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Old 12-03-2019, 08:43 AM   #5 (permalink)
Ecky
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Gaptooth (retired) - '00 Honda Insight
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What kind of fuel do you intend to use? Those 11:1 K20A2's are using alcohol. On a stock engine, you have to pull a lot of timing already at WOT with 87 octane which hurts both efficiency and torque.

Just as an example, on 87 octane the 9.7:1 Accord motor actually produces more torque and power (at high load) than the 10.5:1 TSX up to the point it runs out of air (somewhere around 6000rpm) because the TSX needs to run 3-5 degrees less timing with that fuel. Unless you're intending to run alcohol in your DD, I would stick with a lower compression ratio or just have boost not come on when using a low octane fuel. Higher CR helps with efficiency at part throttle but if cylinder pressures are too high (high load + high CR + boost) you have to retard timing such that you're sending a lot of unused energy out the exhaust.

Last edited by Ecky; 12-03-2019 at 12:33 PM..
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