tune? Not just a stock ECM?

Stock tune will limit your cam choices even more.

Speaking of cams, I could not find anything to match that part number.

 

Last I heard, this was the biggest "ecm" cam...

http://www.summitracing.com/parts/crn-104224

 

its a Comp cams piece sold by classic industries comes up on their website, but I found it in their catalog(about two years old now) and yes, without tuning basically just replacing mechanical parts to increase performance.

 

Your stock 88 ECM system has enough automatic adjustability to get you by for most of your driving situations.
You can monitor your fuel trims with a scanner/datalogger to be sure,
and/or watch your actual AFR by installing a wideband O2 sensor.

It is very likely that once your system develops significant positive BLMs (fuel trims) for loaded ranges of your driving, these will be added to your stock Power-Enrichment fuel and be more than enough to cover waht your stock TPI and heads will flow at WOT.
If not, then you can see this by watching a wideband O2, and you can often compensate if necessary by increasing your fuel pressure via an adjustable fuel pressure regulator.
These measures should get you by until you upgrade the other parts and can get the ECM re-tuned properly.

 

Unless you have a great machine shop


OP you wouldn't believe what my stock chip is runing.

 

TTOP350 - i'm curious what your stock chip is running. i've got an 87 350, that we are fixing to basically make a zz4. cam, intake, heads, exhaust. WE aren't sure how much tuning we will need. I'm MAF not MAP, and supposedly they adjust better.....

 

Anytime you make major modification, you need to have a custom chip made. Even with a MAF car. It's going to run lean in the high 14.0 A/F ratio.

 

A custom chip is truely needed.(and will be for me this spring)

I have a stock chip running a 400 stroker, miniram, afr 235s, solid roller, 11.5-1, long tubes. (with only 24lb injs) 51-2fuel psi.
I have run it semi hard but not hard enuff to melt it down. The car drives very nice during normal operation.

 

Care to share?