http://wahiduddin.net/calc/cf.htm

Though, i was pissng about with correction factors looking at DIN, ISO, SAE etc the other week and trying to emulate the weather from 2-3 month ago - it didnt work it didnt give me anywhere near the same figures when plugging in ambient temp and humidity.

Apprently for every 10C increase in intake air temps, air density is reduced by 3% and therefore horsepower is reduced by 3% so 251/100*3 = 7.5

When i looked around an 8 celcius temperature ambient increase reduced BHP by around 8BHP, cant remember humidy rating.

Only way for a fair test is back-to-back on the same day when using different parts.

 

Dyno's should have an ambient air temp sensor. It factors this in.

It's the easiest way to "fudge" figures - move the probe from the intake, to over the exhaust manifold.

This then compensates and adds some of the "lost" power back.

I've seen runs before where the "before mod" was 20 deg, and the "after mod" was 100 deg.

Supprising it showed an increase in power after the coast down figs were added (but the WHP figures were pretty much the same).

 

Agreed.

Any good dyno should have it's own weather station and apply a correction.

I had my Evo done the other day, and they put the IT probe in front of the intercooler. Technically it should go in the airbox or intake tract...

If you get a big difference between IT and AT it can come up with very suspect results!

 

What did it make Mark?

 

I'd rather not say

370 atf, it's lost a fair bit of boost for some reason. Still peaking at 1.8 as per when it was mapped, but tailing off to 1.3 quite quickly and eventaully 1.2.

Should be 1.5 held. That's a good bunch of horses!

Drives great though, and I suspect it just didn't like 27 deg c on the dyno.

 

That is a hot day for dyno run indeed. Still 370 ATF is not what you would call weak numbers

What boost controller are you using? Could you not dial in a little bit of gain and see if it holds boost better?

 

Just the OEM one mate. It's got a twin port soleniod on the MR model, and worked fine during mapping.

Will bung a boost gauge on there and see what the road figures are like.

It feels quicker than my old one, so I think it should be pushing 390.

I'm just trying to decide wether to go silly with it It's prefect as it is but i'd like more shove

Suspect something like yours would keep me happy on that front...

 

I think up to a point no matter what power you have you become used to it and crave that little bit more. Ive contemplated going bigger blower but have decided enough is enough on this car.

I think you should go for it though

 

Oh it does i agree.

Didnt think about moving a probe.

What i was getting at was using the correction manually by entering the temp and humidity rating to what it was a few months back when i managed to do it, i got no where near what i got on the day. - must of done something wrong