Be-have!

[Thellra]

Another crazy thing I have learned is this...

If you shift progressively (see my other post), accept that you aren't the fastest vehicle on the road (A fact of life for me), and accelerate and don't kick on your Turbo,

You will find your mpg increases, at least for me, I can get 8-11 mpg in CITY driving just by being defensive, speeding up conservatively, and not accelerating towards red lights.

You can also go the other way if you want to have fun,

I ran into a guy that had 3 bottles of propane daisychained together on his catwalk that directly injected propane into his air intakes with a knob in the cab of his truck giving him an extra 150hp with it fully open...

[DRW]

Seriously? Guys are Hot-Rodding their 18 wheelers? That's awesome!

[dieselmech]

Depending on where his valve was and the size of tubing after expansion, he would of gotten modest increase but certainly no where near 150hp.

In another thread I talked a bit about what I did with a bbq tank, electric solonoid and some copper tubing. got 5-8mph difference in speed, that's what 10hp maybe?
Anyway, time went by and I learned/realised what I did wrong.

A bbq tank takes off gas, the liquid stays in the bottom. An automotive propane tank takes off liquid. (that's why they have a pilot hole and you have to clock the tank as you install it)

So, I took a bbq tank (standing upright) in my box and ran 1/2" copper tube up to an electric solonoid in the eng compartment. Then after the solonoid I plumbed it into the top of the breather lid. (drilled a hole and used a bulkhead fitting).
This was a 6.9 Ford 4spd f-250 ext cab.
Problem was, the volume of gas travelling in a 1/2" tube is not enough to add much power (the 5-10hp I mentioned)
In an automotive propane system, the tank is clocked so you draw liquid into the line up to the atomizer where it is heated by coolant and expands something like 100 times in volume. After the atomizer there is a 2 1/2" line running to the carb to supply enough propane to run an engine.

So, If I had ran LIQUID up to my solonoid,(as close as possible to the breather on the engine) and then a large tube to let it expand, then yes I would of had a poop more power in my diesel.

If you look at bullydog or other propane inj kits they have automotive propane tanks and draw liquid for this reason.

Three (or twenty) propane tanks daisy chained will still put out minimal power, just for a lot longer.

(kinda like the guy who wanted the biggest nitrous bottle he could find, I told him the plate under the carb is jetted for 75hp hit...REGARDLESS of the tank size. He didn't understand)

[GasSavers_Erik]

Could someone explain how adding propane to the intake air of a diesel would give it more power at wide open throttle?

IMO- At WOT, a diesel engine is usually blowing black smoke because there isn't enough air to burn all of the fuel. I would think that replacing some of the air with propane (which also needs air to burn) would actually make the problem worse and lower power output.

[Sludgy]

Originally Posted by Erik

Could someone explain how adding propane to the intake air of a diesel would give it more power at wide open throttle?

IMO- At WOT, a diesel engine is usually blowing black smoke because there isn't enough air to burn all of the fuel. I would think that replacing some of the air with propane (which also needs air to burn) would actually make the problem worse and lower power output.

First of all..... diesels have no throttle, so they can never run "WOT".

Second..... in modern diesels, there is always excess air, otherwise diesels smoke like Mt St Helens when they are fuel - rich.

Third.... adding propane uses up the excess oxygen without changing the liquid fuel rate. So, it adds fuel that is normally limited by the ECU.

[GasSavers_Erik]

OK- that makes more sense- that adding propane would increase hp only if the diesel engine was still running lean (no black smoke) when the accelerator pedal was to the floor (yes, I did use "WOT" incorrectly).

So, if you already blow black smoke under hard acceleration- then adding propane would be useless and would actually displace oxygen lowering hp.

[JanGeo]

There maybe some added benefit with the propane in that it adds some hydrocarbons that may help burn the diesel better under heavy load.

[dieselmech]

Guys, it's a catalyst. Pure and simple. Diesel/air burns 80% efficient for example but diesel/air/propane burns 95% efficient. The propane acts as a catalyst to help the diesel burn more completely. At first i thought it was a case of the propane lighting off first and then because of the higher cyl temps made the diesel burn more completely. But it's not. Propane makes a chemical reaction happen which makes (allows?) the diesel to burn more completely.

So, you add propane and then you burn more of the diesel you injected.
You add more and you burn ALL the diesel you injected.
Adding more propane doesn't do anything then because all the diesel is burnt so you...ADD MORE DIESEL and start over. At a certain point, you are adding so much diesel and propane and getting such huge hp/torque (with the resultant massive cyl pressures and temps) the motor goes boom.