Dyno test

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Dyno test


There was a CLAIM of 12.2 for a Dunstall on 17 T gearing , With the ton plus time the rpm's at the line would be ????
nevertheless - the rider / technique & will to win ( Not worried about it blowing ) have a substantial influence .

Back to TOPIC . The 100 Hp per Litre seems the ceiling , with a long stroke ( 89 mm ) the 80 mm short stroke
I think have been recorded at 84 at the crank , tuned . These might not be good for 100.000 miles .
The pommie 1007 is alledgedly 100 Hp , and a Litre . or one and point o o 7 Litre .

power to the People . Horse Power - of course .

64 Hp on the 750 should make a good reliable fast race engine , if its not used for brakes .
and as its at 6000 and still settling in . :mrgreen:
 
The Combat motor at 7200 rpm, the max rpm shown delivers about 55 hp.
At 6000 rpm about 52 hp.
Hard to guess where 8000 would take it with curve still climbing fast at 7200 rpm.

Into scrapmetal in fairly short order , usually . Problem was 18 yr old turkeys thought Tachos were for seeing what the engine would do , if they ever looked at them .
And a well assembled Combat may well have hit 8000 .

7500 seems to be the max safe rpms for racing , with subsequent overhaul life , around 1970 . The 80 mm stroke gave a safe 8000 ( perhaps / depend on build - run in )
for a RACE motor . for a COMPEDITOR . if he could find one or was interested - at the time . perhaps not , then . With suitable maintance and serviceing .

The supplied motor usually ? saw the services of a TUNER , who saw that all was as it should be , as well as improvements , detailing , polishing etc .
They don't sit the motor on the bench and watch television for a week and send you the bill . Virtually all facets of each component are considered .
 
Maxed out clutch drop drag launches are almost as scarey to me as panic braking for same reasons - putting all your eggs on one tire patch that may not take it. TC ran his stock 850's to 8000 shift but some times missed till 8500 he told me and desert racers told me they'd hang on into 8000's to get ahead of new fangled inline 4's. Those were all standard 89 mm stroke w/o special flywheels.

Plugged Dunstall article 7.2 sec 1/8 mile with guessimate 600 lb total mass into Wallace calculator. Was the air and gasoline that much better then?
Your HP computed from your vehicle ET is 88.53 flywheel HP and 79.68 rear wheel HP.
 
Be intresting to interogate the Baja Winning NORTON P11 Pilots , not generally noted it won
the long distance Desert Race , how many times .
 
JimC said:
. The best numbers for a Commando engine at Axtell's was either 76 or 77 hp from a standard stroke 750, and a bit over 80 (memory says 83 or 84, but I can't be positive) from a short stroke 750, both from Ron Wood's flat track bikes.
Click to expand...

Those were some pretty heady numbers in the day. Even though that was in the seventies, I would be surprised if any 750 Norton race bike has exceeded those numbers.

BTW, Ken,did you know Nick Deligianis?
Click to expand...

No, I never met Nick, although I heard about him a lot back in the day.

Ken
 
' Problem was 18 yr old turkeys thought Tachos were for seeing what the engine would do , if they ever looked at them .
And a well assembled Combat may well have hit 8000 .'

I have a set of cases with a crack right through the drive side main bearing housing. The kid who gave them to me used to rev his 850 to 8,000 RPM around our Great Ocean Road on Sundays with his mates. Personally I always use the tacho on a race circuit, however it sometimes gets a bit difficult to force myself to keep an eye on it while watching where I am going. It all happens a bit quickly on the shorter fast straights, if you get into them quicker around the previous corner. With the close box and methanol fuel, it is difficult not to over-rev.
 
acotrel said:
' Personally I always use the tacho on a race circuit, however it sometimes gets a bit difficult to force myself to keep an eye on it while watching where I am going. It all happens a bit quickly on the shorter fast straights, if you get into them quicker around the previous corner. With the close box and methanol fuel, it is difficult not to over-rev.
Click to expand...

http://www.pazon.com/ignition-system/sm ... -unit-twin

The SMART-FIRE has a built-in rev-limiter.
At the push of a button you can set the rev-limit to anything above 3000 rpm.
Can be reset just as easily at any time.
Click to expand...
 
One arranges the device ( Tacho ) so NEEDLE at RELINE is dead vertical , or dead horizontal .
So in fact you dont ' read it ' on occasions . But monitoring it from the corner of your eye ,
its evident if its ' about there ' . Generally the Note ( engine accoustics ) lets you know if your at the last 1000 revs
where its time to keep a eye out . a b great red mark or dot for a intersect is usual . a red line even . :o

a B great red light in line of sight from Oil Pressure switch ( yes Rohan , they dont have them ) would match
automotive practice and is cheaper than new engines or bearings and cranks .
 
IMHO on the racetrack you shift by feel. You tend to shift at the same point every lap and you should be able to tell when the power is running out and that's the time to shift.
If you have to watch the tacho to tell you when to shift, you need to get to know your bike better. If the power keeps coming well past the red line you need to work on your engine to make it work within the rev range by changing the exhaust/cam/inlet length and so on.

I glance at it occasionally and use it for the start, and at the fastest part of the track to check overall gearing.
 
Matt Spencer said:
One arranges the device ( Tacho ) so NEEDLE at RELINE is dead vertical , or dead horizontal .
So in fact you dont ' read it ' on occasions . But monitoring it from the corner of your eye ,
its evident if its ' about there ' . Generally the Note ( engine accoustics ) lets you know if your at the last 1000 revs
where its time to keep a eye out . a b great red mark or dot for a intersect is usual . a red line even . :o

a B great red light in line of sight from Oil Pressure switch ( yes Rohan , they dont have them ) would match
automotive practice and is cheaper than new engines or bearings and cranks .
Click to expand...

You still have to look down while everything is happening very quickly. There is such a thing as cognitive dissonance. If you concentrate on the wrong thing, you become blind to other things.
 
WZ507 said:
To start the conversation off, Jim just posted 65 hp @ 6000 rpm for a 750 racing engine (in this case it's neither crankshaft or rwhp, but something in between - countershaft HP?, and since the engine can rev another 1000-1500 rpm more, we don't know what its max output would be. Also on this forum Mike Hamilton in NZ shared his results from a well prepared 850 engine that developed 65 rwhp at ~ 6500 rpm. Confronted with these 2 examples, I can't for the life of me imagine how one would increase the HP of a well prepared engine an additional 23% to achieve 80 HP. I know more HP can be had from this engine but suspect the gains will be more incremental (5-10%) rather than monumental.
Click to expand...

I used to be nuts about commando performance, back when I had one in the 1980's. Methanol fuel can give a huge boost to power, don't know if these high numbers (80 HP) were using methanol. Not hard to believe if they were burning methanol. Much harder to achieve with gasoline. An engine capable of relatively efficient high-rpm breathing makes horsepower by revving. 80 HP requires 52 ft-lbs of torque at 8000 rpm. A stock 850 could make that torque, but not at 8000 rpm. A stock 750 doesn't make that much torque (except on methanol?), and can't breathe at 8000 rpm. A short stroke motor develops less torque, but can live at higher rpm. Commando valve train needs serious attention to function at 8000 rpm.

Given all that, 80 crank HP with gasoline would require a narrow focus on a short powerband with a radical camshaft, shortened stroke, tuned intake and exhaust, and as much displacement as could be accommodated. It would be very difficult to achieve with a commando 750 engine and stock valve sizes without using methanol. But fun to try!
 
Paul2Earth said:
WZ507 said:
To start the conversation off, Jim just posted 65 hp @ 6000 rpm for a 750 racing engine (in this case it's neither crankshaft or rwhp, but something in between - countershaft HP?, and since the engine can rev another 1000-1500 rpm more, we don't know what its max output would be. Also on this forum Mike Hamilton in NZ shared his results from a well prepared 850 engine that developed 65 rwhp at ~ 6500 rpm. Confronted with these 2 examples, I can't for the life of me imagine how one would increase the HP of a well prepared engine an additional 23% to achieve 80 HP. I know more HP can be had from this engine but suspect the gains will be more incremental (5-10%) rather than monumental.
Click to expand...

I used to be nuts about commando performance, back when I had one in the 1980's. Methanol fuel can give a huge boost to power, don't know if these high numbers (80 HP) were using methanol. Not hard to believe if they were burning methanol. Much harder to achieve with gasoline. An engine capable of relatively efficient high-rpm breathing makes horsepower by revving. 80 HP requires 52 ft-lbs of torque at 8000 rpm. A stock 850 could make that torque, but not at 8000 rpm. A stock 750 doesn't make that much torque (except on methanol?), and can't breathe at 8000 rpm. A short stroke motor develops less torque, but can live at higher rpm. Commando valve train needs serious attention to function at 8000 rpm.

Given all that, 80 crank HP with gasoline would require a narrow focus on a short powerband with a radical camshaft, shortened stroke, tuned intake and exhaust, and as much displacement as could be accommodated. It would be very difficult to achieve with a commando 750 engine and stock valve sizes without using methanol. But fun to try!
Click to expand...

You know, riding my short stroke it does'nt seem short of torque! It has standard valves, but it has long inlets and a well designed exhaust.

Dyno runs were done before it was fully run in so it was not taken to its full potential, but its rwhp is promising.
 
SteveA said:
You know, riding my short stroke it does'nt seem short of torque!
Click to expand...

+1

Most often misquoted is that the short stroke Norton gives up torque, typically by those who have never touched a short stroke Norton let alone seen one in real life.
 
I have the Book ----- Norton, The Racing Story, which is fascinating reading tracing the glory years of Norton's illustrious racing history

in the book's section that talks about Peter William's great 1973 Isle of Man F750 lap record and race victory it is mentioned that some 78 hp was attained but that by the very next year of 1974 the Commando was obsolete and uncompetitive given the Yamaha works racer two stroke power output was some 30hp more.
 
SteveA said:
You know, riding my short stroke it does'nt seem short of torque!
Click to expand...

Dances with Shrapnel said:
Most often misquoted is that the short stroke Norton gives torque,.
Click to expand...

On the face of it, those statements appear complete opposites !
But Dances is agreeing ??
Or am I misreading it somehow ?

While we are here, a 'short stroke' Norton is still (seriously) long stroke,
so you'd bloomin hope the torque wouldn't go away.....
 
Yes Rohan, thanks for catching that typo.

I do agree and I have edited my post accordingly. What most people overlook is what you may lose on the mechanical advantage from a longer stroke you gain on the increased cross sectional area of the piston. One may argue that you may lose torque due to the typical longer duration cams that allow the Commando to breath at higher rpm yet you gain torque back with the increased compression usually associated with the "bigger" cams.
 
SteveA said:
Paul2Earth said:
WZ507 said:
To start the conversation off, Jim just posted 65 hp @ 6000 rpm for a 750 racing engine (in this case it's neither crankshaft or rwhp, but something in between - countershaft HP?, and since the engine can rev another 1000-1500 rpm more, we don't know what its max output would be. Also on this forum Mike Hamilton in NZ shared his results from a well prepared 850 engine that developed 65 rwhp at ~ 6500 rpm. Confronted with these 2 examples, I can't for the life of me imagine how one would increase the HP of a well prepared engine an additional 23% to achieve 80 HP. I know more HP can be had from this engine but suspect the gains will be more incremental (5-10%) rather than monumental.
Click to expand...

I used to be nuts about commando performance, back when I had one in the 1980's. Methanol fuel can give a huge boost to power, don't know if these high numbers (80 HP) were using methanol. Not hard to believe if they were burning methanol. Much harder to achieve with gasoline. An engine capable of relatively efficient high-rpm breathing makes horsepower by revving. 80 HP requires 52 ft-lbs of torque at 8000 rpm. A stock 850 could make that torque, but not at 8000 rpm. A stock 750 doesn't make that much torque (except on methanol?), and can't breathe at 8000 rpm. A short stroke motor develops less torque, but can live at higher rpm. Commando valve train needs serious attention to function at 8000 rpm.

Given all that, 80 crank HP with gasoline would require a narrow focus on a short powerband with a radical camshaft, shortened stroke, tuned intake and exhaust, and as much displacement as could be accommodated. It would be very difficult to achieve with a commando 750 engine and stock valve sizes without using methanol. But fun to try!
Click to expand...

You know, riding my short stroke it does'nt seem short of torque! It has standard valves, but it has long inlets and a well designed exhaust.

Dyno runs were done before it was fully run in so it was not taken to its full potential, but its rwhp is promising.
Click to expand...

I'd still love to see the dyno numbers or chart on yours or any short-stroke commando. Didn't mean to say that a shorter stroke would be short of torque, but if the focus is 6-8000 rpm it is harder to fill the cylinders as efficiently with standard sized ports and valves than it is at lower rpm. And it's true I've never ridden a short-stroke commando, but other 70's era twins that I have ridden had shorter strokes, bigger displacements, and did not develop the kind of low-end torque that the Norton is famous for. (bmw R90, Moto Guzzi 850, Honda GL1000. The Honda had seemingly endless top-end)
 
Well, after a bit of research, it looks like the short stroke engines have extensive head and valve modifications, including larger valves. So no way to compare that to stock valves and heads. The one short stroke dyno chart I found so far shows some serious torque, 60 ft-lbs peak rear wheel torque at around 5800 rpm, and what appears to be about 73 rwhp at near 7000 prm, which would be right around 80 hp at the crank! And equal or better than stock torque from 4000-7000+ rpm. Amazing.

That would smoke any commando I've ever seen or ridden.

https://www.youtube.com/watch?v=jgkLhxxJMGY
 
Dances with Shrapnel said:
SteveA said:
You know, riding my short stroke it does'nt seem short of torque!
Click to expand...

+1

Most often misquoted is that the short stroke Norton gives up torque, typically by those who have never touched a short stroke Norton let alone seen one in real life.
Click to expand...

Isn't a short stroke Norton effectively similar to a Triumph 650 or 750 ? No shortage of torque there unless you go silly. 850 commandos love methanol. However with the long stroke and heavy crank, gearing the bike right can be a big problem. If you don't believe you need a close box for racing, you are kidding youself. I believe in winding the crank up and riding near the top of the torque curve. If you have to wait for the crank to wind up, acceleration is too slow. Off the start line in a clutch start is always a problem. Nortons are better than Triumphs.
 
Paul2Earth said:
Well, after a bit of research, it looks like the short stroke engines have extensive head and valve modifications, including larger valves. So no way to compare that to stock valves and heads. The one short stroke dyno chart I found so far shows some serious torque, 60 ft-lbs peak rear wheel torque at around 5800 rpm, and what appears to be about 73 rwhp at near 7000 prm, which would be right around 80 hp at the crank! And equal or better than stock torque from 4000-7000+ rpm. Amazing.

That would smoke any commando I've ever seen or ridden.

https://www.youtube.com/watch?v=jgkLhxxJMGY
Click to expand...


Numbers on a dyno don't mean much. In fact most modern dynos give a value relative to the accepted value for the Yamaha Vmax using a fiddle factor. What we need is a decent basis for comparison. i.e. test a very good racer and use it as a benchmark. If it is to be Herb Becker's Norton, so be it. Do you think he will tell us his test results so we know what we need to beat him ?
 
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