Check these graphs ..

RB320 with Enginetuner forged motor, SC46 turbo, Perrin front mount.
Mapped by Martyn using Ecutek Race Rom
Notice no loss of power anywhere from stock!
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2008 STi Hatch with Enginetuner forged motor, SC46 turbo, Cosworth front mount
Mapped by Martyn using Ecutek Race Rom
Using the actual log data, the flow rates are the highest figures yet seen by Ecutek on these cars.
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It's the silver one, the other one with virtually identical spec is still running in!

Dyno run for Enginetuner 2.1 stroker with twisted GT35R, Syvecs ECU mapped by Martyn.
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Very impressive Alan...

I think I saw that Hatch at Japfest

Both were there as it happens! and a third.. Hatch city..

Alan, as a novice with no actual experience with using rolling roads, could you explain something for me? I saw a thread on Scoobynet where a guy claimed close to 380bhp from a VF35 with RR graph to prove. He was soon shot down in flames because it turned out the RR used measured the intake temperature against the atmospheric temperature and then in its computery jiggery pokery way calculated the bhp and added extra bhp to compensate for the difference between the two temperatures. I would seem the larger the difference between the two the extra the RR computer gave. He ended up with 30 odd degrees between the two and the computer whacked on approx 50 bhp to his total to give him the 380bhp.

Since then I have always paid attention to the IT / AT on dyno graphs. I have heard that 10 deg C difference is normal. The RB320 graph above is 9 deg C difference and the Hatch 15 deg C difference. Would your RR have adjusted the Hatches figures or is that something you can compensate for, or is it all just one big Scoobynet myth!!

As someone who owns and uses their own rolling road it would be nice to hear your thoughts on the subject.

Also, another thought as I was typing. Does it matter what gear you run in on the RR?

Hi Timmy.
This is my take on it. There is a quantifiable difference between power outputs on internal combustion engines relative to air density. You either take that on board or you don't. If you're going to make allowances for it, it makes more sense to measure charge temperature rather than intake temperature. As the results of doing that are actually quite radical, we may need to seek an alternative correction factor, more in keeping with a reasonable expectation.
Doing it the way we do, we can pretty much pull up the sort of flywheel figures you'd expect compared to cars that are manufacturer tested on engine test beds.
I'd say that's a reasonable yardstick.
If you take a look at the RB320 graph above, you'll notice the stock power figure very close to 320 bhp. As far as we're concerned that gives the datum point to claim 445 bhp from the tuned set up.
To answer your question directly, yes, intake temp makes a difference, and we think we have a handle on it, along with a whole host of other variables that would take an age to run through.

There is a fallacy extant that assumes that anything done on the public highway is accurate, and anything achieved on a dyno isn't. As I say, it's a fallacy.

Which gear to use is often relative to other factors, such as gearing, actual road wheel speed, engine type etc. I tend to run in direct top given most situations, although we'll often run in 4th gear with the six speed box. No particular reason, apart from the high gearing experienced with the UK versions. I'd say 150 mph on the dyno is fast enough thanks very much!

We're looking for consistency as tuners, more than specific power outputs.

Dyno operators are often accused of "sexing up" dyno figures. We aren't interested in that one! We have been told that cars we tune achieve higher figures on other dynos. Excellent!

If customers weren't interested in power figures I wouldn't quote any.

I'd have to say there's something that always makes me laugh, and that's the bit where "sit alongside the owner while he drives" mappers quote power figures, even though they often can't, and end up using dyno figures, even though they say they don't need one.
Funny old world isn't it?

Thank you for taking the time to explain Alan. I am slowly learning these things! Measuring charge temperature makes a lot of sense. I suppose RR are designed for N/A cars as well!!

I seem to recall reading about someone doctoring a graph by adjusting the height above sea level of the RR to achieve better results

I'm sure my RA was run in 3rd last time it was dyno'd which I thought was wrong at the time.