How do I get desired CR?
10-14-2012, 03:46 PM
#1
How do I get desired CR? I am looking to get about 12:1 compression ratio out of my LS1. Im going to be buying TEA/TFS 215cc heads. What cc do they need to be for me to reach the desired compression? Also the thinnest head gaskets i could find were .04 and the entire bottom end is stock. Also as a side not, 12:1 CR is still able to run pump gas 91 octane correct?
10-14-2012, 07:35 PM
#5
If the cam is big enough you can do it.
To get 12.0:1 SCR and have a DCR low enough to run on 91 pump you'd need to do these things:
59cc combustion chamber
.040 head gasket
239/244 112+3 would lower DCR
That would put you at what I would consider the maximum safe compression for running on 91 pump gas. It will probably like 26* total timing and not a touch more. The quench is nice and tight and you've got great compression. You'd be at 11.75:1 SCR and 8.65:1 DCR. Honestly that is still pushing it and you can go one of two ways to fix that. 59.5cc chamber would put you at 11.67:1 and 8.59:1 DCR or you could run 243/248 111+3 profile to put you down to 8.57:1 DCR and stay at 11.75:1 SCR.
To say the least that combination with the right supporting mods would run like a raped ape, but would require fly-cutting.
To get 12.0:1 SCR and have a DCR low enough to run on 91 pump you'd need to do these things:
59cc combustion chamber
.040 head gasket
239/244 112+3 would lower DCR
That would put you at what I would consider the maximum safe compression for running on 91 pump gas. It will probably like 26* total timing and not a touch more. The quench is nice and tight and you've got great compression. You'd be at 11.75:1 SCR and 8.65:1 DCR. Honestly that is still pushing it and you can go one of two ways to fix that. 59.5cc chamber would put you at 11.67:1 and 8.59:1 DCR or you could run 243/248 111+3 profile to put you down to 8.57:1 DCR and stay at 11.75:1 SCR.
To say the least that combination with the right supporting mods would run like a raped ape, but would require fly-cutting.
10-14-2012, 08:11 PM
#6
If the cam is big enough you can do it.
To get 12.0:1 SCR and have a DCR low enough to run on 91 pump you'd need to do these things:
59cc combustion chamber
.040 head gasket
239/244 112+3 would lower DCR
That would put you at what I would consider the maximum safe compression for running on 91 pump gas. It will probably like 26* total timing and not a touch more. The quench is nice and tight and you've got great compression. You'd be at 11.75:1 SCR and 8.65:1 DCR. Honestly that is still pushing it and you can go one of two ways to fix that. 59.5cc chamber would put you at 11.67:1 and 8.59:1 DCR or you could run 243/248 111+3 profile to put you down to 8.57:1 DCR and stay at 11.75:1 SCR.
To say the least that combination with the right supporting mods would run like a raped ape, but would require fly-cutting.
To get 12.0:1 SCR and have a DCR low enough to run on 91 pump you'd need to do these things:
59cc combustion chamber
.040 head gasket
239/244 112+3 would lower DCR
That would put you at what I would consider the maximum safe compression for running on 91 pump gas. It will probably like 26* total timing and not a touch more. The quench is nice and tight and you've got great compression. You'd be at 11.75:1 SCR and 8.65:1 DCR. Honestly that is still pushing it and you can go one of two ways to fix that. 59.5cc chamber would put you at 11.67:1 and 8.59:1 DCR or you could run 243/248 111+3 profile to put you down to 8.57:1 DCR and stay at 11.75:1 SCR.
To say the least that combination with the right supporting mods would run like a raped ape, but would require fly-cutting.
10-15-2012, 10:52 AM
#7
Honestly for a street car I'd do something smaller than the 243/248 profile I mentioned. Even though with the 14.5 IVO that profile would have making it still make great torque in the mid-range it would still need 4.10-4.30 gears in a manual or a 4200-4400 converter in an automatic to compliment it.
If you could live with somewhere around 11.5:1 SCR the DCR with my Polluter V.2 would be a nice well rounded package that would make numbers very similar to the VRX5 TFS215 thread that is floating around here right now. You could even do the 234/240 113+4 we offer in my Elite Series of camshafts.
If you could live with somewhere around 11.5:1 SCR the DCR with my Polluter V.2 would be a nice well rounded package that would make numbers very similar to the VRX5 TFS215 thread that is floating around here right now. You could even do the 234/240 113+4 we offer in my Elite Series of camshafts.
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10-15-2012, 09:20 PM
#11
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