Dyno Day.

[Mr Lefty]

Originally Posted by No Worries

The dyno measures torque. You mean: How did they calculate hp without knowing the rpm? According to the formula, they have to know the engine's rpm in order to calculate the hp.

yeah that's what I meant... I wasn't questioning you NW... I know your right... I'm just wondering how the hell they got any reading at all...

[Cutty72]

I'm guessing they get it somehow off of the speed.

[Mr Lefty]

... huh... so you going back tonight to do it again?

[fnfalman]

Okay, let's back it up here and allow me to correct a few things. Without going into the whole course of thermodynamics and calculus and all that shits, I just want to say that the engine makes both TORQUE and HORSEPOWER.

Yes, it's true that you multiple torque by whatever number to get horsepower, BUT that does not mean that an engine makes only torque and horsepower is some sort of foofoo affair.

An engine makes Work (in this case known as torque). This Work (energy with unit of measurement such as Pound-Feet, Newton-Meter, Joule, etc.) generated over an amount of time (seconds, minutes, hours, months, years, etc.) equals Power. Power has many units of measurements (Watts, Horsepower, etc.) and in automotive we just happen to use Horsepower.

In the simplest thermodynamics terms, Energy = Work (not all the times but in this case it is) = Force x Distance. Hence you have Pound-Feet or Newton-Meter (aka Joules). Work/Time = Power (Joules/Second = Watt and Watt can be converted to Horsepower or any other units of measurements for Power).

[Cutty72]

Originally Posted by Ebbs15

... huh... so you going back tonight to do it again?

Provided the thunderstorms and tornado's hold off...

[fnfalman]

Originally Posted by Ebbs15

so then how did they caculate the hp with out knowing the torque?!

That's why the dyno has the weighted drum that your bike's rear tire turns. That drum is weighted and calibrated. How fast it turns is calculated into horsepower. That's why it doesn't require your bike to have the RPM (aka attaching the clip to the sparkplug wire) to calculate for horsepower. However, it doesn't KNOW how fast your engine is turning, so if you were to want torque measurement then it needs to know your RPM via the spark plug connection thingie so that it can calculate backward from horsepower reading at the rotating weighted drum against your engine's RPM in order to calculate for your bike's torque.

[Mr Lefty]

intresting... I know when I did my dyno runs they had trouble getting my tank off and said with out the RPM's they couldn't do anything... could just be diffrent dyno


good to know fnfalman

[fnfalman]

Originally Posted by Ebbs15

intresting... I know when I did my dyno runs they had trouble getting my tank off and said with out the RPM's they couldn't do anything... could just be diffrent dyno


good to know fnfalman

Could be. I'm only familiar with the Dynojet dyno, and I know that they don't need your bike's RPM to measure horsepower.

[Phenix_Rider]

Originally Posted by fnfalman

the spark plug connection thingie

Amp Clamp or Gausse Loop (or Hall Effect sensor for DC). Detects current by the magnetic field it creates moving through a conductor.

[Cutty72]

Ok... night started out nice, so I went

Ran it again.

129.59 hp
74.35 ft/lb of torque.

Very respectable, and just about everyone was supprised by the numbers.

I will scan in the dyno chart when I get home next week.

Also ran a 06 GSXR 750... 117 hp
05 R1 with Yamaha race baffles 140 hp.

see story of afterwards in my blog...