A few trucks converted to bi-fuel gasoline/CNG in my hometown

[cRiPpLe_rOoStEr]

The CNG tank is easily visible.







This Chevy S10 is actually tri-fuel, since it has the gasoline/ethanol flexfuel engine.




Back here CNG is costing roughly the same as ethanol, a little cheaper than high-sulphur Diesel where it's still available, and since Diesel trucks are more frequently targetted by thieves even some commercial operators are favoring CNG.


Some folks prefer the CNG tank to be mounted under the body in order to save cargo space.

[Hersbird]

I bought a 1996 Chevy Silverado one ton crew cab that had the 7.4 Vortec and a propane dual fuel conversion with a 115 gallon tank in the bed. I also had a 1988 Southwind motorhome that was a 454 with dual fuel propane and unlead. The motorhome worked well but when I sold it the next owner burned it to the ground by trying to run the house propane loads off the unregulated extra tank for the motor. I can only assume he turned the 18,000 but furnace into something much bigger. The 1996 never ran right, I finally found a flat lobe on an exhaust valve but had removed all the propane stuff before finally figuring out the issue. I don't know how that truck would have ran on propane but I still have all the parts for future possibilities.

[cRiPpLe_rOoStEr]

Originally Posted by Hersbird

I bought a 1996 Chevy Silverado one ton crew cab that had the 7.4 Vortec and a propane dual fuel conversion with a 115 gallon tank in the bed. I also had a 1988 Southwind motorhome that was a 454 with dual fuel propane and unlead.

Propane is different from CNG, not just because CNG is methane-based but, most important, because of its storage pressure. While CNG usually goes from 3000 to 3600psi, propane (a.k.a. LPG, liquid petroleum gas) is stored at 225psi. Some propane conversions have a heating system to regasify the liquid propane, while others still use it in the liquid phase (forklifts usually go this way), while CNG is always in gaseous phase altough it must be de-pressurized before it's admitted into the engine. There is also the LNG (Liquid Natural Gas) but it's a totally different animal, requiring cryogenic storage to be kept in liquid phase, and can't be used in an engine in liquid phase.

[Baltothewolf]

I know someone with a veggie dodge ram 1500 or something, pretty cool thing.

[cRiPpLe_rOoStEr]

Originally Posted by Baltothewolf

I know someone with a veggie dodge ram 1500 or something, pretty cool thing.

What do you mean by "veggie"? Ethanol? Biodiesel?

[Hersbird]

Right, my propane systems ran on vapors from the luqid propane, technically even gasoline cars run on vapors from the gasoline as well. Liquid fuel no matter what it is has to be converted to a vapor to burn. Also vapor is just another name for gas but means it has gone through a phase change, it was a liquid but now it's a gas. To me propane seems better for storage and for mobile use then CNG but maybe that is old thinking.

[elhigh]

Originally Posted by cRiPpLe_rOoStEr

What do you mean by "veggie"? Ethanol? Biodiesel?

He probably means a diesel truck that has been adapted to use waste vegetable oil. I don't know how it is in Brazil but in the States we have lots of food deep fried, and the oil has to be changed once in a while. A truck converted to use veggie oil (waste or virgin) will have a tank equipped with a heating system to warm the oil, as well as heated fuel lines to keep the fuel hot all the way into the injection pump, and a small auxiliary tank for starting and ending with pure diesel fuel. I understand it's pretty much impossible to start a modern engine on vegetable oil but once everything is hot it works well.

[cRiPpLe_rOoStEr]

Originally Posted by elhigh

He probably means a diesel truck that has been adapted to use waste vegetable oil. I don't know how it is in Brazil but in the States we have lots of food deep fried, and the oil has to be changed once in a while.

We also have many deep-fried food in Brazil, but the direct usage of waste cooking oil as an alternative fuel is not so popular back here altough it may be more justifiable from an economy standpoint than biodiesel since it doesn't require the fuel to be chemically altered.

Originally Posted by elhigh

A truck converted to use veggie oil (waste or virgin) will have a tank equipped with a heating system to warm the oil, as well as heated fuel lines to keep the fuel hot all the way into the injection pump, and a small auxiliary tank for starting and ending with pure diesel fuel. I understand it's pretty much impossible to start a modern engine on vegetable oil but once everything is hot it works well.

It actually is possible to start a modern engine on vegetable oil, as long as its pre-heated, which can be done thru a tank-mounted electric heating pad. Some European heavy-duty trucks are fitted with a fuel-heating setup even when they run on regular Diesel fuel, due to gelling issues in cold weather However, the most usual heating setup in the vegetable oil conversions relies on a heat exchanger connected to the engine cooling system which only works after the engine reaches a certain temperature.

Originally Posted by Hersbird

Right, my propane systems ran on vapors from the luqid propane, technically even gasoline cars run on vapors from the gasoline as well. Liquid fuel no matter what it is has to be converted to a vapor to burn. Also vapor is just another name for gas but means it has gone through a phase change, it was a liquid but now it's a gas.

The fuel being stratified into very thin drops is not exactly the same as vaporizing it. Also, in LPG-powered forklifts the fuel is used in the liquid phase.

Originally Posted by Hersbird

To me propane seems better for storage and for mobile use then CNG but maybe that is old thinking.

It's all because CNG tanks are heavier and more reinforced due to the higher pressure, but it's not impossible to use Natural Gas at low pressures in stationary applications less sensible to a lower energy density.

[Baltothewolf]

Oh sorry, I forgot I posted here. Yea it runs off of vegetable oil. The guy who owns the truck owns a factory that makes the veggie oil, or refines it or whatever, so he technically gets unlimited MPG as he never has to pay a cent for gas. The truck only runs off diesel when the engine is cold, other then that, it's 100% veg.