I'm looking to convert my F150 with 300-6 over to propane. Propane around here runs about 1.68 a gallon. The main reason I want to convert is for better offroad performance when I convert it over to run trails 100%.

Propane has what, 110 octane? I was planning to bump up the compression on the 300 to around 11 to 1 or so to take advantage, and also run a 4bbl mixer..

also, how do your propane tanks have to be mounted to be DOT legal? Just curious, since I want to be able to retain my state inspection.

 

Propane is 118 octane. 11:1 would be no problem, you could go higher. We have a 2 Cummins B engines, one runs on CNG and the other is Propane, and they are nothing more than the diesel version with spark plugs. I think it is 18:1 compression with a turbo, 195 hp @ 2400 rpm, so the label says.

I know this may sound dumb but when you mount the tank you first need a tank designed for it's intended use, that means no BBQ grill tanks allowed.

Some quick notes for mounting are: Fuel containers have to be mounted to prevent jarring loose, slipping and rotating. The fastenings have to withstand static loading in any direction equal to 4 times the weight of the filled container. If you want to know it all you should buy a NFPA 58 book -->

http://www.nfpa.org/catalog/product....%5Ftype=search

What are you paying for gasoline there anyway? $1.68 doesn't seem like a worthwhile reason to convert, when you'll end up burning more propane to equal gasoline. Our gas price dropped to $1.69 today. If you need a kit try ebay, every now and then you find parts cheap, especially cylinders.

 

First of all, "Propane" as it is sold is a mixture of gasses. You won't ever get "pure propane", so the octane rating will typically be above 100 but not lower than the octane of pure propane. It varies even more widely as you leave the country, for example, in Mexico there is much more butane in the mix.

You could theoretically run 12.5:1 with propane with no problems and if you have lots of $$$ can find pistons for that then go for it

For standard build ups, higher is definitely better. But to really take advantage you need to remap the distributor curve. The Pinto racing distributor mod will do it, using a GM HEI ignition and Heli-Coil on a 2.3L, for example.

Another way to do it is replace the vacuum advance with a mechanical advance like a race car. I can tell while driving on vacuum advance that there is more HP at high speeds but the stock advance doesn't go far enough.

If anyone knows where to get some info on switching from a vacuum to mechanical advance let me know.

Every "Dual-fuel" and aftermarket conversion suffers from severe compromises that has led to its reputation as a poor performer, but the reality is that the land speed record was just set last week by a propane powered engine.

 

BTW a BBQ tank as a backup is a really good idea although the DOT doesn't recognize non-automotive LPG containers as engine fuels and cannot "technically" be used as such but its a fact that your opportunities for refueling after 5 p.m. or worse a holiday or weekend with propane for highway use are drastically reduced. Your state and local laws may vary... widely.

My experience last weekend was trying to find a station with propane that

A: Knew what the fuel laws were
B: How to operate the filling equipment
C: How to remove Sales or Fuel Taxes from the register at the time of sale
D: Would actually pump propane into the fuel tank.

I did not refill until the next day.... in a nearby city, by someone who did not remove the fuel taxes from the bill and was operating a faulty AIRGAS filling pump where the vapor return line was vented TO THE ATMOSPHERE (that was "5 gallons off the price")

Price was 1.88/gal.

Its true it doesn't make economic sense to convert. However, as an upgrade, you can build a solid, dependable, powerful engine with a ridiculous longevity with low maintenance requirements.

 

Well, gas is $1.85-1.90 here. my main reasons are not for cheaper gas, but I am going to use this truck offroad, and I want to keep the emissions dogs at bay..

I talked to my local propane company, and they said they could lease 40# DOT forklift tanks for cheap.. that way I could get 2 tanks and carry them in my truck..

the truck would be single fuel only, and I'd probably get a DUI dizzy and probably a propane ECM to control the mixture.

 

A single 40# tank, as far as I know is only about 8 gallons of propane. I am unclear about the relationship between the # and gal. numbers but AFAIK you divide the # rating by 4.3 (lb per gal. of LPG) to get the actual gallon capacity. Then, allow for expansion knock off 10-15% from that figure to get your average fill in gallons.


I am curious though as to this lease arraingement. I hear that you can find decent tanks off forklifts at industrial slavage yards for good prices. State inspections is another thing altogether. Currently I live in a county with no inspections and the State Patrol recently gave up inspecting vehicles brought in from out of state so I never had my rig looked at.

 

that is about what I figured.. 7-8 gallons.. that is why I was going to carry 2 tanks. Either that, or I was going to fit a bigger round DOT tank, but that might be easier said than done. I've been looking into it, and AFAIK as long as you have DOT tanks, and you have than in open air, you are good to go.

I'm still waiting for a call back.. She said it might be a couple days.. they said new tanks are only $109.00 a piece for 33# tanks (I'm sure 40# tanks are $5000 dollars a piece for the extra 7#).

 

You do relize that DOT approved tanks means it is approved for fuel storage during transportation of fuel and not for a fuel cylinder to power a vehicle. What you need are tanks that are ASME certified, if you want to be legal.

 

I knew there was a catch.. after looking through the 'net, I came up short on suppliers... anyone know of any suppliers?

 

Let me check and I'll let you know, you might try ebay too

 

Manchester tanks out of California are probably the most prolific suppliers I've found, they've been making Tanks for forever. They're on the web.

 

i have a question, hwen at odd angles will the carb lean out, like when gas cant quite make it to the carb cuz of leaning on the side, but since propan is a gas it pressurized and it will keep a constant flow to the carb, right?

 

Yeah I talked to somebody who knows something and he said Manchester is the best. You have to buy them from a local propane supplier though.

www.mantank.com

 

yup. that is why people like to use propane off road.. since it is pressurized, it keeps squirting out at the right ammount, whether you are right side up or upside down.

 

Not to steer him away from propane or nuthin but EFI will acomplish the same thing.