compression ratio, octane, ignition lead
Posted: Sat Apr 30, 2011 8:05 pm
This year, EMC provides Q16 fuel, and the compression ratio is unrestricted.
Several in our group (including me) wanted approximately 16:1. Several in our group (including Gene Adams) wanted approximately 12.5:1, but were "OK" with a little more. Turns out that it's a moot point, as we're limited to high 13's:1 due to our piston of choice (Ross "392" forging).
Detonation shouldn't be an issue, as early hemi's on both methanol and gasoline seem to run best at between 26-30 degrees lead.
As the compression ratio goes up, so does the dome, which might be detrimental. Also, I suspect that as the compression ratio goes up, there are diminishing returns.
Can anyone 'splain all this to me? What might be the range of the optimal compression ratio? How much, if anything, are we "leaving on the table"?
It should be noted that Q16 has a considerable methanol content, or so I've been told. It's not the same fuel (nor legal) as run in NHRA gas classes like pro stock, that utilize compression very high compression ratios.
It's a mystery. lol
Thanks, Danny
Several in our group (including me) wanted approximately 16:1. Several in our group (including Gene Adams) wanted approximately 12.5:1, but were "OK" with a little more. Turns out that it's a moot point, as we're limited to high 13's:1 due to our piston of choice (Ross "392" forging).
Detonation shouldn't be an issue, as early hemi's on both methanol and gasoline seem to run best at between 26-30 degrees lead.
As the compression ratio goes up, so does the dome, which might be detrimental. Also, I suspect that as the compression ratio goes up, there are diminishing returns.
Can anyone 'splain all this to me? What might be the range of the optimal compression ratio? How much, if anything, are we "leaving on the table"?
It should be noted that Q16 has a considerable methanol content, or so I've been told. It's not the same fuel (nor legal) as run in NHRA gas classes like pro stock, that utilize compression very high compression ratios.
It's a mystery. lol
Thanks, Danny