Talking Technical ?

After seeing Peters message ref:- primary chains a couple of things passed through my mind:-

Peter what type of rear chain do you use ? is it Renolds ? and if it is whats the (part) number is it 415 or 420 ?

Nearly 24BHP is mentioned from your cast iron cylindered machine have you had more from it in the past? My bike had 24.5 in 1999 and I made (guessed tested changed) improvements bike felt better and lap times improved. Thinking I must have 27 at least I put it on a mobile rolling road at Cadwell in 2002 (you might of heard/seen it) and the amazing result a not so whopping and dissapointing 22.2 BHP but whats in a number ?

Also I know Peters barrell and Mick Potters (was mine once) are very simular (and when Keith Woods was riding it I borrowed it back to race in Belguim, I had it tested along with mine) yet that water cooled version only knocked out 20BHP

All very interesting ...........

Hi Mike!
What's in a number indeed? If you've got one in your nut when you are racing than pack it in and go home 'cos you are not concentrating enough!
Now:
I hope I don't upset you by asking something very obvious about those power output numbers you quoted...
Were they corrected for ambient temperature and pressure?
If so, was the same Correction Factor Standard used each time?

There are 5 Standards in use at the moment -- the three most popular being ISO 1585, SAE J 1349 and DIN 70 020...
ISO is an International Std., SAE American and DIN Deutsch...
Slick gives his clients/customers the SAE because it is about 1.5 to 2%
better than the other two Stds... See? That is what is meant by 'What's in a number' -- Star rider Bill Bloggs goes slower when he thinks his power is lacking -- is actually a load of goolies. Nutters go quick on any number -- even with 13 (on his fairing), like Ned!
When I used to daily attend that Rest Institution, in which Peter Tibbitts now sleeps from Mon... to Fr... we only went to 4 percent either way in correcting actaul dyno reading. Conditions are either tropical or arctic above 4%.
OK! So take a 22hp reading on the dyno. It has to be corrected UP by a CR of 3% because of advantageous ambients...'t' & 'P' are cold and damp. This is then 22x1.03 = 22.66hp. Rounded off to 23...Now(a fortnight later) because the conditions have changed we have to correct DOWN by 3% (0.97x22 = 21.34) and the number becomes 21.34. Round it up and you have 21... All of 2 horsepower difference from excatly the same motor!
Un-rounded it is only 1.34hp difference yet might stop someone's heart...
-- When the engine is of 1000cc capacity the actual corrected amount is substantial.
Like I said, one time before, the dyno operator might be a little bent and feed in the wrong size of dyno-brake-drum -- which is criminal.

Many apologies -- I came to monitor my e-Mails and nipped across here --
should mind my own business, perhaps!?
Taake care and keep well,
Aye! JayBee.

Talking of BHP the Ted Smith Bantam which Ted (Occasionally) rides was put on a Dyno and was found to produce a whopping 12.5 BHP!!

It went round corners OK

Mike applied the throttle a little early here and unleashed a rush of power to create this massive High Side at Three Sisters

Or do we know better?




Rusty

Mike,

Without referring to my records, I can definitely state that on Pete Gibson's dyno my bike had 17 bhp when I restarted in 1996. My attending to the pipe, and a little port optimisation, over several pipe incarnations, peak power rose to 23.5 bhp in 1998. further improvements to pipe in 1999, resulted not in any increase in peak power, but lower speed torque,. This may have given the impression of more power.

However, making comparisons with other machines on other dynos seems to be tricky. And on the track - if I put a rider of your weight on my bike it would be very interesting.......


Re rear chain. What I did discover when I had a sprocket made recently is that the Japaned chain of the same pitch and width, has rollers of 0.300" OD, whereas the Renold chain has rollers of 0.330" So you can run a Jap chain on British sprockets and not notice the reduced transmission efficency..... but to run a Renold chain on Japansese "bantam" sprockets, should result in not only reduced efficiency, but you should notice the teeth having unusual marking near their tips.

Hi Peter!
Wow! 35% increase in power - some tuning! i.e.... 23/17 = 1.35...
Er humm! Dare I ask? Were those corrected power results you were comparing?

The difference reads very much like the kW-to-Ps & bhp conversion factors at 1.36 & 1.34 respectively - but forget I said that -- of course it was your superb tuning...!

What was that dyno at Cadwell in 2003? A mobile dyno on a trailer? I designed such a one about 18 years ago and asked Slick to get into making it but he told me it was 'NO-GO' idea. I reckon it would be ideal for setting up carbs and for de-tuning the opposition.

Last question before you drumm me out -- and of this site...
How high is Cadwell above sea level?
All the best at Mallory!

Aye! John-Boy!

Our corporate madness is quite understandable -- to some!

John,

Depends which sector of the track

Spot height at entrance , on main road :136m.

Charlies Bend: 130m

Main start finish straight: 100m

Now I've got you! You are now going to suggest I calculate the power of my machine from it (and it's rider's) rate of climb!

Not sure how reliable these contours are, because they have the same 100m contour running through Main straight and Hall bends! My map is and old one, revised 1979, based on a 1936 projection. So my theory is that Chas Wilkinson, or his dad, wouldnt let the Ordnance in to have a look!


I am scheduled to be in the Maritim next tuesday night - see you then?

Peter

Thanks Peter!
Cadwell's height above sea-level was a red-herring but I never realised it was that low 'cos my head was always spinning up by Charlies going into Park hoping the clutch had not stopped sizzling & was not still slipping......
-- I had a giddy feeling once of being in front and staying there...!

And Mike too -- and any others who were confused by what I said...

--- No! I've been waiting on someone picking up on what I've been saying
just recently about power Correction Factors when dyno testing.
I said that (in Rest Ops at Ford Dunton) we never corrected by more than + or - 4%. Well, on 25 that is only +or-1bhp. So it was a load of pils ... But for good development work you must use correction factors.

What's more important are (1), errors that are more likely with the size of dyno; the computer input data and other factors like dyno calibration with older dynos:-
A dyno capable of measuring 250 horsepower is likely to be 2% in error when measuring 25 bhp. If the dyno operator assumes certain factors --
particularly on a rolling-road dyno the error might much much higher. Rear wheel Rolling-Radius for instance...
---
BUT (2), more important still is the shape of the torque curve as against
maximum power output.
-- It comes down to - 'TE' (Tractive Effort) versus 'TR' (Tractive Resistance): the wider the gap of 'TE > TR' the greater the acceleration... A sharply rising torque curve to max torque with it continuing on to max revs at a shallow slope is the ideal. If you have two engines of the same power at the same rated speed and one has a flat torque curve the other engine with a bumpy torque curve it will be quicker on the road - overall - because its acceleration will be better.
-- So Mike, if you had twenty horsepower and a bumpy torque curve you'd definitely be accelerating quicker and going up hill faster than if you had twenty-three hp and a flat torque curve.
With the bumpy torque curve motor the subjective feel is better because you have that extra bit of shove up the rear... and when going uphill -- as at Cadwell -- as the engine speed decreases the torque (the instantaneous effort) increases. With a flat torque curve it does NOT - the revs drop faster and you then have to drop a gear or slip the clutch. Same happens on a flat circuit like Snetterton with a high wind. Going in one direction the acceleration is phenomonal and in the opposite way dismal...
--- I hope that none of you feel insulted by what is known to you already but the question Mike put, "Of what's in a number..." really got me going.
So, I'd better be off now. I only came on to check my e-Mails ...

In 1960 - or therabouts - M.I.R.A. quoted the power required for comparable vehicles with different streamlining to travel at 100mph, and stated that only 2 horsepower was required to keep a vehicle with 0.3 coefficient of drag at 100mph on the flat. Of course, without 'X' amount more power and an adequate amount of torque the vehicle would need a straight and level autobahn to get to 100mph - .
-- I wonder which Bantam rider-plus-bike has a drag factor of 0.3 -- apparently it was the best then...
Can we hire a wind-tunnel ...?
---
Oh! Peter! Sorry! The Maritim? Next week we have visitors - 'cos I'm off to see my sister -- I hope -- soon. Fingers crossed for that.

Take care,
Aye! JB.