Propane Conversion on Chevy Astro 2001 4.3 ltr V6

You'll never get your money back.

Alternative Fuels Data Center: Propane Vehicle Conversions

The cost to convert a light-duty vehicle from gasoline to propane use ranges from $4,000 to $12,000.

Tcmtech can probably do it for a lot less, especially if he gets that 4/7 RV job.

I have seen it advertised in Europe for $600.00 0r less. It has been a common conversion in Italy. I did it on Chevy 7.5 liter blazer, a Volvo 144 and a Jaguar 6 in line. Years ago for under $400.00.

Yea your right Lyn but I probably wont see any of my social security money I have sent to Uncle Sam either but at least I will have had some fun trying to make it happen. And the next time our gas hits $4.65 a gal, I can grin all the way to the bank. I am currently $300-400.00 in fuel a week, I might see a return in about two years. Plus when gas gets hard to get like it did around here early summer I can just go to propane dealer or to the 1000 Gal tank in the back yard and fill up while everybody else waits in line and keep on working without any loss of time. It may very well turn out to be an exercise in futility but at least I tried to do something for my economic position and not just sitting on my soap box doing nothing, And believe me I spend a lot of time on my soap box with three kids two grand kids and now two great grandsons. Whew I am about wore out trying to teach this next three generations that the norm may not be the only way there may be an alternative to the current iteration of knowledgeDuke

Go by train instead. Or, stay over and do the trip once each way each week.

It is a little hard when you have to take your shop tools and parts with you where ever you go to fix whatever they can think of to break (customers). It is amazing the parts of security hardware that people can break accidental or otherwise. Plus some of the parts I have been asked to repair can be anywhere from 50-100 years old, people try to get their monies worth out of their door locks. I have been doing this for 47 years AND THERE IS NEVER A DULL MOMENT. Plus there is no train service for passenger service anywhere near where they send me. Could be a safe today, a panic bar tomorrow, door closers this afternoon, and access control at midnight when some one can't get in. You just never know. Duke P.S. Sometimes my wife forgets what I look like to her it seems like we are dating all over again.

The additional information is valuable.

Thank you sir; I remember several of your posts involving propane injection and figured if anybody had a clue it would be you. How do you go about figuring the unit size, is it based on cubic inch's,vehicle weight ,usage, or some other Black art the average person would not know about or understand. Is it like sizing a carburetor for performance applications or street driving? Duke

yes in a way it's about like sizing a carburetor.

With the impco units their model number tends to give you a clue as to what size range of engines in cubic inches of displacement they will usually work best with.

The 425 series work well with the 400 - 500 CI engines and the 300 series do well with the 300 - 400 CI engines most of the time and so on with the smaller model numbers.

Given you have a 4.3L which works out to around 271 cubic inches and you plan to use it mostly for daily driving that suggests a impco 250 series vapor unit would be a good choice to work with.

Unless you are running some wild cam and high RPM modified engine the odds are a 250 would never run short on fuel delivery capacity with your 4.3l.

Well we were going to increase the exhaust to an x pipe and 2.5 in. exhaust system, an A-chip from super chips and pocket port the heads in the bowl area and remove the cats and no I don't mean Del he is good for somethings I just don't remember what, it might come to me later.We used this combo before will it help us or hinder the swap. Oh almost forgot the throttle body comes out the front will this unit work on its side or will I need to make a turn up to mount it. Duke

Vapor mixers and the vapor regulator units are universal mount so they don't care which side is up.

Even with the basic mods I think the 250 size would be just fine but if you have doubts go with a 300. Unlike normal carburetors being a little oversized on a propane system doesn't really bother anything.

The system I put on my 2.6l Mazda engine was from a V8 combine engine about twice its size and it didn't have any real problems other than after about half throttle there was no more engine power to gain being the little four cylinder just couldn't breath any harder.

From Lyn link notice the statement lower maintenance cost. Well work on Fork trucks ran on propane. Will say that I don't think that's so. Most those vehicles had a LPG regulator or evaporator fail every year or so. Back then you just rebuilt it on site. Rebuild kit was cheap. Now that the EPA has got involved. You have to replace them. About $200 a shot. Most the problem with these devices was the poorly filtered fuel. Left all kinds of oil and sludge in them.

Good point on the filtering. I use commercial high pressure sintered bronze type.

The nice thing about them is they are easy to take apart and once the bronze filter plugs up all that is needed to clean one is to heat it up to a dull red with a torch and burn the crud out!

As far as vaporizer and mixer breakdowns I have not had any serious issues ever. I have had three vaporizers fail in 12 years between 4 vehicles and some 200K+ miles of driving.

One had a valve lever break and the other two were diaphragm rips and pinholes most likely caused by excessive backfiring due to spark plugs going bad.

Your supplier must do a good job of filtering. Around here there are quite a few suppliers most do a poor job of filtering if they do any at all.

Common problem is oils that don't evaporate which are left behind. They either start to clog those devices so they don't work properly or the oil attacks the rubber of the diaphragms.

Propane is just like any other fuel. Some places sell good quality and clean stuff others sell weak diluted down crap with lots of junk in it.

Generally in a vehicle application the vaporizer unit is heated by the engine coolants which keeps it hot enough to boil off the ethyl mercaptan scenting oil and any good brand name propane system will be using nitrile rubber for all of its gaskets and diaphragms which should never have compatibility issues with anything that would be in the propane.

The real junk I ever get in my filters is fine rust particles and the like which any good neodymium magnet placed on the inlet side of the filters tends to pick that stuff right out.

I ran propane on my old Ford F350 Van for over 5 years and worked great. Even drove into the states to see some Nascar races. Propane is not as easy to find in USA as in Canada, we have many filling stations all part of the liquid gasoline system. Any conversion shop should be able to give a price if not since you are in Indiana you may consider a trip North of the Border to have it done. You can also consider a dual fuel that way if propane is not available you always have the gas option. I had two separate fuel tanks on my F 350 so capacity was fine for longer trips. On my trips south of the border I carried a 100 LB home tank with a cheater hose in case I ran out. Not 100% acceptable but better than walking for great distances.

Thanks to the RV crowd over the years propane at gas stations has become a standard feature at most every reasonably sized station.

Downside is some places get pretty greedy on filling a vehicle over filling anything else so go in and ask for the prices up front.

If they are not bulk rate plus 20% or less I pass and go someplace else.

I forgot to mention to run a 50/50 mix of coolant in your system if you are in a northern climate similar to Canada. The propane needs to evaporate and as such absorbs a lot of heat. A common mixture of water to antifreeze will gell and hard starting or no starting will prevail. Also make sure you have a block heater or similar device for an aid in starting.

I've always thought that a 50/50 mix WAS common.

That's what I run in Arizona.

You may be correct in the case of propane you have to go higher on the glycol. It has been 20 years since the old E350 and I parted company now that I think about it the propane shop I used upped it to 75%. They were a very good shop and had a very good handle on propane. When I rebuilt the engine after 300,000 miles I installed 11:1 pistons for higher compression as propane has high compression capabilities but as they say it is a spiky fuel meaning it burns faster and the maximum cylinder pressure is like a spike on a graph. Still I could drive at one time 100 miles with a heavy load for $6.00 CDN at that time. I could at some locations buy propane for .19 cents a liter you get less miles per gallon due to lower thermal density and there is a bit less power but with a E 350 it is not really a performance vehicle any way.

All of my vehicles run on gasoline.

About half of my vehicles run. The others just make sure I have less yard to mow.

I use trailers for that.

Gee tcm did we start something or what?

Roy, I recall from college (years and years ago) that there was a point where the freezing point of antifreeze could be maximized (lower freezing point). 75% sounds too high and you're actually increasing the freezing point. I recall the optimum point being in the 60/40 range. The reason I remember this is because a friend of mine has a frozen engine with 100% antifreeze, where my engine was okay at 50/50.

I don't recall the reason for this. Maybe someone here can expand on this.

I have always ran 50/50 mix here as well plus I tend to plumb the vaporizers in series with the interior heater lines and I have never had any problems with freeze ups unless the main solenoid valve jammed and let the idle circuit bleed propane for hours on end and even then a few cups of hot water dumped over the vaporizer is enough to unthaw it.

In cold winter operation I tend to let the engine idle for few minutes before going on the road and that is more than enough time for the coolant to get up enough heat to keep the vaporizers from freezing up when driving.

As far as spiking? Huh?

I have ran bone stock all the way up to heavy towing/performance modified engines with compression ratios ranging from stock 8:1 and less to over 12:1 and have never had engine issues related to fuel.

Now relating to power loss thanks to emissions regulations most every engine now is so badly detuned to meet emissions compliance that running propane on a stock vehicle tends to come out as a break even and occasionally a bit of gain over gasoline now.

The old stock engines built before emissions compliance will see a 5 - 15+% drop in power and fuel numbers but so far every new emission compliant vehicle I have put a system son has shown so little of long term differences its a wash. In fact with the Ford V10's like my 99 F250 has good quality propane has better fuel mileage and power than running on regular gasoline tends to have.