ls1 block not enough compression for bigger cams?
03-05-2014, 01:24 PM
#1
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ls1 block not enough compression for bigger cams? i have a buddy that was a gm mechanic and basically said the stock ls1 block does not have enough compression for larger cam......
larger cam meaning 23x/23x or 23x/24x such as the popular ms3 or ms4
larger cam meaning 23x/23x or 23x/24x such as the popular ms3 or ms4
03-05-2014, 02:19 PM
#2
Enough compression for what? For the engine to run or for the cam to perform at its absolute best?
Obviously more compression will help those bigger cams down low, but it's not like it's not going to run if you put such a cam in. It will just be lazy as heck below 4000rpm.
Obviously more compression will help those bigger cams down low, but it's not like it's not going to run if you put such a cam in. It will just be lazy as heck below 4000rpm.
03-05-2014, 02:43 PM
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Enough compression for what? For the engine to run or for the cam to perform at its absolute best?
Obviously more compression will help those bigger cams down low, but it's not like it's not going to run if you put such a cam in. It will just be lazy as heck below 4000rpm.
Obviously more compression will help those bigger cams down low, but it's not like it's not going to run if you put such a cam in. It will just be lazy as heck below 4000rpm.
yeah basically he was saying you cant really give what that cam needs
03-05-2014, 04:07 PM
#5
Will have 14.1:1 here...with a 242/252 cam....the mechanic has no clue what he is talking about. I could still run a slightly smaller cam but 11:1 and be fine. Internal components will be aftermarket but still a gen III block.
03-05-2014, 10:05 PM
#6
Well, that's sorta true. A stock ls1 engine - meaning complete stock engine, not just block - has a compression ratio of 10.1.
"Big" cams with a lot of duration and overlap don't run very in low compression engines. Because of the overlap, they don't build cylinder pressure. And cylinder pressure is what makes power. The engine will still run. But it just may not be the right cam for that engine combo. It's a system, and all the parts need to match.
Keep in mind that us old farts can remember when 9.0 was considered high compression, and got really excited about 10.0. How old is your friend?
Sometimes you can put in a "smaller" cam and make more power under the curve by giving up a little off the top.
"Big" cams with a lot of duration and overlap don't run very in low compression engines. Because of the overlap, they don't build cylinder pressure. And cylinder pressure is what makes power. The engine will still run. But it just may not be the right cam for that engine combo. It's a system, and all the parts need to match.
Keep in mind that us old farts can remember when 9.0 was considered high compression, and got really excited about 10.0. How old is your friend?
Sometimes you can put in a "smaller" cam and make more power under the curve by giving up a little off the top.
03-05-2014, 10:10 PM
#7
Then why do the larger cams still make good power? You can tune them although down low may make lazy O2s. If you flycut you can put a big donkey dick cam in them and still make power. Cylinder pressure may make tq, but the engine can still make alot of HP. As long as the engine can breathe in the upper RPMS, thats all it needs to make HP. Even on stock injectors like most like to push them.
The problem normally comes from putting the wrong cam in for the wrong reasons in the wrong combination. Being cheap is never a good excuse.
The problem normally comes from putting the wrong cam in for the wrong reasons in the wrong combination. Being cheap is never a good excuse.
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03-05-2014, 10:39 PM
#8
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The "block" has NOTHING to do with Compression Ratio. Sounds like a "wannabe", as a GM Mechanic ( or just about ANY "mechanic" ) should know better than to make a claim like that !
03-06-2014, 04:00 PM
#11
Then why do the larger cams still make good power? You can tune them although down low may make lazy O2s. If you flycut you can put a big donkey dick cam in them and still make power. Cylinder pressure may make tq, but the engine can still make alot of HP. As long as the engine can breathe in the upper RPMS, thats all it needs to make HP.
But I road race. I don't really care about peak HP numbers. I want torque, and a lot of it. I want lots of area under the curve. I want a broad flat torque curve that will pull me out of a corner and down the back stretch. The flatter the torque curve is the happier I am. That means less time wasted shifting.
When I build a street engine, I want pretty much the same thing. Lots of torque in a light weight car is a real joy to drive.
03-06-2014, 04:17 PM
#12
A proper cam will beat a generic donkey dick and you really dont have to spend that much more.
New custom cam from us is 385 shipped.
Quite a few new cams are that price or higher from some companies.
New custom cam from us is 385 shipped.
Quite a few new cams are that price or higher from some companies.
03-06-2014, 04:17 PM
#13
A proper cam will beat a generic donkey dick and you really dont have to spend that much more.
New custom cam from us is 385 shipped.
Quite a few new cams are that price or higher from some companies.
New custom cam from us is 385 shipped.
Quite a few new cams are that price or higher from some companies.