Razor2001

Hi Guys,

I would like to get a vote on what people think the multiplier should be to get from WHP to BHP. Some say use 1.23 some say use 1.30 other may say inbetween....vote now !

Oh yea, does it matter what MY scooby or what gear you are in ?

Does anyone have a bog standard UK or JDM STI-7 delta dash run so we can kinda figure out a multiplier based on the delta whp and manufacturers claimed BHP figure ?

Cheers,
Ray

john banks

1.22 and off with these cheating Cds of 0.37 and silly weights too And ON with heavy smoothing. Change a few figures and I can get 400 at the wheels yeah right. See if you can work out what I faked. If I used *1.3 then I would have 522 bhp!

Dyno Test: 13
=============

Maximum Wheel Power: 401.4 BHP @ 6380 RPM
Maximum Wheel Torque: 399.3 LbFt @ 4406 RPM
Power to weight ratio: 271.2 BHP per ton

Terminal velocity due to power: 201.9 mph

In Gear Acceleration:
30 - 50mph = 3.0 seconds
40 - 60mph = 2.1 seconds
50 - 70mph = 1.7 seconds
60 - 80mph = 1.7 seconds
70 - 90mph = 1.9 seconds

Speed per 1000 RPM:
1st: 5.4 mph
2nd: 9.6 mph
3rd: 13.7 mph
4th: 19.3 mph
5th: 25.4 mph

Maximum Speed per Gear:
1st: 38.6 mph
2nd: 68.5 mph
3rd: 97.6 mph
4th: 137.2 mph
5th: 180.7 mph

Vehicle Mass: 1480kg
Drag Co-efficient: 0.37
Frontal Area: 2.20 square metres
Wheel/Tyre Setup: 215/45/17
Rev Limit: 7100
Test gear: 3
Max Speed of gear: 98 mph

[Edited by john banks - 2/21/2003 6:02:59 PM]

Razor2001

You faked the gear ?

1.22 man that means my car is a bag of crap bhp and torque

Forester_GP

John, it seems that you've seriously overinflated your tires to reach a "45 profile besides upping your boost to 1.7 bar...LOL

George

john banks

It is not slagging off the software let me be clear, but it really depends what you tell it. Just increased the tyre profile by 5%, used higher weight, light smoothing, and Cd 0.37. Everything else was proper, level road, correct gear.

The Cd actually makes only 1 or 2 BHP difference. Far more crucial is the weight and the smoothing.

[Edited by john banks - 2/21/2003 6:32:31 PM]

nom

Tyres.
Wow, do they make a difference.
And not doing the run in both directions to make sure 100% that the road is totally flat. A couple of degrees down & the numbers go silly...

Razor2001

1.22 seems low to me. Come on chaps give me some more votes.

We need a few DD's of 100% stock Scoobys to try and find a true multiplier.


Ray

Andy.F

LOL @ JB That's just like those stunning rolling road results that people can only get during a private session then they refuse to post the graphs for others to view and verify

FWIW I find 1.22x applies to my AP22 results.

pat

As a general rule of thumb, you can assume that you lose about 23% in the transmission in most Subarus. So if you're losing 23% down the transmission then that leaves 77% at the wheels, so it must be making 100/77 = 1.3 times the wheel figures at the crank.

It is VERY important to get the figures right. I remember early Road Dyno runs, when Bob, Mark and I were playing with them years ago... figures of 1200 BHP weren't uncommon, well at least until we got realistic figures for weight etc.

Cheers,

Pat.

john banks

There is a lot of conflicting data we've gathered then Pat...

A 1.3 multiplier would give my car reading 16% higher on the road than Star's dyno. As it was I got 9% higher on the road with a 1.22 multiplier. Something is wrong somewhere, especially since I got similar torque at wheels on the road to torque at flywheel on the dyno!

This was with the lower drag figure, average of two directions, correct gearing, heavy smoothing, weight was 1360 kg for a classic loaded with me 80kg, ICE 20kg and a half tank of fuel.

If I assume to be ultra conservative on weight, the 1235kg is with a full tank giving a weight of 1315kg for the outfit (60 litres of petrol weighs about 40kg), then it still gives 309 BHP at the wheels. Multiply by 1.3 and I end up with 402 BHP!! Again something is wrong.

Personally can't see it being higher than 1.22 for Delta Dash or AP22.

Perhaps the 1.3 is more applicable to rolling roads with double contact patches and tied down onto the rollers?

Star's fudge factor is 1.39 !!!! with 102.5 BHP losses for mine, which is not dissimilar to others.

I would suggest that the Scooby loses 100(1-1/1.22)= 18% through the wheels for road testing at least. When you set the AP22 up I gather you do a run down to get losses, but some users have got different settings on similar cars.

The truth for my car is somewhere between 356 and 402 BHP then I actually think it is bang in the middle, probably at PE it would be?

Could have told you that anyway without measuring it

How about we all go back to the "oh that feels f***ing fast m8" method since it seems as accurate

Although Alan G did think my car had not torque at 1.7 bar

[Edited by john banks - 2/22/2003 10:22:33 AM]

Andy.F

Yea, looked to me like you had no torque when you were pulling away from the RC Developments Stg 4 (420bhp) EVO7

AlanG