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460 on CNG/LPG ?

9K views 14 replies 7 participants last post by  mudbogtom 
#1 ·
Hi all,

has anyone ever built a 460 which was fueled by compressed natural gas or liquified propane gas? What is the power-loss compared to running it on gasoline?
And yes - you guessed right, it is not for use in a vehicle ;-)

Winchengineer
 
#2 ·
It depends on what you get sold at the bowser. The LPG that we have here in Australia is actually higher octane than gasoline. If you put an LPG specific cam in it you will make Hp, not lose it. If you add LPG to an engine that is built for gasoline, you will notice a fair difference. Sorry, I don't know any actual numbers or percentages.

A little more info here:

http://www.460ford.com/forum/showthread.php?t=148484
 
#3 ·
My 460 runs on LPG. I run dual gas throttle bodies (carbs) and two vaporizers. Not the best setup, but it works.

Actual power loss depends on how you feed your engine, which fuel you are using and what condition your engine is in to start with.

Assuming a stock engine in reasonable condition:
Venturi ring - in my opinion a dead loss. The motor will produce less power than it ever did, on both CNG/LPG and gasoline due to a loss of volumetric efficiency (VE) caused by a mechanical obstruction in the intake system (the ring). Estimate a 15% or more power loss.

Gas Carb - An Impco 425 would be an example. Better than the venturi ring, still a loss in VE as the gas expands and displaces air in the intake tract. Estimate a 10-15% or more loss.

Vapour injection - Emer would be an example. Better than the previous two by far as the VE losses are far lower if you inject the vapour close to the intake valve and just as it opens. It's possible to be on par or slightly better than with gasoline. Estimate less than 10%, but worse if you don't optimize.

Liquid Injection - ITG comes to mind. Much better than all of the above. Depending on where you inject you can actually cool the intake air by a reasonable and helpful amount. It is now common to see liquid injected engines produce the same and in some cases more power than when the same engine is run on gasoline. Piggy back systems don't tend to make more power, dedicated Gaseous EFI systems do (could be remapped OEM, or aftermarket like Bosch Motorsport, MoTeC etc.)

Direct Liquid Injection - I've only seen combustion lab stuff. Huge advantages over all of the above. Phase change from liquid to gas in a hot combustion chamber is beneficial for extending lean burning limits, compression ratio and boost. More power, leaner burning, higher efficiency.

So how much loss do you want? :)
I'd go the injection route and avoid the losses.
 
#4 ·
460 on LPG/CNG

Wow - I didn't expect that many replies!
Here is the scoop: I am helping a fellow pilot in the Netherlands who read about the good success of my winch powered by a 460 (due to the great help I got from y'all). His club's winch has a 460 out of a 71 Lincoln with D2VE heads powered by LPG. That fuel is much cheaper in the Netherlands than gasoline. The 460 has been performing it's duties in that winch for around 25 years (!!) and is just plain and simple 'tired'. It has a ticking noise and is throwing oil out of valve cover breather. So they decided to do a complete overhaul but at the same time give it a serious boost in power since the club is also upgrading their glider fleet to some modern trainers, which are heavier and require a higher launch speed. (You wouldn't get a F-18 Hornet off a carrier deck and into the air using a catapult built for WW-2 Corsairs, right?)
My corner point power requirement calculation shows that they need about 410HP. Is that sort of power feasible on LPG?

Thanks,
Winchengineer
 
#8 ·
I am getting the rear end ratio and the spool diameter of that winch to determine the power band for the engine. The fact that there are several LPG/CNG 460s around give me hope that the project can go forward.
I will have to investigate the 'propane-cam' which was mentioned. Had no idea that such a thing exists.
Thanks for all the good tips.
Winchengineer
 
#6 ·
Nat Gas Carbs

Thunderv12 sells used nat gas carbs that came off irrigation engines.



They were on 1960 702ci v12 GMC engines that were governed at 2,400 rpm.

Some engines had 1 big carb. Some had two smaller carbs.

$35 ea on their parts page. thunderv12.com
 
#7 ·
With a dedicated propane setup you can run quite a bit higher compression ration than on gasoline. This makes up for any potential power losses. If you just bolt a propane setup on a gasoline engine the loss will be 15% or more.
 
#9 ·
With gaseous fuels you want/need to avoid exhaust residuals as much as possible as the extra heat provides the energy necessary for the gas to expand even more during overlap - displacing greatly needed oxygen and therefore reducing VE. Same goes for heat soaked intake tracts.

This doesn't mean you can't have overlap, it just means that there will be more of a compromise during the lower RPM intake cycles if you do.
 
#11 ·
I run 2 Gas Research (GRA) throttle bodies and two GRA B2 converters, with a 190L tank.

GRA recommended running dual throttle bodies in a primary/secondary configuration. I did this at first and found it so boggy and soft that I felt like someone had yanked my BBF and replaced it with my neighbour's Hyundai engine. Boy did it suck. I changed the throttle linkages so both throttles open at the same time and balanced the jets so they acted like two primaries. Wow - what a difference that made. It felt like I had a V8 again.

Although they are supposedly almost infinitely tunable, the idle, transition and cruise circuits are all linked too tightly together. This means you might get a perfect idle, but cruise and transition get messy. You start to fix cruise and although it gets better idle gets worse, so you have to compensate a little in your idle settings. Then you find that there is a big fat lean spot when you stomp on it so you correct that and now idle is so rich your beginning to think you're gonna gas-axe something shortly so you start messing around with idle again and cruise goes up the $hit again. I've tried the different sized restrictors/jets as recommended by GRA and in the order recommended by GRA and yet lambda at idle hangs around 0.84, my flat spot hits 1.24 and cruise is ok at 0.98 - 1.02. I've traded idle for cruise and given that you won't ping if you lean LPG out, I traded out a lot of the progression too, hence the flat spot. I could certainly do a lot better, but I'm not up for all the dicking around again. I'm now used to EFI. Change a value, make it happen, move on.

GRA's setup is a million miles ahead of any venturi ring, but dang it sucks if you're used to quality fueling. Infinitely tunable doesn't mean it's fun to do and you can get it right with ease.

If you have the choice - go INJECTION. More power, more tunability, more precision, more fun.
 
#12 ·
The best thing about LPG is that you can run higher compression. If you want to make the most out of a dedicated LPG engine you want to run a minimum of 12:1 compression. LPG takes more initial timing but less overall maximum timing so you will need to recurve the distributor to take advantage of the LPG.
 
#15 ·
The earlier C8VE,C9VE, D0VE heads are probably a better choice to get you to that ratio... it depends on your piston requirements to get you there. You may be limited on what piston selection you get with the D3 heads to get the higher compression.

The D2VE are the lowest perfomance heads for these engines due to chamber shape and size.

Tom
 
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