Who has LSX-427 Heads

[calbert1999]

Looking for LSX-427 heads for reasonable prices.

Found these

GMPP LS7 heads: $1043 (bare)

http://www.superchevyperformance.com...p/12578450.htm

MAST Motorsports: $1400 (bare)

http://www.mastmotorsports.com/2010/... - Bare&id=359 (Not sure what's the benefit for an extra $400)

All Pro -2 (I'm expecting these will be too expensive.)
http://www.proheads.com/products.html

I'm thinking the most realiable are probably the GMPP parts, 2nd. I like the MAST but can't justify the extra $800 p/pair. All Pro seem to have the best flow numbers at over 400 CFM, but not sure if their over-price will be worth it.

I'm planning a forged 427 LSX build, might use existing heads but thinking might be a better idea to use the machining expense to simply purchase the LS7 6 bolt heads now rather than making that change in the future. My goal is to get about 700-800rwhp. with ProCharger installed using anywhere from 12-16psi. of boost.

[mike25]

I think ive heard more than a few say they arent worth it..but i do believe there is a person on here who has..just cant remember which thread i saw him post in.

[HufferSS]

Originally Posted by calbert1999

Looking for LSX-427 heads for reasonable prices.

Found these

GMPP LS7 heads: $1043 (bare)

http://www.superchevyperformance.com...p/12578450.htm

MAST Motorsports: $1400 (bare)

http://www.mastmotorsports.com/2010/product-view.php?cat=Cylinder Heads - Bare&id=359 (Not sure what's the benefit for an extra $400)

All Pro -2 (I'm expecting these will be too expensive.)
http://www.proheads.com/products.html

I'm thinking the most realiable are probably the GMPP parts, 2nd. I like the MAST but can't justify the extra $800 p/pair. All Pro seem to have the best flow numbers at over 400 CFM, but not sure if their over-price will be worth it.

I'm planning a forged 427 LSX build, might use existing heads but thinking might be a better idea to use the machining expense to simply purchase the LS7 6 bolt heads now rather than making that change in the future. My goal is to get about 700-800rwhp. with ProCharger installed using anywhere from 12-16psi. of boost.

I thought, according to your old sig, that you had over 700 hp on 8 or 9 psi already....?

[calbert1999]

Originally Posted by mike25

I think ive heard more than a few say they arent worth it..but i do believe there is a person on here who has..just cant remember which thread i saw him post in.

Let me know if you recall who. In my case with a new LSX 427ci. forged engien it may be more feasible to purchase LS7 heads than to machine the existing heads to all new parts on a new block. Probably not much to gain on an LS3 to simply purchase new heads to get minimal HP gains, but on a new engine and lots of boost definately worth it.

Originally Posted by HufferSS

I thought, according to your old sig, that you had over 700 hp on 8 or 9 psi already....?

Yup that's right and that was just the tip of the iceberg, had to dial everything down as much as possible and still made 680rwhp.
Now forging and stroking to a 427ci. had planned to do it over the winter, but LS3 internals couldn't hold the power so doing next project much earlier than I had planned.

[HufferSS]

Originally Posted by calbert1999

Let me know if you recall who. In my case with a new LSX 427ci. forged engien it may be more feasible to purchase LS7 heads than to machine the existing heads to all new parts on a new block. Probably not much to gain on an LS3 to simply purchase new heads to get minimal HP gains, but on a new engine and lots of boost definately worth it.



Yup that's right and that was just the tip of the iceberg, had to dial everything down as much as possible and still made 680rwhp.
Now forging and stroking to a 427ci. had planned to do it over the winter, but LS3 internals couldn't hold the power so doing next project much earlier than I had planned.

Ok...but if you had 700 on 8 psi...why would you need to run 12 - 16 with a 427 to get the same power.....?

[CC Performance]

All Pro's are the real deal I run them on my car, they do make more power than ported LS7 heads

[calbert1999]

Originally Posted by HufferSS

Ok...but if you had 700 on 8 psi...why would you need to run 12 - 16 with a 427 to get the same power.....?

Compression will not be the same we'll use 9.1:1 on the LSX (LS3 is 10.7:1). We'll use more boost to compensate. Most likely will end up with approx. 800rwhp. or more. The difference is the LSX427 will be built from the ground up to handle boost (without concerns of breaking), the LS3 is not.
Also, TQ at low RPM will be through the roof this is another advantage of higher displacement, less compression, on higher boost, and forged internals.

Originally Posted by CC Performance

All Pro's are the real deal I run them on my car, they do make more power than ported LS7 heads

Yeah. I really like the All Pro heads, but they're very pricey compared to the GM heads and most likely more than what I need.