LS9 heads on LS3 block - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

nidecker · 11-18-2016, 04:33 PM

Good evening from Germany.
After my Kraftwerks supercharge install I´m now looking to exchange my stock LS3 heads for more durable GMPP CNC ported LS9 heads.
My challenge is not the fitment - that should be fine.
I´m wondering about the head bolts. LS9 needs 12mm head bolts. LS3 block has 11mm. Jegs recommends the standard 11mm GMPP bolts. But there will be obvious a 1mm difference...not sure if this is a sustainable solution...

I don´t want to re-tapp the LS3 block for 12mm.

Any suggestions from the experts?

ADM PERFORMANCE · 12-06-2016, 08:33 PM

Quote:

Originally Posted by nidecker

Good evening from Germany.
After my Kraftwerks supercharge install I´m now looking to exchange my stock LS3 heads for more durable GMPP CNC ported LS9 heads.
My challenge is not the fitment - that should be fine.
I´m wondering about the head bolts. LS9 needs 12mm head bolts. LS3 block has 11mm. Jegs recommends the standard 11mm GMPP bolts. But there will be obvious a 1mm difference...not sure if this is a sustainable solution...

I don´t want to re-tapp the LS3 block for 12mm.

Any suggestions from the experts?

We machined sleeves for our cars when we do this setup.

cc-rider · 12-12-2016, 08:48 PM

Welcome to Camaro5 from Germany! I lived in Düsseldorf from 2011-2014. Good to see some Camaro's running the autobahn's in Deutschland. Wish I was there to enjoy the Christmas markets and have a nice glühwein this time of year.

I looked into these LS9 heads on a LS3 myself. As ADM says...you either need custom sleeves or to machine the block. If you add up all the time and cost in that...there are a lot better options out there for the money. Look into some LSA heads (seen them used for as little as $700) which have a much stronger grade aluminum to them....or even go all out with something like a Trickflow GenX head with a thick deck that can really handle big boost. I suppose if you could get a reputable shop like ADM to machine you some sleeves and find a used pair of LS9 heads...that would be a cheaper option. But heads haven't been proven to deliver huge amounts of power in terms of general flow capabilities. But some of the higher quality heads certainly have allowed for a lot more boost before pushing water which has produced a lot more power. So my advice is think of deck thickness and casting quality first for boost.

Hope that helps. Auf Wiedersehen!

11-18-2016, 04:33 PM	#1
nidecker Drives: 2014 2SS/RS 1LE, Supercharged Join Date: Jan 2014 Location: Germany Posts: 16	LS9 heads on LS3 block Good evening from Germany. After my Kraftwerks supercharge install I´m now looking to exchange my stock LS3 heads for more durable GMPP CNC ported LS9 heads. My challenge is not the fitment - that should be fine. I´m wondering about the head bolts. LS9 needs 12mm head bolts. LS3 block has 11mm. Jegs recommends the standard 11mm GMPP bolts. But there will be obvious a 1mm difference...not sure if this is a sustainable solution... I don´t want to re-tapp the LS3 block for 12mm. Any suggestions from the experts?

12-12-2016, 08:48 PM	#3
cc-rider Drives: 2010 Camaro SS Join Date: Dec 2006 Location: MN Posts: 1,172	Welcome to Camaro5 from Germany! I lived in Düsseldorf from 2011-2014. Good to see some Camaro's running the autobahn's in Deutschland. Wish I was there to enjoy the Christmas markets and have a nice glühwein this time of year. I looked into these LS9 heads on a LS3 myself. As ADM says...you either need custom sleeves or to machine the block. If you add up all the time and cost in that...there are a lot better options out there for the money. Look into some LSA heads (seen them used for as little as $700) which have a much stronger grade aluminum to them....or even go all out with something like a Trickflow GenX head with a thick deck that can really handle big boost. I suppose if you could get a reputable shop like ADM to machine you some sleeves and find a used pair of LS9 heads...that would be a cheaper option. But heads haven't been proven to deliver huge amounts of power in terms of general flow capabilities. But some of the higher quality heads certainly have allowed for a lot more boost before pushing water which has produced a lot more power. So my advice is think of deck thickness and casting quality first for boost. Hope that helps. Auf Wiedersehen!