Grants89iroc-z

I have a 350 Tpi engine in my iroc, but with 305 heads, injectors, and computer.

Im wondering what the power difference would be if i installed iroc l98 heads, injectors, and computer. Would the power difference be minimal? or would it be a big notice in power?

Thanks guys, hope to get some helpful answers!

watajob

iTrader: (29)

The 305 heads are great for compression. Flow, not so much. Injectors are marginal. Would probably be OK with an AFPR on a stock engine. And a 350 memcal would certainly help it's performance. Just my 2 cents.

Grants89iroc-z

how much of a difference would all this be? if i went to the junkyard and picked up some l98 heads, injectors and memcal. Would it be like a big difference? like what? .3-.5 faster?
My engine chokes out wayy sooner than it should. i shift at like 4500 since i stop making power at 4000. i know its the intake but heads and injectors should let my power band last a little longer. I raced an 08 sentra se-r spec-v and was head to head with it. Its a 4 cylinder!! i should be blowing it away!

vette9190

iTrader: (2)

unless ur rebuilding and porting those heads don't expect much. I am running ported 305 heads on my 350 with the portwork they actually outflow stock l98 heads. Mind you I also put larger valves in them which is the only rreal difference in the heads a 1.84 intake to a 1.94 intake valve. the injectors won't make much of a difference unless ur are really old and worm out. consider that they used to use the same injector on both engines. I don't no what year they canged but my 91 that i put a SD TPI on would not run the 350 with the 19lb 305 injectors. i went with rebuilt 24lb injectors. also the memcal won't do alot either. I f you wnat to mess with the chip you should just start burning ur own. If you do do the heads injectors memcal staock from a l98 i doubt you would notice much of an improvement

F-Body Demon

iTrader: (1)

What is the casting number on those heads you got on there now, they may be close to L98 heads. Which to be honest are nothing to write home about really, the L98s that is. In a stock form the L98s would be cutting out at .5 @ 190ish which really just stinks. But if you have a set of heads on there now that is close well then you dont really have to worry about that do you.

Next the injectors, 19lb injectors may be a bit small for the engine but not much. Nothing an AFPR couldn't fix. And to be honest an AFPR is a good decision just because you will most likely be using one further down the road if you decide to stay with TPI so I say you have a good opportunity to invest here.

Lastly you mentioned your memcal. I would call up the guys at PCMFORLESS and they should be able to burn you a custom chip for the car for $200 (at least thats what I paid 3 years ago) and I picked up 20 hp from that chip alone. Make sure you know what size camshaft you have, the flow numbers on the heads (should be able to pull down some rough numbers off line), initial timing, fuel pressure and injector size etc etc. That will all help them help you.

GOOD LUCK!!!

Grants89iroc-z

so you guys are saying that there wont be much of a difference??
Ive got a 350 with a t5 behind it, and the 350 is no faster than my 305 was!

Chevy8588

iTrader: (1)

ok first off im going to say thath there is some mis information here, get the memcal and L98 injectors, l98 injectors are 22 lb, and lb9 injectors are 19lb. also im going to go out on a limb here and say you probably have swirl port heads? if so ditch them, if you have 305 tpi heads? ditch them too, your car is sluggish because your PROBABLY running lean, now mix running lean with the higher compression of the 305 heads and you're going to get pre-detonantion, so the knock sensor is probably dumbing your timing down, making you hit the wall. get the 350 parts! you can't take all of the parts that fueled the 305 and only increase the displacement and expect to make more power, and anyone who thinks that is quite dumb, theres a reason why the 305 only put out 230 at it's PEAK stock form and the l98 pounded out 225-245 across the board

Grants89iroc-z

hey man, i totally agree with you saying 305 parts on a 350 was dumb..
I had a shop install my engine, and basically all they did was get a short block 350 and install all my old 305 parts! it pissed me off!

ploegi

Isn't the knock sensor different between the 305, and the 350 as well?? I seem to remember something along those lines... (although, my memory isn't exactly the best. )

Grants89iroc-z

yes it is different, i made the mechanics who built my engine install a 350 knock sensor since my 305 sensor took a crap

vette9190

iTrader: (2)

Actually alot of parts from the tpi motors are the same. And the only difference from the 081 and 083 heads are combustion chamber size and valve size. The heads themsevles flow almost the same in stock form. I had my 305 tpi heads fitted with larger valves and ported them. They now outflow stock L98 heads and give me a bump in CR. I doubt I could get L98 heads to perform anybetter. Thats why I am svaing for vortecs right now.
Again those l98 heads unless ur replacing the swirl port heads won't make a big difference in power. Like I said before you won't see much of an improvement replaceing the stock stuff with stock stuff. I wouldn't waste the money on 22lb injectors. They will work but i would go bigger inorder to accomodate future mods also you don't need the whole memcal just a chip for it. I burned all my own chips for my car, I use the stock memcal for a 305 and just changed the settings for engine size and injector size in the chip. I have seen more gains out of burning my own chips then anything else. I would say screw the heads unless they are swirl ports and save up for a good set of aftermarkets. Then get some 24lb or 26lb injectors and chip burning equipment. educate urself thru the DIY Prom section of this board and go from there.

Chevy8588

iTrader: (1)

im also going to go out on a limb her and guess they used your old peanut cam too, a short block probably wont come with a cam installed in it. in which case the injectors and cam are your BIGGEST concerns., also i would DEFINATELY get the 350 memcal, i doubt he knows how to burn proms and probably doesnt want to get into it, the 350 should outperform any 305 (except mine :P) anyday

Grants89iroc-z

hah well i should have the l98 cam if they did take my old cam, about the prom burning..i am VERY interested in it, and have been doing a lot of research on it before i started this post! I dont know too much about prom burning yet, but ill get there!

Chevy8588

iTrader: (1)

if you had an l98 cam in your old Lb9, yes you should, if your had an lb9 cam on the other hand, your running a 305 cam then