[Diy_efi] LPG injection

[Greg Hermann]

At 1:33 AM 11/25/02, Altaffer, Eric EM2 wrote:
>>In some ways. It's for SURE why methanol fueled engines tend to foul the
>>plugs before they are warmed up!!  It also is REALLY bad for the efficiency
>>and hurts the power output when some of the heat of combustion goes into
>>evaporating the rest of the fuel !
>>You're getting right AT the reason why some of the mfgr's have played with
>>that 80/20 ethanol/gasoline mix. At stoich, the latent heat of vaporization
>>of that mix is just about PERFECT for having the last of the fuel get
>>evaporated JUST as the spark plug ignites it.
>>It seems like methanol would be very good at
>>surpressing det if this were the case.
>>This very much IS the case, and methanol IS excellent at avoiding
>detonation.
>
>There is a bog problem with adding methanol to gasoline.  The o2 sensors
>that are on the cars are trying to maintain a stioch mixture for gasoline.

Nope. The O2 sensor is EXACTLY that. It senses stoich mixture, regardless
of what fuel or fuel mixture brew you are running.

>When you add the meth, the car is a bit lean at 14.7.  This is BAD for
>detonation suppression.  I live in California where they have introduced 10%
>meth into the gasoline and I could not get the darn thing to stop detonating
>even at low boost.  Luckily they do not add meth to the 100 octane.  That is
>all I run.
>
>>Not to mention that injecting SOME of the methanol pre-turbo (under boost
>>conditions only) would put some internal coolant into the
>>compressor--reducing the work needed to do the compression, thus ultimately
>>reducing backpressure on the motor from the turbine, and possibly
>>eliminating the need for an IC.
>>Greg
>
>Can you explain that one a little more in-depth.  I would never inject a
>liquid into the turbo.  Nitrous no problem, but a liquid, never.  I would be
>worried about the blades destructing not only from thermal shock, but the
>mechanical shock.  Also the alcohol is taking place of air in the
>compression cycle.  Since liquid is nearly incompressible, I would think it
>takes away from compressing the air.  I would however inject the alky after
>the intercooler, or the turbo for those not running an intercooler.  Just my
>thoughts.  ERIC.

A SMALL amount of atomzed liqud doen't really have much of a negative
effect of the compressor blades.
All I am talking about is enough methanol so that its latent heat is
sufficient to transform the compression process from (near) adiabatic to
(near) isothermal.

Greg
>
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