Peter, there is something I wondered about.
Lately, I've been going through the many recent papers about development of various piston engines with port injected gasoline as base fuel and ethanol/methanol as mean of charge coolant. They tested 3 methods of charge coolant delivery: port injected, direct injected during intake stroke and after intake stroke. Last method allowed highest levels of boost pressure and power without detonation due to highest cooling effect I.e. lowest in-cylinder temperature. Difference was really huge, 1.05 bar for PFI, 2.4 bar for second method and 4 bar for last. Note: very low engine speeds and overall Lambda 1.
So my question basically is, do you use pre-turbo system mainly due to simplicity and reliability? I can see the benefit in cooling of inlet air which can dramatically increase mass flow for any given shaft speed. But with the above in mind, would direct port injection I.e. very close to engine block, be superior for detonation suppression @ given flow rate?
Many people talk about time factor for atomization, and surely, water can absorb huge amount of heat even by the time its in the engine so the heat of compression in the turbo is really not a problem, but isn't it a bit of waste? We want maximum cooling effect in the engine, not in the manifold
I would be happy for your input
04-01-2012, 07:34 PM
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