I know lots of people say the TPI is restrictive, but does that apply to the LB9 and L98 or just the L98? I want to have a good running motor, but don't want my gas mileage to decrease. Will larger runners and highflo base help, or would I need more fuel to compensate for the extra air flow that is being injected. What are side effects of these mods. Larger injectors? chips etc. I plan on removing the EGR walls in the plenum and siamesing the runners at the base. Car is a daily driver, but a little extra go would be good. I have shorty headers, and 2.5'' 2-1-2 exhaust with high flow cat

 

the lb9 and l98 have the same exact intake manifold and exhaust manifolds....so why would one...be more or less restrictive?

 

i dont think he means the actual flow numbers of the tpi intake, i think he is wondering weather the tpi is a choking point for a 305 as it is for a 350 as the 350 needs more air/fuel than the 305. i dont have the answer but i am curious myself. if i remeber correctly i read on this fourm a long time ago that the tpi was designed for the 305 and that is why it is a restrctive point on the 350

 

yeah, sorry forgot to clarify that. I did hear the tpi was originally made for the 5.0, so it got me thinking.

 

:edit: n/m

 

Yes the TPI induction set-up is marginally more restrictive on the L98 than the LB9. The soul reason being the increased displacemnet of the L98, more displacement results in the ability to draw more air into the cylinder. This is why you often see better performance response from 350's with things like Aftermarket runners etc. And yes the TPI induction was originally designed for the 305 so with a simple cam swap and headers the RPM range can get up to about 5500, not the case with the 350 as it demands more air than the TPI can flow after about 4500 RPM

 

there is a little room to grow if if you port the stock intake parts and run a 305. do a search. myself and many others have had mid 13sec 305s with ported stock intake parts. Mine trapped one of the fastest trap speeds at 101mph. Just ported stock TPI parts, headers, cam, L98 Corvette heads.