ideal compression with f14?
02-16-2009, 07:43 PM
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ideal compression with f14? ill be in the market for some aftermarket heads soon and im still doing some homework.
im split between high compression and using the direct port kit i allready have or going low compression and bolting on a supercharger.
either way im going to upgrade to better heads and i would like to know; if i already have an f14 cam and i decide to go with the spray what is the ideal compression ratio for this cam.
i have ported 853's now with 2.02 and 1.57 valves now that have been milled but the chambers have been relieved so compression is still only about 10.5:1. i only use 94 octane in the car now and i dont want to have to use race gas. i only intend to run a 125 to 150 shot in the car if i do decide to spray it.
i kinda would like to run more than 11.1 maybe even 12.1 but i would like to know if its even worth it to go that high.
im split between high compression and using the direct port kit i allready have or going low compression and bolting on a supercharger.
either way im going to upgrade to better heads and i would like to know; if i already have an f14 cam and i decide to go with the spray what is the ideal compression ratio for this cam.
i have ported 853's now with 2.02 and 1.57 valves now that have been milled but the chambers have been relieved so compression is still only about 10.5:1. i only use 94 octane in the car now and i dont want to have to use race gas. i only intend to run a 125 to 150 shot in the car if i do decide to spray it.
i kinda would like to run more than 11.1 maybe even 12.1 but i would like to know if its even worth it to go that high.
Last edited by 1999 SS; 02-16-2009 at 08:13 PM.
02-16-2009, 08:33 PM
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Have you seen the DCR spreadsheets by pianoprodigy:
https://ls1tech.com/forums/generatio...sier-than.html
In a nutshell DCR tells you how much compression to run to get the most torque out of a cam without detonating on pump gas. For 92 octane they say you want a DCR around 8.5. Some people do go higher and then go a little conservative on the tune. I put in numbers close to your cam specs and a SCR of about 11.25 gave a DCR of about 8.5.
I used these inputs, some might be wrong for your setup:
compressed head gasket thickness 0.052
deck height -0.006
chamber head volume 60cc
I used cam specs of 232/234, 0.595/0.598, 114 LSA, 4 degrees of advance
https://ls1tech.com/forums/generatio...sier-than.html
In a nutshell DCR tells you how much compression to run to get the most torque out of a cam without detonating on pump gas. For 92 octane they say you want a DCR around 8.5. Some people do go higher and then go a little conservative on the tune. I put in numbers close to your cam specs and a SCR of about 11.25 gave a DCR of about 8.5.
I used these inputs, some might be wrong for your setup:
compressed head gasket thickness 0.052
deck height -0.006
chamber head volume 60cc
I used cam specs of 232/234, 0.595/0.598, 114 LSA, 4 degrees of advance
02-16-2009, 11:08 PM
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thank you it took me a minute to realize what i was looking at. im gonna take your word for it because i dont know what to put into some of the blanks to get the final number.
02-17-2009, 10:46 AM
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Well don't just trust me, this is the internet after all. 
Call some of the sponsors directly and tell them what you're trying to do. I'm probably going with some heads from Texas Speed soon. They have a good tax time sale going on over here:
https://ls1tech.com/forums/sponsor-s...xas-speed.html
I'm going to ask their advice on head chamber volume and some other stuff when I place my order. It's a great idea to do some homework first like you're doing so you have an idea what to ask.
Call some of the sponsors directly and tell them what you're trying to do. I'm probably going with some heads from Texas Speed soon. They have a good tax time sale going on over here:
https://ls1tech.com/forums/sponsor-s...xas-speed.html
I'm going to ask their advice on head chamber volume and some other stuff when I place my order. It's a great idea to do some homework first like you're doing so you have an idea what to ask.