Had another thread about my 460 build, but I am toying with switching to propane when I do. I have done a search, it was very helpful, but Im still a little on the fence as to whether it is worth doing.

This is a carbed motor. I have a set of D0VE heads on it now and I also have a set of D3VE heads. I have not yet purchased pistons, so my compression options are wide open at this point. I planed on having the seats hardened no matter what, even on the D3VE heads since they have had a valve job. The rest of my mods would be a Stealth intake Comp Cams 4X4 cam (the biggest one they recomend with stock converter), light porting of the heads, just on the exhaust side. Should make for a good, strong, streetable motor. Nothing radical.

First, do I need a "kit" or can it be assembled from parts that are readily available?

Second, do I need to re-examine cam, intake or other hardware if I were to do this?

Third, what compression ratio would be best to maximize power and efficiency?

I have a place to purchase the fuel easily and its cheap compared to gas. It is my DD so I should recover costs fairly quickly. Just want to make sure I dont have any surprises.

Oh, and I plan on just using forklift tanks mounted in the bed.

Thanks in advance.

 

It's only worth doing if you can get propane at a low enough price to get a reasonably quick payback. If there's a propane supplier nearby, they can set you up with an account which should get you the best price. You might even be able to lock-in the price for the year during the summer when the propane market is low.

As for tanks, lift-truck tanks are for off-road applications. Use ASME motor fuel tanks (like Manchester ASME or Sleegers ASME) for on-road vehicles to ensure that your fuel system meets NPFA 58. See Propane Fuel Tanks.

Propane has an octane rating of 104. Keep your CR to around 10:1 to 11:1. Generally, any performance mod for gasoline works for propane. Having a reliable, hot spark is important for propane.

It's generally cheaper to buy a kit than to buy individual parts separately. The OHG X-450 (Streamline 475) is no longer available new so you will either have to use an Impco 425 system or Technocarb's Off Road carb kit.

Especially if you go with an Impco 425 mixer, you should build your system to maximize low RPM torque. The 425 mixer is rated at 460 CFM, which means that it will reach that flow with a 460 at about 4066 RPM (assuming 85% VE). The flow rating is where the gas valve reaches the top of its travel. Above that flow, fuel mixtures will become leaner with a corresponding reduction in power.

 

I've been thinking about it as well
check these guys out... GOT PROPANE Propane Conversion Kits

the kit I was consdering is the "Dual Fuel" kit (allowing the ability to switch back to gas)
Propane Conversion Kits : Available Kits gotpropa

 

The GotPropane system referenced above is a dual fuel system using the Model 300 mixer but doesn't specify whether it is the 348 or 432 CFM version. A 460 reaches 432 CFM at around 3818 RPM. The OP was interested in a mono-fuel system and the GotPropane 425 mixer-based mono-fuel costs $1195. In either case, their systems are designed for off-road use because they include lift-truck cylinder tank brackets.

Even if you were going dual-fuel, I would still use a Model 425 mixer dual fuel system on a 460. Before you buy any system, you need to make sure that you know what you're getting and that it's suitable for your application. Just buying on price alone is like buying a 1 bbl carb because it's cheaper than a 4bbl.

Even lift-truck DOT cylinders were legal for on-road vehicles, they are a lot more inconvenient than larger capacity ASME tanks. A 33.5# cylinder holds 7.7 gallons of propane while the 43.5# cylinder holds 9.9 gallons. Assuming your propane fuel economy is 80% of your gasoline economy, that would be equivalent of putting in gasoline 6.2 or 7.9 gallons at a time. Do you really want to be changing cylinders that often?

As for GotPropane's advice, propane's 104 octane doesn't allow you to run more advance. Propane actually requires LESS overall advance (but more initial) than gasoline. The higher octane rating allows you to run more compression (up to 11:1).

A Model 300 mixer (with a 5-1/8" air horn adapter) also requires 6" of clearance between the top of the air horn and not 5" as stated in their dual fuel product description. A Model 425 mixer with a 90° AA9-54 adapter requires about 4-1/4" of clearance.

 

Fraso,

thanks for the info,

I'm still trying to let it soak in



I emailed GotPropane about this kit,
they said it was sufficent for my 460

I would be more interested in a dual fuel kit (as to not have to find propane if I'm outta town)

as far as the fuel tanks,
I may have access to a truck bed tank (about 48" long, I think it's about 18 or 24" across)

I'm still in the early stages of looking into propane fueling (I only posted the GotProane site because it was the first one I found)

Russ


so,
wth my 1977 F250 (460/C6)

you wou recomend this? http://autoparts.rasoenterprises.com...roducts_id=163
about $900 + tank???

does it have everything I need?

it shows Components NOT Included in Kit

Fuel tank
Fuel line from tank to fuel lockoff valve
Remote fill valve (if required)
Fuel Gauge
se GM 0-90 ohm fuel gauge
Or connect to vehicle fuel gauge through toggle switch
Fuel Line Adapters (buy locally depending upon your fuel line):
Fairview 68-5B Gasoline Fuelock adapter, ¼" MNPT x 5/16" tube compression fitting (2 required)
Fairview 68-6B Gasoline Fuelock adapter, ¼" MNPT x 3/8" tube compression fitting (2 required)
Basic Components Package. To make an underhood conversion kit, you must add BCP-EE Components kit. http://autoparts.rasoenterprises.com...roducts_id=144

Basic Components Package.
Model E & Electric Lockoff Kit [BCP-EE] $403.00




This is a basic components kit for engine applications up to 325 hp. This kit consists of the following items or their equivalents:

1 x Impco EB-2 Model E Converter, Silicone
1 x AFC 142 Electric Lockoff & Filter
1 x Impco SV Start Assist Valve
2 x Fairview 49-6B Elbow, brass, 3/8" Flare x ¼" MNPT
1 x Fairview 48-6B Connector, brass, 3/8" Flare x ¼" MNPT
4 x Fairview HC6-12 Gear Clamp, 5/8" hose
2 x Fairview HC6-16 Gear Clamp, 1" hose
4 x Fairview TS17R-10 Strap Clamps, for 3/8" LPG hose
2 x Gann 21EN Vacuum Elbow, Nylon, ¼" Hose x ¼" MNPT
2 x Gann 53EN Water Elbow, Nylon, 5/8" Hose x 3/8" MNPT
1 x Gann 88EN Vapour Elbow, Nylon, 1" Hose x 1" MNPT
2 x Gann VH100 Vapour Hose, 1"
The converter and fuelock are connected with 3/8" hose but hoses are NOT included in this kit. You must source your own high pressure liquid LPG fuel line assemblies (hose & ends), which must conform to your local LPG codes.

To maintain a consistent fuel mixture, a pair of 21EN vacuum elbows are included to hook up a balance line between the mixer and converter. You must source your own 1/4" vacuum hose for this connection.

This kit includes an automatic primer: the SV Start Assist Valve. It provides a slightly richer fuel mixture to the engine while the starter motor is engaged. This item ensures a quick start with minimal cranking.

If you need more than 2' of vapour hose, order the extra hose separately and the additional amount will be added to the length included in this kit.

 

I hope they're including the 432 CFM mixer. I expect they're also including CGA Type I hose instead of Type III to keep the costs down.

 

I see you've edited your post since I replied. Yes, I would recommend the parts packages you referenced.

The items listed as not included are to help you figure out what else you need to make a complete conversion. Fuel lines are not included because I recommend using CGA Type III hose, which is more expensive than Type I hose. I think it's better to buy the exact amount you need rather than unnecessarily paying for hose you don't. In addition, although not applicable to to you, regulations in Canada require the use of CGA Type III certified hose assemblies (hose and ends), which also means buying the exact length required. See fuel line [type one].

If you want to set up your system so that your dashboard fuel gauge also shows the propane tank level, the propane tank level sender needs to be vehicle-specific. That is, you need to use a Ford sender to work with a Ford gauge.

Before you buy anything, I highly recommend that you discuss your project with a local propane conversion shop that can inspect your work before you put any fuel in it. It is important that the conversion meets the requirements of NPFA 58.

 

cool,
thanks for the info
it probably won't hapen for several months
I'm still trying to read up on this proces

 

Havent been on here for a couple of days, but thanks for all the replies. I still have a lot to think about. I want to check around for availability, not just near my home, but around the city. I dont really like the idea of the drop off at 4000 RPM. Not that this will be a high revving motor, but on gas my power band would be solid up to about 5000 RPM. It does burn a lot cleaner though. If I thought I could convert to CNG inexpensively I would do that.

I guess I just need to take a hard look at prices of propane compared to gas and the trends. It is my daily driver, so if the price difference is at all significant I would recoupe money quickly.