I'm thinking of doing a home-brewed propane injection for a bit more power. What I've been looking at is the Impco T-60 Beam regulator with the vacuum lockoff feature. This regulator is commonly used for running small to medium-sized generators - up to 60 HP - on propane.

The way the T60 regulator is designed it has a gas inlet port and a gas outlet port, but it also has a third port to control gas flow. The third port hooks up to a vacuum source from the engine's intake manifold and uses engine vacuum to meter the fuel. Higher RPMs=higher vacuum=higer rate of gas flow. Conversely as the RPMS drop, the vacuum drops and the flow of propane is reduced. If there is no vacuum (engine off) the regulator works as a lockoff and cuts all flow to the outlet port. Basically a demand-based metering system.

My idea is to hook the regulator up to my propane tank using a first-stage adjustable regulator at the tank, and the Beam T60 as a secondary regulator. For the actual injection part of the system I'm thinking of a pipe with orifaces installed in the air cleaner inlet to ensure it mixes well with the incoming air. A lot like Ziggster's system for anyone who's been to his page. With the adjustability of the Beam regulator, and the adjustable first stage regulator at the tank, I think I should be able to "tweak" it easily enough to get a decent performance boost without over-fueling and melting the engine.

Naturally I plan on installing an pyrometer to monitor EGTs and help me with the tweaking process. Anybody see any drawbacks to this idea?

 

The only vacuum you will produce with a diesel is variable depending on the condition of your air filter.

Dirty air filter, more vacuum.
Clean air filter and or ram air will result in little or no vacuum and possibly pressure with the ram air.

That regulator sounds something like the one used to put propane on a turbo engine except the one for a turbo engine works off of pressure instead of vacuum to increase the flow of propane.

 

CJ,

How are you going to use the vacuum to meter the fuel? I think our engines make a little vacuum, but would it be enough?

What's the max propane psi you need at the air cleaner?

93

 

Yup that's the problem, they make NO vacuum. It's because of that big open hole in the intake with no throttle plates.

Manifold vacuum is backwards too, more vacuum at low RPM. Maybe you could rig up a valve hooked to your vacuum pump. Must be why most kits are sold for turbo'd engines only.

 

Well, I knew they didn't make a lot (hence the need for the vacuum pump), but I didn't know that they made essentially none. Guess that idea won't work - back to the old drawing board Maybe take a control signal off the tach sender instead.....

Yup, that's pretty much where I got the idea.....

 

CheaperJeeper,

Did you want the vacuum to vary the amount of propane or just turn it on?

I went to Ziggster’s page and found where he was getting about 4 or 5 psi in the line to the intake, but once the valve opens it drops below 1 psi. What is the pressure output on a regulator for a propane grill; the line to the burner says 1-psi max? How much flow do you need to make a noticeable difference?

I was thinking about using a 12-volt shutoff valve and mounting it as close to the intake as possible to eliminate the lag that Ziggster wrote about, and use a micro switch on the throttle linkage to turn it on. Also possibly using something that works off a 0 to 10 volt signal to control the amount of flow as the throttle is increased?

93

 

The 12 volt switch will eliminate any lag and you can use a toogle switch in the cab in you prefer, to the micro switch.
Propane injection systems work better with a turbo, in fact most if not all after market systems are for turbo applications.

 

I want to design a system that varies flow according to RPM. The idea of a one-rate on/off system doesn't appeal to me. With that kind of system you're either under-or-over supplying propane almost all the time. The flow rate is really only right for one speed/RPM range and is either too much or too little all the rest of the time. Even a system that varies the rate based on throttle position isn't ideal, though it would be much better. Seems to me that the true ideal - since this is a "boost" and not a primary fuel supply system - would be a system that meters the boost fuel according to RPMs. Varying it according to throttle position would certainly be the next best thing.

 

RPM doesn't say anything about engine load. That's why boost is the best way, it's directly related to load.

 

When your adding propane, your just adding fuel, it helps with a more complete burn of diesel, thus better MPG. With mine, I get a real good kick around 2100 RPM,s EMPTY, towing my 5th wheel, it's barely noticably except the increase MPG. Guys that run propane with turbos on their rigs are very impressed until they blow their heads off!

 

Not quite sure what you're trying to say Malcom. Other than RPM not being the best measure. Actually the vacuum idea - if it would work - would really be a load/demand type system more than an RPM-based.

So if RPM off the tach isn't the way to go, what do you suggest? Maybe throttle position would be better?

 

Tell me more about your system, bc6.9. You mention it in your sig, but there's nothing about it in your gallery. Is it a single-stage on/off system like Ziggster's?

 

the t60 regulator is the same regulator that tsperformance uses on their propane systems. it does work off of vacuum. i set mine up the first time to get vacuum after the air cleaner. then i moved the port to the air cleaner housing, before the air cleaner, so a dirty filter would not affect the vacuum. that worked much better.

http://www.tsperformanceproducts.com/propane.html

 

I was rooting around my shop today and found an old walbro lawnmower carb. Then on the net I found this page:
http://theepicenter.com/tow102899.html
which describes how to modify a lawnmower carb to run on propane. My Idea was to mod this little carb to flow propane, and plumb it into my air cleaner box, after the air cleaner. So the suction would be the strongest. Next my idea was to plumb a hose onto the inlet side of the lawnmower carb and use a crankase ventilation filter (those little filters you see on valve covers) and in the line between that little filter and the carb inlet I was going to run a vacuum port to signal the regulator. Then I just have to attatch a cable to my go-pedal to activate the throttle plate in the carb.

This idea is fresh (today) so I havent really gone over it yet....but theres another angle you can look at to give you another idea...meanwhile help me out when you find a flaw in my system

 

That sounds like a great idea! Something I'd like to do as well. Please keep us posted on your progress and any problems that come up.