LQ9 CR on 91?
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LQ9 CR on 91? Im looking into building my first engine. LQ9 flat top pistons zero deck, TEA 243 heads milled, 228r 112lsa or BTR stage 2 cam, Johnson lifters to rev out to 7k-8k. looking to get a .041 gasket quench to get me around 11.3 cr. How much cr is to much for 91 pump? Build would be on C5 mild street with occasional track
On The Tree
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Im looking into building my first engine. LQ9 flat top pistons zero deck, TEA 243 heads milled, 228r 112lsa or BTR stage 2 cam, Johnson lifters to rev out to 7k-8k. looking to get a .041 gasket quench to get me around 11.3 cr. How much cr is to much for 91 pump? Build would be on C5 mild street with occasional track
For quench. Typically for an Na car you want a tight quench. Even if it raises the compression ratio, a tight quench will actually help reduce detonation. You need to know your Piston to Deck height and add that if below deck, or subtract it if above, from the gasket thickness. You want it to be tight but not let the pistons kiss the heads. I've read most agree that for an all aluminum build with iron rods, .036 is as tight as you want. .036 - .045 is probably good.
So if the piston is in the hole .007. Add that to .041. That's. 048, a bit thick but it would work perfectly fine.
It seems you aren't looking for max effort performance. Which tells me you are street driving 95% of the time. I would aim for 11.0 compression. Cam motion track weapon camshaft. Ls7 lifters or johnson drop ins. And quench around .040.
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It's more complex than that. First, the 228r cam will not get you to 7k rpm. That cam would pair great with standard gm ls7 lifters or drop ins with new trays. To be safe. A general rule of thumb is to keep dynamic compression to around 8.5 or less at your given altitude. There are other variables as well it can get pretty complex. So let's say we take a 228r cam with what I guess would be like a 282 duration at .006? If it was, that gives us an intake closing point of 69° ABDC. Plugging that into the Wallace Racing calculator @ 11.5:1 static compression gives us 8.83:1 dynamic at sea level and 8.2 @ 3000 feet asl.
For quench. Typically for an Na car you want a tight quench. Even if it raises the compression ratio, a tight quench will actually help reduce detonation. You need to know your Piston to Deck height and add that if below deck, or subtract it if above, from the gasket thickness. You want it to be tight but not let the pistons kiss the heads. I've read most agree that for an all aluminum build with iron rods, .036 is as tight as you want. .036 - .045 is probably good.
So if the piston is in the hole .007. Add that to .041. That's. 048, a bit thick but it would work perfectly fine.
It seems you aren't looking for max effort performance. Which tells me you are street driving 95% of the time. I would aim for 11.0 compression. Cam motion track weapon camshaft. Ls7 lifters or johnson drop ins. And quench around .040.
For quench. Typically for an Na car you want a tight quench. Even if it raises the compression ratio, a tight quench will actually help reduce detonation. You need to know your Piston to Deck height and add that if below deck, or subtract it if above, from the gasket thickness. You want it to be tight but not let the pistons kiss the heads. I've read most agree that for an all aluminum build with iron rods, .036 is as tight as you want. .036 - .045 is probably good.
So if the piston is in the hole .007. Add that to .041. That's. 048, a bit thick but it would work perfectly fine.
It seems you aren't looking for max effort performance. Which tells me you are street driving 95% of the time. I would aim for 11.0 compression. Cam motion track weapon camshaft. Ls7 lifters or johnson drop ins. And quench around .040.
On The Tree
Joined: Feb 2023
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Looking into that track weapon cam looks like a perfect all around track/drift purpose. I've been looking into stock lq9 deck clearance and some people say it measures out the block about .006 thousandths. I'm also tempted to 408 stroke with a goal of getting around 460-500 whp. Also is it true high displacements are less susceptible to detonation and can run higher cr? Also as for head gasket bore whats a good rule of thumb to oversize over the bore?
You don't NEED a stroker to make 450-500 wheel.. You just need to pick better parts to do it. Secondly, why put an iron block in a c5? I would NEVER put an iron block in mine (hence why I built an ls2 based 408).
If the stock engine is still running, then I would roll with it.
If the stock engine is still running, then I would roll with it.
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You don't NEED a stroker to make 450-500 wheel.. You just need to pick better parts to do it. Secondly, why put an iron block in a c5? I would NEVER put an iron block in mine (hence why I built an ls2 based 408).
If the stock engine is still running, then I would roll with it.
If the stock engine is still running, then I would roll with it.
