DIY_EFI Digest V1 #277

[Robert Harris]

Diesel engines work by compressing air past the ignition temp 
of the fuel, then injecting the fuel near top dead center and 
getting autoignition.Since it runs extremely lean, lots of excess
oxygen is present - hide that fact away.

Prior to the intake  valve closing, the more air that you can 
shove into the cylinder, the better.  Cooler denser air makes 
more power because more oxygen is available.After closing the 
intake valve,more heat is icing on the cake - because the physics
of compression will generate the heat to autoignite the fuel - 
provided there is no excessive heat LOSS to the cooling jacket 
(like trying to start at 40 below)

Simple turbos work fine, because even tho the air is hotter (minor 
bad thing) more oxygen is available, thus more fuel can be 
injected and more power.  Intercoolers (technically after coolers - 
but I'm not wearing asbestos underware this week) make more 
power - but only if you are pushing the oxygen limits by fuel such 
as in tractor pulling engines.  

Dirty little diesel secret.  Propane.  Since a diesel runs with an 
excess of oxygen, with the right fuel, you can make more power.  
Lots more power - like 25% more without busting a wrench. 
(Check BI FUEL references on the internet). 

You merely meter propane to the intake air of a diesel engine in 
proportion to the EXTRA power you would like to make - like a 
throttle plate NOS system, without the NOS.  Since the auto
inanition temp of propane is ridiculously high, it won't ignite
until you introduce it to the fire from the injected fuel.  Since it
requires a relatively rich mixture to sustain combustion ( 
compared to gasoline) a lean mixture is not prone to backfiring.

You now are merely using the excess oxygen you have already
paid the energy loss's to pump and convert to piston pressure,
and so additional fuel adds more output than might be initially
expected. Plus, the extra heat and violence in combustion helps
better combust the liquid fuel drawing even more power out ot the
existing fuel.  Works fine - thousands of RV's, light utility trucks and
tractor pulling engines have been doing it for years.  Bolt on, 
instant no muss no fuss no brainer extra power.



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Robert Harris <bob at bobthecomputerguy.com>


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