Hi guys,

Greetings from Brixton, right in the heart of London, England. Great site. I hope to bring over an Argosy 24 or Airstream 250/Excella 24 in teh next six months. I've decided this is the maximum size I can manage due to traffic/road size in London and countryside in UK. I'm trying to work out the best way to make fuel more manageable in cost terms. I'm a newbie here but it seems that my options are as follows:

1)   modify an 454 engine to run on LPG (which is cheap in the UK). Anyone any idea on how much this will cost is in the US? Also, what MPG would I get on an Argosy 24 running LPG?
2)   if I buy an old Argosy with high mileage and stick in a brand new LPG engine, will I get any better MPG?
3)   Is it worth me considering getting a 350 engine and going LPG?
4)   how do the LPG tanks fit into the chassis and is this an issue?
4)   any thoughts on pros/cons of diesel vs LPG.

Your thoughts are greatly appreciated.

best wishes

Nick

Nick,
Welcome to the site. I did a quick Google search and found this: http://www.gotpropane.com/p4.html#Chevrolet. Looks like it's under $1000 USD for a converion kit minus the tank. From what I understand, LP engines get a lower MPG than Gasoline but it the per gallon cost is lower it might work out to a savings. Many of the Argosy's were smaller (<30 feet) and get better mileage than their larger 310, 325, 345, 350, 360 Airstream counterparts. Also, some early models came with the 350 from the factory. If you plan to tow anything or drive a rig larger than 20 feet I would think a 454 would be the mininum.

We have two members on this site who are planning or working on diesel conversions (Duramax). These are expensive conversions....but for someone who plans to keep their Airstream/Argosy/Motorhome for a long time 300,000+ miles it can be worth it in reduced maintenance and fuel savings.

All of this comes down to how you plan to use your motorhome. If you like the average American motorhomer....you'll only drive 5,000 mile a year (hard to believe but true). If this is the case then any conversion costs wouldn't make much sense.

If you plan to drive the wheels off of it (or keep it for years and years) then maybe it makes sense. For me, I would like to convert to diesel at when my 454 gives up the ghost. But until them I'll just pay at the pump.

hi guys,
just thought i would pass a few comments on the subject of LPG convershions in the Uk,i am at present rebuilding a 1975 23ft kings highway with a dodge 440/3 engine i have been told to expect somthing around 10 to a gallon, i dont know what the price of fuel is in the US but i can tell you that over here it is a stagering £5-50 a imperial gallon or aprox 11 dollars, so i have decided that i will convert to LPG whilst doing the re-build as LPG virtually cuts the fuel bill in half, from what i have discovered the cost of the convershion will be around £1500 fitted, or £800 as a kit if you choise the kit you need to get a safty inspection done by an approved LPG company and they will issue a certificate, which most insurance companys require,another point to bear in mind, if you are converting an engine that runs on leaded fuel you need to install an adative injection system this is not expensive but is most important, one more point which might interest Nick i am given to understand that LPG fueled vehicles are congestion charge exempt.
regards Nigele.

I have now been reconsidering my intentions on stretching the fuel dollar! going back to my original plans to go with the LPG (Propane) conversion on the 454 engine in my 310. I have more or less ditched the idea of the Diesel conversion discussed earlier, as it would appear to be a little more involved in gear ratios than I had with a range Rover conversion I did a few years ago. This all came about after I reassessed the tank-age for the engine propane.

However to put yet another dampener on the subject, I had the following from Dick Patterson at SPRINGFIELD IGNITION, a guru when it comes to Qjets on the Olds engines found in GMC's This all came about as I need to replace my Qjet or get some serious replacements for it, and I contacted him on a friends recommendation (He has the GMC).

"...........My greatest concern is your planned move to dual fuel with propane and gas. Here are the main reasons for my concern---I was a GM dealer for 25 years- (1976-2001)-and we sold a lot of medium duty and heavy duty GMC trucks--- about 1980--fuel costs went  way up--and truck operators  began the switch to add propane  conversions- to save fuel dollars--the results were a complete disaster---all the units we changed over -came back---burnt out valves  -ring problems  oil consumption etc-etc- propane is a very abrasive fuel when burned in a standard engine--there were trucks all over the country with the same service and longevity issues---so it was not the installation.  The problem with dual fuel is that the 2 different fuels call for 2 different tune specifications-----for gas the timing and thermostat call for 195 F and a normal advance curve in the dist -like 32 -34 degrees total---on the other hand propane needs a much cooler motor temp with a 175 thermostat or less  -blocked off heat /intake manifold crossovers-and almost no ignition advance.
Obviously you can’t satisfy both running conditions to be optimum-so the efficiency is the result of this huge compromise--the resulting mechanical failures were far more than the cost of fuel could have ever been. Having said that -perhaps today -there is better technology out there-but I still don’t know how you can overcome those basic dual requirements in a single application. ..........  However based on my experience  with a motor that was not  originally designed or engineered to run on propane I would stick with gasoline and work to  optimize the motor for max efficiency on that fuel.--your move to headers is a step that way.........."

As you can see there seems some doubt on service life.

So chaps, what is your view and if any, experience running the 454 on propane. any hints would be gratefully received

Chuck
Dorset UK

 

hi guys,
chuck you are miroring the same concerns i had, unfortunatly i have no personal experiance with gm engines but i would guess that problems basicly the same with all the older engines,i spoke to many convershion companys and they all asured me that there is no problem as long as the oil injection system is instaled and the general opinion was that engine life is actualy increased, frankly i was not completely convinced so i spoke to about twenty diferent people who had done the convershion on motorhomes and all of them where happy with it and had no machanical problems with it, the only small nigal that one or two said they had encounterd was at full throtle with a trailer on they would lose power, this i have since discovered is due to the system they used being to small for the horse power of the engines, so if you intend to tow you need to tell the system suplier so that they can take it into acount when recomending the system.
hope this helps,
nigele

I have had some further thoughts on this.

The earlier comments related to older 1960/70's vehicles and American petrol (Gas) which has a much lower Octane than UK Petrol (Gas).

I had to retard my 454 by nearly 8 degrees, when I brought it over from Texas, to run better on 95 octane regular UK Unleaded. It now runs quieter and has more performance. With the low compression ratio and the hardened valve seats for unleaded on the later engines, that must go some way to meet the LPG (propane) fuels ignition settings. With the spark nearer TDC it is not far from the very low advance setting for LPG.

As for the corrosion/erosion factor I am still out on that one.

Does that make sense? after all range Rover use the Buick 3.5 to 4.2 V8's and many of those are running LPG, with some success.<!-- / message --><!-- sig -->

Summit.com and Jegs.com both sell blueprinted QJets.