Ballcrusher said:
ok just one more . if a guy goes to a few rolling roads and they all come within a few bhp of each other does make the power output true or or would al the rollers be wrong...... my good man mr ess please explain cos they cant all be wrong.....?
Rolling roads can be very accurate, or very inaccurate.
Differeing makes of RR give different results...I prefer MAHA and measuring coastdown...some don't measurte coastdown at all, and simply add a pre-determined figure from a database (Dyno Dynamics for examply)
If the rollers have been calibrated recently and the operator sets the tyre pressures to the same each time, the owner uses the same fuel, the tie down straps are set to the same tension, the corrections to DIN 70002 (I think that's the standard) are correctly applied, the ramp/acceleration rates are set the same, the gear used is the same then it should read correctly...but I've had some very wild claims.
I've seen increases of up to 20 BHP by using different types of RR...
I can make the car show 15-20 BHP more by using 3rd instead of 4th...
I can pump the tyres up and get 5BHP...
I can reduce the ramp rate and see 20 lb-ft of torque.
It's not as simple as running the car, which is why on Dyno Days, some of the results are inaccurate as a S3 will need different settings to a FWD NA car, for example.
The only way to really find out if the dyno is accurate in my view, is to test a standard, new car.
On Stars dyno my Golf GTI made 151 BHP and 138 lb-ft.
My S3 made 208 BHP and 199 lb-ft.
An ex's Lupo GTI made 126 BHP and 105 lb-ft (I think)
My C4S made 316 BHP and 270 lb-ft.
All spot on the manufacturers figures...
So when I then end up at 275 BHP and 332 lb-ft, on the same dyno, run by the same operator, with the same set-up procedure...with my same tyre pressures etc, I can say reasonably accurately (to withing the 2% tolerance of the dyno + or -) that I've gained 67 BHP and 133 lb-ft.
I've seen my S3 make 285 BHP on other dynos...but I don't believe it.
It made 275 BHP on the dyno I believe to be accurate.
But if I chose to say it made 285 BHP I could...I have a print out (Well, David R does) but it wouldn't be true, in my opinion.
My Golf made 174 BHP on AmDs dyno...it made 160 BHP before mapping....a gain of 14 BHP peak and 18 BHP midrange (I think those were the figures)
On Stars dyno, swapping the chips about gave a BHP difference of 5-6 BHP.
Makes you think, doesn't it?
I've seen a Dubsport Mk3 golf 1.8T on stand-alone management run on Stars dyno...it apparently makes 305 BHP on Dubsports rollers.
It made 265 BHP on Stars...
The owner claiming the fans weren't big enough and it was heatsoaking...funny that my S3 made it's utterly reliable 275 BHP/330 lb-ft on the same day, with the same fans.
Rolling roads can lie...just remember that.
You seem to have a real hangup about your figures....
I've never said yours aren't possible...they are right at the top of what's possible on an S3, in my opinion. They seem a bit optimistic based on the work done...but it's possible for sure.