highest compression on pump gas
07-27-2011, 09:20 AM
#21
My heads are milled down to 59cc chambers and I use a .040 Cometic head gaskets for a nice tight quench. Compression is 11.4-11.5 and with a proper tune it runs great. As sorry as the gasoline is getting now days that is about as high as I want to go on a street car. High Compression is free HP/TQ..
07-29-2011, 10:13 PM
#25
If you have a rotating asembly out of the block and are gonna run near 12 to 1. Open the ring end gaps up a little to like .025 from stock.This keeps the ring land from breaking when the rings run out of clearance due to too much heat and or detonation.This will help it survive if the tune is spot on.
07-30-2011, 03:42 PM
#26
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It's all starting to make since now. Maybe Il just buy dynomation 5 and build my engine on the computer before I buy all the parts. I could still buy my rotating assembly because I could just change the cc on the heads if needed to raise or lower compression. So maybe Il do that. Anyone else have experience with dynomation 5?
Last edited by Chicken Coupe; 07-30-2011 at 03:55 PM.
07-30-2011, 08:19 PM
#27
Your pistons and rod lengths make a big difference also. I would not buy nothing, except maybe a crank if I knew I was not going to stroke it. You can play around with rod length to your compression height of your pistons to change CR'S. You have deck height and all that stuff to consider. And there right, It's all about the tune also. Lot of factors to think about. I am runnin a LQ4 block which is a 9.230 deck with flat top pistons with Patriot 59cc head and .051 gaskets with no problems. Pistons come up above deck .008. Just remember- stroke divided by 2 plus rod length plus compression height gives you total height. You can play around with different pistons to get different results.
07-30-2011, 08:45 PM
#30
Can anyone tell me a formula to figure out dynamic compression? I read the page from the link twice and it didn't out right tell u the formula to figure it out. Can some one help me lol
07-30-2011, 09:14 PM
#31
07-30-2011, 09:40 PM
#33
It can be if you go too far into the rabbit hole. You can end up with over analysis paralysis.
You can avoid the rabbit hole by just using fellow racers practical experience. With that being said, here is mine: I have 10.9:1 static, 8.4 dynamic with a smallish 224 camshaft and I run 93 pump gas at sea level in serious Florida summer heat with no problems.
If you are the theoretical type, I will go against the grain here and tell you that dynamic compression is one factor but more important is volumetric efficiency. All of these dynamic compression ratio calculators that people use are using a generate a figure that will have more to do with a cranking compression test than an actual running engine. For this reason, I don't put a lot of stock in the generic dynamic compression calculators. So, I can see using it as a general guide, but certainly not the definitive science that some people think it is.
This is why I like the fellow racers practical experience approach. There are tons of guys on here with working combinations along with a slew of vendors with tons of practical experience. I bet you can come up with a proven combo without too much "engineering".
You can avoid the rabbit hole by just using fellow racers practical experience. With that being said, here is mine: I have 10.9:1 static, 8.4 dynamic with a smallish 224 camshaft and I run 93 pump gas at sea level in serious Florida summer heat with no problems.
If you are the theoretical type, I will go against the grain here and tell you that dynamic compression is one factor but more important is volumetric efficiency. All of these dynamic compression ratio calculators that people use are using a generate a figure that will have more to do with a cranking compression test than an actual running engine. For this reason, I don't put a lot of stock in the generic dynamic compression calculators. So, I can see using it as a general guide, but certainly not the definitive science that some people think it is.
This is why I like the fellow racers practical experience approach. There are tons of guys on here with working combinations along with a slew of vendors with tons of practical experience. I bet you can come up with a proven combo without too much "engineering".
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