I have been studying the propane controversy for a while now and I have a question. Can propane be used as a cold start assist?
I know that most pane systems have a boost limit and they won't kick in unless there's 2-4 psi boost. If you had a manual override just for cold starting it seems to me that it may help cold starts. Has anyone tried this?
It would have to be better on the motor than ether, but I'm sure that with any fuel you could break a motor. Whadda ya think?

 

i don't know the combustion properties of propane well, but i do know that used moderately in the kits that the propane is the secondary combustion. Diesel is injected, combusted in turn combusts the propane and the remaining diesel left from the initial combustion granted there are not multiple combustions, rather just the order in which the burn takes place, so I would tend to think that it would be harder to ignite with compression than even diesel making it a really crappy cold starting tool. There will certainly be someone here that knows more than I do on the subject.....

 

Don't PSD's have glow plugs? You shouldn't use either one for starting with a glow plug system.

 

Yea - red hot glow plugs + propane = big boom!! Not a good thing!!

 

So.... the only way it could work is if you inject the pane directly in to the combustion chamber?

bigdieseldav-
See if I got this right--a diesel engine combusts diesel fuel at a compression ratio that is say..25:1?
If you built a motor to compress pane to the point of combustion like a diesel does, the compression ratio would have to be higher..40:1?
Am I right? Thanks for the responses.

 

The compression of a PSD is around 17:1 to 18:1, not enough to reliably light propane, so the answer is no. The compression would have to be unreasonably high.

Birken

 

It's 17.5:1 compared to the 18:1 of the new 6.0 PSD. You should not use ether to start the engine or you can cause damage. Read your owner's manual, I remember reading it in there somewhere.

 

I believe the 6.9's and non turbo 7.3's are around 22.5:1 The aftermarket turbo outfitters do not recommend taking those motors above 15 psi, and I don't think most od their kits make more than 8-10.

Propane is not direct injected, it it injected into the intake before the turbo. I don't know how it would work as a starting aid, but I would assume the higher BTU content would make it easier to ignite. Probably a bad thing when the glow plugs are working.

 

you know guys, I am an idiot. I never even considered the affect a lit glow plug would have on the propane/air mixture. I don't use my system until the truck is at operating temperature anyway, but thats a scary thought if the glow plugs could actually ignite the mixture during the intake stroke or beginning of the compression stroke. The instructions for my kit don't even mention it????? I guess I have more research to do...... I don't know the combustion properties of propane but it may be that it has to have a flame or spark so to speak rather than just heat ie. the glowplug?? At least up until its compression combustion threshold which would probably be really high.

 

A diesel works by auto-ignition. That is, it ignites without spark or flame when injected into the superheated air in the cylinder. The air gets superheated by compression. The glow plugs just give it a little initial help. They are actually heating the air, not the fuel. The auto-ignition point of propane is a lot lower than diesel. Propane also has a lower BTU value than diesel.

 

bigdieseldav-
I didn't mean to cause you concern, but if I did let me offer you this. I work on propane powered small engines that run on 12 volt systems. Our application requires a 12 volt solenoid valve that will stop fuel flow (vapor withdrawal system).
One of these type valves could be actuated by a relay, and the relay could close the solenoid valve if the glow plug solenoid was activated.
I plan to put the pane on mine soon and I will use these components to make my own system. If you want specifics on these fuel system components I can tell you where to find them in your area. I deal with these parts daily but I won't make a sales pitch while I'm on the forum, but you can get them too.

 

Ok pane has an unit of working power at 9500, where as diesel is down around 7500. I did the research and posted it here two weeks ago.
Gasoline is on up in the 12000 range.

I have uses farm tractors that were straight pane. They have to spin almost twice as fast to start. Usually two batteries and then the isolator kicks in once started.

We used ether to start pane and diesel engines in cold weather is burn rating is 19800, so yes it will flash, yes even higher than gasoline!!!

One reason you will see WARNING LABELS!!! They say dont use ether unless the engine is turning. Glow plugs or the heating grid as in Dodges will ignite ether.

This is why you need the engine turning!!! The engine will suck the fire down into the cylinder and help the engine on the next compression stroke

I have used ether my whole life to start diesels in cold weather, you just have to be carefull on any engine heating element.

I did see a young E-2 send a 6.4 GM diesel into a thousand pieces by shooting a heavy dose of ether, then hiting the starter in a Hummer!

Just read the instructions before using ether.

 

I replaced my injectors today, so I tried using propane instead of ether as an aide in starting the engine. I just took a small propane bottle with a torch end on it, and stuck it upside down in the intake of my 6.2L Then I turned the ignition key for the glow plugs to ignite, then when the glow plug light went out, I turned the key to engage the starter motor. The engine fired and ran briefly on propane. So, propane can be used as a starting fluid instead of ether, but it might take a greater flow rate than what a simple torch tip can offer.