need compression info
Thread Starter
On The Tree
Joined: Mar 2011
Posts: 106
Likes: 0
From: Shreveport, LA
need compression info Hey guys, im planning to get advanced induction's HCR 219cc cylinder heads w/ 62cc chambers, and cometic .040 head gaskets to raise my compression to 11.5-1 and was wondering if I can get some clarification on things ive been hearing about this plan. My questions are:
1. Can you rev higher with higher compression? And is it safe to?
2. Is 11.5 really the max you can go on 93 pump gas?
3. is detonation or just plain ******* something up a problem when raising compression up that much higher from stock?
The only current mods are 224/228 .581 .588 112lsa cam and 373 gears on my LS1 Z28 M6
1. Can you rev higher with higher compression? And is it safe to?
2. Is 11.5 really the max you can go on 93 pump gas?
3. is detonation or just plain ******* something up a problem when raising compression up that much higher from stock?
The only current mods are 224/228 .581 .588 112lsa cam and 373 gears on my LS1 Z28 M6
Hey guys, im planning to get advanced induction's HCR 219cc cylinder heads w/ 62cc chambers, and cometic .040 head gaskets to raise my compression to 11.5-1 and was wondering if I can get some clarification on things ive been hearing about this plan. My questions are:
1. Can you rev higher with higher compression? And is it safe to?
2. Is 11.5 really the max you can go on 93 pump gas?
3. is detonation or just plain ******* something up a problem when raising compression up that much higher from stock?
The only current mods are 224/228 .581 .588 112lsa cam and 373 gears on my LS1 Z28 M6
1. Can you rev higher with higher compression? And is it safe to?
2. Is 11.5 really the max you can go on 93 pump gas?
3. is detonation or just plain ******* something up a problem when raising compression up that much higher from stock?
The only current mods are 224/228 .581 .588 112lsa cam and 373 gears on my LS1 Z28 M6
2. no, but it also depends on your cams valve events. This is where your dynamic compression ratio should be calculated to ensure that you won't have to pull timing to compensate for too much compression.
3. It can be, but we all run a certain amout of risk when we push a stock short block to its limits.
OP, to answer your question about compression...I run 11:5.1 with 93 octane, and from everyone I talked to this is about the highest i'd want to go "safely" on pump. I'm sure you could go a little higher, but i'd rather have a little room for error if you know what I mean
Thread Starter
On The Tree
Joined: Mar 2011
Posts: 106
Likes: 0
From: Shreveport, LA
So do yall think I should just go to 11.1-1 compression so im not pushing my luck on anything? Sometimes I shift at 6500 rev limiter in 1st gear and 6000 on the others and id really hate to hurt something. Thanks for the replies
If you have a small cam, 11.5:1 might be too much. It's really based on the valve events, the efficiency of the chamber, and the octane you'll be running. And to some degree, the ability of your cooling system.
The 224/228 112 has how much advance ground in? That changes how much compression you want/need. 11:1 would be fine with that cam... you want more compression with a bigger cam to make up for the loss of low-end torque.
The 224/228 112 has how much advance ground in? That changes how much compression you want/need. 11:1 would be fine with that cam... you want more compression with a bigger cam to make up for the loss of low-end torque.
Im going to be running 11.7 in a 418 build. If I were you I would get a custom cam(Martin from tick was very good to me) made for 93 oct. Run the extra compression to have an edge on the competition and to calm your nerves an afr gauge. The cam u have is a great seller on here so its cost effective.
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Yeah I know. Most really big motors run less than 11.5:1 and make great power. The 440s never seem to have much compression. And they have giant cams that could run 12.5:1 all day.
Not sure why they aren't optimized tho. Just cuz it's huge doesn't mean it couldn't make more.
Not sure why they aren't optimized tho. Just cuz it's huge doesn't mean it couldn't make more.
Thread Starter
On The Tree
Joined: Mar 2011
Posts: 106
Likes: 0
From: Shreveport, LA
Im in Louisiana and thats all I use is 93 octane. What cc chambers and head gaskets should I run for 11.1? I do have an AEM digital wideband and I really like my cam and dont want to trade it out for another. I was wanting the cometic head gaskets for the quench but if yall know of any better id sure take a look at them
Yeah I know. Most really big motors run less than 11.5:1 and make great power. The 440s never seem to have much compression. And they have giant cams that could run 12.5:1 all day.
Not sure why they aren't optimized tho. Just cuz it's huge doesn't mean it couldn't make more.
Not sure why they aren't optimized tho. Just cuz it's huge doesn't mean it couldn't make more.
Something to think about.
to get a high DCR you need your IVC to happen earlier, which in turn generally means that your IVO is happening earlier. Does the extra dwell at the TDC momentarily "stall" the intake charge such that you're "wasting" valve lift? or what's going on there? interested in what the connection is.
I think the general consensus is that the longer dwell creates more potential stored energy.
More mechanical leverage against an object that is physically locked into place in that point of its rotation.
I do not see it as wasting valve lift.
More mechanical leverage against an object that is physically locked into place in that point of its rotation.
I do not see it as wasting valve lift.
Well if the end setup seems tame enough Ill shave the heads a little for 12.0. but the Arias race pistons call for 11.7 . Ill find out soon enough. Cant wait to see a good trap speed at Desoto.
I don't know. If you did an ERL 4.185" bore block with a 3.622" stroke.... 399cid short stroke motor. I bet that'd love 12:1 or better with a more conventional short stroke cam. Would rev like crazy... hmm haha
