Anybody know of this being done? If so, I need details, please.

One question: Why?

Though, I like the idea of the propane powered Toyota Forklift at work having NOS! Hmmm, sure, I'll load that in your truck! *grin*

My CJ runs a 421 small block Chevy on Propane(Impco Model-E vaporizer, 425 mixer). I have a competition coming up and part of it is a 150' long X 5' deep mud pit, I want a little extra power(100 to 125hp). I'm having a hard time finding info on modifing propane inductions, thought someone here might have some ideas. The properties of N2o and LPG seem to be very similer(?) and both need to be run at close to the same ignition timing(?). Propane burns at a slower rate then pump gas so what effect would this have on the amount of the N2o injection, more? less? the same? to produce the same hp as pump gas on N2o. Will propane lean out to much for N2o use?
Any info or thoughts about this?

If you want to get serious with the nitrous, you will need a seperate fuel system to inject gasoline with the juice. Nitrous(as I'm sure you know) is just added oxygen. I have not seen any systems or mathematical tables to figure out how much LPG to add to a given ammount of N2O. The propane motor can be run on gas, so if you add a 5-8 gallon fuel cell(possibly smaller) with its own pump and regulator, to a fuel solenoid for an off the shelf nitrous kit, you should be able to run LPG for most of the event and LPG/N2O/Gasoline for the parts where you need lots of power.

AS for the properties of LPG and N2O being similar, there are no similarities. Propane is a fuel(like diesel C.N.G. acetaline or gasoline) while nitrous is an oxidizer(like a super charger or turbo or the oxygen tank for a torch) that simply allows you to burn more fuel. You could probably run a small amount of nitrous(like a sneaky pete system) with out adding extra fuel, but it will never give you an extra 100 horses.

What I was trying to say was propane/n2o and gasoline/n2o seem to be similar, sorry.

Do you see any problem running lpg and gasoline/n2o at the same time?
Use a soleniod for the gasoline, a soleniod of the n2o, fogged together like a standard wet NOS system(to keep it from leaning out) and just leave the propane flowing too? What about timing, propane runs better at lower rpms around O timing, when the n2o kicks in at higher rpms the O timing would work, right?

I don't agree with Jimmy, but to each his own...
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N2O (Nitrous Oxide) is two parts Nitrogen and one part oxygen.
When N2O is introduced as a LIQUID into the intake tract, it boils into gasses.
Most of the performance gains you see from Nitrous are from the 'Boil' when the LIQUID Nitrous Oxide hits the intake manifold and converts to a gas absorbing large amounts of heat in the process.

Cooling the intake tract will condense the intake Charge (Charge = Fuel & Air Mixture).
With the intake Charge condensed, you will get more Charge mixture than normal in the cylinder, and that's where the extra power comes from unless you use Massive amounts of N2O.

N2O is used because it doesn't 'Quench' the combustion like an inert gas would.
Like Halon, Carbon Dioxide, Argon, ect.,
Those gasses would affect the cooling cycle, but would also put the flame out in the combustion chamber.

N2O has the unique property of NOT Quenching the combustion cycle.
As N2O goes through the combustion process, it releases the molecule of Oxygen.
When N2O is used in massive quantity, the Free Oxygen can become enough to affect combustion temps, driving them up.

The common cure for the added Oxygen released is to add more fuel, there by avoiding a potential critical lean condition.
N2O is easy to compensate for, since it's Oxygen release is on a 1 for 1 incremental scale, instead of a heavy curve, that's why there are so many kits for street use.
(If the release was on a steep curve, Average Joe BumbleFu*k couldn't install or maintain the systems)

When we used N2O on our Propane powered drag car (A True Gasser!), we injected raw propane (Liquid) directly into the intake stream (Via NOS Fogger Nozzles), and this seemed to work fine.
Keep in mind you need to sets of fogger nozzles, N2O and Propane don't get along in the same nozzle.
(They don't expand at the same rate, One over powers the other and you will get a Rich/Lean condition)
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I know the NOS guys were right on the stick when we played with the race car, and had a package that almost worked out of the box...

I suggest you find someone currently working with a propane/ N2O system and talk to them.
NOS is now owned by Holley (as in Holley Carbs), and ICE guys don't do Propane as far as I know, but you might give them a call.
I have no idea if NOS is still doing the strange stuff now they are a part of Holley...
(They used to try ANYTHING!!!! Lawn mowers, jet skis, you name it, they've done it!)
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I know the guys that make the 'Bully Dog' systems (Propane injection for diesel engines) played with N2O in the early days, and maybe they can help.
I've been in a couple of the 'Bully Dog' equipped trucks (dual wheel tow vehicles) and I can tell you I'm impressed! The propane over turbo diesel is a complicated, but they seem to have worked it out, and I don't know how far they got with N2O, but it might be worth asking...
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As far as the dual fuel idea presented, I guess it would work, but I have no idea why you would want to have two separate and complete fuel systems, one of which you have to build from scratch...

Thank Arron
I would rather not run gasoline too, If I don't have too.
-snip-
When we used N2O on our Propane powered drag car (A True Gasser!), we injected raw propane (Liquid) directly into the intake stream (Via NOS Fogger Nozzles), and this seemed to work fine.
Keep in mind you need to sets of fogger nozzles, N2O and Propane don't get along in the same nozzle.
(They don't expand at the same rate, One over powers the other and you will get a Rich/Lean condition)
-snip-

How where you metering the raw LPG flow?

What porportion of raw LPG to N2o where you using?

Did you ever have problems with the raw LPG fogger icing closed?

Thanks, I'll check out the other guys you mentioned

*How where you metering the raw LPG flow? *

Liquid regulator for constant pressure, constant (regulated) volume through orifices in nozzles.
Same orifices NOS used for the N2O... Made things easy for us.
Expansion rates were a bit strange, especially on hot days...
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*What proportion of raw LPG to N2o where you using?*

I honestly don't remember, but it was about 3 to 1 in favor of the N2O.
Propane is potent, especially in liquid delivery
We had the benefit of a dyno, so the ratio wasn't an issue for a single engine.
We had instant rich/lean indicators handy.
(use an O2 sensor rich/ lean indicator, they are under $150 and work pretty good! just remember to sneak up on your mixture, don't try and kill dragons the first day!)
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* Did you ever have problems with the raw LPG fogger icing closed?*

You know, I heard everyone wonder about that, but the LP didn't do any worse than the N2O no mater what we did...
Of course, we did have the nozzles screwed into a huge aluminum ('tunnel ram') high rise intake/ throttle body, so that moved heat petty well.
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I don't think I'd have wanted to push the button in the rain, you would have Ice in a second, but it's the same with N2O... Moisture on the nozzles themselves might freeze to them, but if there isn't any moisture in your N2O or LP, you shouldn't have a problem at the nozzle...

I think you may be thinking of the mixers where the LP is being mixed with ambient air, and frost forms on, and in the mixers.
With the fogger nozzles, you are dumping raw LP for just a few seconds directly into the intake tract.
(Don't try port injection! We had REAL problems with dumping the 'Gas' on the back of the exhaust valves...)

We did have some problems at the regulators at first, (weren't using regulators and solenoids/ valves rated for the LP and N2O) but we figured that out pretty quick.