Propane injection (was Nitrus injectors (was Hydrothermal Biomass-Fueled Engines))

[Joe Chiasson]

> At any rate, injecting it as a liquid will cool the intake charge
> somewhat, giving a performance advantage over a system that uses a
> propane mixer.

I agree you will cool the intake charge somewhat, however the farther away
from the cylinders you are the less effective it will be.  I don't know
exactly how less effective it will be.  Injecting liquid into the cylinder
or near should gain 8-10% more power than gasoline lb per lb.  What is the
power gain by injecting liquid into T-body, i don't know.  What formulas
and properties do you still need to perform your calculation?  In any event
if its less than 2-3% gain it may not be worth trying to inject liquid
(i.e. just the imense cost to have a pump in a pressure vessel, wether it
is in the tank or inline, protoyping a one-off could put somebody in the
poor house.)
 
> Rather than adjust the trim of my injecters, I would just regulate the
> pressure at the injecters. 
 
Thats fine.  When you take a pressure drop in liquid propane (i.e. regulate
it) you are going to form vapour bubbles.  If you size your injectors for
liquid and vapour bubbles from the regualtion process enter the injector
you will vapour lock.  Keep this in mind when you design your regulator and
return system.  

> This is what the Holley system does (and
> every other system I have looked at, for that matter).

I don't know much about the Holley system, but are you telling me that
nobody adjusts the trims on their injectors and its all done by regulating
pressure at the fuel rail or injector?  

Regardless of that, if you have a liquid propane system, and have the
ability to fully modify your fueling curves, then triming the curves
relative to either a fuel temp sensor or a pressure tranducer will make it
a lot easier than trying to regulate.  I am not saying that regulating is
impossible,  i am not saying don't inject liquid at the t-body, i have 4
years experience (not much but more than many people) with propane systems
and am just trying to relay some of the pitfalls I have encountered or
witnessed.

j.