basically trying to understand the tech behind some of these tpi motors as im soon to aquire a 1989 iroc-z with a tpi 305 (lb9) and a 5 speed.

heres the questions

1.) whats the cam spec of both the 220 and the 230 hp engines
2. how do you know if you had the factory 220 or the 230 hp engine, not sure if the 230 was only on the dual cat style exhausts, can't quite understand that in the tech article.
3. were these cars factory equipped with a one wheel peel or did they come with factory posi?
4. are these speed density or maf?
5. can i add the edition of 1.6 ratio full roller rockers, an airfoil, k&n filter, headers, a catback, and a the 350 sized injectors and still have this thing run well or should i plan on chip tuning before i've done these mods (suspect this has a lot to do with if its sd or maf).

any other info you may have would be great!

 

The tech articles should help with 1,2, and possibly 3.
4 - i'm not sure if the change from maf to SD happened in 89 or 90. I think 90.
5 - None of those require chip tuning except for the injector size change. Computer tuning, no matter what, if done correctly will be well worth the money invested.

 

Well, I cant answer all your questions, but I can atleast knock out a few...

2. The 230hp came with the dual cats, the 220 is the single cat.
3. Some came with Posi, check your RPO codes
4. Yours will be MAF, the SD only came on 90, 91 and 92; all 89 and earlier are MAF
5. Not sure about the rockers, but airfoil, filters, headers, and cat-back can be done and still have it run good, injectors may need re-tuning your chip

Sorry I couldnt help more, but atleast it is a start.

-Tim-

 

great thanks guys that answers most of my questions, and yes i will get in to chip tuning i plan to buy the stuff when i get the new car, i just made not have it down super quick as i dont have any1 local to teach me (more of a hands on guy).

Basically i just wanted to make sure it wouldnt run like complete *** from a few minor mods.

 

If you want to add 1.6 rockers you will have to elongate the pushrod holes in the heads.

 

re you sure??? I did this on my 1992 l03 with a realy nice gain for the half an hour work i put in it.

I cant imagine these heads being much if any different ateast in terms of the push rod holes, it seemed on my other head they were plenty big wio clearence issues.

more info on this subject wuld be greatly appreciated (anyone)

 

From what I've read here about elongating the pushrod holes, it's a total case by case basis on whether you'll need to or not. Lots of people have put the 1.6's on without elongating the holes, but I've also seen other people say they had to elongate them. One knowledgeable poster a while back said to go ahead and just run them, then pull the valve covers after a couple hundred miles and check the pushrods for tell tale rub marks. If there's no abnormal shiny spots on them, then you don't need to worry about it. On the cam question, I'm pretty sure all the tpi motors in 89 used the same cam. On the earlier ones (around 86), the manual tranny cars got the better cam, and the automatics got the infamous "peanut cam". An 89 is definitely a MAF system, and the good thing about that is the fact that you can do more mods without having to worry about tuning the chip. Like the other poster said, if you change injector size, that would require some tweaking of the chip to run optimal (i.e. changing the injector constant setting in the prom). The other thing that would require chip tuning would be if you upgraded to a lot bigger cam than stock. Outside of those two mods, just about any other mod, mainly talking "bolt-on" ones, won't cause any major issues with the MAF system.