Propane or CNG Festiva

[old yellow]

would converting a Festiva to run on Propane or CNG give you about the same gas mileage for a cheaper cost? thoughts....

[MiltonHavoc]

from all the reading I did on this topic:

cng gets about a gallon less than gasoline.
smart option in the long run. In a festiva it will pay for itself in just a couple of months at 40mpg.
the hard part is the up front fee to have the CNG system and install approved. The government made it unappealing for a reason.

Id do it in a heartbeat if I had the upfront cash. A CNG Bp festiva would be up there with the TDI cars as far as practicality.

[lessersivad]

Both propane and CNG have les BTU's per gallon.

My past experience with propane is yu suffer 10-20% mileage loss on a simple swap for gasoline to propane.

Now you could get a bit closer to the stock mileage if you were to raise the compression ratio to12-13:1.

Then you have the hassle of having a high pressure tank mounted, running the high pressure fuel hose and finding a propane distributor where you can purchase fuel. BTW, at least around here, there IS "road tax" on propane fuel for licensed vehicles.

IMHO, unless you can buy propane real cheap and have all of the conversion practically given to you, it's not worth the hassle.

[old yellow]

well propane for auto use is like 2.17/ gal and i don't think they tax propane here... will have to find out

[old yellow]

well even 30 mpg is good for any car

[getnpsi]

If you are rural and have it delivered for home/farm use, AND can pump it into your car safely and almost legally, then even at a mileage loss that is pretty much awesome to not have to stop/modify routes. Think getting off the highway, back to city mpg, sitting in traffic, buying lotto tickets and sodas at gouge prices to fill with gasoline, the whole idea adds up costs in not just fuel alone.

A b6 with carb would be a good candidate.

[Bert]

Propane-power adapted cars were gov't promoted and heavily subsidized for fleet and taxi use in Canada during the mid 1970s. Most were dual-fuel (because filling stations were rare outside of cities) and required some sort of manually-switched carb jetting arrangement. Novel idea at the time but these vehicles were so noticeably underpowered (compared to gasoline) whenever they ran on propane that subsequent purchasers usually moved up to big V8s. For taxis it was a short-lived phenomenon right after subsidies dried up and because the cylindrical propane tank(s) eliminated much of the vehicle's trunk space.
BTUs available per liter for LNG and propane are considerably lower (30% or more) than what is generated by gasoline. Consequently these fuels have to be at least 1/2 the price of gasoline in order for you to begin to realize any advantage.
However they do burn very clean so you can go quite aways between tuneups and oil changes and, by gosh, you can loudly proclaim that you are being environmentally Green and buying n. American.

[Tommychu]

I've thought about this. Here's the best way to do it:
Step 1: get an early small-nose B8ME head- the oldest one you can find so the dizzy ends up keyed the right way. Install on EGT BP block so you get the piston oil jets,but use the B8 crank because you're not going to be putting down enough torque for the extra strength to matter
Step 2: install factory replacement Miata Dometop pistons, the '99-'00 (IIRC) 9.5:1 clear the B8 head with only minor clearancing of the combustion chamber but I don't think the 10.5 ones will work. Could be wrong though I've never tried with the 10.5s.
Step 3: deck block and head as far as possible (and go to the max overbore too because POWAH and you're probably not going to rebuild this mess again anyway) to further increase compression, change valve seats to the hardest ones you can find and take a carbide to the combustion chamber to clear dome tops.
Step 4: plug injector holes, and eliminate any other gasoline-specific pieces
Step 5: install Carby B3 dizzy and propane mixer/regulator off a forklift (The Caterpillar-badged Mitsubishi 1/2 and 3/4 ton forklifts we got here had a just-under-2.0l 4cyl, I can't remember which one but the propane system looks like it would adapt well to a B-motor. Failing that the Daewoo G20P has a system that might work too)
Step 6: Install into Festiva, and duct tape a barbecue cylinder to the roof and run a garden hose to the regul-NO DON'T DO THAT. There's some funky sized/shaped cylinders that are made to bolt in place of gas tanks, find one that fits and get a propane-certified shop to mount it and run the lines to your crazy forklift/protege/miata hybrid gong show and make it certified and legal and stuff. Optionally you might want to get such a shop to pick the right mixer and regulator for your engine, they know better than the internet does which combo will work best.
Step 7: Drive the snot out of it and don't park in parkades.

[sketchman]

1. Go plug-in electric with BIG deep cycles in place of the gas tank. eBay has what you need, besides ingenuity.
2. Win all freakin' day long! Homie.

[Huli]

Hmmmm.... I am seeing Dickmeyer custom head 13:1 with efi propane injectors!

Sent from my DROID RAZR HD using Tapatalk

[nitrofarm]

from all the reading I did on this topic:

cng gets about a gallon less than gasoline.
smart option in the long run. In a festiva it will pay for itself in just a couple of months at 40mpg.
the hard part is the up front fee to have the CNG system and install approved. The government made it unappealing for a reason.

Id do it in a heartbeat if I had the upfront cash. A CNG Bp festiva would be up there with the TDI cars as far as practicality.

All you need is $50.00 I'll go pick this up for you and mail it to you. I bettcha he would take less than $50.00

http://milwaukee.craigslist.org/pts/4254211564.html

[MiltonHavoc]

where are you guys getting your ratings?
ive only read some articles and so CNC forums. they said about 5-8% loss.
so Im curious, not saying you're wrong.

[lessersivad]

where are you guys getting your ratings?
ive only read some articles and so CNC forums. they said about 5-8% loss.
so Im curious, not saying you're wrong.

http://www.afdc.energy.gov/fuels/fuel_comparison_chart.pdf

http://en.wikipedia.org/wiki/Liquefied_natural_gas

FROM WIKIPEDIA;
"The energy density of LNG is comparable to propane and ethanol but is only 60 percent that of diesel and 70 percent that of gasoline.^{[5] "}

(I know wikipedia isn't usually a reliable source, but at least this page has some backup to the claims.)

So, doing simple math propane/CNG comes in at a 30% loss right out of the gate.

I was in the middle of the "great propane carb swap over" of the early 1980's. The propane company I worked for swapped over fleets of school buses. We also swapped over everything from lawn mowers to straight (farm) trucks.

Standard procedure was to do the swap, change the sparkplugs to 2 steps colder, and advance the timing another 6°-10°.

We had to use an advanced air/fuel ratio meter (tail pipe sniffer) because when adjusting a propane carb, as you're making the adjustments, the mix comes to more of a peak for RPM's vs. a sort of a plateau with gasoline until RPM's drop from being to rich of a mixture.

At the time, propane was approx. 50% the price of gasoline AND there was no road tax. Even after the customers were informed of the mileage loss, which we would state that it could be 10-20%. (20% not being seen, but still possible. 12- 15% was the usual) they were still money ahead.

That quickly changed (tax) as the government was going to see a loss in revenue. (Much like the 'lectrics)

Now granted, this was back when carbs were the norm and fuel injection wasn't even really heard of, at least not around here.

I would imagine that with advancements in engine management systems the loss could be closer to 10%. Yet you still have the hassle factor of retro-fitting all the accessories. On a larger vehicle, especially a pickup truck it's not too big of a deal. Infact I have a propane conversion, complete with tank and engine management "box" for a 4.3 TBI GM.

I bought it during my 2nd round of working in the propane game in the late 90's/early-mid 2000's. It was installed on my daughter's S10 for a while but was later removed upon her request so she could actually get fuel where and when she wanted instead of hitting me up to either drive it to work or her stopping by during business hours.

Advantages of propane is that it will keep for a VERY long time. No fuel spoilage. Also the engine will be much cleaner internally because of no carbon buildup even on a poorly tuned engine.

Hope this answers your question(s).

[nitrofarm]

Thanks for sharing Lesser,that's interesting about the Carbon build up (never thought about that). I know the propane ice Augers are the shizzy around here for cold starts. But they are 4 strokes compared to 2 strokes.

[MiltonHavoc]

yeah. that kinda answers. but they were still only reporting up to a 15% loss with a CARB back then. I wonder with the advancements in fuel tech what the real world loss would be today. And if there are any performance advantages.