To The People Losing Their Minds About My E36 M3's Dyno Results, Here's An Explanation

My E36 M3 was put on the dyno recently. The resulting power figure was 279bhp, but it seems there's a lot of confusion between bhp at the wheels and bhp at the crank. So here's an explanation!

Alex Kersten

09 Jul 2016

This video has caused a lot of confusion in the YouTube comments, with people saying stuff like “I thought he was a car guy… This dyno doesn’t measure bhp. It measures whp. 279 x15% loss is around 317” and “You guys are aware that dynos read WHP and not BHP?“

So to set the record straight, I Facebook messaged Charlie from Surrey Rolling Road this morning and asked for an ‘official’ response on the matter. Here’s what he sent back, which I’m hoping will clear things up for people…

What does the dyno measure?

WHP

Are the figures for Alex’s car at the crank or wheel?

Crank

Whoa… you just said that the dyno measures at the wheels!

It’s common in Europe for dynos to add the drivetrain loss to make a crank estimation graph. It is always an estimate but it allows the customer to relate to the manufacturer’s crank figures.

Does the dyno also plot in WHP?

Yes, it stores a WHP graph for every car, then depending on what the customer wants we can print out WHP or crank HP.

Why do I see lots of WHP figures around the internet?

America uses mainly WHP figures only, as does Russia and the middle East. Australia uses Wheel KW mainly.

So who’s right?

No one, and everyone. There is no wrong or right way of doing it. As long as you get a consistent number you can compare to when you’ve done some mods.

What do you think is wrong with Alex’s car?

Alex bought it. It was probably putting out over 300bhp before he got his hands on it…

To The People Losing Their Minds About My E36 M3's Dyno Results, Here's An Explanation

So there you have it, ladies and gents. From the horse’s mouth, this is why my car was making 279bhp at the crank and not 279bhp at the wheels (that would have been incredible had that been the case!).

Next up, I’ll give the car a proper service, get those valve clearances and suspension issues straightened out, and will fit a new exhaust system and a Pipercross air filter that was donated to Colin just last week.

Then, it’ll be back to Charlie’s dyno to see if my E36 M3 can get over 300bhp (at the crank).

Comments

You know. It makes me wonder how stupid some people can be. They focused on you, but also fail to notice that it must be proper due to the trained guy who was doing the dyno..

Trying to get it over 300bhp…

That car is pure dyno-might!

You made two puns by using one word; that’s awesome!

isn`t the rolling road calculated power loss of RWD?

sry did not read whole text =) so yeah as I thought

THE DYNO DOES NOT MESSURE HP!!!
It messures torque!

And then does this:

P = Power (in KW) [so; P x 1.3 = HP]
M = torque
n = revs

That’s what the dyno calculates for you and that’s why torque figures are more important than horsepower/Kilowatt figures.

It converts it automatically, torque is not the only factor. For example if two cars have the same amount of torque (and weight) but one has higher HP the car with the higher HP will be faster.

P x 1,36 = HP To be more precise

I personally always use 2pin * M = power in watts. Outcome is thesame however, although 9549 would be more accurate lel. Torque and horsepower figures are of equal importance IMO. Just depends on the situation.

That’s like saying a ruler doesn’t measure the area of a circle, it measures diameter.

Doesn’t matter, it gets the measurement you need to work out the thing. A dyno is used for many things, just like something as basic as a ruler. It’s a measuring tool and you can use a measuring tool and math to make numerous amounts of different calculations, and the primary use for that tool is whatever the person using it wants it to be.

or horsepower=(foot poundsxRPM)/5252

probably just worn out cams? i would go for aftermarket performance ones (not race ones) and that car would turn into a monster.

1500 eur worth of aftermarket ECU installation will sort those working properly right out! Good advice!

Only care about the wheel hp.

Bhp is at the crank, hp is at the wheels

whp* is at the wheels
Since hp and bhp are essentially the same thing

For me, WHP is all that matters 😁

Exactly! Torque is nothing without revs. And torque x revs is WHP. I can get 5000Nm of wheeltorque with my hands while using a 10m wrench, but i cannot rev fast enough to build up any usable power. So torque does not help me to be fast. Wheelhorsepower does!

So, how do you arrive to 15% drivetrain loss? It always amuses me how these “drivetrain losses are universal for all cars at any given dyno center”. Quattro? 15%, RWD? 15%. Flat tooth superlightweight transmission? 15%.

According to the experts I’ve met when dyno my Quattro the drive train takes away around 60 brakes… That’s a lot of horses

Im no expert but how i’ve heard it the dyno measures the drivetrain losses by letting the wheels spin down after the dyno run and during that time it measures the rate of change of the the rotation speed of the wheels, using that you can estimate the drivetrain losses as with more losses the wheels would slow down more quickly than a more efficient one with less losses.