Propane/water/alcohol injection and O2 sensors

[Geddes, Brian J]

> -----Original Message-----
> From: Garfield Willis [mailto:garwillis at msn.com]
> Sent: Sunday, April 07, 2002 1:11 PM
> To: diy_efi at diy-efi.org
> Subject: Re: Propane/water/alcohol injection and O2 sensors

<snip>
> But another thing about your question puzzles me; you ask 
> "will a petrol/propane
> mix influence ...?". It's the word "mix" I'm wondering about; 
> I'm going to
> assume you just mean alternating between these fuels? I trust 
> you don't mean
> actual mixing of petrol & propane as a compound fuel? Or do 
> you? Inquiring minds
> wanna know.
</end snip>



Yep - I'm planning a petrol/propane mix.  I've got a nice, normal multiport
injected 6-cyl turbo gasoline engine (Mitsu VR-4, for those who care).
However, when I turn up the boost too much, temps in the combustion chamber
get too hot and I get knock/pre-detonation.  Not good.  Additionally, I'm
nearing the limits of my stock fuel system, so if I turn up the boost much
more I'll run lean, and get even more knock.  VERY not good.  

Enter propane injection.  The basic concept is to open a solenoid and inject
propane around the time when the engine starts entering the knock "danger
zone"...probably around 1 bar for my purposes.  Propane is stored as a
liquid, so thanks to good old Mr. Boyle it's gonna be darn chilly when it
gets squirted into the intake, cooling things down considerably.  This has
two advantages over the standard water/alcohol injection:  the propane is
quite a bit colder, and it is in gas phase and so there's no danger of
pooling or uneven distribution.  

The other benefit is that by injecting propane, I get some extra fuel to
suppliment my nearly-taxed fuel system.  I'm still going to put in larger
fuel injectors, but it's a nice measure of safety against running lean.

In tuning this kind of a system, my primary tool will be EGT.  WB O2 would
be a nice compliment though, if I can swing it.

Thanks for the very informative reply, BTW.  I'll have to chew it over for a
little while to let it all sink in.  :)

- Brian Geddes 
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org