Re: GAS-L: Internal Combustion with Producer Gas

[Reedtb2@cs.com]

Dear Robert Luis et al:

Good points about compression pressure vs compression ratio.  

I would presume that producer gas gives lower compression pressures at high 
compression than comparable gasoline, propane or methane fuels at the same CR 
because the fuel charge is more dilute and the flame temperature is down.  

Therefore, increasing CR with producer gas to regain lost power should be OK, 
but not to exceed original design specs.  

If not, please warn me....

Yours, TOM REED

In a message dated 4/27/00 9:15:50 AM Mountain Daylight Time, 
rabello@uniserve.com writes:

<< 
 Mike Norris wrote:
 
 > If as you say the knock limit of producer gas is 150, then one could
 > increase the compression
 > ratio by reducing the volume of the combustion chamber at
 > top-dead-center.
 
     Your idea is essentially correct, but I'd like to introduce a
 caveat.
 Compression pressure is more significant than compression ratio,
 strictly
 speaking.  Changing valve timing, ignition advance, engine rpm or the
 density of the intake charge can impact compression pressure.  Most
 automobile engines have been designed to tolerate no more than about 150
 psi.  Exceeding this can lead to internal component damage.
 
     I have experience in this regard with my most recent propane
 conversion.  I built a small block Chevy with a static 10:1 compression
 ratio.  When I first fired the engine, it sounded like a diesel! 
 Subsequent
 checking of its compression pressure revealed a range from 180 psi on
 the
 lowest cylinder to 205 on the highest.
 
     The engine ran very well, but suffered from detonation at part
 throttle.  I installed water injection to remedy this problem, and it
 worked, but some water condensed in one of the cylinders.  The next day
 when
 I tried to start the car, that water could not compress and I ended up
 with a bent connecting rod!  Inspection after tear-down revealed fairly
 heavy wear on the main bearings.  The engine lasted about 35 000
 kilometers and probably wouldn't have gone too much further before
 experiencing bearing failure.
 
    The moral of this sad story is this:  Most passenger car engines are
 not designed for high compression pressures.  You're better off with a
 diesel if you increase compression pressures beyond 150 psi.
 
 robert luis rabello >>
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