Pro's & Cons of Dyno's

[Stuart]

Ahhhhhhhhhhh Mr Hayward. How you love a parting shot

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As mentioned above, I can take my 4 litre V6 down there and try both ways. Can report my findings if there is sufficient interest

[gary@apt]

Which reminds me Gary, have you still got your old 2WD portable unit. Last time we talked I recall you saying that you wanted shot of it, if that's still the case drop me an email.

sorry thats long gone now :-D

[duncan]

What car was this alleged discrepancy on?

Is the transmission that unusual to cause you to worry about whether the piece of paper print out shows every last HP or over estimates your power ?

[cng1]

Dyno-dynamics themselves say that you will always get a difference in accuracy between shootout and mapping modes so it's more than just an alledged inaccuracy. Indeed it's pretty common sense that if you take an average of one sort of thing and then use that for another sort of thing that your results won't be as good as if you measure things each time as you do when you use the dyno in normal mode.

My own experience is with a 360-370ish BHP cosworth engined westfield - which is about as far from the cars that dyno dynamics used to calculate the "typical" compensation tables so in their opinion presented just about the worst case for shootout mode.

I personally don't give a damn what a piece of paper from a shootout mode says, as long as people have their eyes open and compare apples with apples then they should have no issues.

[Stuart]

Appropriate comparisons are vital. Westfield sounds like a giggle

[ScoobieWRX]

These are the gear ratios for my car, 02 WRX. Can anyone tell me which one of these is 1:1 and why?

1st - 184.2105263
2nd - 102.9411765
3rd - 72.16494845
4th - 51.09489051
5th - 38.88888889

Final Drive - 3.9

Genuine question

[cng1]

Erm, yeah I guess that "giggle" does just about cover it... The 2.5 litres of fuel a minute at full chat is rather less fun but hey-ho it's got similar aerodynamics to a brick wearing a parachute so what do you expect

In some ways the best bit is turning up to a trackday with 4 spare wheels and tyres strapped to the roll bar and parking up next to somebody polishing the 'rari that their prep-team towed there on their race transporter. They expect you to be on their tails through the corners but they don't expect a "plastic pig" to outdrag them down the straights at 150+. For some reason they give me a wide berth for the rest of the day

[cng1]

These are the gear ratios for my car, 02 WRX. Can anyone tell me which one of these is 1:1 and why?

5th - 38.88888889
Final Drive - 3.9

Are you sure about those ratio numbers, they all look rather odd to me. I'd expect them to be more like this in form:

1st - 2.8:1
2nd - 1.9:1
3rd - 1.3:1
4th - 1:1
5th - 0.8:1

That said if you've just got the decimal point in the wrong place then 5th would be 1:1 by virtue of dividing by the final drive. That would be a very short ratio box though and would be geared for a low top speed.

[ScoobieWRX]

Apologies....i copied the wrong bit....they are rpm per mph

Here is the correct info....

1st - 3.454
2nd - 1.947
3rd - 1.366
4th - 0.972
5th - 0.738

Final drive is 3.9

sorry and cheers

[cng1]

On that basis you don't have a 1:1 ratio which is rather unusual. 4th is close but not quite.