Ideal Turbo heads
06-11-2006, 08:02 PM
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Ideal Turbo heads I've been doing some research, and I don't want this to turn into some HUGE debate as many of other threads have. Lets put money and all other variables aside. What would the ideal heads be for a 391 LS2 with a T88 turbo?
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06-12-2006, 04:29 PM
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I'm putting cnc ported AllPro heads on my little 8.25:1 348ci LS6 block. Points to consider:
-Aftermarket heads have thicker deck, better clamping surface
-Some are designed better than stock, and don't break through anywhere, like the roofs of the runners.
I'd go with aftermarket heads if you are trying to make some serious power, but stock ported heads have made 500-900rwhp a number of times. My current 6.0 heads have made 754rwhp.
-Aftermarket heads have thicker deck, better clamping surface
-Some are designed better than stock, and don't break through anywhere, like the roofs of the runners.
I'd go with aftermarket heads if you are trying to make some serious power, but stock ported heads have made 500-900rwhp a number of times. My current 6.0 heads have made 754rwhp.
06-12-2006, 04:35 PM
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There Stage 2 ported ls1 heads on the 391 LS2 now... flowing 305cfm @ .500.. I'm just reaching for a little more. I don't know what would be best for a 391 LS2 w/ a 4" bore... I'm looking at a set of All Pros right now PSJ. They flow 332 @ .600. Whatcha think PSJ?
06-12-2006, 09:09 PM
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Originally Posted by Pro Stock John
Better flowing heads = less restriction = more power made on motor = less boost = more total potential = whatever you want to do 
06-12-2006, 09:44 PM
#13
Originally Posted by MrDude_1
the ideal head would produce zero boost since it poses no intake restriction.
But back to the topic, Vizard recommends that turbo, supercharged, and nitrous motors increase the exhaust valve size as much as possible. We've been able to fit a 1.625" exhaust valve in Chevy heads without changing the seat.
Mike
06-13-2006, 03:20 AM
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Originally Posted by turbo'd stang
I'm going to using the ET245's on a 396 with an 88. IMO, that would be a really good head.
06-13-2006, 02:11 PM
#17
Originally Posted by engineermike
Not so. If your heads pose zero restriction, you still want to fill the cylinder at BDC with compressed air. In fact, a fully tuned NA motor can get as much as 3 psi positive pressure in the cylinder at BDC before compression. If your heads and intake are tuned well enough, imagine running 18 psi boost in the plenum, but getting 21 psi pressure in the cylinder!
But back to the topic, Vizard recommends that turbo, supercharged, and nitrous motors increase the exhaust valve size as much as possible. We've been able to fit a 1.625" exhaust valve in Chevy heads without changing the seat.
Mike
But back to the topic, Vizard recommends that turbo, supercharged, and nitrous motors increase the exhaust valve size as much as possible. We've been able to fit a 1.625" exhaust valve in Chevy heads without changing the seat.
Mike
ok, zero boost IN THE MANIFOLD... (pressure is always relative anyway...)
and if you want to think about it that way.... i take back my statement anyway... the ideal head would have infinite vacuum, (or absolute vacuum, depending on how you want to think of it) because it would be cramming all air into the cyl.. not wasting it in the head.
06-13-2006, 04:31 PM
#18
Originally Posted by MrDude_1
ok, zero boost IN THE MANIFOLD... (pressure is always relative anyway...)
and if you want to think about it that way.... i take back my statement anyway... the ideal head would have infinite vacuum, (or absolute vacuum, depending on how you want to think of it) because it would be cramming all air into the cyl.. not wasting it in the head.
and if you want to think about it that way.... i take back my statement anyway... the ideal head would have infinite vacuum, (or absolute vacuum, depending on how you want to think of it) because it would be cramming all air into the cyl.. not wasting it in the head.
I think what you're really trying to say is that an ideal head/intake/cam would at minimum get the same pressure in the cylinder at BDC intake as what's in the intake plenum. In other words, if there's 20 psi boost in the plenum, then ideally, you want 20 psi in the cylinder too.
I wonder if we can use ram tuning to achive a greater cylinder pressure than boost pressure??? You can NA, but I'm not sure if we've optimized ports, runners, and cams for the higher density and mass flow rate of a boosted engine.
Mike
06-13-2006, 04:40 PM
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If I was you I would use AFR 225 heads for your engine, the 3/4 inch head deck on these puppies guarantees that they arent going to blow under extreme pressure. They run cooler than factory castings because of there greater mass.
