6 replies to this topic

[CW Fab]

I figured this would be a good place to ask this question since the Warthog is a propane burning beast!  

I'm looking at building a sbc 400 or buying a slightly built 454.
My plan is to run propane when I build my trail/ competition truck, but how much compression can I get away with?
If I build the 400 I won't go too crazy, but if I buy the 454 it already has pretty high compression, if propane won't cut it I won't buy that motor (I think it was a mud truck motor).

[G-Man]

CW Fab, on 24 February 2011 - 07:12 PM, said:

I figured this would be a good place to ask this question since the Warthog is a propane burning beast!  

I'm looking at building a sbc 400 or buying a slightly built 454.
My plan is to run propane when I build my trail/ competition truck, but how much compression can I get away with?
If I build the 400 I won't go too crazy, but if I buy the 454 it already has pretty high compression, if propane won't cut it I won't buy that motor (I think it was a mud truck motor).

I don't know what the upper limit is but more is definitely better. The current 467" is 11 and a bit to 1 and the new 496" will be over 13 to 1.

Depending on the head, it's really easy to get 12+ in a 400 SBC with flat tops. Stock stroke BBC's with available open chamber heads of 118-120 CC's need some kind of a domed piston to get that.

Anything that was built for race gas or alcohol should work good on propane with just a cam swap. That is a wider lobe separation and earlier exhaust opening point seem to work well with propane. In addition to the usual matching the cam to the overall airflow and application.

[CW Fab]

Awesome info, that's EXACTLY what I was hoping to find out.

I'm pretty sure the 454 was running domed pistons and about 13:1, burning alcohol I think. The guy that has it now is local to me, I don't think he has decided if he wants to use it in something or sell it, if he sells it I don't think he knows how much he wants for it yet.

Blazin has a healthy 468 setup for propane ready to go, but I may decide to build my 400 sbc.
I've had it kicking around for awhile, not really sure what I was going to do with it... I think it's calling me... it's ready!!!  

[G-Man]

CW Fab, on 27 February 2011 - 03:28 PM, said:

Awesome info, that's EXACTLY what I was hoping to find out.

I'm pretty sure the 454 was running domed pistons and about 13:1, burning alcohol I think. The guy that has it now is local to me, I don't think he has decided if he wants to use it in something or sell it, if he sells it I don't think he knows how much he wants for it yet.

Blazin has a healthy 468 setup for propane ready to go, but I may decide to build my 400 sbc.
I've had it kicking around for awhile, not really sure what I was going to do with it... I think it's calling me... it's ready!!!  

One thing to consider is fuel supply. The common Impco model E converter is only rated for 375hp and the common Impco 425 carburetor (mixer) flows a max of 450cfm. That's why the Warthog has 2 separate fuel systems for a max capacity of 750 hp, although it's a bit shy of that right now. Depending on how much power you're making, you may need to modify the tank(s) for bigger pick ups or dual pick ups using 2 fuel lock-offs, 2 converters and 2 mixers on a dual quad manifold or some kind of a Y adapter to a single throttle body. Other considerations are pressure balancing the liquid and vapour lines and replacing the secondary regulator springs with the -.5"WP versions.
All of this is actually real easy to do, let me know if you run into trouble.
BTW- don't get too freaked about the cam swap, if it worked good on gas or alky, it will work with propane. It can just work a little better.

[CW Fab]

Thanks for all of the info.
When I get closer to that stage of the build I'll be asking you lots of questions so I make sure and get things setup right.

[gohnracing]

G-Man, on 28 February 2011 - 10:20 AM, said:

One thing to consider is fuel supply. The common Impco model E converter is only rated for 375hp and the common Impco 425 carburetor (mixer) flows a max of 450cfm. That's why the Warthog has 2 separate fuel systems for a max capacity of 750 hp, although it's a bit shy of that right now. Depending on how much power you're making, you may need to modify the tank(s) for bigger pick ups or dual pick ups using 2 fuel lock-offs, 2 converters and 2 mixers on a dual quad manifold or some kind of a Y adapter to a single throttle body. Other considerations are pressure balancing the liquid and vapour lines and replacing the secondary regulator springs with the -.5"WP versions.
All of this is actually real easy to do, let me know if you run into trouble.
BTW- don't get too freaked about the cam swap, if it worked good on gas or alky, it will work with propane. It can just work a little better.

http://www.nashfuel....=78833138346672

[Eastcoastyoda]

Gotpropane.com has lots and info and seem pretty reasonable in pricing.