Supercharged, Fuel Injected V10 Engine, At 1/3 Scale

Nearly three years in the making, behold the raw power and precision of this 1/3-scale V10 engine.

Coming in at 125 cubic centimeters displacement, [Keith Harlow]’s fuel injected masterpiece isn’t too far from the size of some motor scooter engines. We doubt the local Vespa club would look upon it as legit mod, but we’d love to see it. [Keith]’s build log is a long series of forum posts, but from what we’ve seen it looks like every part was made by hand with the exception of the fuel injection system. Even the caps for the spark plugs were custom injection molded right in [Keith]’s shop. And it appears that no CNC was used – even those intake headers and the rotors for the supercharger were hogged out of aluminum using a manual mill. The exhaust headers alone are straight up works of art. There’s a staggering amount of work here, which begs the question: why? The answer in this case is obviously, “Because he can.”

Few builds compare to the level of craftsmanship on display here. The Clickspring skeleton clock comes to mind, but for model engine builds we’d have to point to [Keith]’s earlier 1/4-scale V8 engine. And we’ll hasten to add that as much time as [Keith] has spent building these works of mechanical art, he’s probably dedicated just as much time to documenting them and giving back to his community. We can all learn a lesson from that.

83 thoughts on “Supercharged, Fuel Injected V10 Engine, At 1/3 Scale

    1. I thought so too, but I looked up low-end bikes and they all clocked in at well above 125cc. Vespas and the like all seemed to be in the 100-150cc range, hence the reference.

      Heck, even a Vespa beats the hell out of the second-hand Honda 50 minibike we had as kids. With a dodgy centrifugal clutch and anemic engine, we spent way more time pushing it than riding it.

      1. A Vespa’s more like a motor scooter grown to the lowest-end motorcycle size, though. Smaller motorcycles certainly used to exist (I’ve got a 125 cc 1972 Honda), and they have a bit of a resurgence now, too. I always think of motor scooters at the 50 cc (OK, ’49 cc’) level, since in certain states that allows them to avoid a motorcycle license/insurance/etc. Then I have to remember that those Vespas and clones are *huge* comparatively.

      2. There’s dirtbikes with 80 cc engines, and that was a common modification for the minibikes as well. 16mm carburettor instead of the 11mm stock, and an 80 cc cylinder with racing ports and carbon fiber intake reeds, then drill out the chokes in the exhaust or put a racing pipe in, and the engine goes from 1-2 HP to 10-20 HP.

        A buddy of mine had a minibike that went 110 kph on the straight, until the chain started glowing red. Mine did just 75… 85 downhill.

      3. A 125cc fuel injected V10 will get as fast as you would want to go on something that doesn’t have wings – probably 80 – 100mph.

        And it would look the perfect piece in a light weight sports bike.

        Modern larger bikes are more about show than speed because they can all go so fast that your probability of surviving becomes very thin.

        1. I have ridden motorbikes of all sizes and am still here, as have plenty of others. I think you mean that if one has an accident there is a high risk of fatal injury. Or did you really mean to say that if one rides a high-speed bike one will, by default, have a high mortality? I’d like to see the data on that.

          1. Reasons to own a high powered bike….

            1: Hitting a semi tractor head on while accelerating, the last thing that goes through your mind is your arse, but at least you scratched the bastards bumper.

            2: It’s a purging experience to spend huge wads of disposable income on back tires monthly.

            3: Hunter S Thompson made the Vincent Black Shadow sound cool.

            4: Why get minivan mileage with the speed an acceleration of a minivan *cough*harley*cough*

    1. From one of the builder’s YouTube comments:

      “I have made a supercharger for this but not fitted it. Haven’t decided whether to continue with this project or sell it and do a W16 Veyron type engine.”


          1. Yeah, he really knew how to build engines. He was doing a really interesting project for saab in the 90’s. He had designed a variable compression engine of HCCI-type (homogenous charge compression ingnition). This type of engine may run on any combustible fuel, diesel, gasoline, ethanol, hydrogen etc. This would have been a true flexifuel engine and would also have been very efficient on all types of fuel. GM killed that project before it ended up in a saab. Guess oil companies don’t like the idea of an independent fuel source engine…
            They actually had a working prototype. As I recall it had a displacent of 1.6litres and produced around 300hp with a impressive torque. I wonder what happened to the prototype…

            Vila i frid Per!

          2. The prototype(s) of the variable displacement SAAB motors are at the Valmet Automotive museum in Uusikaupunki, Finland.

            Couple other interesting SAAB prototypes on display there, too, like a SAAB V8 made out of two B202 four cylinders stuck together at a 65 degree angle.

            GM killed a lot of interesting things slated to come out of Trollhattan. :/

      1. W engine, sounds fun. For a real challenge? Try for a W6, around the 60cc size.
        The Anzani W3 powered Louis Blériot across the English Channel in 1906. W6 motors are rare, bordering on non-existent.

        The idea of a W6 variant of the Anzani motorbike engine, powering a modern Vespa or similar is appealing.

        1. They are rare because they are needlessly complicated… a good old “V” configuration can get you all the power you dare to put into a vehicle (and more), so the only “W” in production is mostly “because we can” showing off…

    2. A couple of the pictures in the thread show beautiful rotors for a Roots-type blower being milled. One shot even shows the blower fitted and powered by a timing belt off the back of the engine. I was confused because normally you see the blower pulley up front, but there it was.

  1. There was a time when this sort of modeling was a necessary proof of concept step in the design of complex machines. The British Museum of Science has several of these on display from the Age of Steam. They are of particular value in my opinion, as the full-sized machines have often been broken up and these models stand as witnesses to this technology. It may be that these miniature ICE models may serve the same end one day.

    1. This is how engineering was done once upon a time – a miniature was made and scaling factors applied.If you read through an engineering manual from the 19th century, there are all kinds of variations on this. Imagine committing a rail line to a thousand foot long bridge based on a small model!

      The analytical tools of the day would only take you so far so if you were doing something substantial you’d have to start building prototypes a lot earlier in the process than we do now (one of the reasons for the continuing development of modeling (FEM/CFD etc.) software. Easier to make mistakes in silico than in steel.

      Also cf. Patent Models (which usually didn’t have to work completely as much as demonstrate the innovation):

      1. I think you mean: “Easier to CORRECT mistakes in silico than in steel.” You have to wonder how many “Oh shit” moments those old model makers had and were forced to start over.

      2. Small scale models are fine for construction details, but they don’t give you much about the material properties or fluid flows because these things behave differently at different scales. Hence it’s not a substitute for FEM – you still got to do the calculations so your bridge won’t sag – or find an analog material that behaves proportionally at scale.

  2. Back in the day… there was a hobby shop closing up ( :-( ) and they reduced their on hand Cox 0.020 glow motors to under $10 … so was coming up with wild schemes like making a V12 out of them for a Spit or ‘stang… nothing much backing that but wild youthful enthusiasm, so only result was the initial purchase of one, which I still have.

  3. Wow, this is amazing. Not only is it functional but if it has a cooling system (I cant tell if it does or not) it would have everything needed to actually be built into a vehicle of some kind.

    Imaging building THIS into one of those Power Wheels kiddie cars… :)

    1. Yes and no. As shown in the video, the supercharger looks like it has been removed. But back in November of 2015 it was clearly in progress and mounted:
      This picture confused me. I think you can understand why:

      Just before Christmas [Keith] decided to shelve blower development in favor of just getting the engine started. Can’t blame him, what with it being on the bench for three years. I have no doubt he’ll finish the blower and mount it, so I’m going to stick with the claim that the engine is supercharged.

  4. If you are in the Eastern US you can see a lot of engines like this up close and personal. The biggest US show is next weekend, Jan 14 and 15 at Lebanon PA. Its called there will be a few hundred exhibitors and many gas, steam, stirling engines, all running and with the maker sitting there to talk to.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.