L92 heads + boost
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Teching In
Joined: Oct 2008
Posts: 20
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From: Kitchener Ont Canada
L92 heads + boost How would a set of stock L92 heads flow on a LQ9 6.0L block that has been bored out to 6.7L with twin turbos?
I've read a few guys are using these heads with this block combo and most are making pretty good power. Now what if you added boost?
Whatdya think?
I've read a few guys are using these heads with this block combo and most are making pretty good power. Now what if you added boost?
Whatdya think?
On The Tree
Joined: Aug 2007
Posts: 112
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From: Finland
Some say that L92 castings are thinner than catethralports and therefore substantially thinner than aftermarket castings. But, several people still use them succesfully on boosted applications, so I think it is more matter of knowledge than material thickness.
Another point of using L92s or not is the exhaust/intake flow ratio. My opinion is that turboengines like lots of exhaustport flow and the intake flow could anyways be corrected by upping boost.
Also have been wondering a lot why people want to stroke their turboengines. I am gathering parts for my 6.0 buildup and I want to make the shortblock as reliable as possible (within lowbudget ofcourse), so engine must be geometrically as good as possible. I think the rod/stroke-ratio is the keyword with any engine and especially with boost engines because you don't want to stress the engine geometrically, there will be just enough dynamic stress. I will be using stock stroke and maybe even stock crank...
Another point of using L92s or not is the exhaust/intake flow ratio. My opinion is that turboengines like lots of exhaustport flow and the intake flow could anyways be corrected by upping boost.
Also have been wondering a lot why people want to stroke their turboengines. I am gathering parts for my 6.0 buildup and I want to make the shortblock as reliable as possible (within lowbudget ofcourse), so engine must be geometrically as good as possible. I think the rod/stroke-ratio is the keyword with any engine and especially with boost engines because you don't want to stress the engine geometrically, there will be just enough dynamic stress. I will be using stock stroke and maybe even stock crank...
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lifting early as in what 700-800hp with a boosted application? "Lifting early" can be different for everyone according to their past experiences, im sure you've had alot of exeperience so if you could clarify and/or give out some numbers so we get a better perspective on whats "early" to you, it would be greatly appreciated!! 
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I assure you its a issue of having 4 bolts per cyl. and the deck height. I can make 35psi and not have them lift either if the engine is a dog and doesn't make power. Its a matter of hp more then boost. At about 900-1000fwhp I would expect to start moving water after multiple passes. If making 1200+ it will happen sooner then later. This is why people with o-rings and copper gaskets and even bigger studs still move water eventually.
OK, so up to say 850 rwhp the L92 should work.
Now back to the exhaust port. Would it be good to have a CNC'd exhaust port with a 1.6" valve and 3 angle valve job and pair that with a stock intake port and valve size and a 3 angle valve job? Would it still need a traditional split cam like NA, or would a straight cam be better?
Now back to the exhaust port. Would it be good to have a CNC'd exhaust port with a 1.6" valve and 3 angle valve job and pair that with a stock intake port and valve size and a 3 angle valve job? Would it still need a traditional split cam like NA, or would a straight cam be better?
If you are looking for 800 or so whp then I would do some porting on the exhaust and run a ls7 cam, should work well for your power level. Or just save the money and run 317's and still make 800+whp. No need to spend a ton of money on cylinder heads to make a easy 800. If any thing I would foot the cash for some afr's with the thick deck and then have a better chance of keeping them down under boost.
TECH Regular
Joined: Aug 2007
Posts: 479
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From: Sweden
I assure you its a issue of having 4 bolts per cyl. and the deck height. I can make 35psi and not have them lift either if the engine is a dog and doesn't make power. Its a matter of hp more then boost. At about 900-1000fwhp I would expect to start moving water after multiple passes. If making 1200+ it will happen sooner then later. This is why people with o-rings and copper gaskets and even bigger studs still move water eventually.
But i donīt use mls gaskets..
Never pushed any water at all.