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Techical Discussions => General Tech => Topic started by: Stewart Van Petten on March 07, 2010, 04:09:23 PM

Title: Propane powered engine question
Post by: Stewart Van Petten on March 07, 2010, 04:09:23 PM
Today I was playing around with a pickup truck that I purchased a few months ago that runs on propane. It had a slight misfire now and again at mid to higher rpms so I started checking the ignition system from the distributor down to the plugs for any obvious problems. Found a loose spark plug wire on the dizzy and fixed that but carried on with my inspection.
 
I pulled a spark plug to see what the condition of it was. It was a little bit dirty but not in bad shape so I buffed it up on a bench grinder wire wheel, adjusted the gap and reinstalled it. The next plug was extremely tight and I broke it off unfortunately. (http://www.moparfins.com/forum/smileys/smiley36.gif) I was able to remove it though. I am going to be more careful with the rest. Also I plan on doing a compression test while I am at it. 
 
Anyway this leads me to my question as I have never owned a propane powered vehicle before this one. Does a propane engine prefer a different heat plug than when you run gasoline? Do they like hotter plugs or colder plugs? I have some colder plugs than what were in it but if it requires the hotter plugs I will go purchase some new ones. I will mainly be using this truck for plowing snow in the winter but will probably also use it to pull the occasional trailer load.
 
Thanks guys!
Title: Propane powered engine question
Post by: Steve on March 07, 2010, 04:14:04 PM
That is a question for SJak.  He's our resident Propane user.  Well in Finland he is.
 
He ran an Imperial on Propane for as long as we've known him and he's converting his 71 Fury to Porpane.
 
He'll know
 
Broke a Plug?  Must be a Chebby
Title: Propane powered engine question
Post by: Stewart Van Petten on March 07, 2010, 04:40:04 PM
Yup, she is a 1974 Chevy BB 454 in an 85 Sierra 4x4. I was looking at the engine rebuild sheet and it was over bored .030...so probably a 460 ci now! lol I was not using a very good extention on my spark plug socket and I side loaded the plug...

It starts and runs very well but I am sure that after I finish tuning it will run even better. I doubt it has been tuned since it was put together roughly 30,000 kms ago. There were a lot of deposits in the distributor cap so I will get new parts.
Title: Propane powered engine question
Post by: Steve on March 07, 2010, 04:56:15 PM
Heh  How did I know. . . . .
 
Try PMing him  Sjak is in and out, but you'll get quicker answers.  Send him the link to the thread too
Title: Propane powered engine question
Post by: Snotty on March 07, 2010, 05:47:21 PM
I believe Firedome has had experience with it as well.
Title: Propane powered engine question
Post by: Guests on March 07, 2010, 07:11:23 PM
Propane runs at  100-110 octane, so a hotter plug would be best, higher compression is an advantage, but not necessary (9-10:1 works well), and it can take a little more advance since the octane rating takes more to make it explode without a spark.
 
Amazing what you can find with a little bit of a search, but I still imagine Sjak has a little more info than this. I saw one article on a diesel that was dual diesel/propane. A combination of the two was able to improve mileage, especially in towing situations better than one or the other only, with a 50/50 mix, which I thought was pretty cool, kind of like an igniter for the diesel or something.
Title: Propane powered engine question
Post by: Stewart Van Petten on March 08, 2010, 06:27:30 AM
Thank you for the help with this machine! I did a bit more research yesterday and found out some more useful things about propane engines. Lots of things I have heard through the grape vine, but it is sure nice to know the actual facts and also hear from people who have direct experience!
 



After I do a compression test I will know more about the engine to determine what compression ratio it has. Judging by how it runs and sounds I believe it to be running around 10 to 1.
 
I have tried running propane in one of my old Mack trucks many years ago to mainly help fuel economy but also to add a small amount of torque. I found that it did help a bit with fuel economy by adding a small amount to the engine's intake system. Some diesel engines respond better than others to this mod from what I have heard and read. The Mack engines that I have are fairly efficient already but I did notice enough difference to keep injecting propane for certain jobs. It definately cleaned up the burn and I also noticed that the oil stayed cleaner.
Title: Propane powered engine question
Post by: Leaburn Patey on March 08, 2010, 07:44:37 AM
What propane does to diesel engines is what nitrous does for gas engines.
Title: Propane powered engine question
Post by: Guests on March 08, 2010, 08:11:56 AM
Propane, like natural gas, and alcohol, all run very clean and don't require oil changes as often.
Title: Propane powered engine question
Post by: Steve on March 08, 2010, 08:16:38 AM
What about those Hydrogen generators?
Title: Propane powered engine question
Post by: Guests on March 08, 2010, 08:20:57 AM
Quote from: POLARACO
What about those Hydrogen generators?
I haven't seen anything on the market producing enough hydrogen to make it worth the cost yet. Chrysler was doing some minivan conversion things 5-8 years ago, but I think DBAG stole that, too.
Title: Propane powered engine question
Post by: Stan Paralikis on March 08, 2010, 09:05:59 AM
Quote from: POLARACO
What about those Hydrogen generators?

 
It's already been done.  And they still can't get it to work...
 
(http://www.eta.co.uk/files/images/hydrogen_car1807.jpg)
 
 
Title: Propane powered engine question
Post by: Riyad on March 08, 2010, 09:30:21 AM
there is a very good success in running LPG on these engines in Holland, the imperial ran on LPG only from 1999 until 2009, Sjak went racing with LPG powered engine!
Title: Propane powered engine question
Post by: Jacques on March 08, 2010, 11:36:34 AM


Regarding the initial question, try the original spec sparkplugs, but of a good quality, like NGK. Usually, you will be fine with a stock engine on LPG.

After a few thousend miles, you will be able to tell if the plug choice is good or not.


Quote from: dana44
Propane runs at  100-110 octane, so a hotter plug would be best, higher compression is an advantage, but not necessary (9-10:1 works well), and it can take a little more advance since the octane rating takes more to make it explode without a spark.
Regarding the octane rating and compression, for a normally driven vehicle, it is better to keep on the safe side. In theory, you could run a 12:1 compression, but EVERYTHING has to be PERFECT ALL THE TIME. For a racing engine, that's not a problem of course. However, in real life, fuel is not "straight" propane but a mixture (e.g. in our area it is about a 50-50 mixture of butane and propane) or has contaminations of some other gases seriously influencing the octane rating (propene is bad)

Also, when intake charge temperature rises, the octane rating will decrease, making a high compression engine very susceptible to knocking or worse under load in hot weather.

A very usefull upgrade on an otherwise stock vehicle is a stronger ignition and a recurve of the distributor. Propane has a much higher combustion point than gasoline, therefore is more susceptible to ignition troubles. In case of malfuntion, start with checking ignition parts (plugs, calbes, cap+rotor, ECU, coil), then start looking for vacuum leaks. Also, check airfilter.
Sjak Brak2010-03-08 16:36:46
Title: Propane powered engine question
Post by: Stitcherbob on March 08, 2010, 01:58:39 PM

Quote from: Commando1
Quote from: POLARACO
What about those Hydrogen generators?

 
It's already been done.  And they still can't get it to work...
 
(http://www.eta.co.uk/files/images/hydrogen_car1807.jpg)
 

Hey that car would work for some of the guys here if you changed that balloon to an enema hose........

Title: Propane powered engine question
Post by: Guests on March 08, 2010, 02:07:29 PM
Quote from: stitcherbob
Quote from: Commando1
Quote from: POLARACO
What about those Hydrogen generators?

 
It's already been done.  And they still can't get it to work...
 
(http://www.eta.co.uk/files/images/hydrogen_car1807.jpg)
 

Wow, TMI......
Title: Propane powered engine question
Post by: Steve on March 08, 2010, 03:43:35 PM
I didn't mean that. . .There are Hydrogen systems which suppliment the gas and rais the HP and economy.
 
It's like injecting the porpane into a diesel, as mentioned above.
 
There ar kits out there that make Hydrogen as you drive with just water
Title: Propane powered engine question
Post by: Guests on March 08, 2010, 08:30:04 PM
Quote from: POLARACO
I didn't mean that. . .There are Hydrogen systems which suppliment the gas and rais the HP and economy.
 
It's like injecting the porpane into a diesel, as mentioned above.
 

Yes, and those little systems don't produce enough hydrogen while driving to be cost effective, period. Hey, if you are still interested in something like that, maybe you would like to buy some magic beans I have a small surplus of....(http://www.moparfins.com/forum/smileys/smiley2.gif)
 
On a serious note, have you seen the amount of hydrogen necessary to produce power in a vehicle? Mercedes Bends had the back of a van that was filled with the necessary equipment to produce hydrogen in large enough volume to run the vehicle. A minivan was basically a 2seater there was so much garbage. At least Chrysler's minivan had seating for six still, it was all nice and compact under the floorboards. Whatever happened to the system I do not know, but bringing it back would be a little more realistic. Day before yesterday I saw a news article about a tiny battery which did not lose its charge, and actually charged on its own, including the power generated by absorbing the heat from the human body, a vibration could charge it, static electricity, you name it, it would hold the charge and continue to charge to capacity. No grants, no government involvement, nothing like that, so I am hoping to see more information on it coming soon.
Here's a link article I found, the news report I was was an update of this:
http://www.technologyreview.com/Biztech/18086/ (http://www.technologyreview.com/Biztech/18086/)
If this is true, it is the power breakthrough of the century, which would totally (getting political here) knock off the CAP and tax and global warming garbage for good. To be able to drive 200miles on an electric mode and recharge in ten minutes would totally be acceptable even for me, but then again, I would figure out a way to make it hybrid, hook 10 120amp alternators up to run for ten minutes at a time, so the only reason to stop on a trip would be to refill the Big Gulp and take a leak.  I'm not into cathing quite yet, but those diapers sound pretty cool right about now Steve.(http://www.moparfins.com/forum/smileys/smiley2.gif)
Title: Propane powered engine question
Post by: Herman on March 09, 2010, 01:42:54 AM
So, is this a Propane topic, or hydrogen?
Can someone please BAN the admin for derailling this topic! (http://www.moparfins.com/forum/smileys/smiley23.gif)


As for the original issue;
A backfire "usually" has a vacuum-leak as the cause.
Weak or mis-firing ignition can cause this aswell, but not that often.

Is this a dual-fuel setup?
If so, check to see if the mixer is still mounted airtight on the carb.
Dual fuel-setups usually have a cable running to the dash to operate a airvalve in the mixer. If this valve is not seating well or just cracked open, the propane 'sees' a vacuumleak and will run lean because of that. Hence the backfire.
A good backfire could also disrupt the (idle)setting of the propane-system in a mixer.



Title: Propane powered engine question
Post by: Jacques on March 09, 2010, 02:29:09 AM
[/QUOTE]Actually, it's more often ignition related, about 70% of the time, and some 25-30% is vacuum leak.
Other causes for problems are uncommon. Although lean mixture doesnt help, but usually, the cause for a lean condition is vacuum leak.
On some type of closed loop feedback-systems, a flat spot can occur when abruptly flooring the throttle, and this can lead to a backfire.
The fuel system itself is usually much more reliable than a gasoline fuel system. After 10 years / 100.000 miles, a rebuild of te vaporizer is recommended but often not needed yet. Some mixers will require regular adjustment and may need rebuild/replacement after the same period.
 
Quote from: BigBlockMopar
Dual fuel-setups usually have a cable running to the dash to operate a airvalve in the mixer. If this valve is not seating well or just cracked open, the propane 'sees' a vacuumleak and will run lean because of that. Hence the backfire.
 
The cable for dual fuel operation is only applied on the Impco 300 mixer, and on some older design Beam mixers. But worth checking, it will result in lean mixture and backfire.
 
Once backfired, some mixers can indeed be out of adjustment, although e.g. an Impco 425 is pretty consistent even after a few backfires.
 
On dual fuel systems, vacuum leaks can occur in the "gasoline"-part of the system, e.g. defective injectors, vacuum leak at the throttleshafts (especially Quadrajects are susceptible to this problem) and this will have a negative effect on the LPG-operation.
 
Sjak Brak2010-03-09 07:33:23
Title: Propane powered engine question
Post by: Jacques on March 09, 2010, 02:36:51 AM
Reading the first post again, its not backfres but misfires.....
 
This is almost for sure ignition related, unless the installation is too small for your engine. What type of propane system is in the car?
Title: Propane powered engine question
Post by: Stewart Van Petten on March 09, 2010, 04:13:51 AM
Thank you very much for your help with my project guys! I have been reading lots and learning many things since yesterday!
 
My truck has the Impco 300 dual fuel mixer on top of a Q-jet. I have not found any cable attached to it. Also there is no fuel pump on the engine so it is just running on propane now.
 
When I throttled it wide open it was missing a bit at mid to high rpms. My thoughts were that it was build up on the contacts in the distributor. When I pulled the dizzy cap off I found a loose ignition wire and lots of buildup in the distributor...the center contact to the rotor was just about worn out...definately needs new parts.
 
After I install some new parts I am sure that it will run better. I am wondering if this setup provides enough fuel for the displacement of this engine? Maybe I need a dual mixer setup? I have to check also if the secondarys are opening. It sure does not sound like they are but maybe that is a limitation of this system...not enough fuel and air flow to open the secondarys?
Title: Propane powered engine question
Post by: Jacques on March 09, 2010, 05:43:52 AM
 
 
You might as well install a new HEI distributor, it will give a much stronger spark and is basically maintenance free (but keep a spare module in your glovebox). This will greatly improve the behaviour of the truck.
 
Regarding the secondaries: I thought those are mechanically operated on a Q-Jet?
 
If you have a few more bucks to spare, order an Impco 425 mixer, build it as single fuel. You will notice a big improvement in throttle response and in performance. Probably also on economy. Buy a new mixer, dont bother about used pieces, the price advantage is very small (if any at all), and some used mixers typically show some wear that make them hard to adjust.
 
Also, a converter rebuild can help.
 
I have some experience with Impco setups, I sold some 50 mixers during last year, mostly 425s which were applied as upgrade to an existing system, but also 300 mixers, and converters + rebuild kits.
 
Sjak Brak2010-03-09 10:47:44
Title: Propane powered engine question
Post by: Steve on March 09, 2010, 06:31:32 AM
Toad ya Jak was the man
Title: Propane powered engine question
Post by: Riyad on March 09, 2010, 08:10:22 AM
Sjak you once mentioned a megasquirt-like LPG injection system, any good things about those?
Title: Propane powered engine question
Post by: Stewart Van Petten on March 09, 2010, 11:05:43 AM
I am pretty sure they are mechanical secondarys however they won't open unless part of the mechanism that is hooked to the choke is tripped after the choke is shut off. 
 
One of my friends told me to bring my truck out to his farm as he has a dozen or more mixers and I could try out one of them. He used to run a few propane powered trucks hauling propane a few years ago. I am sure that he said he has some 425s that would work for my application. I will let you guys know how I made out and also try to post some pics so other people may learn with me.


 
Thanks again for the excellent information and ideas!
Title: Propane powered engine question
Post by: Jacques on March 09, 2010, 11:31:29 AM
Remove choke. Chokes have no place on a propane engine.The fuel is already gaseous immediately on startup. A fuel will have an adverse effect on propane.

If the throttlebody of your QJ is OK, then its a simple matter of applying a simple adapter plate and mounting the 425 on top of it. Cold air induction will make the car run better, but add a balance line in that case.

425 mixer:

(http://img.photobucket.com/albums/v704/sjak_brak/techtalk/LPG/425-1.jpg)


QJ-425 adapter plate:

(http://img.photobucket.com/albums/v704/sjak_brak/techtalk/LPG/425-QJ.jpg)


440 with 425, with and without aircleaner:

(http://img.photobucket.com/albums/v704/sjak_brak/full%20size%20talk/73imp/2644C1800C4111DCA59EB32ED594ED6A.jpg)

(http://img.photobucket.com/albums/v704/sjak_brak/full%20size%20talk/73imp/P1010028.jpg)


Title: Propane powered engine question
Post by: Stewart Van Petten on March 09, 2010, 02:55:24 PM
Your 440 looks like a lot of fun! Thank you again for your input! I think that I am going to change it over to the 425 system based on your advice. I am not interested in the dual fuel setup. I would rather have one system working efficiently than have a poor propane and a poor gas setup. If I am lucky my friend will have a complete setup and all I may need is a rebuild kit to finish the conversion.
 
Out of curiosity what is the price of propane where you guys live? Up here in Edmonton Alberta Canada I paid 57.9 cents a liter when I filled it up. I have seen it priced up to 76.9 a liter in some places around here though. I will have to keep my eyes open for the better prices it seems.
 
If I really need more fuel capacity I could remove the outboard fuel tanks and install some tanks in their place. As it is right now the previous owner said he could get around 600 kms per tank. So far I am getting around 700 kms per tank...even with the snow plow on it! After tuning it I hope it gets better!
Title: Propane powered engine question
Post by: Jacques on March 09, 2010, 10:40:57 PM
A 425 usually is either just fine, or in need of replacement, as problems that are mixer-related are usually caused by wear on the main body. Only if the diaphragm is the problem, then rebuild can be considered. Also keep in mind that a new mixer on your end shouldnt cost much more than $150 or so, and the 2 diaphragms for the mixer will quickly add up to above $60.
Prices over here are high and will likely decrease a bit within the next few months. Currently vary from 57 to 72 eurocent a litre, so about $ 0.77-1.00. Over the border, it is cheaper. However, regular euro 95 costs over $2 a litre.
 
If economy is your main concern, you can later on install the AV1644 lean valve in the 425 mixer, it will trade a tiny bit of power for more economy. Not recommended in applications where the engine is under heavy load most of the time.
Title: Propane powered engine question
Post by: Stewart Van Petten on March 11, 2010, 10:02:38 AM
I have been repairing some other things on the truck and still have not completed my igntion tune up. Who ever installed the rear ujoint on the drive shaft put it in backwards...so you have to pull it off in order to grease it. I pulled the drive shaft off my old 81 4x4 that blew up the t-case but it was shorter and had larger ujoints also. Probably because it has a larger rear diff. I learned something at least. I believe that the front drive shafts will interchange though.
 
I have not taken apart the 300 mixer as I did not want to disturb things yet. Someone has replaced the nice wing nuts with some ny-lock nuts. You can see by the pics that this install was kind of a hack job IMO. I am not sure if any of the extra wires should be hooked up or not. I have already taken off most of the AC compnents as there was no compressor and I really don't need AC for snowplowing! lol
 
Some of the spark plugs sort of look rusty. Is this normal for a propane engine? I did a quick compression test on the hole that I broke the spark plug off. I was not very happy. I spun it over and then checked my gauge. It was at 60 psi. I was shocked so I rechecked my testor to see if I had it hooked up correctly. Then I started the engine and watched the gauge. It climbed to 90 psi and would not go much higher when I reved it up.
 
I am used to seeing A LOT more than that in most of my engine buildups. The engine was stone cold but it should not make a lot of difference would it? I will continue to check the other cylinders to find out what they are running at. I kind of thought it would be higher based on how smooth and strong this engine runs. Maybe I have a dead or dieing cylinder. Not sure if I want to rebuild this engine. If they are all at 90 psi and it does not use oil would it still need a rebuild or is it just how they built this engine? Hmmm, Maybe I should turbo it...
(http://i75.photobucket.com/albums/i313/Rockwerx/454propane1.jpg) 


(http://i75.photobucket.com/albums/i313/Rockwerx/454propane3.jpg)
 
Title: Propane powered engine question
Post by: Steve on March 11, 2010, 12:03:44 PM
Stu
 
Squirt some oil in the cylinder and read it again.  That will tell you rings or valves.  Don't use allot
Title: Propane powered engine question
Post by: Jacques on March 11, 2010, 01:20:26 PM
Just a thought:

Truck engines sometimesare built with a de;liberately low compression.

E.g. International, who have some of the toughest trucks, built their propane engines for heavy duty use at only 7.5 compression. Dont know about GM though.

The propane installation on the pics has a lot of simple improvements that can be done at no cost or just very low cost.


Title: Propane powered engine question
Post by: Stewart Van Petten on March 15, 2010, 04:55:25 PM
Okay, I finally got some work completed on this machine.
 
Did a compression test. All the cylinders are cranking 90 psi. I installed new plugs, wires,  distributor cap and rotor. It runs a lot better now. I noticed that all of the plugs were rusty. It this a condition from running propane? I ran it around the yard cleaning up some snow piles to help them melt faster. It seemed torun smoother. I did not take it out for a road test to see if I still have a mid to high speed misfire yet though.
 
I still want to change it over to the 425 mixer at some point.
Title: Propane powered engine question
Post by: Jacques on March 16, 2010, 12:20:40 AM
Plugs will not rust because of propane.
 
Because the combustion of propane is much cleaner, you wont get fouled flugs from running rich.
 
Probably those plugs needed replacement.