Mini OcUK Rolling Road Day: Powerstation Saturday 22nd January!

MrLOL said:
People have always read on the internet that the only true figure is the power at the wheels figure, that the power at the fly figure is a figure generated to massage people's egos by looking bigger. And that the only true indication of a car's power is the power at the wheels.

The american's are very much in this mindset, its not uncommon to hear people on american forums talk only of RWHP - rear wheel horsespower. Very rarely do they quote crank horsepower.

However in europe we nearly always quote the engine power instead of the power at the wheels. As a result the Maha dyno that powerstation use has been geared up to produce a more accurate engine horsepower figure by using two rollers. Whether you believe this works or not is up for debate. I've no idea if its true or not, but thats what Maha who make it think.

Because the wheels have two contact patches, there is more resistance at the wheels than you would get in a real life. You could possibly choose to take account of this, and quote an accurate power at the wheels figure, but powerstation choose not, and use it purely as a figure for calculating the crank horsepower.

However, because people see power at the wheels figure that are horribly inaccurate, they conclude that the dyno itself must be horribly inaccurate also. This is not true, the Maha dyno that PS use is not intended to quote accurate power at the wheels figures. It quotes it on the graph purely for reference. Maybe they should remove it to avoid confusion ? who knows. Its german and you know what those crazy germans are like ...

But anyway, main point is the Maha Dyno doesnt produce accurate power at the wheels figures and aims instead to produce accurate power at the flywheel / crank figures.
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Good point. It makes people with 4WD feel better, because they can loose so much power through the transmission.:D
 
MrLOL said:
People have always read on the internet that the only true figure is the power at the wheels figure, that the power at the fly figure is a figure generated to massage people's egos by looking bigger. And that the only true indication of a car's power is the power at the wheels.

The american's are very much in this mindset, its not uncommon to hear people on american forums talk only of RWHP - rear wheel horsespower. Very rarely do they quote crank horsepower.

However in europe we nearly always quote the engine power instead of the power at the wheels. As a result the Maha dyno that powerstation use has been geared up to produce a more accurate engine horsepower figure by using two rollers. Whether you believe this works or not is up for debate. I've no idea if its true or not, but thats what Maha who make it think.

Because the wheels have two contact patches, there is more resistance at the wheels than you would get in a real life. You could possibly choose to take account of this, and quote an accurate power at the wheels figure, but powerstation choose not, and use it purely as a figure for calculating the crank horsepower.

However, because people see power at the wheels figure that are horribly inaccurate, they conclude that the dyno itself must be horribly inaccurate also. This is not true, the Maha dyno that PS use is not intended to quote accurate power at the wheels figures. It quotes it on the graph purely for reference. Maybe they should remove it to avoid confusion ? who knows. Its german and you know what those crazy germans are like ...

But anyway, main point is the Maha Dyno doesnt produce accurate power at the wheels figures and aims instead to produce accurate power at the flywheel / crank figures.
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I still don't get it despite reading the explanation several times :o The dyno has only one point of reference, the power at the rollers. This figure is deemed by most to be inaccurate. How that inaccurate measurement can suddenly become an accurate at the flywheel figure just doesn't equate. If it is simply a correction factor or something then why not have it applied instantly so that you see an accurate ATW figure?
 
mattyprice4004 said:
Shame it isn't summer though, as I really enjoyed seeing the Citroen C5 on fire at the side of the road, and also having to drive home at 50mph as a boost hose literally exploded on a spirited drive with agw_01.

Fun times... :D
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Remember this Mat?

26200_334501341149_684656149_4031190_5811340_n.jpg


bwahahaha :D
 
Ill attend and run been wanting to run, bit more than I normally pay but who cares :p I have a new SX which I have modded but still! have boost leak issues, will still be nice to get a baseline.

we going to pub after? (for food obviously!)
 
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Rich1988 said:
Ill attend and run been wanting to run, bit more than I normally pay but who cares :p I have a new SX which I have modded but still! have boost leak issues, will still be nice to get a baseline.

we going to pub after? (for food obviously!)
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Yeah was the idea and looks like there is gonna be 5-8 of us going so far. :)
 
lordrobs said:
I still don't get it despite reading the explanation several times :o The dyno has only one point of reference, the power at the rollers. This figure is deemed by most to be inaccurate. How that inaccurate measurement can suddenly become an accurate at the flywheel figure just doesn't equate. If it is simply a correction factor or something then why not have it applied instantly so that you see an accurate ATW figure?
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We had a huge debate on here a while ago about this.

The crux of it all is that "at the wheels" is not a fixed definition. A dyno with one roller quotes "at the wheels with one contact patch" and a dyno with two rollers quotes "at the wheels with two contact patches". Both are correct for what they are and neither one is more accurate than the other. Neither one is "at the wheels on the road" because a roller isn't a road. You cannot compare an "at the wheels with one contact patch" to an "at the wheels with two contact patches".

By measuring the drag on the rollers during the dyno run you can work out how much is being lost in the system and add this to either a single roller or double roller readout to get the fly figure. The fly figures should be the same for both the single roller and double roller. The single roller at the wheel power figure is higher with lower drag, whereas the double roller at the wheel is lower with higher drag.
 
I don't quote my RR figures too much now, despite having it done on two different types of rollers 12 months apart by two different companies 150 miles apart and getting the same figure to within 0.2bhp people still had a big fight that the figures were made up crud. One of them was even Powerstation at a OcUK RR meet infront of 20 other members, stock cars getting exactly what they should etc...

They may not be accurate to the millionth degree but they will do for me and allow me to know pretty much how much power the engine is putting out.
 
My car did better than I thought, for a battered 420 diesel anyway. 130bhp up from 103, with just a variable resistor mod. :p

I don't doubt their figures, as it got the same a couple of months later.
 
PMKeates said:
We had a huge debate on here a while ago about this.

The crux of it all is that "at the wheels" is not a fixed definition. A dyno with one roller quotes "at the wheels with one contact patch" and a dyno with two rollers quotes "at the wheels with two contact patches". Both are correct for what they are and neither one is more accurate than the other. Neither one is "at the wheels on the road" because a roller isn't a road. You cannot compare an "at the wheels with one contact patch" to an "at the wheels with two contact patches".

By measuring the drag on the rollers during the dyno run you can work out how much is being lost in the system and add this to either a single roller or double roller readout to get the fly figure. The fly figures should be the same for both the single roller and double roller. The single roller at the wheel power figure is higher with lower drag, whereas the double roller at the wheel is lower with higher drag.
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the source of the confusion is that Meridian has had his car run on a dastek dyno (iirc ?) which also uses 2 rollers but gets more reliable at the wheel figures. We can conclude from this that either they apply some sort of correction factor to that result to take account of the 2 wheels ...

either that or ..

they too have two contact patches but get more accurate figures and the stuff maha says is just a load of excuses to make up for the fact their dyno is inaccurate.

Take your pick who you believe.
 
MrLOL said:
the source of the confusion is that Meridian has had his car run on a dastek dyno (iirc ?) which also uses 2 rollers but gets more reliable at the wheel figures. We can conclude from this that either they apply some sort of correction factor to that result to take account of the 2 wheels ...

either that or ..

they too have two contact patches but get more accurate figures and the stuff maha says is just a load of excuses to make up for the fact their dyno is inaccurate.

Take your pick who you believe.
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erm, did you read the post. You have provided answers to a question that was not asked (or implied)
 
eh ? :confused: of course i did, my post was entirely related.

PMKeates was elaborating on the fact that quoted "power at the wheels" figures from dynos with one roller and two rollers cannot be compared

I was pointing out that other dynos with two rollers get vastly different and more likely power at the wheels figures, which is the source of the doubts about Maha's dyno.

What was your point again ?
 
[TW]Fox;18245134 said:
50 quid for 10 minutes work?

lol?
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Aye far better margins than selling computer components.

Suppose the argument is its the time of 1-2 operators, the money originally invested in the rolling road and the maintenance of it. :)
 
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