Dual fuel help.
 

Ok, so i want to do somthing to help with my milage on my truck, what kind of mileage increase could i expect from a dual fuel system on my 302? Would i need a new carb or what? (i have an edelbrock performer now) Or would i be better off with a pure propane system? I want somthing that's cheaper than gas with equal or better milage that costs under like $200. I was told i could assemble a dual fuel system for like $200.

If you can assemble a system for $200 that is "Cheaper than gas with equal or better mileage", you will very soon be a very rich man, because you can easily sell such a system for at least ten times it's cost!

The most common "dual fuel" system would allow you to use either LP (Propane) or CNG (Compressed Natural Gas) alternately with gasoline. A "pure propane system" is not usually practical because of short range and limited availability.

I guess carburetors are available, or could be modified for the alternates, but I think it would be difficult to do a dual fuel set-up that way. Current development is on fuel injected vehicles because the electronics and feedback make it relatively easy to change fuels.

Actually, I am currently pursuing the possiblity of converting my truck (4.6) to CNG/gasoline. If I could do it for $2000, I would be ecstatic!

I just bought a near complete system off ebay for 175- got a free tank- 80 gal- ready to go! Under 200.00. oh yea- i'm also rebuilding motor- $2k to get all the goodies out of the 110 propane. Buying propane at $1.50/gal as of today...so savings is there.

That's great! Let us know how it goes.

Can you still use gasoline, or will it be strictly LP now?

I have the equiptment for both...but from research that I've done the best option is to go with a propane dedicated system. In order to burn dual fuel-gas- you have to keep compression within pinging range of intended octane which keeps you from building an engine that really takes advantage of the 110 octane of propane. Also have to get the engine to handle both fuels which can be challenging or cakewalk- depending on who you talk to. My first build may be dual fuel and a 9.5:1 or so motor where i can still burn premium but get a little more from the propane. My optimum build would be 12:1 compression, with forged pistons yada, yada and is about a $3K project just for the motor. But...if done right should yield a 400 that iswell over 450Ft lbs torque, 350hp and still able to get 13-15 mpg on propane in a '77 f150 4x4. I'm looking at getting the most out of an rv and mileage build with cheaper fuel...about 1000 miles between fills that, at todays cost, would be $1o5.00 tank or 11 cents/mile for fuel. With the same mileage and gas it would cost $210 or 21 cents/mile. Plus I will save on maintenance, oil changes etc as propane engines last a lot longer and are really clean.

It's confusing and I'm learning a lot while I go along but I hope to have a system by xmas.