The dyno is correct/calibrated as the power and torque cross at 5252rpm.

The wheel figure is always correct as that is what the dyno actually measures.

The flywheel figure is calculated and has been done incorrectly. Take the car to PT and a bet you get less to me 234 wbhp = 280 BHP.

I'm sorry if that sounds harsh but that dyno is giving you wrong information.

on the dyno i went on my Wheel bhp came out at 247...
my clutch/flywheel power at 259...
Thought these figures were a little close together??
But as it is actually the wheel hp they measure i'm not to bothered at the mo.
Once i've put 3" downpipe on in addition to the 3.8 bar fpr (only had 2.5 bar one in when last dyno'd!!) i should be pretty close to where i wanna be.
i'll get it R/R at a local place first then i reckon a few of us from round the midlands area should all have a day a Powerstation???
It would be good to compare results from one dyno to another to see how much it really can vary???

Nick

I'm amazed at how often this comes up

The wheel power on a MAHA dyno is ALWAYS lower... ALWAYS. This is simply a product of their technology, nothing else.
The MAHA is pretty much the most expensive dyno available used by Porsche and Audi as their OFFICIAL dyno in house.

There have been 100+ coupes run at Powerstation including individual power runs to full rolling road days. Nobody, and I repeat nobody has ever had a "bad" reading there. That includes standard cars and modified cars such as:

Scooby - 227bhp & 222lbs/ft (171 @ wheels) - STANDARD
Jimbo - 278bhp & 268lbs/ft - SUSPERSPOOL
Nobby - 305bhp & 285/lbs/ft (232 @ wheels) - GT28RSR
Nigel - 302bhp & 245lbs/ft - GT28R
Flea - 360bhp & 323lbs/ft (287 @ wheels) - GT28RS 0.86
_Tom_ - 249bhp & 208lbs/ft (179 @ wheels) STANDARD CLIO V6

The list goes on...

I have run there many times especially with my old 28RS setup. I was consistently making 350-360bhp at Powerstation and 350-360bhp at PTS, Luton.

The FACT is wheel power cannot be compared between dynos. PT use a Dastek dyno which reads VERY high wheel power. You could argue that Dastek inflate the wheel power considerably with silly low transmission losses.

My own example:

PT (Dastek) - 423bhp & 368lbs/ft (393 @ wheels)
Powerstation (MAHA) - 480bhp & 367lbs/ft (358 @ wheels)

So at PT I get 35bhp MORE at the wheels with ONLY 7% transmission losses which is pretty much IMPOSSIBLE!!!

I like both dynos but to say one is right and one is wrong when they are BOTH as right/wrong as each other If Ash went to PT then he would get a HIGHER wheel power guaranteed, that is simply how Dastek dynos work. I have spoken at length with the designer of the Dastek dyno and believe me he has a lot of respect for the MAHA dyno except for the fact it's pretty much twice the price!

Look at the facts and figures I have mentioned, and no amount of hearsay or speculation changes that.

I think that many of us are just curious that there is a big difference between wheel HP and Fly HP. And now we now that there is a big difference between RR places.
Don´t be amazed Flea, many of us have not been here since day one and don´t know the downright story

The only thing you can reliably go on is the WBHP. Whose dyno is calibrated right is the only question worth asking here.

Thanks for the input Flea, my engine has 155psi on all 5 cylinders as was checked by myself using snap on gear afew months ago. The engine is running sweet and feels very quick (wish my gearbox was the same )
I was expecting around 300bhp mark as that's what everyone seems to get and i got all the correct mods before the dyno (been getting right mods for over a year now and been waiting to up the boost) The bloke that did the test said both cars seemed very well modded and couldn't believe how well they performed compared to the Subaru's they do
I had mine rolling roaded at noble motorsport in January on a hybrid with cat and small intercooler and it made 251bhp at 1.2bar, after doing these extra mods ( gt28rsr, decat, apexi, bigger intercooler) the car is lots faster i can feel the difference at least 40/50bhp.

Leighton do you know why my power dips off at 5800 for abit then starts to rise again?

Ash

leighton I've not spoken with dastek but perhaps you can explain for all of why they produce such odd results, between the equipment one of them must be wrong! They only have to measure torque, please enlighten me.

Its true about comparisons, do all the tuning on one RR. No FWD transmission losses 20% power think about the logic all that energy has to go somewhere, and you can guess the oil temperature increase from it specific heat capacity. Was matey at dastek trying to sell you a RR of course he's going to tell you what you want to hear!

Rich

Modern dynos are no longer a simple bit of kit. In the old days, and still in the US, you could calculate the torque very simply by measuring how quickly a car could rotate the known mass i.e. inertia, of the single roller where the wheels sit on top. This is very consistent (other variables aside such as wheel slip, mechanical problems) however it has a downside in that only wheel power can be measured and it is much harder to tune a car as there is a fixed load invariably lower than experienced on the road.

Modern dynos are designed to offer a great deal more most notably 1. Variable loading to simulate many road conditions 2. Flywheel power via a coastdown measurement. By varying the load you can tune a car much more effectively by holding various load points in the maps and rpm range which is simply impossible via an inertia dyno. While wheel power is useful for the "tuning" world, the industry standard from factory is to quote flywheel power therefore modern dynos use a number of methods which primarily incorporates a coastdown measurement whereby the car is put into neutral as soon as the clutch is dipped and the resultant transmission resistance is measured throughout the full rpm range.

Between dyno manufacturers they use greatly different hardware from single drums per axle, twin drums per axle or independan twin drums per wheel. The wheel can simply sit on top of the drum or actually sit within a twin roller recess which can in many cases pinch the tyre to provide greater tractability. All these methods place diiferent loads on the transmission right from the tyre pressure, contact patch and actual loading on the wheel. The important consideration is to ensure that the software algorithms used can accurately account for all these manifestations.

Dastek dynos were built with flywheel as the goal not wheel power. They are supremely consistent between runs and can really detect minute changes. The same is true of the MAHA dyno which is built for flywheel measurement and also has fantastic accuracy regardless of temps or other conditions. You cannot compare the wheel power of these dynos but you can compare flywheel power all other variables aside. One thing I will say about Powerstation compared to any other dyno I have been to is that they have the most sophisticated temperature controlled dyno cell. The power of their fans and exhaust extraction is exceptional.

All this doesn’t really explain why there is such a big difference between dynos. What we can all agree on is that the torque measurement is correct.

Since BHP is a measurement of torque against engine speed. In your example:

PT (Dastek) - 423bhp & 368lbs/ft (393 @ wheels)
Powerstation (MAHA) - 480bhp & 367lbs/ft (358 @ wheels

You both have the same ft-lb but at what rpm is this peak power for each?

The same engine will vary peak torque and at different rpms based on a number of variables i.e. boost, inlet temps, fuel, load, heat soak. Even on the same dyno you will get variations from day to day and month to month because the environment is very fluid. You only have to watch a car do 3,4,5,6 power runs and it will slowly loose power and come in later due to the changing conditions... the dyno is the same.

The above does explain the difference between dynos, they load the car differently via the actual hardware used. You have different rollers, size and mass, different dyno brakes from eddy current to water, different contact patches and friction, different cooling capability and finally different software algorithms to interpret the data... that's a lot of variations.

If you want to start picking results apart then you have to look at all the variables behind it. DoctorFrag knew how to play the game well He had his car mapped at PTS a few times which invariably ment 20+ power runs on the dyno. While this is a requirement for mapping the AFR and timing it doesn't do the power figures any favours. So he would leave the car on the rollers and then first thing in the morning when the car and dyno room was cool as a cucumber fire it up and do a power run. That was good for an extra 10-15lbs/ft and 10-20bhp from the day before... nothing has changed on the dyno, just the conditions When I ran at Powerstation and made 480bhp it was 0c, I rolled up from cruising on the motorway and straight into the dyno room for an ice cold power run. We have all experienced the benefits of cold air on the winter nights where the car justs goes so much better, well you can measure that too. Cold air and a cool engine does wonders for turbo efficiency and combustion.

I'm not being that picky I'm just curious as there is a big difference to say 423BHP then say 480BHP? When people ask you 'what you running' what you gonna say? Do you see what I mean?

5 degrees air temp is 1% power.
A hotter engine actually produces more power.

Why don't you post your PT dyno so I can compare it with the power station one?

Heat soak in an engine will loose you power. Higher ambient temps will loose you power. Tyre pressures will affect your transmission losses. All these little things make a difference.

When people ask me what I am running I invariably say somewhere around 450bhp. It doesn't matter so much to me as the car is proven as they say on the black stuff whether that's the 1/4mile, 3/4 mile, 1mile, track day. Late last year I went on another Dastek dyno and made 430bhp. At the time it was the most powerful car he had had on the dyno out of 200+ cars. That included two Ferrai 360 Modenas who were both down on power by 20bhp at 380bhp. What can they say, Ferrari says the 360 has 400bhp but the dyno says no...

I was updating my hall of fame results and then i stumbled on this.

I have a new question. Why have you mixed your dyno results?

In the hall of fame http://www.online-presence.co.uk/_coupe/
you have put your BHP at 480 your WBHP at 393 and your ft/lb at 368. When in this thread you have got these results:

PT (Dastek) - 423bhp & 368lbs/ft (393 @ wheels)
Powerstation (MAHA) - 480bhp & 367lbs/ft (358 @ wheels

Now that is blatant lying because you know you cannot mixed two different dyno results together to suit you. So all this technical talk above means nothing in your case as your figures are now false. Would you care to explain this?