Turbo heads
Can't you get LT1 AFR's that are pretty good? I'd look into a set of those maybe with bigger combustion chambers than stock if you need to work on your compression, and plan to run a lot of spring pressure.
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From: Twin Cities
No one has answered his question..
I'd guess that port volume can be increased over N/A heads. The heads I have on my truck flow decent numbers @28 inches of water but out flow the best heads out there when the flow bench is turned up past 28"'s 
Would the heads meant for a turbo car be ported any different than heads designed for a N/A setup?
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Yes, they would be in an ideal world. The I/E flow ratio would be skewed to favor the exh ports over that which a set of heads intended for a NA or supercharged application would shoot for. The chambers sometimes are modified differently as well - it all has to do with the exh. flow "resistance" & tremendous heat a turbocharged engine sees, that a NA/supercharged engine never has to deal with.
The heads would also be "built" differently for a dedicated turbo application as well - valves, guides & seats all have specific wants, specs, & materials to live with the heat a dedicated turbo engine makes - and it goes without saying that the cam timing for a turbo'd engine is completely in it's own world as well
NA & supercharged engines heads are built essentially identical - turbos aren't.
The heads would also be "built" differently for a dedicated turbo application as well - valves, guides & seats all have specific wants, specs, & materials to live with the heat a dedicated turbo engine makes - and it goes without saying that the cam timing for a turbo'd engine is completely in it's own world as well
NA & supercharged engines heads are built essentially identical - turbos aren't.
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So should I opt for a different valve size other than the fairly standard 1.600, 2.02 valves?
Also what has to be different about the seats? Would a five angle valve seat be sufficient?
Also what has to be different about the seats? Would a five angle valve seat be sufficient?
Is there any difference between OEM and aftermarket LT1 castings, in terms of deck thickness? If so, and if it's significant, I would go aftermarket. I don't anything about valve sizing, but I'd at least go 2.02/1.57.
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Originally Posted by TurboZ28
So should I opt for a different valve size other than the fairly standard 1.600, 2.02 valves?
Also what has to be different about the seats? Would a five angle valve seat be sufficient?
Also what has to be different about the seats? Would a five angle valve seat be sufficient?
5 angle would be good, but a good race engine shop can do a full-radius valve job.
AFR decks are thicker than stock LT1.
Mike
Maybe this question is better suited for Advanced Tech, but which is more preferential: a smaller combustion chamber on the heads w/ a deeper dished piston, or a larger combustion chamber w/ less dished pistons? For example, if you're shooting for the same compression ratio e.g. 8.5:1, which is the better way to go? I'm planning on running a turbo on the stock short block for a while while I save up for a built bottom end, so I'd hate to spend much money on a set of LQ9 heads to lower the compression ratio now if I'm gonna have to turn right around and buy another set of heads for the lower compression,forged bottom end. Any insight on the subject would be greatly appreciated.
Great question. I always thought the less the dish the better but then again we really don't have access to more than 72cc heads. So maybe it does not matter. I have heard of folks mirroring the pistons to reduce the potential of detonation.
Originally Posted by FUroundeye
a smaller combustion chamber on the heads w/ a deeper dished piston, or a larger combustion chamber w/ less dished pistons? For example, if you're shooting for the same compression ratio e.g. 8.5:1, which is the better way to go?
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From: Boise Idaho
Originally Posted by Pro Stock John
Is there any difference between OEM and aftermarket LT1 castings, in terms of deck thickness? If so, and if it's significant, I would go aftermarket. I don't anything about valve sizing, but I'd at least go 2.02/1.57.