10:1 on 93
Jul 10, 2013 | 11:16 AM
#17
Evolving Member
Joined: May 2008
Posts: 194
Likes: 0
From: Oxnard, CA
Consider that MIVEC changes the dynamic compression ratio when you adjust both intake & exhaust cam timing.... It's all about the tune.
So at any time you could sacrifice the ideal cam timing and lower the pressure in the cylinders.... In transient situations where the pressure might spike, run less intake advance and less exhaust retard to artificially lower the dynamic compression. (waiting longer to let air in, and releasing it sooner essentially)
You can also drop boost, refuse to hold boost high as long, adjust ignition timing, or refuse to build boost in the lower RPM etc.....
MIVEC is the key if you ask me.... Even if it robs power to not run ideal MIVEC settings, you can bet it's safer on the motor with a smaller dynamic compression ratio.
So at any time you could sacrifice the ideal cam timing and lower the pressure in the cylinders.... In transient situations where the pressure might spike, run less intake advance and less exhaust retard to artificially lower the dynamic compression. (waiting longer to let air in, and releasing it sooner essentially)
You can also drop boost, refuse to hold boost high as long, adjust ignition timing, or refuse to build boost in the lower RPM etc.....
MIVEC is the key if you ask me.... Even if it robs power to not run ideal MIVEC settings, you can bet it's safer on the motor with a smaller dynamic compression ratio.
Whoever is reading this thread should be aware that it would not be the ideal way to go.
Jul 10, 2013 | 01:23 PM
#18
My take is 10:1 should only be used by e85 and track cars. Not used for a DD something that will be driven alot in non race situations.
Jul 10, 2013 | 01:43 PM
#19
I am just going to echo what has already been mentioned... If you want to run pump gas ever, particularly 91, stay below 10:1 compression ratio. Not worth the risk. Play it safe, run low(er) compression, and turn up the boost to compensate for the lower cylinder pressures realized with low(er) compression motors.. You can still play with e85
the larger margin for error, will allow you to not grenade your motor when say for example you get a bad batch of fuel.
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