408 compression ratio
10-22-2006, 03:37 PM
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408 compression ratio
I will have everything to assemble my turbo 408 pretty soon and wanted to get some opinions on a static compression ratio. I have -32cc pistons and 74cc heads and end up with ~8.0 to 1 with a .040" head gasket. Should I shoot for a little more compression, or leave that room for extra boost? This engine will run on 91 octane only, I don't plan on any meth or water injection. Any opinions are welcome!
10-22-2006, 05:17 PM
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what would be an ideal cr with a truck as heavy as his. I'm going to be doing the same kind of build (turbo 408) in my HD and am curious about desired CR while not in boost that will still have good power.
10-22-2006, 05:45 PM
#6
Originally Posted by EXTREME
what would be an ideal cr with a truck as heavy as his. I'm going to be doing the same kind of build (turbo 408) in my HD and am curious about desired CR while not in boost that will still have good power.
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10-22-2006, 07:43 PM
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I was planning to run about 15+ pounds. I have been told that I can run a lot more, I may want to get to 20psi eventually. I don't plan to race my truck and I don't care what times it will put down (obviously not good because of the weight), I just want tons of street friendly power. I was thinking of a 226/220 .600 on a 115. My heads and pistons are already bought, so all I can do at this point to raise the c.r. is a thinner head gasket. Do you guys think 20psi @ 8:1c.r. would be too much stress on a possible daily driven truck?
10-22-2006, 08:00 PM
#9
No need to run that much boost. With a 8.5:1 comp 408 and a 88mm on it you should be able to make mid to high 6xxrwhp all day long for a long time at like 11lbs of boost. That is the best way to do it. Trust me I know. I drove aroung at 15lbs all the time with my 4.8 set up and would turn it up to 18lbs every once in a while and they dont really like that. :