PROPANE & CATALYTICS

[Tigger4X]

I am going to be running with a dual fueled 360 in my Cherokee. Does anyone know with 110% for sure if propane will harm cataltytic converters??? I want to make sure before I plunk down the $$$ for a set of high-flo cats. I am not too sure of the size of exhaust I should run. I have heard quite a few people say that having the stock manifolds cerami-coated would work well. But, what size cats and exhaust tubes, cans, etc. And does the propane off set these sizes at all. I don't think it would but I wanna be sure before I waste $. THANX, TIGGER4X

[BigStupid]

Ok, I don't think we have too many members running propane (could be mistaken) I have seen a propane set up on a willys that was pretty sweet. This might be a wild goose chase so don't get mad at me, but at www.truckworld.com/ (http://www.truckworld.com/) you can go to custom off road and the willys is featured there. The propane was set up by a guy named ak miller and truckworld has a forum that may be more helpful. Just a thought. Good luck!

( the set up sounds really cool you gotta post some pics when you finish.) smile.gif smile.gif

[reddog]

I know of one member here (graham) that runs gas/LPG in his Cherokee. He is in Aussieland but here is his website.

Bearhunters Place (http://www.geocities.com/ozbearhunter/)

Kerry

[Tigger4X]

REDDOG ... thanks for the pointer to BEARHUNTER! He has an interesting webpage and I was able to email him some questions. THANX again!

BIGSTUPID ... I went to TruckWorld and found 1 Willy's but nothing about propane. Thanks anyway.

I appreciate all the help I can get. If anybody else has anthing to add... let 'er rip!

TIGGERZ4X

[mrclean]

Propane won't hurt a thing. It burns much cleaner than gas. And raw fuel is usually what ruins cat converters. Headers or manifolds, your choice. Manifolds will be quieter, depends on what you are doing with the vehicle. If you go with headers, spend the extra coin and get them ceramic coated, lasts much longer. I would get 1-5/8" primary tubes, and run 2-1/2" pipe all the way out.

[Tigger4X]

MRCLEAN ... Thanks for the reassurance. I knew that propane is a cleaner fuel but wasn't sure if it might cause any side effects or if it burned in a way that might cause some havoc. I am planning on running the stock manifolds and having them cerami-coated. Since I am supposedly going to lose a little running the propane, where would be the best place to go to the 2 1/2" pipes? I thought it was behind the cat system. If so do you happen to know if anyone makes a set of cats that bolt to the manifolds or some kinda cat-back system. I tried Borla but they don't have squat for FSJs. THANX!!

[reddog]

I am curious - why coat stock manifolds? Is it worth the $$? I would suggest finding a quality muffler shop to do your exhaust system and going 2.5 inch with a flowmaster muffler (70 series) with a high flow cat. Go to the 2.5 after Y pipe. the JMHO

Kerry

[bentpushrod]

I have nothing useful to add, but propane is intriguing. There was a plant that made propane where I lived back in ND. Most of the employees ran propane in their trucks, because they got as much as they wanted for free. Kind of nice to run your vehicle with an unlimited supply of free fuel.

It's also used like nitrous oxide for diesels. Supercools the fuel just like NO2 does on gas, letting you pack more into the cylinders.

[Mikel2]

Tigger,
If your Cherokee is a 76, shouldn't it be exempt from emissions? If so, you can run your truck with not cats smile.gif

[Tigger4X]

BENTPUSHROD ... thanks for stopping in. I plan to do a full write with pics when I am done with my project.

MIKEL2 ... In CA the cutoff year is 1973. As far as AZ goes, I dunno. Even if I don't hafta run the whole :mad: smog route, I will more than likely still be running Hi-Flow Cats. I don't like to be skunked out by the rig(s) upwind and don't want to be the jerkie doing the skunkin'!

Anybody on this board know the smog regs and cutoff year for AZ?!?

[Tigger4X]

REDDOG ... about Cerami-coating. A lot of people agree that if you keep your exhaust gases hot they flow better. Not to mention the coating reduces under hood temps dramatically, which translates across the board as a BIG smile.gif!!
I am going to be running with a fully custom snorkeled intake so the volumetric efficiencies will be doing just fine. But underhood temps affect batteries, braking system, radiator temps, clutch res, etc. It may be a little overboard but I am going to be insulating a lot of these items to help keep out as much of the heat as possible.

[reddog]

I know about theoretical efficency gain but was wondering why stock manifolds. Why not go the extra $$ and get headers like the Edelbrocks? Others here have done the coated Edelbrocks but it is costly.

Kerry

[Va-Rob]

I looked in to converting my 83Wag LTD to LPG. I eventually gave up. From what I remember running LPG does not give you any exemptions as far as smog equipment. In virginia all the stock compoments had to be in place (air injectors and cat) and the vehicle still had to pass emmisions. The problem I had was finding tanks that would fit somewhere under the wag. I just figured it wasn't worth all the trouble in the end.

Good luck
Rob

[Tigger4X]

REDDOG ... I have been considering keeping the stock manifolds, at least for now, to keep initial cost down as well as I have to comply with smog regs here in AZ. I just found out today that AZ's cutoff year for smog is '67, Ca is currently '73. I might go with the Edelbrock intake & exhaust manifolds providing they fully comply with AZ & CA regs. I might go with a full "Edelbrock Power Package" later when I upgrade my 360 to something like the 385(?)stroker(360 w/401 crank). But either way the cerami-coated exhaust manifolds/headers is a definite mod for me. High-flow cats and full exhaust will be in order and 98% likely to be done in stainless. If I am gonna spend the bucks I'd rather save a little more and get the good stuff thats really gonna perform and last me a long time.
VA-ROB ... What size motor are you running? Do you already have the stock smog equipment on your Waggie? If you do, then all you need is the propane set-up. LPG burns hella cleaner than gas so you shouldn't have any problem passing any test. If you do then you have bigger problems to worry about! As far as smog exemptions go, at current diesel is smog exempt and so is propane. Hey, I could be wrong on this as I am not UTD on all 50 states but would figure propane to be so. LPG fuelers also get "priviledge" of driving in the "diamond"/"hpv"/"carpool" lane even if you are solo. Check into it and see for yourself and kill off the myths. Good Luck, TIGEER4X

[reddog]

I THINK the edelbrock headers are CARB exempted - meaning smog legal here in CA. They have the provision for the air injection tubes.

Kerry

[Tigger4X]

In-due-bet-ably & most truly SHHWWEEEEET! I'mma gonna hafta check into those!

THANX AGAIN REDDOG!!

[ December 10, 2001: Message edited by: Tigger4X ]

[graham]

Tigger4X, I've replied to your e-mail so this may benift others.
Propane/LPG/Gas with do no harm to catalytic convertors. If you were to run soley on LPG you may not require them because of the clean burn of LPG.
Exhaust gas is ehaust gas, so no special requirements for the exhaust system other than for performance.
There are a couple of other thing to be concidered though.
Firstly the storage tank has to fit somewhere. Depending on the size of the tank and where it can be fitted. Mine is a 60L tank and fits where the spare tyre was fitted. This did created clearance probs until the rear shackles were flipped.
Secondly LPG is a dry burning fuel. Unless you motor has been setup for LPG, you will need to get hard valve seats or fit an upper cylinder lubrication system.
Thirdly LPG has an octane rating of 100. If you are going to run dual fuel, tuning of the motor is difficult. Either you setup for optimum performance on one fuel, sacrifising performance on the other. Or you setup around mid range for both, then your not running a 100% on either. I'm working on being able to adjust the timing from inside the cab. this will give better performance on either fuel.

The conversion system I'm using came out of the Ark, and is not running correctly. At its best I get a little less MPG running LPG. This is made up in the cost difference of LPG v's Petrol. LPG is 30c a litre cheaper than petrol. There should be no difference in power between. Newer conversion systems may be better than Noah's unit I'm using.

Hope this helps.

[J20fan]

I am running propane on my Wag. It is a much cleaner fuel as stated earlier in the post. Here is a link to the Impco Tech centre Propane Tech Centre (http://www.ibuild.ws/techcenter.htm) I have called this company and had a return call in a short time. The tech rep was very helpful with tuning info and there are a lot of files on installation and setup here. I am using propane only and at $1.21 a gallon compared to apx $2.70 for gas it is much more economical for me. My tank replaced the original gas tank and holds 95 litres. Graham is right, with the tank in a Cherokee it would be tight with duel fuel unless it is a J truck. I am using a plug 1 range colder and have my timing set at 17 degrees. With the higher octane this works well for me. Rule of thumb is 1.3 gallons of propane to equal one gallon of gas.

[graham]

<BLOCKQUOTE>quote:</font><HR>Originally posted by J20fan:
I am using a plug 1 range colder and have my timing set at 17 degrees. With the higher octane this works well for me.<HR></BLOCKQUOTE>

J20fan,
Your timing has me confused. A mate of mine runs LPG in a 345 Scout, and runs his at nearly zero degrees. He cliams to be getting in the 18-20 MPG range on LPG!!!!
I've only tuned the LPG by ear, MISSION IMPOSIBLE, but when you learn what to listen for you can get close but not close enough for LPG. Completely different animal when tuning LPG to Petrol.
At the moment my Jeep divours more petrol than LPG, due to the LPG setup not tuned right. I'm runing at 12 degrees and 92 octane petrol.
I will not be beaten by thisand pay someone else to do what I consider a basic tune up. This is my challenge.

My question of you is; When I run, say in your timing range, it runs like crap. How is your economy and power compared to petrol? My mate with the Scout can bearly notice the difference :confused:

Oh for an dohickey that can easly change the timimg between LPG and petrol :(

[reddog]

Graham, MSD Ignitions makes timing controls that go with the MSD6T ignition system. It is a knob that mounts inside the cab and gives you up to 15 degrees adjustment in timing. Look here at their site :

MSD Ignitions (http://www.msdignition.com/)

Kerry

[J20fan]

<BLOCKQUOTE>quote:</font><HR>J20fan,
Your timing has me confused. A mate of mine runs LPG in a 345 Scout, and runs his at nearly zero degrees. He cliams to be getting in the 18-20 MPG range on LPG!!!!<HR></BLOCKQUOTE>

Graham,
I cannot remember the timing spec on a 345, the last one I owned was over 10 years ago but I find it odd that he runs with the timing so close to TDC. I have been playing with my timing a bit and find that it performs much better as the advance comes in to play. I will be adjusting my vacuum advance this weekend to try and get a more rapid response. Next will be the mechanical advance springs. A friend of mine has a factory propane set-up in a Dodge that calls for 18 degree advance. I am not getting exceptional mileage by any stretch of the imagination but it is much cheaper. In full time 4 x 4 apx 9 to 10 mpg and in 2 wheel that jumps to an amazing 12 mpg :D. I am running a straight propane system so I cannot give you a mileage comparison. I found that the fuel mixture is a difficult adjustment as I do not have an exhaust sniffer. The Impco factory tech rep has told me that when tuning without one to turn the main mixture jet out 4 turns and start driving with a full load on the engine on the highway and fine tune it by trial and error. It is very easy to have a mixture that is too rich giving poor mileage, I have done it myself. To answer your performance question is difficult as my other Jeep on gas has a completely different set-up and gear ratio but the mileage sucks on it as well. I will say that the propane system performs much better when the RPMs are in the 2500 to 3000 range and up. I don't know if this helps but I am no expert by a long shot and am trying to learn more about this system all the time.

[graham]

reddog, Ya bloods worth bottlin' :D . I've made equiries with MSD. Save a lot of work rather than the cable setup I was tring to perfect.
J20Fan, I would like to run soley on LPG, but it would be difficult to find space to fit another cylinder. I also like to have to security of having a backup systeme. If one fails, just switch over to the other. Very handy option on some of the remote beaches I fish on :D

[STEVE-UK]

I dont know if this is of any help but on the OZ and NZ site there are half a dozen or so pages on LPG http://home.off-road.com/~ozifsja/tech/lpg.htm
may help. I run a Shogun permanently on LPG dont have a petrol (gas) tank on it
Steve