Prpane as a MPG Booster

[racprops]

Tmugz88

Any details why?? What does the systems so for the cars?

Rich

[freebeard]

Propane is heavier than air. Don't store it in the basement.

[Tmugz88]

Originally Posted by racprops

Tmugz88

Any details why?? What does the systems so for the cars?

Rich

Sorry for the delay, I tried reaching a buddy who I worked with at the Sheriff's office but he's been busy.

Here is a useful link Wisconsin departments use them pretty regularly.

https://www.amerigas.com/amerigas-bl...olice-vehicles

[racprops]

Looked at the link.

Those are 100% converted to Propane cars, not a mix of propane and gas.

I find the claim of greater performance with Propane, must have done some work on the engine (higher compressed ratios) and computer programming.

A straight non engine mods have always reported LESS power.

Rich

[Caddylackn]

Propane as a fuel, has about 15-20% less energy than gasoline. If you raise your compression ratio and change your timing you can get a propane set up motor close to the output of a gasoline motor.

When used in a dual fuel motor, you have to pick one or the other setup. Usually it is set up as a gas motor, that can switch to propane but it will be down about 20% in power when using propane. IDK about gas mileage. They usually compare it as $cost of fuel per miles driven. Propane usually wins since its cheaper, that is why they use propane in fleet vehicles that do not need a very long range.

[racprops]

Caddylackn

That has always been my understanding BUT on this site:

https://www.amerigas.com/amerigas-bl...olice-vehicles

They claim:


"Unit 1075, as this vehicle is called, is used to promote propane run vehicles to law enforcement agencies throughout the south .While the car is on location officers are encouraged to test drive the vehicle so they can fully compare it to their normal squad cars. Every agency who has tested the vehicle has agreed this car has more power and torque than its gasoline powered counterparts."

If so it was specially preped.

Rich

[cRiPpLe_rOoStEr]

Originally Posted by racprops

Those are 100% converted to Propane cars, not a mix of propane and gas.

I find the claim of greater performance with Propane, must have done some work on the engine (higher compressed ratios) and computer programming.

A straight non engine mods have always reported LESS power.

Basically the same situation that used to happen with dedicated-ethanol cars in my country, even though they couldn't resort to some "extreme" tuning as they would still often require a gasoline cold-start at least during winter.

[ps2fixer]

From my understanding, an unmodified gas engine running on pure propane will give around 10% less fuel econ, it's not super common here, but some vehicles are swapped over to save on fuel costs.

If you switch over to the diesel world, propane injection is known to act like putting NOS in the diesel engine, but it's much cheaper and it doesn't have to be floored if it's metered going in. I've seen claims of around 30% better fuel econ. I've read up a fair bit and that 30% most people don't account for the propane used. The propane is used as a 10-20% mix with diesel and the theory is the propane helps ignite and encourage a more complete burn of the diesel. The other added benefit is more power which is the most common focus for people wanting those systems. I've seen figures of propane vs NOS and they were real similar, propane + NOS had just at tiny bit more power but separately it was a huge jump over just diesel. Of my understanding, the only extra power from propane over NOS is propane is also burning as a fuel while NOS isn't. The guy doing the tests found even at 10% the jump was massive, I don't think he tried under that figure.

The setup for those tests were a ford power stroke turbo, I think 7.3L if I remember right, with a tuner. I think they were around 400ft/lb of torque on diesel, propane or nos was around 600ft/lb and combined it was like +10-20 ft/lb. I don't recall if there was a 10% mix figure as well or not, been a while since I watched the vid.

I've seen those claims all over, and never really seen anyone debunk those claims. So if my 7.3L powerstroke normally gets 20mpg, a 30% increase in mpg would be 26mpg + 260mpg of propane (10% target). 1000 miles normal would be 50 gal diesel vs 38.5 gal diesel + 3.9 gal of propane (almost a 20lb tank). Today's price for diesel is roughly $6/gal, so $300 vs $231 + propane (should be like $3-4/gal in bulk, even a tank swap out place is $20-25). So MPG alone it saves money, plus you get extra power if the figures are true and accurate.

The OP doesn't say if their vehicle is gas or diesel, but I think for diesel it makes sense, for gas I'd say full conversion is probably the best route if you can get a high compression engine that's more ideal for propane use.

I've always wanted to modify a gas engine to be more ideal for propane and compare the econ of before and after. It's been a while since I researched it but I think the ideal compression ratio for propane was something like 12-14:1. Compressed natural gas engines should be somewhat similar I'd think.

[Piotrsko]

Looked at all those 7.3 propane enriched claims years ago (2005). Diesel mileage went up, total mileage calculating adding the total quantity of both fuels went down. (Funny the enriched people hardly ever added the propane to their totals) Propane also has gotten crazy expensive. However, the Propane did improve emissions somewhat particularly reducing the soot particle quantity and size.

Hmmm you have me by .34mpg lifetime.

[racprops]

Back at the earlier gas crunch when I was trying a number of so called MPG devices and systems one was propane.

The claims was just about the same for running propane was reported as above: A 20% improvement it power and MPG.

These systems were computer controlled.

It was said when you ran out of propane you felt it in how you engine lost some power and smoothness.

It seems to cost just as much in fuel costs so it seems to be a break even set up.

IE There is no savings.

The 20% savings in gas mpg was off set by the 20% costs for the propane.

And your out the then cost of around $1K in the system.

So as far as I can tell it is a dead end.

Rich