Steam Car Club Forum
Steam Car Club : The Steam Car.....Forum
The Official Forum for the Steam Car Club
The fastest message board....ever.
Having trouble logging in or posting messages? Email for help.
Goto Thread: PreviousNext
Goto: Forum ListMessage ListNew TopicSearchLog In
Subaru Justy 3-cyl = Steamer?
Posted by: (
Date: May 17, 2009 09:07PM

Hi Live Steamers,
Please assist me in a steam engine application. I've been offered a used, mid-90's Subaru Justy engine. It's a 3-cyl inline, w/FWD constant velocity transmission attached. I understand 3-cyl inlines are good for steam conversions due to the fact that 1 piston will always be in a power stroke on a 120-degree crankshaft, this being a single-acting configuration.

Obviously, the engine must be modified to make the cam run at the same speed as the crank so it will be in 2 stroke mode. Positive rotational direction control will be achieved by allowing the starter to run in both directions as required (as well as by the CVT transmission, if I keep it).

My next question is: should I use the OEM intake for the steam inlet or shoot the steam into the spark plug hole and convert the intake valves into 2nd exhaust valves, via cam lobe mods, for higher cylinder clearing efficiency? This would mean a new steam inlet control system. I envision using the distributor shaft to manage the valving for it.

Last one: rust and how to control it.

This engine will be available to other experimenters if I pass on the deal. The location is northern Colorado near Greeley. I will pass on inquiries to the owner. Thank you for your assistance! 8^)

Edited 1 times. Last edit at 05/17/09 09:54PM by jopower.

Re: Subaru Justy 3-cyl = Steamer?
Posted by: (81.168.70.---)
Date: May 18, 2009 05:49AM

Hi Jo,

I'm interested in your project.

You're not necessarily committed to matching cam speed to crank. Two lobes on each cam is a possible. I'm not saying you shouldn't change cam to 1:1 - just another way to approach the problem.

I have come across conversions that use original inlet valves, but reverse the direction of steam flow.

Watch out for compression ratio. What's the design working pressure? IC c/r is likely to prove very greedy on steam.

What about heat losses? Aluminium pistons are good at sucking the heat away. A stainless or ceramic plate on top would help.

Cylinder walls? Are they well insulated?

Water leakage past the piston rings? What strategy do you have to remove this from the sump oil?

Maybe you're just planning to use the original pistons as cross head guides & fit steam cylinders atop - joined by piston rods, but then the valving would be completely new.

Watch out for how you lubricate valve stems. Steam pressure will be higher than standard oil pump will deliver. Just make sure you know how the oil will get into where it's needed.

Rust? Tends not to be a problem - although others might argue otherwise. For rust, you need the oxygen. Yes, some will be drawn in each time you shut down, but it should be much less of an issue than for disc brakes, because it's a closed chamber.


Re: Subaru Justy 3-cyl = Steamer?
Posted by: (
Date: May 20, 2009 07:09PM

Thanks for all the tips, Greg (though I'd considered a double lobed cam... custom cam builds are more expensive than a pulley swap w/ longer belt). This is my 1st steam project consideration and mainly cause the engine was offered out of the blue. I did find steam spec oils that appear to tolerate water infusion. I figured someone had solved the water separation issue and work from there. I had wondered how valve stems (and several other items) stayed properly lubed. Most OHC I/C engines rely on oil splash from the cam lobe channels to lube stems and guides (OHV use oil flowing off the rocker arms). Also, it does appear important that the engine be used regularly. 1-2 month layups get you some nasty scaling intenally.

I believe operating temps would be lower, obviously, but the water jacket would still be functional for several reasons: keeping the heating system separate for one and as insulation of the cyls for another. In this case the radiator would be separated from the block plumbing and used for returning vapor condensation. Perhaps the other idea would be to use the water jacket for return vapor initial condensation and insulation of the cylinders, though the radiator would still be required for the final cooling stage. The heater would have to be worked in there some place.

Too bad I can't work in a simple double expansion system... like center cyl is 1st stage and outer cyls as 2nd stage for more economical output. But the outer cyls aren't phased 180 degrees and I fear there would be a pressure buildup in part of the 1st stage exhaust cycle. I need to research this engine more for specific details before I go thinking of changing the crank phasing.

Re: Subaru Justy 3-cyl = Steamer?
Posted by: (
Date: May 23, 2009 05:06AM

Caught some interest here:


Will let them know about you too.

Re: Subaru Justy 3-cyl = Steamer?
Posted by: (
Date: May 23, 2009 06:31AM

They know! I own the Barrett ;-)


Sorry, only registered users may post in this forum.
The Steam Car Club Forum
Having trouble logging in or posting messages? Email for help.
Web by NPC