450bhp / 580nm

[BlackBeast]

Tyre size is 235/35/17.

As an UK Volvo tuner (and I use the term tuner very loosely) has branded those who went on the dyno day and the dyno operator themselves as cheats I will be taking the car to a dynojet RR (same as what they use) out of pure curiosity more than anything else.

This is an email from Powerstation in the UK, that have the same dyno as what mine was tested on. Should explain a few things.

As you will have seen, when your car was on the rolling road, it is gently accelerated and progressed into the appropriate gear for the run. This gear is determined by the power of your car and the speed achieved when peak rpm is reached. If we tried to run your car in say third gear we would not be able to stop it wheel spinning and also the acceleration of the vehicle would be far to quick. In sixth gear the run would take much to long and the terminal speed would be too high, so we chose 5th gear (Andy will make this choice almost instantly through experience).

Once he is in 5th gear he will push the accelerator to the floor. The car will be allowed to accelerate at a fixed rate by the dyno’s power absorber varying the resistance at the rollers. Once the power starts to drop away on the graph the operator will clutch in and select neutral. He then lets the vehicle coast to a standstill. Whilst the coast down phase in operation the dyno measures the drag caused by the accumulated losses of gearbox, diff bearings and (much more than anything else) by the tyres on the rollers. The drag of the tyres on the rollers as huge and much greater than those experienced on the road. This is because on the road the tyre sits on a flat surface whereas on the rollers it is deformed by two, fairly small radius, contact patches.

It is important to note that on the Maha dyno the drag curve is not calculated it is measured, it is real. The fly wheel figure is calculated by adding the wheels figure and drag figure together, both of which are real world measurements.

Some things to consider when looking at your graph.

1. The drag curve is exponential. The faster you go the steeper the curve. This how you ended up with a very high drag figure, your car will have hit over 140mph.

2. The wheels figure is meaningless without a drag curve. If I ran your car in 4th gear you may have 140bhp/120mph at the wheels. If I then ran it in 5th gear you would have around say 125bhp/145mph. The engine is still producing the same power so why are the two figures different? It is because of our old friend the drag curve. At 120mph there is a far lower drag than at 145mph so the wheels figures will differ.

3. Some dyno’s do not have the ability to measure drag so they are forced to try and calculate it (dyno dynamics etc.). In my experience this calculation is always flawed for the simple reason that the drag curve rises exponentially. The favourite way they calculate this is by adding a percentage to the wheels figure. This can never work as the drag of the tyres is not influenced by the power of the engine in any way. A good little check you can do with your graph is to look at the peak power rpm at the wheels. Because of the shape of the drag curve this will always be at a lower point than the peak power rpm at the flywheel. If they are the same then the calculation used is fatally flawed and must, by the laws of physics, be giving you incorrect information.

I hope this is of use to you and has given an incite into how the dyno works. I have great faith in our Maha dyno and this faith is shared by a number of vehicle manufacturers and major race teams who use this unit.

Best regards

Rich

Powerstation UK Ltd.

[ozzimark]

Power lost to tire/gear/bearing/etc friction scales linearly with speed.

Aero drag scales with the square of velocity.

Nothing that a dyno looks at will scale with an "exponential" curve, since that would mean that the drag increases at a rate equal to e^x, where x some variable based on the velocity.

[JCviggen]

That's a good result BB, nothing wrong there.

It's normal for a MAHA dyno to show a drag curve like that, I've not seen them lose quite thàt much with a FWD setup but that's probably explained by the fact the run was done in 5th gear with a very high tire speed.

4th gear is a little more suitable in my opinion, but the end result shouldn't be too different.

Dynojet would probably show 400 at the wheels (though you never know with the lack of load)

Post up some 62-120+ videos would you, those are more fun to look at :D

[Johann]

Forget the dyno debate.

Those are great numbers. Probably, like Jan says, 400+ WHP with a good swing..

The 5100 RPM issue is a flow thing. Engine characteristics. I can understand the urge to buff it out but I don't think your butt dyno can replicate it. Maybe your boost gauge can.

[BlackBeast]

That's a good result BB, nothing wrong there.

It's normal for a MAHA dyno to show a drag curve like that, I've not seen them lose quite thàt much with a FWD setup but that's probably explained by the fact the run was done in 5th gear with a very high tire speed.

4th gear is a little more suitable in my opinion, but the end result shouldn't be too different.

Dynojet would probably show 400 at the wheels (though you never know with the lack of load)

Post up some 62-120+ videos would you, those are more fun to look at

Thanks Jan, I agree that it would have been more suitable in 4th, hopefully they will allow the car to run in that gear when I find a decent unbiased dynojet operator.

As for videos, I have none, will have to sort some out.

Forget the dyno debate.

Those are great numbers. Probably, like Jan says, 400+ WHP with a good swing..

The 5100 RPM issue is a flow thing. Engine characteristics. I can understand the urge to buff it out but I don't think your butt dyno can replicate it. Maybe your boost gauge can.

Thanks Johann, I have an obd2 datalogger (Innovate OT-2, not the OT-1 lol) which will be slightly better than my butt dyno. The last time I set up the EBC was a few months ago, since then the manifold has been welded to the turbine housing (T3 side) and the ATP ultimate internal wastegate welded to the turbine housing as they were found to be leaking badly. You could well be correct that it's down to boost.

[lookforjoe]

Definitely get some video footage when you can! I'd love to hear your wagon. Logging data will also be good to look at, I'm curious to see what your AFR's & timing look like on a road pull over a similar range.

Around 400 wheel makes more sense, based on the torque figures. :)

[flyfishing3]

I am running about the same wheel HP right now.

Josh's motor correct? i wondered what that thing would put down.

[850wagonT5]

"china rods?"

Haven't heard that term yet...who makes em, where did you buy em, and what do they cost??

[BlackBeast]

"china rods?"

Haven't heard that term yet...who makes em, where did you buy em, and what do they cost??

Most of the smaller companies get their rods from a factory in China, the likes of Kalmar Union in the UK to RSI in the states if im not mistaken. Unless the vendor states that they are an actual make like Pauter etc etc, 99.9% of them are chinese rods.