I wanted to know if I changed my cam, intake, runners, etc. would it make a noticable difference to the car? Also would I have to reprogram the computer?

thanks for the help.....

 

Yes. And to take full advantage of the cam and intake, yes.

 

Programming the ECM is best-advised for significant enough changes that it makes a "noticable difference". That said, there is a member who ran a TPIS large-tube intake, hotcam, TPIS-ported-heads, and TPIS headers w/o a tune. He did up his FP and install 24lb Ford injectors (~26 in our rails). IIRC, he upped his pressure to 50psi.

The end result was a gain of 100hp and 60ft/lbs of torque.

A superram will provide about another 30hp, a miniram another 50-60, and a 383 another 30tq/hp.

Exactly how you configure it (w or w/o long-tube headers, what cam, and what intake) make a big difference on where you end up.

There are tons of threads on this topic. It used to be the thread of the day....then the thread of the week. Things are slowing down around C4 these days, but thread after thread is still there for you to read.

 

Oh yeah....My favorite webpages for learning about the possibilities are:

"Ten Times the Torque" Shootout of 10 TPI intakes.
"Stealth that TPI" Build-up of an L98 (383)
"Welcome to the Dark Side" (website by member Vader86)

SEVERAL members like to recommend John Lingenfelter's book on building SBC engines

Whatever you decide to do, you'll easily find people willing to help you get there.

 

Yes, Yes.

The engine will run awful without a tune.



Once completed you will be very happy with the results.

 

Not only will it run awful, but it could do serious damage to your motor if the tune is off very far...Way lean can kill a motor pretty quick...WW

 

Now I asked the same question about just putting a high flow base, big runners, and ported plenum (no cam swap) and everyone said it would be fine as long as injectors and TB stay the same. But would be better with a tune. Im in the middle of the swap so im praying it all works when I race this next weekend.

 

With a MAF car you should be fine.

 

I'm guessing that the two guys above have never learned to tune, nor did they read my post(s) above. When a member does a complete cam, heads, intake, headers, injector swap, and races auto-x for two years w/o blowing up a motor, they're ignoring emperical evidence proving how extensively you can mod a motor and have the stock tune "work" for you.

This isn't to say you can do any old thing you want. You have to be reasonable about the injector-size change AND with any FP changes you make, you need to monitor the result using WB on/off a dyno.

You could say member mcr24x got lucky using this approach and it would be a reasonable statement. OTOH, you could say the MAF system is very adaptable and be just as correct.

To blindly say a motor will run "awful" lacks insight into the way the system works, ways you can fool the system, and ways you can stretch it to work when: a tune isn't desired, isn't possible, or isn't allowed. (For the member who a heavily modified motor using the stock tune, he did so in a race class where running w/o a tune provided access to a class and/or extra points. (I forgot which BUT there was a REASON.)

I've also seen video and dyno of the motor in question. The AFR was within acceptable limits for WOT AFR. I did not see scans for normal street driving, but I'll assume it's possible it's MPG wasn't quite as good as one with a perfect tune. For someone taking this approach, you always need to err on the side of being too rich vs too lean. As often mentioned, people worrying about MPG need to look elsewhere for a "hobby".

I will conclude by saying...I would never "recommend" heavy bolt-on/modification alterations w/o doing scans -- and probaby a tune. But, I would never assume what can't be accomplished without a tune. To tell others "it can't be done" would represent biased and incomplete information.

 

I agree with GreggPenn in that you don't have to do a tune with mods, but when you get a chance, a dyno tune will help get the most out of your mods.

 

Doing the work is not the problem. Tuning is because I have no idea where to go or what exactly has to be done. This is my first TPI vette. My other Vettes were C3's. Never had to deal with a computer. Could someone explain the procedure and what kind of shop I am looking for.

thanks again...

 

Any tuner shop with experience iwth GM engines should be able to help you. Maybe if we knew where you were from, someone that is from your area could chime in.

 

Northern NJ........

 

Tunes can be done remotely. Dynos can not. Any dyno can run an WB AFR check of your setup but you need an extra O2 bung (like the one where your O2 sensor is installed) to mount the wide band (WB) sensor. Shops will charge to put that in.

OTOH, people who know the setup you build can guess pretty close and you could take your chance that WOT operation is rich enough to avoid problems. You could also learn (by reading and talking to people on the net).

Computers on EFI cars can make pretty big adjustments. You just need to setup an initial BIN (electronic file) for your computer to run off of. Tuners would do that if you don't want to. The initial BIN is configured based on injector size and modeled after intake type (curves). I suspect good tuners can get really close on their first (initial) BIN.

If you want to mod your car, budget about $500 extra for tuning. You may get away with less -- especially if you're a good learner and/or find a good, knowledgeable friend as a helper (from a forum). Or, you could flat-out pay someone at a local dyno to do your tune. They would probably charge in the $500-$600 range for a tune.

You need to find someone who tunes ODB1 computers. I learned to do it myself for my 1989.

 

Well Gregg, you guessed wrong. My experience with cam changes, a custom tune is always in order.
Some run OK and others like S**t. OK, my bad. Saying awful is not completely correct.
But leading anyone on this board to believe that engine mods are OK without a tune is also biased and incomplete information. And you recovered well in your last paragraph by unsaying everything you said.

Whatever the case without a tune the engine will never produce to its potential.
And the potential for engine damage can result for those not ready to spend the time/money for a tune.

And now that I've read your posts, I "guess" your the only one on this board that has any knowledge on the subject.




.

 

Oh chit,
You are going to get Greg all wound up again.

The way I read his posts in my own thoughts.....

" Good Luck to everyone that says EFI tuning is not required with any major engine mods such as camshaft swaps, higher flowing cylinder heads, headers, ect".

The same to me as not tuning with a Carb & distributor curves on the street or track.
Results will not be optimal & car likely will not run very well.

 

I'm not riled up. I just think one sentence "absolutes" need to be absolute.

If you read the OP, he asks if a tune is necessary...not if it would be desireable. I gave an example where a heavily modified car ran fine with the stock tune. That's providing complete information -- which is better than answer a question with an incomplete absolute -- that MAY not apply to the OP's needs.

I also didn't undo what I said. I simply will not guarantee a modded car will run like chit w/o a tune...because I've seen otherwise. Talked to the owner too.

If you feel violated for communicating all scenarios, tough.