Natural Gas E-250

[MANTUS]

I had a car dealer sell my mustang and i asked him to get me a work van. He found me a 97 E-250 with 35,000 miles and wants 5,500 for it. He said since i am so cool with him he will give me a better deal since that was more than i was looking to spend. He said the van was owned by an electric company and they must not have used it much and He tells me the van runs on natural gas but he'll convert it to regular gas for me. I'm just worried that the motor is now used to natural gas and won't run as good on regular gas and i really don't even know how complicated it will be to convert and i'm also worried they may not know how to do it properly. Should i worry and can someone explain what it takes to convert and anything else i should know? thanks ....

[curtis73]

The conversion is pretty straight forward. The NG vehicles used different parts from the intake up. The shortblock should be identical. What I don't know is how NG affects the rest of the engine. Some fuels reek havoc on engines, like Alcohol and mixed fuels. Propane is pretty gentle, but I've not had direct contact with NG. All I can say is maybe do a search on the internet for alternative fuels and see what you turn up.

Otherwise, here's what I'm thinking: Even if the engine blows up into a million pieces on your way home, you could have a new engine installed and still be bucks ahead. A 97 van stripped down with V6 and no A/C specs out to 7000-8000 retail in NADA and KBB. For $5500 (provided its not a salvage title or has a severe history) you have a good deal. For $2000, have someone put a new gas engine in it and drive it for 150k miles with a smile. Sell the NG engine on Ebay and get back some of your money

[freakray]

Natural gas tends to fire hotter than regular gas, this could create some accelerated wear on the pistons and valves.

Curtis has a good point about swapping the engine out, just swap it out without doing anything to it, then you definitely have something to sell.

[MANTUS]

that clears a lot up for me. thanks ..... i don't really have the time or place to change the motors so i was thinking of just running it with the NG converted to gas in it until i need another motor. My friend said he would take it for a ride and inspect it after they convert it. He said one thing he does is power brake it and sometimes he can tell if the motor is strong or something wrong with it. I never really get into technical works of auto which is why this is all new to me so thanks again for all the help. I am going to go to ebay just to see if i can get an idea on natural gas motor prices.

[MANTUS]

OK now the guy tells me it ran on propain and i didn't say anything about propane being easier on the motor. Is he bullshitting me or can this van really be running on propane? He is going to convert it or they already did i think and i will take it for a ride when i get around to it.

[curtis73]

Gasoline, NPG, and LPG all have very similar BTUs and burn rates, so they are very similar systems. Converting from NPG to gas would be the same basic intrusion as converting from LPG to gas

[Evil Result]

I wonder if that engine was bulit for LPG, NG, Propane, ect. typically engines that bulit for it have a much higher compression ratio because the octane is around 120 far higher than gasoline.

But low compression engines can still run fine on propaneor NG or LPG......hum what are the differences anyways?

[curtis73]

To the best of my knowledge, the cars here in CA that are equipped for NPG and LPG are identical shortblocks. Heads, compression ratios, cams, etc. Some of them have the same intakes, its just that the fuel system and engine management systems are different.

Evil Result, although you're right about propane having different octane, there is some other property about its combustion (golly I'm racking my brain here) that makes it require about the same compression as gasoline. Anyone chime in? I'll bet SaabJohann knows...

[MagicRat]

I have converted a couple of vehicles to propane, so heres the scoop.
1. Propane can tolerate higher compression ratios than gas engines, but factory conversions never take advantage of this, because its far cheaper just to use the same gasoline long block.
The cost to produce a special high compression versin just for a small number of propane vehicles would be prohibitively expensive for the manufaturer.
So your engine will be the same as a gas engine.

2. Propane has only about 66% the BTUs as an equivalent volume of gasoline. Therefore, this engine has been producing less power than a gas engine and, all else being equal, likely shows less wear and stress than a typical fleet vehicle.

3. Propane runs exceptionally clean. The usual hyrdocarbon soup that contaminates engine oil is not present in propane, so these engines have cleaner, longer lasting and better lubricating oil than a gas engine. Therefore, that engine will be clean as a whistle inside, with, theoretically less wear.

[Evil Result]

If Propane contains less BTU's than gasoline per unit volume could you still extract a compairable ammount of energy through compression or other means to compete with gasoline based on equivalent volume?

it would be sweet to have a 500 HP propane engine.

[MANTUS]

OK now i talked to the owner....I hate salesmen....and he says it's natural gas but natural gas runs cleaner than unleaded gas and therefore its better for the motor. I looked at it and it looks like a nice van but I know i can't trust him already so im taking it to a car dealer my mother works for and the manager who i am friends with said he will run a fine tooth comb through it. thanks for all the help

[MagicRat]

Originally Posted by Evil Result

If Propane contains less BTU's than gasoline per unit volume could you still extract a compairable ammount of energy through compression or other means to compete with gasoline based on equivalent volume?

it would be sweet to have a 500 HP propane engine.

This is a problem......but there are a few things you can do.......propane can handle more compression and a bit more ignition advance, for a bit more power.
The traditional propane "carburetor" is a bit restrictive, for performance, but it is possible to use two of them, if you get the right intake manifold.

Try a "dual quad" intake, a tunnel ram design with long intake runners would be great, because the fuel would not fall out of suspension, like a gas engine.

The best for power would be 2 carbs on a big blower, like a GMC 6-71.
That would be cool on the strip, especially if you go down the quarter running on your BBQ tank.