Alternate fuel

[Atilla the Fun]

First, go look around on www.gotpropane.com. Note they have kits for older, 4-barrel pickups at just $995 for everything but the bottle. If you have 5.5" between the air cleaner and the hood, you can have it dual-fuel, switch between propane and gasoline at will. That's just $895. They used to convert government vehicles.
Great. Now go try to find a CNG conversion kit like those. Can't be done. Why? Our government. In Thailand, you can get it for $1500 US, but here it costs 10 times that. Because our voters won't stop voting for incumbents who won't ban lobbying.
Propane is like $2.30 per gallon. CNG is about 1/4 - 1/5 that. And CNG has been a factory option on many cars.
So why can't we have cheap kits for cheap fuel? Our effing government.
But that's no surprise.
The real question is why don't they regulate these factory CNG vehicles? There's nothing stopping me ( except my lack of disposable income right now ) from getting a totalled '98 Chevy CNG pickup, and planting it's CNG Vortec 350 in a '67 Camaro, with the truck tank in the back end of that Camaro.
If you have the Camaro and know what you're doing, this can be done for $500. So it makes excellent sense. Fit it with a 700R-4 and a 3.08:1 axle, it'll still do 25 MPG. Compare the cost of joining the Power Tour in this, versus a '67 camaro SS, still a 350, but gasoline, and 18 MPG with no overdrive.
Wanna play it extra safe? Build a tank enclosure out of welded 1/4" steel, vented to the rear, away from the exhaust, and in a high-flow, low-drag area of the car's tail. May have to cut out the car's trunk. But Camaros aren't for trunk use anyway.
So, in light of this, why is the gov way over regulating CNG conversions of older cars / pickups? That's not the question.
These $10,000-per-vehicle-converted taxes are going in the bank accounts of the lawmakers who voted these taxes into law. With smarter citizens, we wouldn't need term limits.
The miracle is that the propane kits are available at the price they are. The low cost of CNG fuel inflates the resale value of all the factory CNG vehicles.
Buying the propane kits now is a no-brainer. Use yourself or later resale, either is fine.
My next research project is learning about converting / adapting the propane parts to work with CNG instead.

[crzyone]

Supply and demand. If cars start burning CNG and the supply goes down, the price goes up. Diesel used to be a junk cheap fuel, so people started buying diesel trucks. Now there is a large demand and the price goes up.

I'd rather cars not burn natural gas and leave it for heating homes and running power stations. Keep the price reasonable.

There is also the fact that CNG has about 2.5x less BTU value than propane and about 3.2x less than butane. You are going to have to burn a LOT of methane to haul around a car. Your fuel economy will go out the window.

[Atilla the Fun]

Amber's CNG 2.3L Ford Ranger is getting slightly more mpg than it's gasoline cousins.
Admittedly, her tank occupies the front third of her Ranger's short bed, but smaller twin tanks are possible.
Amber doesn't do spirited driving. She does great at rowing her own gears, however. I just can't get her to try powershifting. I bet she'd be a natural.
Anyway, I don't see a problem with CNG as a motor fuel, and the supply situation isn't anything to worry about.
But using it in homes? Mom's house is within 100 sq ft of mine, she prefers natural gas, I prefer electric. And every month for the past year, my utility bills have been a solid 40% less. Translation: Electric wins, natural gas loses.
But since homes having it is such a common thing, it makes the Phill look wise. ( Phill is the compressor that Honda advocates for home-refueling of their CNG cars. Takes about 6 hours, uses about 800 watts. )
CNG is clean, cheap, competitive and effective, no doubt. But since it does burn so cleanly, why the heck do Americans allow the EPA to call it emissions-tampering? If anything, it's emissions-reducing, which is the entire point of the EPA.

[crzyone]

It's physically impossible to get metter mileage using Natural Gas than Gasoline. If you require 25hp to propel your truck at highway speeds, it's fairly easy to calculate how much natural gas you burn compared to gasoline.

Same way Diesel gets better mileage than gasoline. Higher energy density.

I've driven Propane trucks. They are generally gutless and burn a lot of propane. It would take a lot of propane to pay off the cost of the conversion.

If you were to build an engine to take advantage of propane's 120 octane rating with high compression and advanced timing it would probably make a large difference. But again, that costs money.

[Atilla the Fun]

First, CNG being 1/5 the price of gasoline, means we can run up to 5 times as much of it. Stoich for gasoline is nominally 14.7:1. So the stoich for CNG could be like 3:1 before I'd care. I have no problem with how much extra fuel it takes when I'm at WOT.
Now, if the gasoline 2.3 Rangers are a bit over-geared for best cruise MPG, and that is a real possibility, then the alt fuel could and should show the improvement Amber reports. Let me illustrate by exaggeration: If I put a 383 in my '84 Trans Am, then add a Muncie M20 4-speed without overdrive, then install a 4.10:1 axle gear, then it's obvious that I'm having to give extra throttle just to keep up with traffic. Gasoline has a limit to how lean it can run. So, I'm delivering more torque than the total drag requires.
So, with that straightened out, moving on to taking advantage:
These affordable propane kits are targeted at older pickups with 4-barrel carbs. And most of those remaining now have the ubiquituous 350 Chevy. And for propane, why not?
Flat top pistons are the rule for about half of all rebuilds, because of the commonality of 76 cc heads. Same cost as dished, basic castings can be had for under $70 per set. And usually don't need the crank re-balanced.
So flat tops in a 350. Do like 99% of the third-gen guys and top with 305 heads, you're just a hair under 11:1, which seems to be the magic number for propane. Cost? Well, at several salvage yards around me, a pair of heads is $75-80. Add in the Summit Racing cheapo gasket set, you're still under $200 invested to alter your engine to take advantage of propane.
I'm sure that's not unreasonably much, even to your sensibilities.
And let's not forget that gasoline is delivered as a liquid, so there's some fuel puddling even in Edelbrock's latest intake manifolds. Puddling is inefficiency. The mixture must be enriched to compensate. Power and mileage both suffer. With gaseous fuels, this just isn't so. Therefore, the relative power and relative mileage both improve versus gasoline.
What interests me is how much of the oxygen-carrying atmosphere does each fuel displace from the intake ports? Can't burn more fuel with less oxygen, unless the fuel carries oxygen.

[The Dark Side of Will]

Same way Diesel gets better mileage than gasoline. Higher energy density.

The diesel cycle is also more efficient than the Otto cycle and diesels don't have pumping losses...

[The Dark Side of Will]

If I put a 383 in my '84 Trans Am, then add a Muncie M20 4-speed without overdrive, then install a 4.10:1 axle gear, then it's obvious that I'm having to give extra throttle just to keep up with traffic.
What interests me is how much of the oxygen-carrying atmosphere does each fuel displace from the intake ports? Can't burn more fuel with less oxygen, unless the fuel carries oxygen.

Actually, you'll be using *less* throttle. The engine will get worse gas mileage because of lower manifold pressure increasing pumping losses, lower manifold pressure resulting in lower cylinder pressures and lower thermal efficiency, and greater internal friction due to the higher RPM.

1 CFM of propane displaces 1 CFM of air...

[Atilla the Fun]

Aside from the BMW stupidity, I thought you had some smarts. But less throttle? Your grasp of basic automotive physics has fled. I have tried something very similar to my example, and obviously, you have not. Unless yours had a pair of 1150-cfm Holley Dominators on top. Did it?
Your vacuum gauge would indeed be reading as high as could be, were you to fit one. And if you're comparing a more moderate example versus a nearly-lugging alternative, then you're getting it, albeit not helping with the understanding how Amber is getting such good MPG.

[The Dark Side of Will]

Say for the sake of argument the vehicle requires 25 HP to go down the road at 80 MPH.
If your engine is turning 4000 at 80, then if will have to produce about 33 ftlbs to develop that power.
If your engine is turning 2000 at 80, then it will have to produce about 66 ftlbs to develop that power.

It takes more throttle to make 66 ftlbs than 33.

If there's something wrong with my reasoning, explain it.

Either way, don't be insulting.

[Emc209i]

Dude.... when do you get ONE running vehicle finished, land a nice job at a machine shop, and fuck all the pussy you can get your hands on? Stop arguing about this stupid dopey shit on the internet and get back to real life... There are people who get paid to think about all of this, you aren't getting paid.

Seriously...

[Atilla the Fun]

I found a complete used Propane kit, I just have to finish removing it from the '78 Dodge Ram 250 with 440 / 727 / D60 that I'm already getting the D60 from. It's a dual-fuel config, switch to or from gasoline on the fly. The tank won't fit anything less than a full-size pickup, but I found a smaller tank I can trade for. Whole deal is totally free, too! Just gotta pull the 440 & 727 for a guy.

[CincinnatiFiero]

Thats probably the most interesting thing you've gotten in 2 years. I'll be interested to see if you get it, and get it hooked up. Though the carb to propane kits aren't nearly as complex as the EFI CNG kit.