Propane as a fuel and performance

[rickpilgrim]

Chapter 5 -part 2

The importance of writing down or recording the model and serial numbers of your propane conversion kit or componants used on your motor.

The first propane headache was my cousins 85 Ford F-150 with 300-6 and 5 speed. His motor is 11/1 compression not setup by me.
His regulator started leaking and not knowing what exactly what regulator he had ordered a replacement from an eBay seller. He installed it with adapters and while his truck would start/run no power above 2800 rpm. At this point the truck was brought to our shop.
The first thing I notised was how much smaller in diameter the eBay regulator was. Where both mine and the former one(indicated by paint shadow) on the ford were dinner plate sized the new was maybe 3/4 of that. Secondly it was set to much higher pressure than needed to compensate for the smaller metric ports. The higher pressure was overwhelming the impco 425, which at idle had little effect as the rpm came up to much fuel was blowing through causing the motor to "flood" with fuel. At a steady rpm you could slowly close the tank valve and get it to smooth right out and gain rpm.
Fortunately he still had the old regulator which still had limited parts support and a new diaphragm/rebuild kit put everything right again. He tried to return the eBay regulator but no luck there and all the un necessary adapters put him out about $350.00 plus my bill when if he had the model/serial he could have saved a bunch.

The second was my shop landlord looking for a plow truck and finding an 85 K10 with plow that had a dedicated propane system installed by PO. He said he paid $500 for it and a no rust powder blue 350/th400 with 105K mi I would say cheap.
He dropped it off as he said "runs like dog, either scap the propane for pump gas or make it run right whatever's cheaper"
First this was a stock 85 gasoline motor not meant for propane. Second all gasoline tanks,lines, fuel pump carb and gas guage were missing. I gave him cost both ways and he opted to stay propane as long as it would start a have power like a normal 350.
First was heads off and a switch to my old 86 305 HO heads. The valves are slightly smaller but with the small chambers it gives you close to 10/1 compression. I used new GM steel gaskets and 1.6 ratio rocker arms. On went a non egr intake with a 2" open spacer under the mixer. The truck had dual exhaust so on went used headers. I used a HEI adv curve ki and a adjustable vac adv can with timing at 14static, 13 mechanical and 15 on vacumn all by 2800 rpm. This truck did not have the starter activated cold start system so I added one. All this woke that 350 up enough to hang with a stock 350 TBI truck and start on the coldest days with ease. He was happy with it and told me later fuel use was cut in half.
You can't through a propane kit on a stock carb motor and expect much.
At minimum you need:
Compression close to 10/1 or better
Ign timing all in by 2800 and close to 14-14-14
Good flowing exhaust, headers are nice
Carb spacer with under cfm mixers
At least a 14x3 air filter on V8

[Feel the 'Pane]

I can't believe this thread isn't a 'sticky'.

I've been running a first gen. 350ci propane motor in my '76 K25 since 2014 & my ONLY complaint: fuel price varies immensely! I've found it as cheap as $1.79gal, to $4.25gal., all in the same county!

EVERYTHING in the above thread is GOSPEL!! Read & heed & you will believe!

Yes, my engine isn't anywhere near 'stock', but worth every penny spent when calculating:
price vs. power vs. fuel consumption vs. longevity.

If I wasn't typing this on my phone I'd go into greater detail.


FtP

[70K10Hunter]

Tuned in...

[manimal]

I know this is a year old, but any more info? I've always been intrigued by propane.

[Feel the 'Pane]

Originally Posted by manimal

I know this is a year old, but any more info? I've always been intrigued by propane.

Propane conversion is pretty much covered in this thread but I'll try to answer whatever questions you may have.

I KNOW I'll never go back to gasoline as a fuel...

[Clyde65]

My experience with a propane converted v8 was the mileage was about half and when the cost for propane went above 3/4 of unleaded it just wasn’t a savings.

[COCONUTS]

Originally Posted by Clyde65

My experience with a propane converted v8 was the mileage was about half and when the cost for propane went above 3/4 of unleaded it just wasn’t a savings.

Propane prices can be all over the board. We live rural and propane is considerably higher than my sons location 45 miles from Chicago. It’s all supply and demand. We have 4 suppliers competing in a tri-county here are and my son has a couple dozen to choose from in a 15 mile radius. I pay even a higher price due to only having a 100 gallon tank versus neighbors who have 500-1000 size tanks. I’m working on a 2400 sq. ft. building we just had put up and am going with propane for heat, hot water and stove/oven as electric is even higher than propane. I had a natural gas generator down in Florida and it sure was nice not having to worry about ethanol breaking down from lack of use like I dealt with in quite a few times with our boat.

Great source of knowledge here. Someone should make this a sticky. Even if it’s not economical for me I sure enjoy reading about the technology.

[andyh1956]

Greetings from Mississippi!
There is a small amount of missinfo on the OP's original post about CNG that I can clear up.
He posts that a gallon of gasoline has 125k of BTU content. This is correct. But he lists a gallon of CNG as 100K BTU content.

I'll start by saying (This is confusing) that the BTU formulas are used to get Apples & Oranges to make Apples & Apples. Gasoline is a liquid while CNG is a Vapor. So, to get a Gallon of CNG we calculate the amount in Cu Ft of Vapor that would have the SAME BTU content as a gallon of gasoline. That figure gives us a GGE or Gas Gallon Equivalent. One Gas Gallon Equivalent has 126.7 Cu Ft of Natural gas that equals 125K of BTU content. So by using this formula one gallon of gasoline & one GGE of natural gas have the SAME BTU rating.
What is NOT the same is octane rating. Whereas a gallon of regular gasoline is like 88 octane CNG is something like 130 or so, I can't remember right off have to look it up. Anyway it's WAY hotter than Propane or Gasoline in that respect.
Here is the company we started when I came home from Afghanistan in 2010. Lots of info about CNG here.
We sell compression packages, build fueling stations & I convert vehicles to run on CNG. Also Bi Fuel vehicles. Lotsa info about CNG here.
Thanks
ngvsoulutions.com

[jamyers]

Subscribing to this thread, with my '62 Ranchero's 200 cid straight six in mind...

[mattfranklin]

Old thread, but I just saw it. I've converted a couple of engines (a VW 1.7-liter liquid cooled and a Hercules G1600 generator engine) to run on gaseous fuels. This was all in a laboratory. On recommendations from others in the industry I used Bosch fuel injectors (from Kinsler, designed for offshore boat racing with big block Chevys running on methanol -- I may have a part number somewhere -- EDIT: part number Bosch 0-280-150-837) at 150 psi rail pressure. I ran propane to get the system working, but then switched over to compressed natural gas, because Gas Research Institute, our sponsor, wanted that. Also ran propylene for fun (it runs about the same as propane but had 30% higher NOx emissions).

They all ran great. It was a good time. On the theoretical side of things, yes, you'll probably lose 10-15% of you power because the gaseous fuel crowds out the air going into the engine. But as you said, you can run a higher compression ratio to partially compensate. And of course given the high knock resistance you can boost the heck of with a turbo or a blower and gain back way more than that.

[68post]

So an aftermarket RPM style dualplane and larger runner iron heads with very small chambers, and hotter and re-tuned ignition, should go a long way on a gaseous fueled engine to make it perform as good as or better than it's gasoline equivalent. Mileage with high compression (dedicated engine) should equal-out I'd think , but performance should be even better !?

I'd thought of the dedicated high compression 20 yrs ago when I started my business, but to get the tax credits I couldn't do the installation so I contacted a "certified" installation center and it wasn't worth the expense even with huge tax breaks.

12-1 compression 350's would have been fun tho' !

[andyh1956]

That sounds about right...To get a Gov Tax Credit you have to give the Governor's brother n law all your tax credit!