L92 heads + boost
10-09-2008, 04:14 PM
#1
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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?
10-10-2008, 02:35 AM
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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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10-10-2008, 07:44 AM
#8
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!! 
10-10-2008, 08:09 AM
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10-10-2008, 08:10 AM
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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.
10-10-2008, 08:54 AM
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10-10-2008, 11:43 AM
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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?
10-10-2008, 12:55 PM
#17
10-10-2008, 01:44 PM
#18
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.
10-11-2008, 03:14 PM
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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.
But i donīt use mls gaskets..
Never pushed any water at all.