True Horsepower(tm)

The Industry wide achievable HP standard

Problem:

Today, the entire world's hp values are a mess of dynojet "hp", dynojet clone's 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..... (right....)

All because some guy thought that a 1985 prerelease version  V Max made 145 crank hp according to the marketing dept. and he couldn't have his "new" inertia dyno read 90 hp on a stock dealership V-Max. Well, he WAS right at 85-90, but he made it read 120 to sell more people on his dynos. And that's where the chassis dyno hp mess started.

Simple Solution:

True HP.
They can all do it.

DEF:
Corrected True HP is the:
Actual power under Steady State or Sweep with CORRECT inertial mass value at 20 fps/ps
delivered to the drive roller of a chassis dyno
to which is ONLY added the dyne coast down parasitics and then
corrected to existing atmospheric test conditions.
 

Factory Pro has confidentially  refused to exaggerate measured and corrected horsepower figures to sell more dynos.

Since Factory Pro hasn't rescaled horsepower for the last 20 year and our software reads the same files the same under

Some Dynamometer companies add to measured rear wheel power readings a factor that is based on ESTIMATED rear wheel power losses (under what power conditions? 125cc? 1200cc? under coasting conditions? with a 3.00x17 bias ply tire? a 190x17 radial tire? New heavy radial tire vs. worn old, light, stock bias ply tire? Who knows?) 

In short, there is NO meaningful "average" tire to get a correct rear tire power transmission loss measurement for all bikes - so obviously, unless they actually measure the power lost in the rear tire, under driven load conditions, NO  dyno company should BE ADDING incorrect power figures into the measured power. It's simply wrong.

The fact that they add varying amounts of power to the actual, "true" amount of power delivered and measured  to the surface of the drive roller creates a situation that makes it an onerous task to compare power figures from different brands of dynamometer systems.

On simple inertial dynamometers, some (most, actually, all that I know of in the MC market) companies use an average for the inertial mass value of the engine, transmission, rear wheel, sprocket and chain on every bike - as if a YZ125 has the same rear wheel or internal rotating mass as a 1340cc Harley Davidson. Needless to say, if the software thinks that the YZ125 had a HD rear wheel on it, it would look like the 125 makes more HP at the rear wheel than it does at the crankshaft. It's simply wrong.
And - that's why you hear of 125cc Karts that make 43 hp at the rear wheels!!!!!

It's expensive to measure frictional losses in the engine and drivetrain, requiring the dyno to be able to drive the vehicle with engine off. Add the cost of a 50+hp electric motor, controlled power supply, etc. It's just not likely that $20,000 dyno will be equipped with that equipment.

It is also common for dynamometer companies to add to the power readings by adding transmission and primary gear/chain losses back into the measured power readings. Some companies make a concerted effort try to measure frictional losses and, optionally, add the power to the measured readings. Other companies - some that would surprise you - say that it's not important and give a blanket, single factor for frictional losses in every engine. That includes some $25,000-$35,000 dynes.

Some simply say that there is a meaningful "average" for every motorcycle,(2 stroke, 4 stroke, 1 cylinder/1 transmission, 4 cylinder/1 transmission) and apply it to every bike and that it is not a significant difference.

Blanket estimates of "average" losses and corrections are, quite simply, incorrect. At the upper levels of the industry, (we are talking about $150,000 - $500,000 AC or DC 4 quadrant dynamometers) it is not tolerated - shouldn't be - and needn't be.

There is a dyno company that actually has different versions of software that displays their own identical data files as different amounts of power depending on whether you use the DOS version or the Windows version of their software!!

True Rear Wheel Horsepower (tm) is Factory Pro's standard of measuring the power that is actually delivered to the rear wheel. It is honest, true, fair and duplicable. It is the ONLY standard that can be duplicated by the entire industry - regardless of the dyno manufacturer.

Following is a reference table so that, if you are used to rather inflated HP figures, you can see what your vehicle would generally make on the True HP Scale.

Need a reference scale?

True Rear Wheel Scale Samples

HD True HP page - click here

True HP as compared to DJHP

It's not possible to give an absolute conversion factor, as it appears that dj dynos don't all read the same (my experience, other's, too - and  Mag Articles and 2002 Roadracing World gsxr1000 and R1 comparison articles), but, you can take True HP from EC997's and produce an "average" djhp of of an "average" dj dyno - empirically derived, over 12 years of comparison of the two hp scales.

Chassis dyne HP
What is it? What to call it?

EC997 = "True HP"
Dynojet = "DJHP"
It's not really proper to call "djhp"  "rwhp", as neither the EC997, dynojet, Fuchs, Superflow or Land and Sea will necessarily produce the same numbers as a dj dyno, except by luck - and the whole idea of True HP is that EVERY dyno manufacturer HAS the capability to provide those numbers!

The Superflow chassis dynes, the EC997's, Land and Sea and Mustangs are all capable of measuring power in steady state mode and producing the same numbers - they can all measure: torque x rpm / 5252 = horsepower
We've not diddled with physics!

The only factor that is added to the measured reading, in True HP Mode, is the additional energy (dyne parasitics) required to spin the dyno roller to whatever speed the roller is turning at - logical, proper and required for any measuring instrument,

torque x rpm / 5252 = horsepower + parasitic power = True HP
We've not diddled with physics and joined a power "puff" derby.

Whether they provide a number that is comparable to other dynes (like  Factory Pro did), or not, is completely up to the manufacturer - some like to squirrel away their "puff factors" and some actually "lost" their source code and made up new ones that were 2% higher than the old DOS ones.
 

Chassis dyne HP - Intertia
What can inflate HP readings on an inertia  dyno, but not really make more engine power in the real world?

A few things can affect HP when using inertia dynos (not a dyne in Steady State Mode) to measure power (what else would you do??:-):

1. Changing to a light, worn stock rear tire will improve power output on an inertia dyno, but, not improve real world top speed.

2. A heavier (brand new race) tire that replaced the above, light, worn tire, will decrease measured power on an inertia dyno, but not decrease real world top speed.

   1. Lighter wheels are a good thing!
      Better acc. in lower gears, esp. 1st and 2nd (accelerating less inertial mass!).
      Better suspension is possible, too!
      Flicks from side to side easier and hence, quicker in the "esses".
      Riding hard on worn, light tires is foolish.
       

3. Problems with Inertia dyno test procedure and fuel injected vehicles:

   1. A Sweep Test (hold throttle wide open and sweep from low rpm to high rpm) will often trigger the ACC. FUEL Map, along with the Main FUEL Map, causing the dyno operator to to lean out the main fuel map to compensate for the additional fuel the ACC. FUEL Map delivers. Of course, in the real world, upper gears, the acceleration rate of the engine is much slower than what they tested, doesn't trigger the ACC FUEL Map, and the bike ends up a lot leaner in reality in top gear.
      It's not that common of a problem, since most people never ride that fast for that long to cause engine damage - but, the manufacturers will find out soon enough about that.

      1. Work around:
         Tune full throttle fueling in real world usage at dragstrip (to best trap speed) or in Steady State Mode on different dyno.
                    

Chassis dyne HP
How can a bike with 132 djhp race and lead with bikes with 141 djhp at Daytona?

You can optimize tuning for a dj dyno and make big numbers - and you can tune the bike to make best power under load on an EC997 and blow off the big dj dyno numbers - That's what that happened at Daytona a couple of years ago...
132 djhp Jimmy Moore gsxr750 (115-116 True HP) lead Daytona CCS over 141djhp Team Suzuki's gsxr??? and Zlock Racing's ZX9 -
How? It's impossible to spot competitors 8 real hp and lead the last few laps until the drafting battle at the line on the last lap!
The answer is obvious (no - Jimmy's bike was legal - we didn't need to limit the power on it.... It was an end of the year experiment that went awry....)
The answer is obvious (read above rantings :-) and is just another example of non-real world power figures.

Can a tuner cheat and make an EC997 read higher?

The only way that could happen is in a Sweep Test - Sweep Tests are the least reliable of all tests. Period. Ours or others. There is NO question about that.
Since the Rotating Mass is a variable in a Sweep Test (but NOT a Steady State Test! - where it's not a factor), the actual inertia factor entered affects the final HP figure - - Tell the software that the vehicle has a lot of rotating mass to accelerate, and the HP number increases. (torque, rpm, acc. rate and mass are the factors) - just like dj dyno ignoring the difference in mass of all bikes -

So - True HP, again -
Steady State Test - No acceleration, mass makes no difference, anymore. Torque, RPM and dyne parasitics. Period. True.

Can you make a Steady State Test (normal EC997 mode) read higher?
I can squeak, maybe, 1/2 to 1 HP extra out of an rpm point, at the most. I was curious (big surprise??) and I tried and tried - 1/2 to 1 True HP. That's about it. And that's pretty hard and you have to consciously try hard to do it - and you have to know how to do it -
The software will NOT take data unless speed and load are completely stable - eliminating cheating (the accuracy is hard coded into the program, so it can't be diddled with!)
As far as other dynos - and being able to make "flash readings" - that's now, ancient history on most newer dynes. Our dynes have always factored a base inertial mass factor to prevent "overloading" and resulting high hp "flash" readings - even in the Steady State Test.
I think that that's more possible in older manual controlled systems that happen to be water brake type engine dynos, but, I can't really talk much about them because I do not have recent firsthand experience.

As far as atmospheric conditions making a +/- 10% difference? Unless you really(!!!) mess with the barometric pressure (and you can look at every atmospheric factor on every test report sheet - it's hard coded to display - not an "option" to display, it is simply, absolutely impossible to do without obvious evidence.

Some dynamometers will actually display "actual HP" and not specify that it is "uncorrected" to standard air ("SAE Corrected", for example) - A STD HP shouldn't ever be given to a customer - The customer probably doesn't know that "actual" means "uncorrected" and that the results can't be compared to anybody else's dyno chart - I was just reading some UK dyno operator explaining on a cbr600rr forum that "STD" hp was some sort of recognized "standard"... (April, 2006). It's not a standard hp number - it's the actual amount of power the bike made THAT day with that temp, baro pressure and humidity. You can't compare it with any other day and different atmospheric conditions. Period. It's a pretty useless chart for comparison purposes. The only time anybody gives an "STD" hp chart is if he's trying to make the power look bigger than another test with different atmospheric conditions.

I saw a recent South Bay (San Francisco south bay) chart reading "Actual HP" instead of "SAE Corrected" HP - The dynojet "tuning center"  had just installed an undercut transmission on a gsxr1000 and had somehow lost 10-15 djhp - They gave the customer a chart displaying "Actual HP" because it was 3-4 djhp higher than "SAE Corrected" - to try to hide some assembly error - They denied all responsibility......... They should have just figured it out and I never would have had their customer at my door telling me the story -
The moral? Sometimes the cheapest isn't the best deal - or an honest deal either -

Are final tuning optimal dyno settings different on an Inertia dyno vs. an EC997
For many reasons, final tune settings are different - and, since the EC997 does Sweep and Steady State horsepower testing, we have a choice of tests - from a dj style Sweep Test to Steady State.
Having a choice of those types of tests to do - and having been, firsthand, involved in all sorts of racing - AFM, AMA (250 GP #1,#2,#3,#4), WERA, CCS, Formula USA (750 National Champ and 6 USA Track records!) road racing, drag racing, MX, Speedway, dirttrack, scooter - we have had the opportunity to verify the results of different types of tests and their relevance to the real world operation -
Without a doubt - the Steady State test Mode is the most consistently superior method of tuning - anybody who has the capability to do it will echo that sentiment - it's only an arguable point with those who can't do it properly.
One of the reasons why the EC997 provide settings that work better in the real world is that combustion chamber temperatures are more in line with the actual operating temperatures that the engine - Tests done by Champion Spark Plugs at 4&6 Cycle, Chicago area, provided information that combustion chamber / spark plug temps, on a a common inertia dyne were 300f to 400f LOWER than the real world and the EC997 Steady State Test Mode - Nobody should ignore that - that means ignition timing AND fuel are incorrect when set at sub normal temps - too rich and too advanced is not un common error. (unless you are tuning FI - then it can be either too lean or rich)
On a TZ250? A dj dyno indicated that 3.1mm btdc was optimal ignition timing for best power - and the EC997 indicated 2.6mm btdc - if you knew gp bikes (or even rd350's like me!) that's a HUGE difference!
How much different? About 6 to 7 hp improvement on the EC997 at 2.6mm - and the bike, now, "ripped" on the track instead of droning in sorry misery - it lost a bunch of power on the dj dyno, but, who cared anymore, the EC997 said that the bike was better and the track performance verified it. The only dissenting opinion was the inertia dyne test results.
Given an open mind, desire and equipment, one could make up their own mind -
As for me? I've been here and I've been there - And I like "here" a LOT better!
If I had to resort to sweep tests, only, I'd quit this line of work (boy - would some people be happy!)

Final statement - "It's not important which dyno you use - it's only the amount of power improvement that's important." has  never been said by a qualified tuner who has the ability to use modern designed dyno systems and verify results on the track.
Never.

"True HP" vs. "False HP"
"True HP" is a term that signified that the rear wheel horsepower figure was derived from the actual power delivered to the drive roller - nothing added (except normal dyne system parasitic drag).
If some other dynamometer company provides HP figures that will conform to that, they can use the term "True HP". If they don't, then they can't.
Truth in advertising.
If they did, then their dyne systems would at least read the same as another "True HP" dyne system - eliminating a bit more confusion in the industry. (but what would make the internet boring).
Superflow has agreed in principle, so has Mustang and Land and Sea.

Does altitude make any difference at all in HP?
The engine couldn't give 2 hoots at what altitude it is tested at - it only cares what the air pressure, temp and humidity is.
Sea level at 28.02 inches baro is exactly the same as 4000ft/1000 meters at 28.02 inches, as far as the engine is concerned -
When we test at 5000 ft, we get virtually exactly the same power (corrected to atmos. conditions, of course) as we do at sea level - It's just about 24%-25% less on the track and on the EC997 dyno!
I am confused (sometimes, easy to do - but not this time :-) why some dyno manufacturer's insist on putting altitude on their charts and having the dyno operator swear that it's a factor....... Might as well swear that there's some Merlin the Magician reason as to why one should test in 4th gear!!!

Crank HP vs. True Rear Wheel HP
That's a tough one - and LONG....
The short?
Take crank HP, subtract 14.6% (please don't email me and ask - I won't answer - search SAE and old Yamaha), take that, and subtract around 10% to 15% and you'll get about True HP at rear wheel.
The actual formula contains a curve for power loss through gears and  there SHOULD be another curve for power lost in a tire (it's the majority of loss on a motorcycle....
Remember, too - that you are only likely to get a crank number from the manufacturer and that's probably a "good" one that the marketing department is providing... (sound of blowing up a marketing and sales balloon? :-)  That's not everybody - but it has happened - leaving names out! :-)
When someone gets engineering data from engineering...... give me a call - :-)

What TEST would you suggest that I ask for when I Go to a Factory Pro Dyno Center?
Ask for the Steady State data, base and final tests - that has the 4 Gas EGA information and you can see the gas differences and how it relates to True HP - and you get the True HP numbers -
Some EC997 operators who are afraid that the information is too confusing and just give the owner the Quick Sweep (rough dj simulation) to keep - Get the True information - we can always work with that here, at 800 869-0497. Marc

And finally,
This stuff is confusing!!!
If you've got questions, give me a call at 415 491-5920 between 2pm and 5pm pst, tues. - thur.
I left out a ton of information -
Have a great, curious, open minded day -
 
Marc Salvisberg