L92 Heads/Intake - Cam Question
08-30-2006 | 12:03 PM
#41
Originally Posted by SStrokerAce
These things aren't going to need intake duration, and until you get flow numbers on a 4.0" bore your not going to know the split. Even then they will still want more exhaust duration than that. These heads are made like any good NA race head, HUGE intake valves, as big as you can get in there and small exhaust valves. We are talking a diameter/circumfrence ratio of 73% compared to 77% in standard LS or SBC heads. When we get flow numbers on the smaller bore and with intakes and exhaust pipes then it should give us a better indication of how much split, but even so it's still going to be more than 10 degs difference at .050", so the traditional LS cams will not give the best results.
Bret
Bret
08-30-2006 | 12:17 PM
#42
Yes,
Believe me I'm a proponent for the least amount of exhaust split as I can put in a street motor, but when you see 350cfm intake and 220cfm exhaust there is no way around it. Now combine that with the fact that these intakes will move 20-30cfm more than a LS6, LS2 or FAST 90 then it's going to make it worse not better.
Your not going to be able to run a TRex or FM13 with these things, in fact I think those are going to be too big on most of these setups. These heads will be a balancing act, but if it's right they will be driveable AND make power.
Bret
Believe me I'm a proponent for the least amount of exhaust split as I can put in a street motor, but when you see 350cfm intake and 220cfm exhaust there is no way around it. Now combine that with the fact that these intakes will move 20-30cfm more than a LS6, LS2 or FAST 90 then it's going to make it worse not better.
Your not going to be able to run a TRex or FM13 with these things, in fact I think those are going to be too big on most of these setups. These heads will be a balancing act, but if it's right they will be driveable AND make power.
Bret
08-30-2006 | 12:37 PM
#43
Originally Posted by SStrokerAce
Yes,
Believe me I'm a proponent for the least amount of exhaust split as I can put in a street motor, but when you see 350cfm intake and 220cfm exhaust there is no way around it. Now combine that with the fact that these intakes will move 20-30cfm more than a LS6, LS2 or FAST 90 then it's going to make it worse not better.
Your not going to be able to run a TRex or FM13 with these things, in fact I think those are going to be too big on most of these setups. These heads will be a balancing act, but if it's right they will be driveable AND make power.
Bret
Believe me I'm a proponent for the least amount of exhaust split as I can put in a street motor, but when you see 350cfm intake and 220cfm exhaust there is no way around it. Now combine that with the fact that these intakes will move 20-30cfm more than a LS6, LS2 or FAST 90 then it's going to make it worse not better.
Your not going to be able to run a TRex or FM13 with these things, in fact I think those are going to be too big on most of these setups. These heads will be a balancing act, but if it's right they will be driveable AND make power.
Bret
08-30-2006 | 06:12 PM
#46
Maybe something like this? Honestly don't have a clue, just trying to keep people talking.
http://www.lingenfelter.com/store/ls1-gt1-1.html
229/242 .631/.631 w 1.7 rocker 114 CL
http://www.lingenfelter.com/store/ls1-gt1-1.html
229/242 .631/.631 w 1.7 rocker 114 CL
08-30-2006 | 06:32 PM
#47
Originally Posted by tmoneyr007
Maybe something like this? Honestly don't have a clue, just trying to keep people talking.
http://www.lingenfelter.com/store/ls1-gt1-1.html
229/242 .631/.631 w 1.7 rocker 114 CL
http://www.lingenfelter.com/store/ls1-gt1-1.html
229/242 .631/.631 w 1.7 rocker 114 CL
08-31-2006 | 06:47 AM
#48
TECH Fanatic
Joined: Aug 2005
Posts: 1,691
Likes: 1
From: Sunny London, UK
I think you will find the longer LSA of stock L92 cams is for emissions not power.
If you tighten that up you will reap the benefits of scavenging on the intake. Perhaps open the exhaust a little earlier and hold it open longer. Of course lift it high and fast too to make the most of the high initial pressure. The large intake will act like a larger duration and lift on the intake lobe anyway. Look at the pressure difference between atmospheric pressure for intake and combustion pressure for the exhaust.
Duration of exhaust will be determined on how long it takes to exit the exhaust gases, some interesting trial and error over the next few month I think. Katech seems to have a good head start on the LS7 cams which should be closer in spec to L92 cams than LS1 cams. IMHO.
If you tighten that up you will reap the benefits of scavenging on the intake. Perhaps open the exhaust a little earlier and hold it open longer. Of course lift it high and fast too to make the most of the high initial pressure. The large intake will act like a larger duration and lift on the intake lobe anyway. Look at the pressure difference between atmospheric pressure for intake and combustion pressure for the exhaust.
Duration of exhaust will be determined on how long it takes to exit the exhaust gases, some interesting trial and error over the next few month I think. Katech seems to have a good head start on the LS7 cams which should be closer in spec to L92 cams than LS1 cams. IMHO.
08-31-2006 | 06:53 AM
#49
That's getting closer, I'm going to need some more hard numbers to give a solid answer. Generic depends on the application, a LS2 short block is different from a 402. I don't have 4" bore ported numbers and all the data out there. We are probably talking smaller intake durations than what we normally think due to the CSA of the intake port and 15+ degs of split most likely just because of the flow bias. It's like LS7 cams, I don't think people are going to be putting the specs out all over the place when they get something that works. A lot of people have learned NOT to do that because of all the standard LS1 and how cam centric it is.
Bret
Bret
