TPI heads?
Thread Starter
Supreme Member
Joined: Sep 2001
Posts: 4,231
Likes: 1
From: Manassas, VA
Car: 89 Formula Firebird
Engine: 305 - Demon 525
Transmission: 700R4
TPI heads?
Somewhere I hear if you are converting from TBI to TPI you need different heads. What
Well my car needs better heads anyway but thats a ways down the road. Could this be true?
Well my car needs better heads anyway but thats a ways down the road. Could this be true? 
Supreme Member
Joined: Jan 2001
Posts: 4,415
Likes: 2
From: Surrey, BC
No. The TPI heads use the 416 heads and the TBIs use the 187s...the 187 heads have cast in swirls and valve shrouds. I dont think the 187s will really have a big effect on the TPI so you could stick with the L03 heads for awhile and be fine.
Junior Member
Joined: May 2001
Posts: 90
Likes: 0
From: Brighton, MI
Car: 89 GTA, 89 Formula
Engine: L98, LB9
Transmission: Auto, 5-Speed
Redbird,
Are talking about heads for your 305 or for a 400? If you're talking 305, you may want to consider a set of the L98 Vette / ZZ4 aluminum heads. The combustion chambers are the correct size, they have bigger valves, flow better, and are lighter than what you have now. I'll be putting a set on my car in the coming weeks. Horsepower gains? Don't know for sure... 10, 20, 30? Maybe someone has dynoed this combo before and after.
Good Luck.
Are talking about heads for your 305 or for a 400? If you're talking 305, you may want to consider a set of the L98 Vette / ZZ4 aluminum heads. The combustion chambers are the correct size, they have bigger valves, flow better, and are lighter than what you have now. I'll be putting a set on my car in the coming weeks. Horsepower gains? Don't know for sure... 10, 20, 30? Maybe someone has dynoed this combo before and after.
Good Luck.
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