Projects I'm building a steam powered Model A

Howdy from sunny/snowy Reno Nevada! I decided it might be a good time to document my build, and this seemed like the right place to do it. I'm a long time fan of the HAMB, and hopefully this build is HAMB-worthy.

This build started after I received an amazing Christmas gift from one of my employees (Drew), a miniature toy steam engine:



I've loved steam powered machinery since I was little, but this was the first time I'd had something steam powered to play with. I was hooked. This damn tin toy triggered a months-long, multi-thousand dollar build.

Knowing that I lack the machining skills to make my own steam engine from plans, on Christmas Day I started browsing the internet for a suitable steam engine to power a small car. I thought it would be easy to source one, but after a couple hours of not finding anything I realized that most guys who are into steam aren't really into the whole internet thing. I'm not saying they are all old, but based on most of the websites I encountered, they all still have dialup. Ebay came to the rescue after setting a few automated searches for a week or so. I found a promising engine in Washington state, built by a gentleman with many years of steam experience. After sending some cash, the engine arrived via Fastenal freight about a week later:



The design is from a marine-style steam engine from the early 1900's. Twin piston, dual action (steam pushes up and down on the pistons). 3" bore, 3" stroke. Depending on the boiler the engine has a theoretical potential of 7-10 hp. Doesn't sound like much, but steam is amazing when it comes to torque. Based on the bore, stroke and some 1800's steam power math, this engine should develop about 300 lbs/ft of torque at 1 rpm.

Here's the engine running on about 60psi of compressed air:


Next up was boiler design. I had a few design goals that led me to build an "Olfelt" style boiler: Safety (I didn't want to make a bomb), packaging, ease of fabrication, cost, weight and aesthetics. I ruled out "fire tube" boilers, like the ones in old steam trains mostly due to safety concerns. With a fire tube boiler, you are heating a large amount of water by passing your flame through tubes submerged in the pressure vessel. These work great, until you run low on water. If the fire tubes are not submerged they become extremely hot and eventually melt. Usually the engineer notices the low water level, panics because he's about to melt the boiler, so he adds more water. The water contacts the exposed hot steel, flash boils and blows the whole thing up. Blowing up is not attractive to me, so I went with a water tube boiler instead. Technically it's a hybrid of water tube and fire tube. My design heats a relatively small amount of water (about 2 gallons total) by passing water through copper tubes exposed to the flame. This has a few advantages over the fire tube design, namely if I run low on water one of many brazed copper fittings will fail individually, reducing the chance of catastrophic explosion. Also, if there is a failure I'm releasing the stored energy of a few cups of water vs. 20-30 gallons.

Boiler fabrication started with a couple 3,200 psi rated nitrogen cylinders. Here is one of them after bead blasting the paint off and prepping for fittings:



Milling ports for the steel nipples that will connect the copper coils to the steam drum:



Many, many drilling, cutting and chamfering operations later:



My attempt at "TIG on MIG" welding in an attempt to remove any porosity:



I made the copper coils using a 3" piece of exhaust tubing clamped into my shop vice. I used 3/8" refrigeration tubing since it's very ductile and easy to work with. I considered filling the tubes with sand or salt and sealing them before bending to reduce kinks, but after a couple test coils I was satisfied with the results.



Here's the partially assembled boiler system, minus the copper. I joined the steam drums (steel nitrogen bottles) with a couple pipes to keep the water level balanced between the two.


I used a high-temp silver braze to join the copper tubes to the steel nipples. Brazing copper to steel is a huge pain in the ass. The copper melts only a couple hundred degrees above the melting point of the brazing rod, so you have to be on your game. I also learned that the more copper you add, the more heat you need. The conductive qualities of copper are pretty impressive. If I heated the steel nipple, the copper coils would suck all the heat out the assembly and redistribute. I ended up preheating the whole thing with a rosebud oxy torch to get everything to work.



One side done, one to go:



Finally got all the copper coils brazed in place. Now it's time to pressure test and see how good my welds/brazes are:



My desired operating pressure is about 150psi, so I hydro tested to a little more than 300psi. I wasn't paying attention at one point and saw 400psi but everything survived. I found a few small pinholes in a couple joints so I re-brazed and called it done. No major issues!

During the boiler design/fabrication process I was also looking for a good chassis donor. I considered building a chassis from scratch, but I always like to have a title in hand when heading to the DMV. It's a lot easier than doing a constructed vehicle title or whatever. Plus, I figured that whatever I found for a donor would add to the character and theme of the car. After a couple weeks I found a perfect candidate (a 1928 Model A, no body) for sale in northern California. Poor Drew went over the pass to pick it up for me (a 3 hour drive) and ended up in a huge snowstorm. The return drive was about 12 hours...whoops. Once off the trailer and in her new home I started putting parts in proximity to each other to get a sense for the packaging:



Since I'm concerned about the potential lack of horsepower in the build I am trying to keep weight to a minimum. To set a baseline we put the 1928 Model A chassis on my Longacre race scales:





1,310 lbs overall. Not too bad, but not great either. I'll be removing the Model A engine, but the weight of the steam engine, boiler, water tank etc. could add up. We'll see how heavy she ends up.

 

This is going to be interesting.

 

You should have had the welding done by a certified pressure vessel - Tig welder, it would have been much nicer and safer too.

 

I like steam. Doble steam cars are pretty interesting. I thought about converting a Cushman I have to steam just for giggles.

 

What Jeff said, going to be real interesting!

 

I was a licensed stationary engineer by trade for 35 years . This is my kind of project . I see a few issues I have questions about but I will watch the progress . You may already have the answers determined . Steam has an expansion rate of 1700 to 1 , major amounts of energy on tap. Major amounts of energy that can hurt you or bystanders beyond my detail . Just be sure to be safe at lease a factor of safety of 4 , I would recommend .

 

I agree with Larry. Stored energy and questionable connections aren't something to mess with. Not questioning your ability, maybe just the materials and processes used to make the assembly . It's fine you pressure tested, but I'd be concerned with the added parameter of heat while in operation.
This may be one area where budget should not be the dictating factor.

Good luck with the project. Love stuff outside the box!

 

Are you serious? I want to see how all this pans out!

 

I wanna drive it!!!

 

I'm in. Take us back to the steam age..

 

I just noticed when you tested , looks like 150 lb rated black iron fittings . Please use caution if you plan to use these for steam operations . Hydro test is one thing , not so bad a leak is a leak . Steam operation , could be an explosion . Sorry , I need to shut up allow you to continue , I have just seen the effects of steam fitting failures , please be safe as possible , major energy is on tap with 150 lb steam operating pressures .

 

Definitely don't see this every day ! Will be watching this one for sure.

 

Good point, this whole thing looks like an accident waiting to happen.
Those fittings are definitely 150 pound malleable iron fittings and should NOT have been used even for pressure testing.
And the nipples welded into the nitrogen bottles also look like they are made from too thin tubing.
On top of that it appears like the copper coils were just stuffed into the ends of the pipe nipples and brazed in.
Very sloppy and extremely poor design.

The nipples should be minimum schedule 80 seamless pipe and then they should have 3000 pound socket weld reducers welded to the end of each nipple ( reducers with the nipple size on one end and a smaller socket weld end for the insertion of the copper coil) .
After that the copper can be properly silver brazed into the reducer fitting.

Honestly, I would start over and have this properly and professionally done. ( with proper quality welding and materials)
We are essentially looking at a pressure vessel assembly here with very questionable design and shoddy construction.
Which in the end could be more than dangerous, it could be fatal.

 

If I am not mistaken, you will be required to obtain a certificate of operation from the state, which means inspection.

 

I don't know anything about steam. I do know how to look at an avatar and see that his engine is running and working. You can't judge a worker from his surroundings, but based on what I see in the background, I trust his ability more than 95% of the flux core welded "traditional" crap posted here every day. I dig it, I want to see more.

 

Looking forward to see how this will all work. Would you still incorporate the tranny?

 

It's really cool but it ain't a traditional hot rod,I fear when the moderators see this it will get deleted.

A better site for this would be, www.DOGFIGHTMag.com HRP

 

i built a steam powered model A roadster back in the mid 80's for my father. it used a Stanley Steamer motor in the back with the boiler under the hood. operating pressure was around 600 PSI. the boiler was made from DOM tubing and i hydrostatic tested it to 2000 PSI before building any steam pressure. it was mig welded

as others have said , things have to be done right or you will have a big problem. i never was able to get the boiler inspected and licensed in Minnesota because of some regulations. i did trust it completely. i never had a license to operate a boiler, but my father did. he had put a steam engine in a Willys jeep back in 1953. he also owned other steam cars and tractors

if you want to know more, the model A roadster was featured in the December 1987 issue of Street Rodder

 

This is cool and outside the box. looking forward to seeing it come together.

 

What an interesting idea. I'll be following along to see how this goes.
I don't know much about steam other than I like it.
Good luck and be safe

Bobby

 

True, that was a consideration. But then I didn't "build it myself", ya know? That being said I didn't approach this as my first welding project. I like projects that encourage me to hone my skills or learn new ones, properly.

 

I agree 100%, this is not a project to take lightly or carelessly. I probably should've mentioned that I did subsequent pressure testing, both warm and hot...but I had to stop at some point for my first post

 

I learned a lot about flux on this project. A high-temp flux was critical due to my long braze times and high heat involved. After about 10 lbs of copper was sacrificed in testing, I found that the Stay-Silv High-temp flux works exceptionally well for long-duration brazing operations. It tends to crystalize if you use too much, but it's easily removed using a hydrochloric acid solution later on.

 

No need for a transmission with steam. All torque is available at 1 rpm! This will be direct drive, no clutch (at least for the first iteration).

 

Well, of course I also had safety concerns as soon as I started reading this thread, but since I'm a spectator and safely out of the blast zone I'm just going to track this and see how it goes!
Way cool build.
I can't wait to see how the many problems are worked out and how it does on the road!
You already know to be exceedingly careful. Many a story back in the days when people knew how to build and run steam engines ended in an explosion and death, but you aren't depending on steam to survive and make a living so that leaves lots of room for safer judgement calls when running and subsequently inspecting it before each run.

Sent from my SM-G920V using The H.A.M.B. mobile app

 

If you want to make it howl , super heat it , and strap down the governor a bit tighter . It will be a blast !

 

Ohhhhhhhhhhhhhhhh Myyyyyyyyyyyyyyyyyyyyy.This looks like fun.Think I`ll saddle up and ride along.
Good luck.Have fun.Be safe.
Leo

 

After all the pressure testing, leak fixing, re-testing, etc...I was finally able to attempt to clean the boiler up and move onto the rest of the build. The particular flux that I used for brazing is a very high-temp flux, and if you don't clean it off while hot it can crystalize and is a pain to remove. My local welding supply guy suggested a solution of hydrochloric acid to remove it. Into the bath it goes!



My intention was to remove the flux, but I noticed a secondary benefit...the hydrochloric acid solution takes a couple free electrons from the copper and plates them to the steel. The effect was pretty cool, so I decided to ramp it up a notch with some DIY electroplating:



The anode (positive lead in this instance) is some sacrificial copper left over from fabrication. The cathode is the boiler assembly. Add some salt, a couple amps at 12 volts (3 volts would be better) and presto! Rudimentary copper plating. It's thin, but it'll actually hold a polish.




I ended up dumping a bunch of fittings into the plating bath to see if I could copper plate everything. Pro tip: plating requires a surgical level of cleanliness. A dip in TSP prior to the plating bath would've saved me a lot of headaches after some oil contaminated 10 gallons of acid. Lesson learned.



After polishing, they look pretty good to me. The effect is more "Rose Gold" than copper, but I'm happy. It was a bit of a waste time, but now I know how to improve upon the process next time.



One of many shopping lists for fittings. You can never have enough nipples hahaha!



After the boiler was cleaned, tested, tested, plated and re-tested, I decided to do a "real world" test on the good ol' bbq. We hooked up my vintage pressure gauge and gave it a whirl outside the shop:


The test was successful and I got to blow the Aeromore Model A exhaust whistle I repurposed. It sounds way better on steam than compressed air for sure. Definitely a deeper tone. I love how the copper changes colors due to the heat.

My new Knuckle super-duper pressure relief valve showed up, along with a great gift for my birthday, an original Stanley Steamer owner's manual. Very cool. I love how it has about 10 pages dedicated to "steaming up" the car, and then 2 more chapters about actually getting ready to drive.

 

That is awesome, I'll definitely look it up. I'd love to have a Stanley but I can't justify the asking prices.

 

I was hesitant to post here at first but I read the rules and my intention is to do a "traditional hot rod build"...with the exception that my power source is steam instead of a flathead. I'm even using a real Model A. The styling is based on race cars from the 1900's/10'/20's, I doubt my wife would be able to distinguish my project from any other car at TROG, and she's a smart chick.