The Engine Technology of the Honda RC174

[Lee]

I originally posted this on the Southern Forum for some friends. I thought it might be of interest on the main forum so I'm posting it here as well.
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This post was derived from an article in the April, 2006 issue of Motorcyclist magazine.

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The Honda RC174 was an otherwise unremarkable race bike that would have been completely forgotten except for its engine. And what an engine it was. The bike was built, and raced by Mike Hailwood in GP racing, in the 1960's. When Honda built it, the Honda Corporation's racing program was only 5 years old.

About the engine: It's like nothing I've ever read about it. Every aspect of the engine was exotic:

> 297cc inline 6 cylinder
> 24 valves driven by 4 overhead cams, each barrel shaped; all cam lobes were of different profiles
> a crankshaft with no flywheel and comprised of 13 press fitted components, each no bigger than a domino; unsupported, it can be deformed by hand; counterweights were pure tungsten; an inadvertent throttle blip would instantly take the rpms to 20,000 and destroy the engine; letting off the throttle would instantly take the rpms to zero; riding and shifting gears was much like keeping a ball in the air, it had to be done perfectly
> the 2 halves of the engine case were made of magnesium
> a redline of 19,000 rpms
> 3 different types of connecting rods, each only as long as a credit card
> some oilways so tiny they can only be seen with xray equipment
> pistons that were machined from solid billets and had no oil ring
> the 6 carburetors, each unique, cost $35,000 to manufacture
> a 7 speed transmission
> exhaust valves were made from PER72 superalloy steel, @ $5,000 per kg
> springs for the engine cost $18,000
> all screws and bolts were drilled for safety wire; cost = $5000

It outran Yamaha's and Suzuki's 2 strokes.

The article is about the modern day reconstruction of an RC174, almost from scratch. The technological difficulties were formidable. After reading the article, I had to marvel, just like the article's author, that an engine encompassing such exotic technology could have been built in the 1960's.

Lee

P.S. Also mentioned in the article was the 50cc RC116. It had a redline of 22,500 rpms and produced 16 bhp at 21,500 rpms. That's 320 bhp per liter, a figure yet to be equaled by a normally aspirated engine.

Additionally, the RC174 was supposedly one of the loudest bikes ever made. People (who didn't appreciate motorcycles) complained about its sound at 3 miles.

This is a link to a website that has audio tracks of many famous motorcycles:
http://www.vintagebike.co.uk/Sounds.htm.

I am pretty sure there are 2, maybe 3 audio tracks for this bike: "1967 Hailwood 6", "1967 MV Hailwood", and maybe "1967 Hailwood", but I'm not completely certain about any of them. The first 2 are different. The bike had an odd sound when it was wound up, almost like a warble or something.

Of all the soundtracks, I liked the "1957 Guzzi V8" the best. Some of the Norton tracks were pretty good if you like big, side by side, twins.

[Buddau]

That is very interesting.
The way that 6 cyl. sounds reminds me of a modern day F-1 car.
I like the pit sound clips also.

[MattTLS]

Back when the MRA still had its street race in Steamboat Springs, one year Team Obselete brought its Honda RC166 (I think that's right) 250cc six cylinder, very similar to the RC174. The original mechanic, Nobby Clark, was there as well. Don Canet of Cycle World took the bike around the course a few laps, and I watched, and listened, to something I'll not forget. The bike had six megaphone exhausts, made power between 18 and 20k rpm, and was the loudest engine I've ever heard. When the bike was bump started, you could tell when each of the cylinders really fired up -- at first quite rough, and then more and more deafening. I've got some pics somewhere or other.

[Lee]

Wow. I wish you had a recording of the sound of that engine. I'd like to hear what you described.

Lee

[Buddau]

Oh, please find those pictures!
I spent a long time looking at those pictures at http://www.vintagebike.co.uk/
A 4 stroke out running a 2 stroke, who would have thought.

[Keyser Soze]

What a sweet piece of ass!

[rybo]

Lee,

If you check the motorcyclist article you referenced I think there is a link in there to a website with a recording of the RC174.

[Lee]

RYBO,

I did and I listened to them (I think there were 3). I simply wanted to hear what MattTLS described.

Lee