thanks...I had no idea they made a 625, 575. never seen them advertised anywhere and I've looked all over the net. So any confirmation you can give would be much appreciated.

rog

 

Hey roger Ive had a look at both mine and they run the same "E" typr converter but I don't know what model as there is nothing else stamped on them.

 

The Impco CA425 mixer is rated at 460 CFM and is their largest automotive mixer. Larger Impco mixers are designed for industrial engines that don't require an idle circuit. A 400 CID engine will draw 460 CFM at around 4675 RPM so it would be good for most normal driving. If you need more air flow, you can either use a dual quad intake or Impco's dual quad adapter for a single throttle body (PN A3-80). Alternatively, you can run a single Technocarb feedback carb, which is designed for big block engines but is a lot more money. For more information, you can check a similar propane thread on the BBD board.

The CR of 10.5:1 you are building with your current engine is great for long-term durability of a propane engine. Although you can run much higher compression, you would then be subject to the possibility of detonation from timing and fuel mixture variances.

Pure propane (or HD-5) propane has an octane rating of 104 and has been around since the 70's. Commercial propane often has a large portion of propylene which can greatly reduce the fuel's octane rating. Always be sure to use HD-5 in an automotive engine.

 

I'm not running a carb, the truck is a 99 v10 f350 and i'm trying to find out what I have to do or change fuel injection wise to run such a setup.

 

Technocarb makes a bolt-in dual-fuel (gasoline-propane) kit for your truck. Look for it under PN DP-FO68-99-02. They have a list of installers on their web site or you could try a list of a American or Canadian conversion centers. They do not at this time have a propane injection kit for the V10.

 

Meanie, I've read about the V-10's getting head damage on propane or LPG, I'd be weary.

 

I'll take that into consideration maples. thanks.

 

Running LPG in an engine (any engine) is similar to running unleaded gasoline. Engines must be in good mechanical condition before undergoing a conversion because LPG can potentially cause exhaust valves to wear out quickly. Propane engines must have hardened valve seats but, as all modern engines are equipped with these for unleaded fuel operation, this is not a concern today.

The main reason that a relatively fresh, recently converted engine would have problems with its exhaust valves is that the fuel mixture is too rich. Gaseous-fuelled engines react opposite to gasoline engines with respect to fuel mixture. While enriching the fuel mixture will cause a gasoline-fuelled engine to run cooler due to the evaporative cooling effect of the atomized fuel in the combustion chamber, there is no effect like this with a gaseous fuel.

A rich LPG fuel mixture will burn hotter than a stoichiometric (ideal - neither rich nor lean) fuel mixture. Also, both lean and rich fuel mixtures burn slower than stoichiometric. The combination of hotter and slower combustion can result in a fuel mixture that is still burning when the exhaust valve opens. If this happens for a long period of time, exhaust valve damage can occur.

The solution for this is easy enough - don't do a half-fast conversion. For a fuel injected engine such as the V10, do a conversion with a system that incorporates feedback (exhaust O2 sensor) control of the fuel mixture. Modern model-specific conversion kits are designed to do this and should operate seamlessly on LPG and, properly done, should also result in an engine with better longevity and lower maintenance.