need some help with cam/compression
04-21-2008, 01:56 AM
#1
need some help with cam/compression planning out my build some more...considering buying a shortblock i found on here...its a forged ls2 (stock crank) with compstar rods and diamond coated pistons
first question
pistons are -14cc and i was going to run 317 castings on them...what compression will that come out to roughly?
id like mid 8's but i think its goana end up higher than that...can you safely take material out of the cobustion chamber on 317 without sacarficing deck streingth? also how think of a gasket can i stick on there to help lower it or should i not worry?
planning a running a pt-88 and make about 800rw for now hopefully not have to do gaskets very often...
next question is i need a cam and im considering a stock z06 cam...from later years like 02-05, i want a very tame idle almost if not like stock...this would get it...plan to only rev this thing to about 6500...should i go with a custom cam...later on plan to do some aftermarket heads so not sure if i should wait till then or not
chime in your opinions....
first question
pistons are -14cc and i was going to run 317 castings on them...what compression will that come out to roughly?
id like mid 8's but i think its goana end up higher than that...can you safely take material out of the cobustion chamber on 317 without sacarficing deck streingth? also how think of a gasket can i stick on there to help lower it or should i not worry?
planning a running a pt-88 and make about 800rw for now hopefully not have to do gaskets very often...
next question is i need a cam and im considering a stock z06 cam...from later years like 02-05, i want a very tame idle almost if not like stock...this would get it...plan to only rev this thing to about 6500...should i go with a custom cam...later on plan to do some aftermarket heads so not sure if i should wait till then or not
chime in your opinions....
Last edited by daniel6718; 04-21-2008 at 02:04 AM.
04-22-2008, 07:55 AM
#3
The block shortblock with 317 heads will be 8.67:1 static compression. 317 heads can be safely opened up to 74cc with will give a static compression level of 8.52:1. That is pretty darn low even for a turbo IMO. If I remember correctly the PT-88 turbo is pretty big and will have a slower spool time. Between the compression level and the spool time, the thing is be a dog at lower RPMs.
The ZO6 cams make way better S/C cams than turbo cams. Turbos favor more intake duration and lift than exhaust. For the LS2 block and crank, I would look at something in the 232/226//598/578//115 range. Definitely upgrade the springs on the heads.
Keith
The ZO6 cams make way better S/C cams than turbo cams. Turbos favor more intake duration and lift than exhaust. For the LS2 block and crank, I would look at something in the 232/226//598/578//115 range. Definitely upgrade the springs on the heads.
Keith
04-23-2008, 05:54 AM
#7
Yes you can certainly get away with the stocker, it will work just fine. Can more horsepower be made with swapping out cams? Certainly, but for what you are looking to make I don't see a problem with the Z06 camshaft. Bob
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04-23-2008, 08:53 AM
#8
The lingenfelter turbo cars seem to run great with their normal splits .They give stock like idle and are easy to tune and are very similar in specs on paper to z06 cams. The last two are their main fi grinds. The gt7 is the newer one they use the most now. At least think they use the most. The gt2-3 was also used a lot in many of their fi cars.
APS seems to be doing good with their gt11 cam but that one has a lot of lift so not sure how hard on springs it will be. Ling I think said might have to change out springs every 20,000 or 30,000 miles and might be close to valve float under boost with that cam.Its near 650 lift.If it was around 600 would likely have tried that one.
I am not sure if they have different lobes or ramp rates than the gm z06 cams.
01 ZO6 cam: 204/211 .525/.525 -116 LSA
Lingenfelter GT2 205/212 .540/.540 –116.5CL
02-03 ZO6 cam: 204/218 .551/.547 -117.5 LSA
Lingenfelter GT2-3 207/220 .571/.578 –118.5CL
05-07 ZO6 cam 210/230 .561/.557 –120.5 LSA
Lingenfelter GT7 208/230 .554/.546 –121CL
I am still waiting to see some mag like high tech performance do a big cam comparison on same engine with like 9 different cams in turbo application. Test duration ,normal,reverse and no split, test lift and test lsa. or even combos of the above but that might require like 30 cam tests for the different combos.
My main goals were also stocklike idle, easy to tune ,no surging and easy on valve springs. Think the gt7 should work out ok for those goals and got it cheap used off the board. So going to try it at least.
APS seems to be doing good with their gt11 cam but that one has a lot of lift so not sure how hard on springs it will be. Ling I think said might have to change out springs every 20,000 or 30,000 miles and might be close to valve float under boost with that cam.Its near 650 lift.If it was around 600 would likely have tried that one.
I am not sure if they have different lobes or ramp rates than the gm z06 cams.
01 ZO6 cam: 204/211 .525/.525 -116 LSA
Lingenfelter GT2 205/212 .540/.540 –116.5CL
02-03 ZO6 cam: 204/218 .551/.547 -117.5 LSA
Lingenfelter GT2-3 207/220 .571/.578 –118.5CL
05-07 ZO6 cam 210/230 .561/.557 –120.5 LSA
Lingenfelter GT7 208/230 .554/.546 –121CL
I am still waiting to see some mag like high tech performance do a big cam comparison on same engine with like 9 different cams in turbo application. Test duration ,normal,reverse and no split, test lift and test lsa. or even combos of the above but that might require like 30 cam tests for the different combos.
My main goals were also stocklike idle, easy to tune ,no surging and easy on valve springs. Think the gt7 should work out ok for those goals and got it cheap used off the board. So going to try it at least.
