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Ratio's wanted for road dyno calcs.

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Old Jun 18, 2003 | 11:51 AM
  #1  
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I've just done a single run in my car using the road dyno.

I'm not sure if I've got all the ratios right, 3.54 for drive and 1.9 for 2nd gear. Can anyone shed any light on the subject because I only seemed to manage 204bhp and 197 Ilb torque.

MY97 uk
Full decat
K+N
VTA
I/c tilt mod
Sit i/c and pipes
60k sevice just been done
And drives mint!!!

It cant be right but then again it was only my firs run.

Anyone wants a pic of graph I'll try and e-mail it.

Also which cylinder fires first? Nearest driver or drver side front?

[Edited by Nick200 - 6/18/2003 12:15:13 PM]

[Edited by Nick200 - 6/18/2003 3:43:00 PM]
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Old Jun 18, 2003 | 12:33 PM
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204 sounds about right to me. Remember that a road dyno gives you the power at the wheels - it can't give you power at flywheel (250ish at a guess for your car)

Who's road dyno did you use? (I'm interested, as I've designed my own and am currently testing it...)
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Old Jun 18, 2003 | 12:40 PM
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sounds like the "road dyno" product, uses an RPM pickup

power sounds about right for at the wheels.

Paul
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Old Jun 18, 2003 | 12:46 PM
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It works in a similar way to mine then... Must get it finished.
Yet another job for the weekend!
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Old Jun 18, 2003 | 12:55 PM
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Well I'm baffled now.
I just went out and found an ideal road, pulled off in second upto 1200 rpm then floored it, WTF 316bhp 298 torque??????????

Dyno from brd 117 all in.

Also got to 60 in 5.7 seconds (pull off in second gear!!!)

Try my bro's corsa tonight

[Edited by Nick200 - 6/18/2003 12:56:44 PM]

[Edited by Nick200 - 6/18/2003 12:58:42 PM]
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Old Jun 18, 2003 | 01:14 PM
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Right then I changed the diff ratio from 3.54 (as said by most people) to 3.9 (as per subaru) and figures went down to 254 bhp and 240 pound.

Its going to take some getting used to is this.

[Edited by Nick200 - 6/18/2003 1:15:45 PM]

[Edited by Nick200 - 6/18/2003 1:21:33 PM]

[Edited by Nick200 - 6/18/2003 1:23:55 PM]
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Old Jun 18, 2003 | 02:17 PM
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yes it has a 3.9 final drive ratio

3.9 at the front and a 1.1 drop and 3.545 diff at rear

I don't have figures to hand, but they are included in the deltadash "delta dyno" which you can download a demo of

Paul
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Old Jun 18, 2003 | 02:35 PM
  #8  
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cheers m8.

So it looks like my final figure is - 255bhp@6100 / 238 torque@4500.
Cant wait for the vf28 to be put on with gems!!!

[Edited by Nick200 - 6/18/2003 3:46:50 PM]

[Edited by Nick200 - 6/18/2003 3:47:49 PM]
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Old Jun 18, 2003 | 07:25 PM
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Still could do with knowing which lead is number 1 though people.
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Old Jun 18, 2003 | 08:03 PM
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I have recently purchased Road Dyno, where did you get the weight stats for your car from? I have a public weighbridge near to me, thought this would be the most accurate. If you have the same version as me it does take tranmission losses into account but only if you enter a value.

[Edited by Delboy2 - 6/18/2003 8:05:51 PM]
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Old Jun 19, 2003 | 07:56 AM
  #11  
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Transmission loss on 4 wheeldrive typically 25% so value is 0.25

I put weight to be 1380k icludes Me/ fuel/ all mods/ and other add ons.
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Old Jun 21, 2003 | 02:39 AM
  #12  
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What values did you use for Drag Coefficient and Frontal Area?
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Old Jun 21, 2003 | 01:28 PM
  #13  
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2.2 m2 for area and 0.32 for drag.

Seems to be what most people are using. And it really doesn';t make that much of a difference unless you change it to say 3 m2 which will make a huge difference.
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Old Jun 22, 2003 | 01:35 AM
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Where did you get the 2.2m2 and drag coeff from?
Also are you using 3.90 drive axle ratio or 3.545?
Cheers

[Edited by Delboy2 - 22/06/2003 01:37:58]
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Old Jun 22, 2003 | 01:45 PM
  #15  
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3.9 ratio, I got the drag etc from other websites using different hardware and software. It seems to be the norm for a scoob.

Besides if you actually measure the cars area it comes out about right.
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Old Jun 22, 2003 | 01:57 PM
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Cheers for that M8. Carried out a fair few mods now and wanna check the results which from driving seem extremely good
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Old Jun 22, 2003 | 07:21 PM
  #17  
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I would like these results clarifying:-

MY96uk wagon
Full Decat - JW racing twin dump pipe d/p
Scoobysport decat centre
Scoobysport Backbox
Jetex panel filter
MY95WRX ecu with custom mapped scoobyecu
HKS EVCIV Boost Controller
ERL Water injection.

With the boost set to 0.8kg/cm2(11.4psig)

Did a run using road dyno using the following parameters:-
weight approx 1380kg
Drive axle ratio 3.9
test gear ratio 1.366 (3rd)
Drag coeff 0.32
frontal area 2.2M2
drivetrain loss 25%
temperature 73Deg F
barometric pressure 29.71in
Elevation 22M
R/H 69%

The following results were obtained at the flywheel :- 246lb/ft @ 5100rpm
273hp @ 6600rpm
Do these figures look about right?
I am gonna do another run shortly using max boost available

Cheers

[Edited by Delboy2 - 22/06/2003 19:22:01]
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