Here's a site that claims True Hp reports for many cycles and looking for reports to fill in the blanks on old-new, big-small cycles. Worth a scan through for those trying to keep score on impossible to compare shaft vs chassis dyno tests or any conversion method to explain their differences.

http://www.factorypro.com/dyno/true1.html
Today, about 75% of the entire world's hp values are a mess of dynojet "hp" and dynojet dyno clones' rough approximations of dynojet horsepower , some brake dyno mfgr's "dynojet channel" that's "+/- 10% of a dj number" , some dynos that out exaggerate the dj numbers and imply that they know what the transmission hp and crank hp is, and even other dynos with the most expensive brochure that read whatever the user wants them to read, True, Real, SF and DJ..... or make up your own inflation factor (sigh...)

mightve been covered hear , but ' Welding Journal Throws ' .

Is the steel the crank ends utilise suitable for redimensioning , as per 50s V-8 strokeing tecnology .
Which type welding rods , any heat treatment required .

Being Awkward , will they fit in the Crankcases .

How much clearance to case from rod end retainers ( rod nut , bolt end ) .
1 or 3 m.m. envisaged , but whats visual clearance stock for bolt in . ?

Here's a pic of a 90deg nourish weslake cranshaft from a 750 regular (not short stroke) engine.
It's a pratice for posting pictures so I thought I'd stuff it in here.
Rods Carillo, pistons Omega.

Are those Omega pistons lightened?

Swoosh,
I don't think they're especially lightened - they're not as light as the JS norton pistons. A complete 73.04 mm bore piston is about 319 grams.
These Carillo rods have conventional little end bronze bushes in them but I guess they could be called long rods since they are 6.5" on a 88.5mm stroke ( =1.87ratio)
The reason this engine was being rebuilt was because when I switched it to a 90 deg crank I didn't realize I had to recalibrate the tach. When I did check it with our instruments at work I figured I'd been turning the engine to 10,000 -10,500 rpm through the gears. The bottom end stayed together through this abuse for 1/2 a season ( the long stroke meant it was a silly piston speed) but the rather tired timing side crankcase cracked first.

figured I'd been turning the engine to 10,000 -10,500 rpm through the gears. The bottom end stayed together through this abuse for 1/2 a season ( the long stroke meant it was a silly piston speed) but the rather tired timing side crankcase cracked first.

Gosh impressive to think how the rush of that felt, but helps make me feel rather a timid abuser.

[quote="RennieK"Once you have your intake, exhaust and combustion chamber maximized it will be capable of producing a fixed amount of energy or power. [/quote]

There is a problem with that line of thought when you are talking about a four-stroke engine because there is a long pause between power pulses. If it were possible to build an engine with zero mass, it would not run because there would be no stored energy to turn the crank through the strokes that consume power to pump and compress.

The Norton tuner John Gregory of Sunset Motors fame once had a 500cc Norton road-race bike. He once tried a very light crank for it that was welded together into one piece, just three pork-chops. He ended up having to add weight to it to get it's top speed back.

It is easy to find top road-racers quotes about how the most time is saved on the fastest parts of a track. In high gear the engine has the least power-pulses per say, 100 feet, and is balancing itself against the highest resistance, wind, rolling, road etc..
In high gear at high speed the flywheel stores the energy fed to it by the crankshaft at regular intervals but the times that the power is taken from the flywheel have nothing to do with the operation of the engine at all. changes in wind direction, wind gusts, a bend in the track or traveling up or down hill will give the bike with a heavier flywheel and more stored energy a big advantage over a bike with a light flywheel with less stored energy to draw from to fight the mentioned obstacles.

A heavy flywheel would also give a rider more control to charge harder out of the turn leading onto the fastest part of a track than a rider who is riding a bike with no flywheel, which would make him have to modulate the throttle a lot more to keep the power pulses and increasing power-curve of the engine from overwhelming the traction of his rear tire.

There is an older(sorry) AMA expert dirt tracker named Jim Challingsworth who ran a Triumph Cub, a rigid Goldstar and a Trackmaster Triumph through the 1960's. If you talk to him he will tell you that he can not find a flywheel heavy enough to race with. He is all for building power at high-rpms with big cams and carbs etc.. but he wants that heavy flywheel to get the best control and traction out of the turn for the charge onto the straight.

The acceleration might be better up through the lower gears with a light flywheel, but the only race you would win would be the one on dry pavement in a straight line from a rolling start that ended when you shifted into high gear.

I have been down that road also, to the extreme in lightweight cranks. Sounded hotter- went slower. The only upside I have found was when you carried them across the shop.

I have seen and worked out the SAE formulas for the correct crankshaft inertia to extract the most power from a particular bore and stroke ratio. Norton was obviously aware of them as their stock crank fit the formula perfectly.

Now if they would have used nodular iron for the flywheel and a little larger PTO shaft they would have had a good thing. Jim

RennieK wrote:Once you have your intake, exhaust and combustion chamber maximized it will be capable of producing a fixed amount of energy or power.

beng wrote:There is a problem with that line of thought when you are talking about a four-stroke engine because there is a long pause between power pulses. If it were possible to build an engine with zero mass, it would not run because there would be no stored energy to turn the crank through the strokes that consume power to pump and compress.

The Norton tuner John Gregory of Sunset Motors fame once had a 500cc Norton road-race bike. He once tried a very light crank for it that was welded together into one piece, just three pork-chops. He ended up having to add weight to it to get it's top speed back.

It is easy to find top road-racers quotes about how the most time is saved on the fastest parts of a track. In high gear the engine has the least power-pulses per say, 100 feet, and is balancing itself against the highest resistance, wind, rolling, road etc..
In high gear at high speed the flywheel stores the energy fed to it by the crankshaft at regular intervals but the times that the power is taken from the flywheel have nothing to do with the operation of the engine at all. changes in wind direction, wind gusts, a bend in the track or traveling up or down hill will give the bike with a heavier flywheel and more stored energy a big advantage over a bike with a light flywheel with less stored energy to draw from to fight the mentioned obstacles.

A heavy flywheel would also give a rider more control to charge harder out of the turn leading onto the fastest part of a track than a rider who is riding a bike with no flywheel, which would make him have to modulate the throttle a lot more to keep the power pulses and increasing power-curve of the engine from overwhelming the traction of his rear tire.

There is an older(sorry) AMA expert dirt tracker named Jim Challingsworth who ran a Triumph Cub, a rigid Goldstar and a Trackmaster Triumph through the 1960's. If you talk to him he will tell you that he can not find a flywheel heavy enough to race with. He is all for building power at high-rpms with big cams and carbs etc.. but he wants that heavy flywheel to get the best control and traction out of the turn for the charge onto the straight.

The acceleration might be better up through the lower gears with a light flywheel, but the only race you would win would be the one on dry pavement in a straight line from a rolling start that ended when you shifted into high gear.

There's considerble anecdotal evidence here and I am glad that the point was made that Challingsworth's applications were it is common racer knowledge that in dirt, a lighter flywheel mass would promote too much wheel spin. Some of what is presented is somewhat conflicting with "heavier is better" but clearly to a point. The flywheel stores the energy but if the energy is not all stored in the flywheel, where does it go? .....acceleration.

On asphalt most anyone would give their left testicle for more useful drive out of a turn and that would be diminsished with a heavier flywheel; what road races are won on a flat out up hill against the wind. An appropriate balance must be met between application, rider ability and practical engineering design limitations. I am not a proponent of light as possible but there is an appropriate balance for every instance.

This all gets back to another thread about the merits of a brake versus inertial dyno which I am not going to get into here.

>This all gets back to another thread about the merits of a brake versus inertial dyno which I am not going to get into here.<

My dyno showed more power with the light flywheel until I engaged the eddy currant absorber. Then it showed more power with the heavy flywheel. Jim

comnoz wrote:>This all gets back to another thread about the merits of a brake versus inertial dyno which I am not going to get into here.<

My dyno showed more power with the light flywheel until I engaged the eddy currant absorber. Then it showed more power with the heavy flywheel. Jim

Yes, exactly. They are showing or measuring two slightly different things (regardless of what they are calling it), both useful information. Just curious, what were the differences and where; an engines power and torque performance are not a point estimate.

If we had the ways and means it would be neat to do a series of power & torque curves through several flywheel weights to see what happens and where.

If we had the ways and means it would be neat to do a series of power & torque curves through several flywheel weights to see what happens and where.

If I can get Ms Peel's act together this year she's set up to do this already so want to dyno at Jim's or Texas Big D. I want as much power as anyone but more concerned on how it delivers power when tire traction is iffy. I will not need a dyno station to know for sure. oops, can only test BF not much crank total mass changes.

Dances with Shrapnel wrote:

comnoz wrote:>This all gets back to another thread about the merits of a brake versus inertial dyno which I am not going to get into here.<

My dyno showed more power with the light flywheel until I engaged the eddy currant absorber. Then it showed more power with the heavy flywheel. Jim

Yes, exactly. They are showing or measuring two slightly different things (regardless of what they are calling it), both useful information. Just curious, what were the differences and where; an engines power and torque performance are not a point estimate.

If we had the ways and means it would be neat to do a series of power & torque curves through several flywheel weights to see what happens and where.

I did tests with top gear acceleration runs. I was testing with inertia only at 450 lbs simulated bike weight. Then I was repeating the tests with reduced inertia and the computer controlling the acceleration rate with the brake. Also set at 450 lbs simulated weight.

The differences were in the 3 to 5 horse range and pretty well though-out the power band. Unfortunately I no longer have any records as this was done pre-fire.

Other things I have noticed:

Most modern bikes show higher readings with inertia only. Most Nortons show about the same power whether inertia only or with eddy currant control.

Under steady state RPM control most bikes normally show less horsepower than in an acceleration run.

Under steady state RPM control the heavier crank always shows more power.

How much of this difference is caused by the dyno operating system I do not know.

Dances with Shrapnel wrote:

RennieK wrote:Once you have your intake, exhaust and combustion chamber maximized it will be capable of producing a fixed amount of energy or power.

beng wrote:There is a problem with that line of thought when you are talking about a four-stroke engine because there is a long pause between power pulses. If it were possible to build an engine with zero mass, it would not run because there would be no stored energy to turn the crank through the strokes that consume power to pump and compress.

The Norton tuner John Gregory of Sunset Motors fame once had a 500cc Norton road-race bike. He once tried a very light crank for it that was welded together into one piece, just three pork-chops. He ended up having to add weight to it to get it's top speed back.

It is easy to find top road-racers quotes about how the most time is saved on the fastest parts of a track. In high gear the engine has the least power-pulses per say, 100 feet, and is balancing itself against the highest resistance, wind, rolling, road etc..
In high gear at high speed the flywheel stores the energy fed to it by the crankshaft at regular intervals but the times that the power is taken from the flywheel have nothing to do with the operation of the engine at all. changes in wind direction, wind gusts, a bend in the track or traveling up or down hill will give the bike with a heavier flywheel and more stored energy a big advantage over a bike with a light flywheel with less stored energy to draw from to fight the mentioned obstacles.

A heavy flywheel would also give a rider more control to charge harder out of the turn leading onto the fastest part of a track than a rider who is riding a bike with no flywheel, which would make him have to modulate the throttle a lot more to keep the power pulses and increasing power-curve of the engine from overwhelming the traction of his rear tire.

There is an older(sorry) AMA expert dirt tracker named Jim Challingsworth who ran a Triumph Cub, a rigid Goldstar and a Trackmaster Triumph through the 1960's. If you talk to him he will tell you that he can not find a flywheel heavy enough to race with. He is all for building power at high-rpms with big cams and carbs etc.. but he wants that heavy flywheel to get the best control and traction out of the turn for the charge onto the straight.

The acceleration might be better up through the lower gears with a light flywheel, but the only race you would win would be the one on dry pavement in a straight line from a rolling start that ended when you shifted into high gear.

There's considerble anecdotal evidence here and I am glad that the point was made that Challingsworth's applications were it is common racer knowledge that in dirt, a lighter flywheel mass would promote too much wheel spin. Some of what is presented is somewhat conflicting with "heavier is better" but clearly to a point. The flywheel stores the energy but if the energy is not all stored in the flywheel, where does it go? .....acceleration.

On asphalt most anyone would give their left testicle for more useful drive out of a turn and that would be diminsished with a heavier flywheel; what road races are won on a flat out up hill against the wind. An appropriate balance must be met between application, rider ability and practical engineering design limitations. I am not a proponent of light as possible but there is an appropriate balance for every instance.

This all gets back to another thread about the merits of a brake versus inertial dyno which I am not going to get into here.

Well put DWS. There is a 10lb. range between various cranks posted on these threads. What is the tipping point? At what point is a crank too light or too heavy?

Jim who has a lot of experience with Norton cranks seems to favour the stock weight which is about 24 lbs. Using the stock weight as a reference or "norm" we could say anything heavier is a heavy crank and anything lighter is a light crank. We obviously can't just keep adding weight to gain power, there is a point where it becomes disadvantagious. Do we always want to store maximum power in the crank? How often do we call on ALL this stored power and how often is it not being utilized or required?

beng wrote:There is a problem with that line of thought when you are talking about a four-stroke engine because there is a long pause between power pulses. If it were possible to build an engine with zero mass, it would not run because there would be no stored energy to turn the crank through the strokes that consume power to pump and compress.

Other than your very last paragraph you've made some good points beng but I find the above hard to follow as well. There has to be enough energy from combustion to compress for the next power stroke after all that energy is what provides the stored power to the the flywheel in the 1st place AND compresses the fuel at faster and faster rates and eventually drives the bike with passengers. I would think the power from a 375cc cylinder burning high octane fuel at 9:1 compression will easily spin the engine enough to re-compress a new fuel air mix for the second and other subsequent firings specially on a zero mass engine. By this consensus a rocket ship would require a flywheel.

To translate this last conflict of concepts, if there is no mass in a flywheel to carry the piston power stroke on past BDC, then the rotation is over after one power stroke stops at BDC. Staggered firing order of multi pistons could over come this.