Heavy hitters and L92 heads
01-31-2009, 03:40 PM
#1
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Heavy hitters and L92 heads I asked this question that was not my thread, and felt as though I may have started a 
, so I figured I would start my own thread instead.
Why are there no "heavy hitters" running the L92 heads? Cuz of teh thin deck? Lack of options on rocker arms? Intakes? What? I mean, this head (aside from teh thinner deck) has all teh makings of a head that can make boat loads of power. Huge runners. Great flow #'s for stock heads. Large intake valve (especially good for you NA guys). So, I was just wondering what the holdup was, and why you don't really hear of the '92 in competition, or am I just missing you guys that are running them
The reason I am asking is (as alot of you know now) I have a set for my 414" iron 6.0 build and that build is coming to a close very soon, and I will have teh HP #'s to throw at ya, BUT...
I just picked up a LS1 block that I am gonna have sleeved by RED for a big bore/short stroke combo and really want to make some killer NA power, and would be nice to know that I already have teh heads to do it. So, just wanted some thoughts on teh '92 and making serious power. Even you turbo/blown guys running the '92, I want to hear from ya!
Edit: What are some flow #'s on some CNC heads tha tyou guys have seen?
, so I figured I would start my own thread instead.Why are there no "heavy hitters" running the L92 heads? Cuz of teh thin deck? Lack of options on rocker arms? Intakes? What? I mean, this head (aside from teh thinner deck) has all teh makings of a head that can make boat loads of power. Huge runners. Great flow #'s for stock heads. Large intake valve (especially good for you NA guys). So, I was just wondering what the holdup was, and why you don't really hear of the '92 in competition, or am I just missing you guys that are running them
The reason I am asking is (as alot of you know now) I have a set for my 414" iron 6.0 build and that build is coming to a close very soon, and I will have teh HP #'s to throw at ya, BUT...
I just picked up a LS1 block that I am gonna have sleeved by RED for a big bore/short stroke combo and really want to make some killer NA power, and would be nice to know that I already have teh heads to do it. So, just wanted some thoughts on teh '92 and making serious power. Even you turbo/blown guys running the '92, I want to hear from ya!
Edit: What are some flow #'s on some CNC heads tha tyou guys have seen?
02-01-2009, 09:01 AM
#3
I think one of the big reasons is after market manifold support, but other than that I have no idea.
Here are specs on the GM CNC L92's:
Here are specs on the GM CNC L92's:
88958698
Casting Number 12595364 or 12582716
Valve Angle 15-degree
Combustion Chamber 70cc*
Intake Port Volume 279cc*
Exhaust port Volume 99cc*
Minimum Cylinder Bore 4.000”
* Approximate, Numbers are within +/- 2cc’s
Milling Information for Combustion Chamber Sizing:
- Approximately 0.006” per 1-cc
For 68-cc Chamber Remove 0.012”
For 65-cc Chamber Remove 0.030”
Specifications:
Springs: Stock LS1, 12589774
Max Lift: 0.500"
Locks: Stock
Retainers: Stock
Valves: Stock
Flow Chart:
Flowed @ 28” H20 on a 4.155” Bore
Lift 0.100 0.200 0.300 0.400 0.500 0.600 0.700
Intake 69 154 222 266 309 345 358
Exhaust 46 100 136 166 189 202 209
Casting Number 12595364 or 12582716
Valve Angle 15-degree
Combustion Chamber 70cc*
Intake Port Volume 279cc*
Exhaust port Volume 99cc*
Minimum Cylinder Bore 4.000”
* Approximate, Numbers are within +/- 2cc’s
Milling Information for Combustion Chamber Sizing:
- Approximately 0.006” per 1-cc
For 68-cc Chamber Remove 0.012”
For 65-cc Chamber Remove 0.030”
Specifications:
Springs: Stock LS1, 12589774
Max Lift: 0.500"
Locks: Stock
Retainers: Stock
Valves: Stock
Flow Chart:
Flowed @ 28” H20 on a 4.155” Bore
Lift 0.100 0.200 0.300 0.400 0.500 0.600 0.700
Intake 69 154 222 266 309 345 358
Exhaust 46 100 136 166 189 202 209
02-01-2009, 09:23 AM
#4
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Thanks. Yeah, i was wondering why not, and I thought manifold selection might have something to do with it, as well as teh lack of adjustable rocker arm selection.
Do you know (or anyone) know if anyone has had problems with teh deck?
Do you know (or anyone) know if anyone has had problems with teh deck?
02-01-2009, 11:16 AM
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My WCCH CNC L92's flow around 355-360 on the intake. They have made great power so far, 1000-1100 flywheel hp, but I have pushed water about everytime on the dyno. Even with a very mild tune. Mine are just decked enough to make them flat, just a couple of thou, with a 75 cc chamber. ARP studs with an LS7 head gasket. Iron 6.0L block. I am going to swap the head gaskets to the LS9 7 layer, before I give up on these heads. I am thinking the LS7 gasket is not the hot ticket with the smaller bore.
02-01-2009, 11:33 AM
#6
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My WCCH CNC L92's flow around 355-360 on the intake. They have made great power so far, 1000-1100 flywheel hp, but I have pushed water about everytime on the dyno. Even with a very mild tune. Mine are just decked enough to make them flat, just a couple of thou, with a 75 cc chamber. ARP studs with an LS7 head gasket. Iron 6.0L block. I am going to swap the head gaskets to the LS9 7 layer, before I give up on these heads. I am thinking the LS7 gasket is not the hot ticket with the smaller bore.
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02-01-2009, 12:21 PM
#8
My WCCH CNC L92's flow around 355-360 on the intake. They have made great power so far, 1000-1100 flywheel hp, but I have pushed water about everytime on the dyno. Even with a very mild tune. Mine are just decked enough to make them flat, just a couple of thou, with a 75 cc chamber. ARP studs with an LS7 head gasket. Iron 6.0L block. I am going to swap the head gaskets to the LS9 7 layer, before I give up on these heads. I am thinking the LS7 gasket is not the hot ticket with the smaller bore.
02-01-2009, 12:53 PM
#10
With a copper gasket, you can be a little more flexible with the o-ring. The tolerance doesn't have to be as tight.
02-01-2009, 03:59 PM
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That is what was recommended from Rich at WCCH for the heads. I think I will just try the LS9 gaskets and not worry about the o-rings and see what happens. I am seeing 36% converter slip, so a custom converter is going in, and we will see how it does. I don't really need to take it much past 1000 rwhp.
02-01-2009, 11:58 PM
#13
The reason we stay away from them is that when you Cam them up the midrange turns to crap. The heads flow good enough to make 900rwhp which is great for a pure drag car but not for what we build 99% of the time.Then add on the intake selection.
I prefer a nice TFS,AFR type of head for a strong average power.
I prefer a nice TFS,AFR type of head for a strong average power.
02-02-2009, 08:59 AM
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OK, things are making more sense now, coming together so to speak. Of course, my block is studded and I was given a set of the FelPro MLS, and I am gonna try those out to start with. My machinist kind of rolled his eye's when I brought them in, so, we'll see. I have always had good luck with anything made by FelPro, however, it has been 8+ years since I last built a motor and I was running the FelPro Loc Wire's back then. Any of you guys run that FelPro MLS? Any luck? Trash?
Thanks guys
Thanks guys
06-21-2009, 10:41 AM
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Well, to bring it back from teh dead, I FOUND OUT MY ANSWER!!! You can't run a big cam/spring with this head 
My cam is right under .800 lift, and you can't put a spring on this head to make it work, without alot of work! Machine shop went to work on the head the other day, and were like....Whoops, no room! There are some options, but not easy one's. So, alot of work is necessary is the reason why. Talked with Richard over WCCH teh other day (Great guy by the way) and he said, you are OK until about low to mid .700, any more, and gonna have problems.
So, guys, if I can save anyone the hassle, now you know. BIG cams= no go (for teh most part) on teh L92. So, if you plan on going this route, just be forewarned. But, everyone I talked to (including Richard) said this head is a KILLER head, till a certain point.
My cam is right under .800 lift, and you can't put a spring on this head to make it work, without alot of work! Machine shop went to work on the head the other day, and were like....Whoops, no room! There are some options, but not easy one's. So, alot of work is necessary is the reason why. Talked with Richard over WCCH teh other day (Great guy by the way) and he said, you are OK until about low to mid .700, any more, and gonna have problems.
So, guys, if I can save anyone the hassle, now you know. BIG cams= no go (for teh most part) on teh L92. So, if you plan on going this route, just be forewarned. But, everyone I talked to (including Richard) said this head is a KILLER head, till a certain point.
06-21-2009, 11:25 AM
#20
Well, to bring it back from teh dead, I FOUND OUT MY ANSWER!!! You can't run a big cam/spring with this head
My cam is right under .800 lift, and you can't put a spring on this head to make it work, without alot of work! Machine shop went to work on the head the other day, and were like....Whoops, no room! There are some options, but not easy one's. So, alot of work is necessary is the reason why. Talked with Richard over WCCH teh other day (Great guy by the way) and he said, you are OK until about low to mid .700, any more, and gonna have problems.
So, guys, if I can save anyone the hassle, now you know. BIG cams= no go (for teh most part) on teh L92. So, if you plan on going this route, just be forewarned. But, everyone I talked to (including Richard) said this head is a KILLER head, till a certain point.
My cam is right under .800 lift, and you can't put a spring on this head to make it work, without alot of work! Machine shop went to work on the head the other day, and were like....Whoops, no room! There are some options, but not easy one's. So, alot of work is necessary is the reason why. Talked with Richard over WCCH teh other day (Great guy by the way) and he said, you are OK until about low to mid .700, any more, and gonna have problems.
So, guys, if I can save anyone the hassle, now you know. BIG cams= no go (for teh most part) on teh L92. So, if you plan on going this route, just be forewarned. But, everyone I talked to (including Richard) said this head is a KILLER head, till a certain point.
