What's the difference between 305 n 350 TPI? - Third Generation F-Body Message Boards

lameusername · 09-03-2009, 12:30 PM

I don't know much at all so I'm asking for you're help.....I've always heard more fuel + more air = more power. With that said, I wonder what's the difference between the 305 TPI and the 350 TPI. I'm wondering if I can put a 350 TPI in place of my 305 TPI? If so, what am I going to run into, what would I need to buy?? I think I'm good with replacing what I can for more air as far as a bigger throttle body, k+n air filters, hooker headers with 3in collectors, 3in cat back with 3in duals in the back.....I do plan on doing the vortec L31 heads if that helps. Thanks. By the way, it's the 1986 305 TPI Iroc. Just to note incase someone brings it up, I am keeping the 305. I plan on being dynamite in a small package. Once again, thanks!!

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TPl383 · 09-03-2009, 12:34 PM

You will want bigger injectors.
and a different chip for the 350.

okfoz · 09-03-2009, 02:26 PM

Pretty much they are the same, the difference is obviously the combustion chamber size, the 350 has a slightly larger diameter for the extra 45ci. Some of the notable differences is they used a different knock sensor, and believe it or not depending on year they actually used a different positive battery cable, I think the LB9 & L98 used the same cable from 1987-1990 (year for year), but in 1991 & 1992 they actually used different part numbers for the cables. The other obvious change has been mentioned that the injectors are different for the 305 & 350. Many people have done the swap...

Your chip would probably work for now, but to get the full potential you would probably want to either A) program one yourself, or B) have one made.

John

lameusername · 09-04-2009, 10:23 PM

Thanks for the info guys now I think I have enough to go on for now.