GM experimented with a number of electric cars in the 60s (as well as other alternative propulsion systems). Although they tried all sorts of exotic (expensive) battery technologies, such as the silver-zinc batteries in the 1966 Electrovair, range was still a disappointing 40+ miles, and the cells were shot after 100 recharges. So an on-board generator was called for, and GM went exotic with that too, using a Stirling engine in the back of a modified Opel Kadett to feed the 14 conventional lead-acid batteries in front, which fed a 3-phase induction motor driving the rear wheels.
I’d forgotten about this car until I stumbled into this ad in a 1969 Hot Rod I was perusing for possible material. I didn’t expect it would be this, given the source. Googling only brings up one image of the Stir-lec in motion. Apparently it had a top speed of 55 mph, but no other details are available. GM presumably used the Sterling (Heat Cycle) engine, which is externally heated by a wide variety of fuels, because it emitted very low emissions. And of course it was almost totally silent.
Sterling engines have been around since their invention in the early 1800s, but have found little practical application due to their low power-to-weight ratio. But some are now being used in some non-nuclear submarines while submerged, fueled by diesel (and liquid oxygen) precisely because they are so quiet.
I’ve heard of the Electrovair, but never heard of this. The idea doesn’t suprise me as locomotives had this concept for decades, but when I got to the Sterling heat engine, I was taken aback! I don’t think I’ve heard of a major manufacturer trying one! Cool! (Pardon the pun.)
Traditional diesel-electric locomotives don’t use this concept. Their electric motors are not fed by batteries. A diesel-electric locomotive requires that the diesel engine speed/power setting be adjusted to correspond to the needs of the electric traction motors. There’s no buffering, or hybrid functioning (power coming from two distinct sources).
The Stirling engine can only be used in this approach because of the battery bank, since the Stirling engine cant be readily increased in its power output. In fact, the engine in this car only produced 8hp, so it didn’t produce enough to propel it alone. It could only extend the range of the batteries during slow speed or while being stopped, as at higher speeds, it would have taken more than 8 hp to keep the Opel going.
It’s basically an EV with a range-extender gen set aboard.
Most diesel-electric locomotives don’t use large battery banks for propulsion, but diesel-electric submarines do, running off batteries when submerged, and running motors and/or charging batteries when surfaced and running on diesels. After World War II, many of the same power train components developed for diesel-electric subs were used in locomotives, including GM’s Winton diesel engines or Fairbanks-Morse’s OP.
Gas-electric propulsion systems date back at least to 1900, with the Lohner “Mixte” hybrid designed and built by Ferdinand Porsche. Porsche had already designed pure EVs for Lohner, but wanted more range.
GM’s diesel engines were designed well before WW2 (1933), and were originally designed for railroad use, not submarine use. But it was adapted for that purpose.
Fairbanks-Morse had been building diesel engines since 1924, and its large diesels were in use in ships and locomotives before they were adapted to submarines.
There’s nothing new or especially distinctive or original about gas/diesel – electric propulsion. What was used for the subs was essentially just the same technology Porsche was using in 1900.
And gas-electric rail cars and locomotives go back to the 1910s. When diesel engines came along, they just replaced the gas engines. Diesel electric locomotives were a mature technology by the time WW2 came along.
My point was that it’s a bit different to run an electric motor from batteries which are then partially re-charged while underway by a gen set than having a gen-set directly supply the needs of a gas or diesel engine. Not a huge difference, but different, nonetheless. That’s why the locomotives are not called “hybrids”, as they don’t draw on more than one source for their power.
WOW! I never knew about that one. Pretty neat for 69. Not too many years later Victor Wouk would be developing a regenerative braking system on a 72 Buick hybrid.
That sent me down the Stirling engine rabbit hole as well. Finding info on a NASA project using AMCs, Celebrities, an Opel, and others powered solely by a Stirling cycle engine.
.
http://blog.hemmings.com/index.php/2009/01/27/nasa-gets-spiritual-and-drops-stirling-engines-in-some-odd-vehicles/
Wow! How cool is this!
GM always seemed to be ahead of the game in technology with very interesting projects in research and development, yet somehow they ended up falling behind the competition in many ways which always bothered me.
The Sterling engine is more efficient than diesel or gasoline engines. For generating electricity is would work, but they don’t do well in start stop operations.
+1
Its mostly a niche tech solution in search of a problem.
Aside from air independent propulsion in non-nuclear submarines the only other recent application I know of is Solar Thermal Electricity generation. As Photovoltaic solar continues to get cheaper they have largely made them obsolete.
Oh GM you had such potential many times during the latter 20th Century and squandered too many chances which makes articles like these a bit disappointing. Wonder how long the deluge of foreign vehicles could have been kept at bay if the Big 3 were competent?
If people have an assortment of equally good vehicles to choose from, I think that all of them will sell in about the same numbers.
Between the natural tendency of larger firms to pursue the upper strata of any market for maximum profit and the higher cost structure of UAW Labor and strong dollar there was no way the domestics (GM, Ford & Chrysler) could have held on to their peak market share.
Toyhondissan would have had to work harder for market share and it might have taken us another 15-25yrs to get to the current current market distrubition; but the end result would be the same. Coming into a fiercly competitive market in the 80s and 90s Hyundai-Kia got to 6-7% of the market largely on a value proposition of more car for less $.
Niedermeyer strikes again. To think that GM had a potential game changer on the level of the Prius 30 years before Toyota is simply stunning, and could be one of the bigger “what might have beens” in automotive history. Imagine if GM had stuck with development and had this ready to go for production by the time of the first OPEC oil embargo, then stuck with it during the run-up of the highest oil prices during the early eighties (instead of wasting billions on the Wankel). Just simply…wow.
Of course, fast-forward to today with historically ‘low’ fuel prices at the pump, and GM is stuck with expensive, 2nd generation Volts. More than ever, the old industry saying “Timing is everything” really applies to alternative-powered vehicles.
Practical affordable hybrids wouldn’t have been possible any sooner than the late 1990s. It took that long for electronics to get powerful and cheap enough. When Prius came out they asked the chief engineer what was the hardest part to develop, and he said “software”. The hybrid system computer chip in 2000 was more powerful than the biggest mainframe of 1969.
If GM had stayed with this technology they could have beaten or at least matched Toyota when hybrids finally did make it to market. Too bad they didn’t.
I love that the ad copy capitalized Engineers.
For perspective, the CDC 6600 was the hot mainframe of the late ’60s, rated at 3 MegaFLOPS (Floating-Point Operations per Second). I don’t know what the Prius uses, but modern PowerPCs, popular in embedded applications, have been in GigaFLOP territory.
I wouldn’t read any more into this advertisement than what meets the eye. Why can’t you find anything on this? ‘Cause there wasn’t anything produced. Just a wire-frame drawing on an artists’ drafting board.
Corporate ‘research’ projects go nowhere all the time. Advertisements in 1969 showing what advanced research an automobile (or an appliance or a telecommunications) company is doing have almost no credibility with respect to any actual plans for production. It’s mostly just fodder to keep lines like ‘…Progress is our most important product’ (fron G.E.) going…
Umm…that image of the red Kadett in the post is the actual Stir-Lec being driven on the GM proving grounds. It really was built, along with some other hybrids I’ll get to another time.
About the same time a guy in Arkansas was electrifying an Opel GT with pretty good results. Name was Dave Arthur IIRC. Have mentioned him more than once and he was the genesis of the classroom EV that I wrote about on this site.
Arthur used his as a daily driver to the tune of about 75 mpg and a bunch of miles.
I know of no Stirling engine in use on non nuclear submarines. What Navy. Would like to hear about it.
Lee – Here’s an article for you
https://en.m.wikipedia.org/wiki/Gotland-class_submarine
That’s pretty interesting stuff. I always thought a stirling put out way too little power to be useful for propulsion. Well, I guess it’s just about right for a slow moving but quiet non-nuc submarine.
Btw: I ran a small model stirling engine for almost 45 minutes setting on top of a hot coffee cup. It amazed me then and when I think about it I suppose it still does.
Thanks for the link.
Around WW2, Germany was working on a large Stirling engine to power a submarine. I saw part of the engine on display at the museum of technology in Munich. I don’t recall if they actually got a prototype sub working or not.
The Germans still specialize in Diesel subs, which are more affordable to many nations than nukes. Germany is wise to produce exportable weapons with fewer strings attached.
I see the Stir-Lec diagram shows a helium bottle. I wonder what that’s for? If I had to guess, I’s say cooling one side of the Stirling engine to increase the temperature difference for higher output.
Yes, I noticed that as well. Talk about a non-renewable resource! “Honey, I’ll be home late tonight. I’ve got to stop by the party store after work and pick up some helium for the car.”
Fascinating to see things like this–GM was still at the top of their game at the time. How differently things had gone if they had kept innovative ideas like this under development?
Aside from the power train, what caught my eye was the statement that “if you saw it … you’d think it was an ordinary Kadett”. A good indicator of how common Opels once were in the US; I’m pretty sure they were frequently the #2 import behind VW.
So many advanced projects from GM back in those days… Wonder if they ever made any return on them. Maybe for military applications?