Revs, how high do they go?

[alangla]

eldar said:

52,000 rpm.

http://www.bikez.com/bike/index.php?bike=20204

Rover's gas turbine efforts in the 1960s ran at similar speeds from what I can tell.
The idle speed on the Rover was apparently 35,000rpm... http://www.rover.org.nz/pages/jet/jet5.htm

[shoehorn]

Not a car as such but my nephew has a nitro-methane powered r/c car that revs to 39,000 rpm.
4.5cc/3 bhp at 35,000 rpm.
Which by my reckoning,forgiving the implications of sizing up etc. is around 667 bhp/litre!

[Otispunkmeyer]

JonnyVTEC said:

Check the Integra type R DC2 piston speed

Indeed! 87.2mm stroke and 8600 rpm red line. Nigh on 25 m/s piston speed. Same as an 18000 rpm f1 car.

25 m/s must be some where very close to a physical limit before things begin to come apart or cost significant amounts of money.

[shoehorn]

alangla said:

Rover's gas turbine efforts in the 1960s ran at similar speeds from what I can tell.
The idle speed on the Rover was apparently 35,000rpm... http://www.rover.org.nz/pages/jet/jet5.htm

http://www.theengineer.co.uk/Journals/2013/04/24/c/w/w/rover-gas-turbine-car.pdf

[Otispunkmeyer]

shoehorn said:

Not a car as such but my nephew has a nitro-methane powered r/c car that revs to 39,000 rpm.
4.5cc/3 bhp at 35,000 rpm.
Which by my reckoning,forgiving the implications of sizing up etc. is around 667 bhp/litre!

Those have a nice advantage with that calc as they are 2 stroke. And then what 15 mm stroke? 17.5m/s piston speed. Not as impressive as the Honda !

Nitro is nasty stuff isn't it? I remember at Santa pod the top fuel crews having to wear gas masks because the exhaust gases are pretty horrible to breathe.

[Chiswickboy]

Layacable said:

I'm sure I remember a 250cc 2 stroke bike a friend of mine had a few years ago hit the rev limiter at 22500 rpm!!!

In the sixties Honda produced a 50cc racing engine which, if the old grey matter is working properly, revved at 22500 rpm. I think it was also a six cylinder arranged as two banks of three. (What do you mean,"you had just taken the pistons out when you sneezed and now you cant find one"?).

Tried googling but cannot find any info on it. Anyone?

[matchmaker]

Tango13 said:

Layacable said:

I'm sure I remember a 250cc 2 stroke bike a friend of mine had a few years ago hit the rev limiter at 22500 rpm!!!

That would almost certainly been something like the four cylinder 16 valve fourstroke CBR250RR that was posted earlier, two strokes don't rev that high.

Small 2-stroke glow motors in model aircraft or cars can rev up to 30,000rpm.

[mozza42]

Kawasaki zxr250 was over 20k rpm IIRC

[fourwheelsteer]

Chiswickboy said:

In the sixties Honda produced a 50cc racing engine which, if the old grey matter is working properly, revved at 22500 rpm. I think it was also a six cylinder arranged as two banks of three. (What do you mean,"you had just taken the pistons out when you sneezed and now you cant find one"?).

Tried googling but cannot find any info on it. Anyone?

You're close but not quite there. IIRC Honda built a 50cc twin and a 125cc five-cylinder racer (same piston dimensions for both). The 125 revved to 24,000rpm, sounded amazing and developed something like 33hp. It was codenamed RC149 and won a World Championship.

[JoeMk1]

Mastodon2 said:

That would be a much better video if it wasn't only available in 240p.

Your wish is my command

http://www.youtube.com/watch?v=nsa6kq-qqIE

And have the valves as a bonus

http://www.youtube.com/watch?v=vcyT18qk8ls

[Rouleur]

Chiswickboy said:

In the sixties Honda produced a 50cc racing engine which, if the old grey matter is working properly, revved at 22500 rpm. I think it was also a six cylinder arranged as two banks of three. (What do you mean,"you had just taken the pistons out when you sneezed and now you cant find one"?).

Tried googling but cannot find any info on it. Anyone?

There's the 50cc RC115 which revved to 21,500 and had a 9-speed gearbox!. You were thinking of the RC164 and RC166 which were 6-cylinder 250cc bikes which revved lower. Sound amazing though https://www.youtube.com/watch?v=eaRop_ZMwo0

[eldar]

Chiswickboy said:

In the sixties Honda produced a 50cc racing engine which, if the old grey matter is working properly, revved at 22500 rpm. I think it was also a six cylinder arranged as two banks of three. (What do you mean,"you had just taken the pistons out when you sneezed and now you cant find one"?).

Tried googling but cannot find any info on it. Anyone?

I remember reading about that 50cc 6, years ago. The engine was never raced, as the rules changed. I think it was 2 stroke, but I'm not certain. Honda did race a 125cc 5 cyl.

http://www.youtube.com/watch?v=Xuvx15DLDmc

[Ki3r]

R1gtr said:

I reckon the highest rpm may be on a 600cc bike, possibly a R6, prob around 14000rpm.

My XJ6 redlines at 13,000, so would think an R6 would be higher.

[xRIEx]

eldar said:

I remember reading about that 50cc 6, years ago. The engine was never raced, as the rules changed. I think it was 2 stroke, but I'm not certain. Honda did race a 125cc 5 cyl.

http://www.youtube.com/watch?v=Xuvx15DLDmc

Probably a four stroke, Honda have a deep dislike of 2-smokes, which is why they came up with all the fantastic multi-cylinder four strokes, the ones already mentioned and things like the NR500 and NR750.

[Spoof]

S14 on Alpha n will rev to 8k no problem. That's 22 m/s + from a 25+ year old road car.

[tercelgold]

Ki3r said:

My XJ6 redlines at 13,000, so would think an R6 would be higher.

2006 R6 will do a real 16,000rpm, I think that's the highest rpm motor people run on the road.

[shoehorn]

xRIEx said:

NR750.

I saw one about 8 years ago for sale and thought that because of it`s mechanical complexity and potential cost of ownership that all bar the most foolish would be scared off and hence be cheap(ish),I genuinely fancied a punt,Holy Moly!!!

[5lab]

Tango13 said:

The NSR500 ran about a 54mm stroke so at 13,000rpm it has a piston speed of about 23m/s. It's also a factory built race bike so doesn't count.

A Ducati 1198 has a stroke of 67.9mm and will rev to 9750rpm which is around 22m/s.

Actually, the speeds are way higher. you guys have the average speed right, but within each stroke the piston accelerates from 0 m/s, up to the maximum speed at mid-stroke, then back to stationary at the top. I don't know how to do the maths to figure out what the peak speed actually is, but I suspect it may be double.

[Tango13]

5lab said:

Tango13 said:

The NSR500 ran about a 54mm stroke so at 13,000rpm it has a piston speed of about 23m/s. It's also a factory built race bike so doesn't count.

A Ducati 1198 has a stroke of 67.9mm and will rev to 9750rpm which is around 22m/s.

Actually, the speeds are way higher. you guys have the average speed right, but within each stroke the piston accelerates from 0 m/s, up to the maximum speed at mid-stroke, then back to stationary at the top. I don't know how to do the maths to figure out what the peak speed actually is, but I suspect it may be double.

The online calculator I used was for average speeds, the formula for peak speeds is a lot more complex and needs the con rod length which I didn't have.

[Chiswickboy]

Thanks for the info guys on the 50cc Honda. I could have been confusing the 50cc with the 125 but I'm sure it was a 50 but, as mentioned, it may have been a prototype that was dropped because of a change in regs.