Ian Drysdale thought we might want to know a little more about the Honda XR600 based 9 cylinder radial engine Russell Sutton is building that we mentioned last year, so he sent some more up to date photos. Ian’s working on the crankshaft and rods for the engine while Russell keeps himself busy with the rest of it.
Russell really likes radials, he says his personal favorite is the Bristol Centaurus 18 cylinder sleeve valve by Roy Fedden, fitted to the Sea Fury. If you’ve ever watched a big radial come to life, you can understand the attraction, it’s motorhead heaven.
Well, Russell is a “doer,” he thought he might like to build one and started thinking about what he would need and after going through some options, decided the top ends from the Honda XR600 would work and he began buying up enough for the project. It’s quite a collection of pieces from a lot of different sources.
The 7893cc engine uses V6 Holden Commodore dished pistons running through a bore and stroke of 96.5 X 120mm. A Nissan gear driven oil pump supplies the crank and rods, a high volume electric pump oils the cams. The throttle body is from a 5.7 liter Chevy. Cam drive consist of 12 gears in three planes in the front section of crank case.
There’s a Nissan electric starter turning a 370 mm diameter ring gear. The crankcase is fabricated and machined from 5083 aluminum. Crankshaft is 2 piece, single throw with 60 mm mains and 55 mm crank pin.
The engine, provided everything works as planned, is headed for airboat duty. Heck, I just want to see this thing fire up.
Ian is still working on the crank and rods, I’m looking forward to seeing some photos of all of the rods bolted in place, that should be a bit of mechanical artwork. Doers, gotta love ’em.
More photos below:
Spartandude says
Very cool. I wonder how he is going to keep the oil out of the bottom cylinders when the engine is off.
Peace.
ADEggman says
Oil just collects in the bottom cylinders. It’s part of owning a radial. Watch when one of those WWII bombers light off the engines. Massive amounts of smoke!!
Spartandude says
ADEggman,
Thanks. That makes sense. So does the oil have to get change/replaced more?
DONH says
Many years ago I was a mechanic in the U.S. Air Force. I worked, and went on flights in many aircraft with radial engines. The engines all had dry sump oil systems, but a bit of oil would collect in the bottom cylinders when parked. We would, at specified times, remove and clean the filters (strainers) but never changed the oil. However, oil control rings were not as good then as now, and they all consumed oil. So in effect the oil kind of changed it’s self. It was not unusual after a 4 or 5 hour flight to add several gallons of oil.
todd says
Nice. This must be the world’s only 4 valve per cylinder HEMI-head radial engine.
-todd
JC says
Sigh, I really need to start thinking big. My latest work in progress is a design for an air cooled XR650 cruiser, seems so boring in comparison.
I can’t wait for the video of this thing firing up!
tallsteve says
You have to say that the camchain’s going to be thing of wonder!
GN says
” … Nice. This must be the world’s only 4 valve per cylinder HEMI-head radial engine. …”
Maybe, but I doubt it. Every radial aircraft engine I know of is a Hemi; Harley-Davidson copied a Radial when they built the original OHV (ie not flathead) engines (Knucklehead 1936 to Shovelhead 1984 are all true hemi’s). I would not be surprised to learn of 4-valve aircraft engines from 1930~1950; everything else we do today (supercharging, turbocharging, fuel injection) comes from aircraft of the era.
todd says
Hemi? No big deal. Four valve? No big deal. Hemi AND four valves? Big deal. Never done before on a Radial engine, certainly never on any Harley motors. Outside of maybe some pre-war racing bikes Honda has the only Hemi head, four valve motorcycle engines.
-todd
rafe03 says
1930 Rudge Ulster – Single cylinder 500cc, 4 valves arranged radially just like shown on the Honda XR600 that has copied them Rudges were pushrod engines & had 6 rocker-arms! The 1939 models were used for Speedway in Europe where they were competitive until the 50’s or 60’s
rafe03
steve says
Both Harley and Indian had 4 overhead valve per head designs in the teens on thier boartrack racers and later in the twenties on thier hillclimbers which also ran on alcohol. Very fast for the time.
Steve
DONH says
I don’t recall ever seeing, or even reading about, a four valve per cylinder radial aircraft engine, or for that matter one with an overhead cam. They all had pushrods. But they were not high RPM engines. As I recall, for example, the Wright 2800s on a B-26 had a max RPM around 3000. However the V-12 liquid cooled engine on the British Spitfire, and later on the P-51, and P-38, and others, all had four valves, and overhead cams. They also used a form of fuel injection, and had superchargers, but the supercharger was more for high altitude flight. Even the radials had superchargers, and injection carbs.
jp says
I’d be curious to see the mechanism driving the cam chains. Can’t quite get my head around how it’d work. Very cool project, I’m a sucker for round motors.
todd says
The Harley and Indian (and others) 4-valve heads are “pent-roof” heads (wedge), not Hemispherical (ball shape). We’ve covered this before. Apparently there is no real advantage to overcome the complexity – the Honda XR head has 8 rocker arms – for the small increase in torque.
-todd
DONH says
The old radials had ring cams in the nose of the engine, with several lobes, (and roller followers) and the ring cams were geared to the crank, to turn the correct RPM. I suspect a simular ring with gear teeth is used to drive a sprocket for each cylinder, and a cam chain little, if any, longer than on the motorcycle is then used for each cylinder.
Mike Holgate says
For answers to most of the above questions about how old-fashioned pushrod radial engines worked, try this website: http://www.agelessengines.com
tri hakni putra says
very cool i like that engine
Tin Man 2 says
Todd, There are quite a few 4 valve Hemi heads in use on HiPo Harley racing engines, However on the street 4 valves tend to make good power in the higher RPM ranges at the expence of low end Torque, Not many want a Harley that has the high RPM power band of a Honda. Witness the slow U.S. sales of the V-Rod.
todd says
I’ve never seen or heard of any. Just because they are called “HEMI” does not mean the combustion chamber is in the shape of a hemi. Besides, the whole point of using four valves per cylinder is to get more torque. Smaller valves flow better at low velocities than larger valves do allowing a more consistent fuel charge. The small intake runners associated with multiple small valves have more than their share of surface area and restriction to high flow rates. Let’s not get on this subject again. There is plenty of engineering journals available if you want to research it some more.
-todd
larry poch says
it is so simple how the cam chains are run off a set of gears that circle the motor and each gear has one or two sprockets welded to them and then go to the cam and then it makes setting timing so easy . but to make a crank is no problem but to make a rod set up for this motor will be a work of art i build motors at home in my garage when frends said it could not be do and twenty years ago i built a belt drive for a 650 triumph on the primary side and all said it looked great but it would not last i still ride the bike today a 1958 pre unit it also has a joe hunt mag and a generator that dose not run off the gearing on the pointside but off the primary and i did it in my garage with no really special tools and no parts made out of house larry
PAT says
THIS IS A COOL DESIGN HOW DID YOU COME UP WITH IT. HEY DO YOU HAVE ANY CYLINDER HEADS YOU DONT NEED
jorge gallizzi says
Felicitaciones: que buen proyecto, yo soy de argentina, estoy trancitando tus mismo pasos, estoy juntando informacion hace algun tiempo,y espero comensar en este 2010, pero mi proyecto es de 7 cilindros ,espero seguir en contacto, y poder escuchar ese gran motor
John says
rafe03 , is the only one so far that I think picked up on the fact that the valves are radially arrainged in the heads on this radial motor.
todd says
Correct John. Those radially arranged 4 valves are what makes this most possibly the only 4-valve hemi radial engine ever to see the light of day.
-todd
Harold says
The main reason for a 4-valve setup is to maximize gas flow at ALL rpms, as the velocity is higher through a smaller passage, adding to turbulence and cylinder filling. Also, smaller valves are lighter, so they don’t float as easily, nor do they need to be lifted as high by the cams to get the same volume of airflow. So, lighter valves, less radical cams, and softer springs make for reliability, as well as rpm’s. Also, the burn is more complete, as there are no “blind spots” in the chamber, since a pop-up piston which blocks part of the chamber, like in many true hemis, (like an iron head Sportster) isn’t needed for higher compression ratios. So, the piston can be lighter, too. With the same lift and spring pressure as a 2-valve head, there would be much more RPM potential, as well as more torque and HP at all RPMs. Low RPM torque is better on F.I. engines than on carbureted ones because the fuel is atomized better at low speeds; the same is true for 4-valves, for the same reasons.
And no, I’m not an engineer, I just read Kevin Cameron…
John says
I am wondering about those radially arrainged valves. since the cam shafts and the valves are not perpendiculare, in other words it seems the rocker would slide sideways on top of the valve stem when pushing down, how does it work?
Russell Sutton says
John. The radial four valve arrangement uses intermediate rockers arms between straight rockers operating off the cams, and the valves. The intermediate rockers are hinged into the valve cover in four positions. Their tips have an angle cut on them . This together with there geometry makes the angle change possible with a vertical push from the straight cam rocker. There is still some sliding action on the top side of the intermediate rocker. On the valve side, the stem is pushed with precise geometry. It’s a clever design and very reliable.
Russell Sutton
steven says
NEEDSSSS a BIG ASS TURBO to go with it 🙂
glittleman says
I hope he puts a gear on the fan….
Airplanes have 3000 RPM redlines for a reason; its so the propeller tips don’t break the sound barrier.