Compression ratio and cam question
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Compression ratio and cam question
I have a 2001 stock bottom end.
Put a cam in it based on ... 1 it was available, and 2 i was planting on going with an A&A supercharger.
The cam is a 239/247 .624/.624 on a 114 LSA... love the way it sounds, plain nasty.
other mods are a set of ported 241 heads.
GM MLS head gaskets.
4:11 gears
xs power 1 3/4 long tubes into a custom cat back.
ported LS6 intake and 85MM throttle body.
I am wanting a bit more torque ... and sooner... would bumping the compression by milling the heads help . ... I have also noticed that when doing WOT pulls the car burns a bit of oil... every time.. I"m wondering if i should step up to ARP head studs instead of the stock style head bolts ( bought new with the head swap)
my last dyno which flat lined at 5700 RPM presumably due to stock throttle body and MAF. after porting the LS6 and the bigger throttle body and a much better air intake than the freebie i had on there the car very noticeable picked up in the HP range.. but of course all above 3700 RPM.
Thanks guys!
Put a cam in it based on ... 1 it was available, and 2 i was planting on going with an A&A supercharger.
The cam is a 239/247 .624/.624 on a 114 LSA... love the way it sounds, plain nasty.
other mods are a set of ported 241 heads.
GM MLS head gaskets.
4:11 gears
xs power 1 3/4 long tubes into a custom cat back.
ported LS6 intake and 85MM throttle body.
I am wanting a bit more torque ... and sooner... would bumping the compression by milling the heads help . ... I have also noticed that when doing WOT pulls the car burns a bit of oil... every time.. I"m wondering if i should step up to ARP head studs instead of the stock style head bolts ( bought new with the head swap)
my last dyno which flat lined at 5700 RPM presumably due to stock throttle body and MAF. after porting the LS6 and the bigger throttle body and a much better air intake than the freebie i had on there the car very noticeable picked up in the HP range.. but of course all above 3700 RPM.
Thanks guys!
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With that cam your car should not be peaking at 5700 rpm even with the stock TB and MAF. It should be more like 6200 or so. You could mill the heads and whatnot, but more compression is not really the best idea if doing a blower at some point
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That's a pretty damn big cam for a stock cube motor and definitely shouldn't be flatlining at 5700 rpm's. Maybe you got some valvetrain issues that need to be sorted out. Anywho, compression I think would definitely help but then you'll have to worry about PTV clearance.
#7
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That's a pretty damn big cam for a stock cube motor and definitely shouldn't be flatlining at 5700 rpm's. Maybe you got some valvetrain issues that need to be sorted out. Anywho, compression I think would definitely help but then you'll have to worry about PTV clearance.
i doubt that you could really take advantage of a cam that big with stock-ish heads and intake and you're not going to be able to do much appreciable head milling without running into ptv issues. i'd look at something in the 228-23x range duration wise with a lower lift....something that has an earlier intake close event to boost your dynamic compression. with lower lift also, that gives you more options in terms of head milling / running thinner gaskets. I'd recommend cometic 0.040 gaskets also to improve your quench. talk to one of our vendors to help you pick out a cam. Martin from Tick is excellent to deal with.
also I would not replace your head bolts with studs unless you plan on resizing your bores via torque plate hone. the studs load the metal differently than bolts and will likely distort your bores worse than what they are already. how many miles are on the motor?
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#8
First of all lift has nothing to do with piston to valve clearance. Second its his duration in combination of the LSA which makes it harder to mill the head down and get higher compression out of the cam. The 114 lsa actually helps him a little. He can flycut and mill it some and run a .040 gasket though.
#9
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First of all lift has nothing to do with piston to valve clearance. Second its his duration in combination of the LSA which makes it harder to mill the head down and get higher compression out of the cam. The 114 lsa actually helps him a little. He can flycut and mill it some and run a .040 gasket though.
I can take a given engine combination that has given amount of valve drop, a given head gasket thickness and the piston out of the hole a certain amount and run one cam that has an identical duration@.050" as another, but gain a large amount of P to V in the process. How quick that lobe is off the seat has a large affect on P to V as the valve is seated or closest to its seat when the piston is at TDC.