230/238 cam with l92s?
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I have a friend that is trying to decide if a ls3 top end will work on his ls2 six speed gto. His cam specs are 230/238 .600/.615 112+2. What do you guys think?
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I would say the cam is on the large side for running heads that flow that well. But despite the loss in power in the lower RPMs he should enjoy the gains in the mid and upper.
Last edited by jmgak47; 09-12-2012 at 10:45 PM.
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I got a stupid deal on a complete ls3 top end. Heads, offset rockers, intake, rails and injectors and he was thinking about using them. He was going to mill them some and he would probably need to fly cut as well. He is just worried about doing the swap and only trapping 115 like what a lot of people do on ls2gto forum.
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I got a stupid deal on a complete ls3 top end. Heads, offset rockers, intake, rails and injectors and he was thinking about using them. He was going to mill them some and he would probably need to fly cut as well. He is just worried about doing the swap and only trapping 115 like what a lot of people do on ls2gto forum.
Our LS3 with 231 239 .617 .624 113 in the same 3880lb Monaro has now run 121mph.
That cam you are looking at using should be OK!
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I don't think that's a real bad cam, although the LSA is a little tighter than I think an L92 head likes. Because these intake ports are so big, you want less overlap to avoid reversion. A lot of people run a lot of exhaust duration on these heads because their flow isn't quite up to par with the intake flow, but in doing so, you create more overlap, which I think is going to hurt power. I think this is why guys with huge cams don't make a lot more power than guys with small cams on these heads... the reversion from all that overlap eliminates most of the benefit of the extra duration.
Following this school of thought, some guys are choosing to aim for a specific (small) amount of overlap, which also means that your total intake & exhaust duration is only going to be so big. Within that constraint, they choose to favor the intake duration a bit more by going with specs closer to a single pattern cam design.
But what do I know? Until I get my motor on a dyno, I'm just a bench racer.
Following this school of thought, some guys are choosing to aim for a specific (small) amount of overlap, which also means that your total intake & exhaust duration is only going to be so big. Within that constraint, they choose to favor the intake duration a bit more by going with specs closer to a single pattern cam design.
But what do I know? Until I get my motor on a dyno, I'm just a bench racer.
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I had Patrick g spec my cam for my build. He went with a 222/226 on a 115+1 for a 370 and LSA heads. When he sent me the specs he said he liked the narrower split because I'm running a turbo. I was expecting a cam in the 230s/240s but then I did some research and found that the ls3 style heads respond very well to cams in the 220s/230s.
I know a 230/238 cam might be a hair on the large side but I think it should perform very well with the ls3 heads and better ls3 intake compared to the shitty ls2 intake. Dev1360 went 12.70 @ 112 if i remember correctly with just a full exhaust and a intake. No reason why he shouldn't pick up a decent amount with the top end swap.
I know a 230/238 cam might be a hair on the large side but I think it should perform very well with the ls3 heads and better ls3 intake compared to the shitty ls2 intake. Dev1360 went 12.70 @ 112 if i remember correctly with just a full exhaust and a intake. No reason why he shouldn't pick up a decent amount with the top end swap.
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Post 6 is right on..... The intake runner is pretty large and flows real well,
however this causes a terrible intake to exhaust flow ratio. This explains why
most custom spec cams for LS3/L92 heads have 12-14 more degrees exhaust
duration. Something like a 218 or 222 intake lobe with a 232-234 exhaust is
quite a stealthy yet potent bumpstick which can have a wide lobe separation.
This takes away from peak torque but flattens out the curve & makes for a
35-3700 rpm window of torque...perfect for a street car.
however this causes a terrible intake to exhaust flow ratio. This explains why
most custom spec cams for LS3/L92 heads have 12-14 more degrees exhaust
duration. Something like a 218 or 222 intake lobe with a 232-234 exhaust is
quite a stealthy yet potent bumpstick which can have a wide lobe separation.
This takes away from peak torque but flattens out the curve & makes for a
35-3700 rpm window of torque...perfect for a street car.
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IMHO the cam will work well. I've run 5 cams in my mild L92 setup and the best results I've had were with intake durations between 230 and 234. That seems to be the sweet spot in my experience. I've run up to 18 degrees split but again best results were 10 and less. The cam I liked best and made the best numbers was the 230-240 111 in the 403ci build. Don't buy into all the wide lsa stuff. I'm still running a 113+3 in the 427 with an intake duration in the sweet spot.
Just my $.02
Just my $.02
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You guys are forgetting lobes? What lobes do LS3 heads like for quiet valvetrian?
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I don't think that's a real bad cam, although the LSA is a little tighter than I think an L92 head likes. Because these intake ports are so big, you want less overlap to avoid reversion. A lot of people run a lot of exhaust duration on these heads because their flow isn't quite up to par with the intake flow, but in doing so, you create more overlap, which I think is going to hurt power. I think this is why guys with huge cams don't make a lot more power than guys with small cams on these heads... the reversion from all that overlap eliminates most of the benefit of the extra duration.
Following this school of thought, some guys are choosing to aim for a specific (small) amount of overlap, which also means that your total intake & exhaust duration is only going to be so big. Within that constraint, they choose to favor the intake duration a bit more by going with specs closer to a single pattern cam design.But what do I know? Until I get my motor on a dyno, I'm just a bench racer.
Following this school of thought, some guys are choosing to aim for a specific (small) amount of overlap, which also means that your total intake & exhaust duration is only going to be so big. Within that constraint, they choose to favor the intake duration a bit more by going with specs closer to a single pattern cam design.But what do I know? Until I get my motor on a dyno, I'm just a bench racer.
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If your on the bench, your must be the 6th man...LOL good stuff here....
Many people do not know how to cam these heads so they automatically write them off. And just because they cannot make them work then they hate on them or come up with many hypothesis(educated guesses) and excuses of why they don't work for them.
But guys who truly understand general cylinder head function, understand that all heads have their place and attributes that can make them be sucessfull. No head is perfect, from ETP,AFR,TFS,MAST,PRC,243,LS3,LS7, etc..... All of them have pros and cons.
P.S. Dayum I just made post 666.....
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The L92/LS3 heads love lift but that can create problems throwing the big intake valve around unless your entire valve train is properly setup. That include lifters, pushrods, springs and spring setup and the valves themselves. The stock L92 intake valve is not a bad valve and very often considerably lighter than some of the stainless variants out there.