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I've not been directly tied into any work in GDI, however I have a couple concerns about this design and technology:
- DI would require very high injector pressures relative to port injection. Diesel injectors can go into the >10,000 PSI range, whereas current gasoline is in the 50 PSI range. This brings up lubricity issues with injectors and fuel pumps in gasoline service, especially when considering the trend toward lower sulfur for emmissions benefits.
- Diesel engines operate with WOT, injecting as much diesel fuel as needed for required power. Diesel fuel essentially combusts as it is injected into the combustion chamber, utilizing the available oxygen up to stoichiometric conditions. Gasoline engines don't have the same lean operations capability/range, and are spark ignited. Don't know how consistent the flame front would be, nor how well fuel would mix into a homogoneous vapor in the combustion chamber at high rpms.
- Deposit formation on injectors would likely be very harmful to the efficiency of the engine. Deposits on the intake valves would likely occur more slowly as unburned vapors "varnish" the intake valves opened at shutdown, but would not be cleaned up through fuel additives, as the air/fuel mixture doesn't flow across the valve. Hesitation would likely not occur, as these deposits wouldn't "sponge up" the vaporized fuel in the air/fuel mixture.
- I understand tests by a US fuel additive concern on a Mitsubushi (the Cleo?) aquired from Hong Kong (?, it was left hand drive) produced unusual deposits in the combustion chamber, though I don't know the nature of the deposits (don't think enough testing was done to draw conclusions).
Anyway, just some thoughts/concerns for consideration.
posted by 146.27.12...
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