Friends,
I just completed reading Jason Scott's book "How to Tune and Modify your Camaro 1982-1998".

found here.. http://www.amazon.com/exec/obidos/tg...books&n=507846

It's a pretty good book, but it raises some questions for me.
I have a 1987 IROC Z/28 with a 305, 5 speed and TPI MAF system, this is a dedicated RACE CAR, and it is NOT street legal. TRAILERED....

According to what I read in the book, these MAF systems can be easily improved by just shoving more air at the TPI intake. There are a few more mods but most of all, he suggests that shoving ALOT of cold air down the engine and opening up the exhaust ALOT will significantly improve the performance. Is this right? Does the ECM 'learn' and add fuel to keep the AFR constant? Less benefit from PROM burning than just air?? sounds reasonable, but I am not sure..

So, I have been reading the groups here for a while, looking into some CHIP modifications and such to improve my car's performance, and now it turns out that I should just open up the intake and open up the exhaust and go racing (SCCA SOLO2)

What are your thoughts? You are the experts, eh?

(obviously, i need a few small bolt ons, listed below)
1) 160" therm $15 bucks
2) increased fuel pressure $90 bucks
3) new higher flow injectors $100 bucks??
4) K&N Filter and forced fed filter system (homemade with flexi-tube) $70
5) Gut the CATBACK brick to make it free flow $FREE
6) Buy a TPI Airfoil. $49 bucks

So, what are the thoughts of the 3rd gen engine masters? should I proceed with my plan in the off season? It won't cost alot of money to hop this up a bit, but I want to make sure that I understand MAF systems. I should focus on steps 1-6 above rather than chip burning, right?

Brian
#18, E-Street Prepared Atlanta Region SCCA.

 

You can do those six items and waste your money. The stock Maf flows at 450/475 cfm Max and thats what the ecu calutates on. I have a Wells SU-145 Maf that flows 750 cfm and a different chip to take advantage of the increase
(results maybe 15 Hp by my last dyno test.) So I would look into chip burning & Wells Maf instead of your choice of bolt ons.

 

Forget the Airfoil also,you want to put more air then you'll want to go to a bigger TB,which most of them already have this feature built in. The airfoil dose'nt help much anyway.

 

i also have an 87 iroc with a 5 speed but sadly its a carburated 305, i'll be doing an engine rebuil in spring and i'm going to convert to tpi, so i did a little research and discovered that tpi systems come in two forms, speed density and mass air flow, difference being speed density calculates air flow based on manifold pressure and engine rpm, its basically guesswork, and mass air flow actually measures the mass of air going on

down side to mass airflow is the mass air flow sensor, crappy arflow, and the stock sensor becomes more inaccurate as the air mass increases, meaning, if it was boosted in anyway,. the maf wouldnt read all of the air and the engine would run lean

speed density's downside is that any engine mod and the computer need to be recalculated

if u have the high flow maf sensora good exhaust system will free up some horsepower and requie no modification to the compuer

 

I'm going against the grain here and saying that the stock MAF system is pretty damned adaptable. I've personally taken a ported stock MAF well beyond 400HP without "maxing it out" and pegging the annoying 255g/sec programming limit in the ECM (now THAT's a limitation!). On a little 305 that isn't going to be making anywhere close to 400HP the MAF will be a LOT more forgiving of changes/improvements to the basic breathing characteristics of the engine. Don't expect it to give you perfection, bit it's a lot more forgiving than later speed-density systems are when it comes to tuning a non-stock application.

If you are doing more than basic bolt-on upgrades you are STILL going to be giving up power if you don't have a custom chip programmed for you. MAF systems aren't magic. And the ECM STILL has pre-programmed fuel tables that it starts from and then TRIMS based on MAF readings. It doesn't just read the MAF and throw in fuel based on it's reading.

Near as I can tell it's basically true that the TPI engine will respond to increases in it's ability to inhale an exhale freely just like any other engine. It's only when you start changing stuff INSIDE the engine that the ECM programming starts to get outta whack.