JamesGT3RS

....and yes a light weight flywheel does not increase absolute BHP

GT3 Rob

Reply from WRC on Pistonheads..



Dontcha just love it. What are the odds on one man owning two consecutive Porsche's with higher BHP than standard ? Would certainly get the sceptics going ?

A certainty is that on over 650 different dyno runs on our Dyno Dynamics rollers, in general "standard cars deliver standard horsepower" Particularly Porsche and Subaru as these were the cars used to model the extrapolations for the categories : 1] Rear engined 2wd and 2] Four Cyl Four wheel drive centre diff. The numbers are regularly revisited by Dyno Dynamics who take engines out and run them on bench dynos for comparison.
Another key factor in assuring accuracy is that in order to become a Subaru STi dealer in Australia it is mandatory that you have a Dyno Dynamics dyno !

A weather station is another "must have" to ensure that you provide corrected horsepower, that way if you test the same car on different days,hot or cold, the result should be within 1%

Our Dyno has had 2 seperate calibrations this year to ensure it is accurate but it is important to understand the importance of air flow in a dyno cell in assisting with BHP delivery. We have over 100,000 ft cu per min of fresh cold dense air pumping through our purpose built dyno cell. We have a dedicated 22,000 ft cu ceiling mounted Porsche fan delivering cold dense air drawn from outside through a plenum chamber onto the engine lid/intake. This creates a similar air flow to actual on the road driving, which some dyno companies may find difficult to replicate.

Let us look at Porsche in isolation, I believe the factory quote a minimum BHP and have a tolerance of 5% upwards... So 380 x 1.05 = 399 so it is entirely plausable that Rob's GT3 MK2 achieved 397 BHP on our rollers. My own GT3 Mk1 only achieved 348 on a similar set up because it got nursed around everywhere and ran on whatever fuel was available but on the same day as mine was tested other standard GT3 Mk1's ran 360 and over because their owners caned them and only ran Optimax. So with the GT3RS it is entirely possible that higher number can be achieved, particularly when the car is full of good fuel and the ECU is in full open mode on ignition etc.

I am not saying every make or installation of rolling road is 100% accurate merely stating that we have done everything possible on our dyno installation to recreate conditions as close as possible to on road real life driving. Hopefully this has resulted in accurate results. I firmly believe that this is why Evo Magazine chose Weltmeister as their preferred rolling road. They take our figures over manufacturers and use them in their road test results.

Cheers

Allan
Weltmeister

GT3 Rob

Link to Pistonheads thread..

http://www.pistonheads.co.uk/gassing...19562&f=48&h=0

Rolo

Well, I have never had mine tested, and its a simple run of the mill GT3. But I can hold my own on the track against Tech Art 500HP TTs and PSI 500HP TT....Now I am not faster, but the difference in straight line speed is not all that different. If this car truely is only a 380 hp car....Well it does a hell of a job getting the power to the ground, thats for damn sure

rockitman

my dyno sheet overlaid with Larry Herman's from Mustang chassis dyno. Larry's Gt3 with bypasses... not sure if muffler or cat. They are Loud !!! Probably muffle byp. Mine is "Base" with the Europipe. 372 at the wheels. Closely translates to 420Hp @ the crank.

sweanders

Does this person know anything about dynoing a car? He seems to have overlooked a small thing called driveline losses.

rockitman

yes sweanders...it's the rubber to the pavement figure that counts

GT3 Rob

Think the dyno is capable of calculating transmission losses.. derr

These figs are ATF.

No very knowledgeable into how a dyno works myself.
But thought it interesting that the WRC setup, is capable of re-creating the ram air effect of the RS on road.. would explain someway as to why the figs are higher than GT3.

Rob

sweanders

All chassi dynos on the market except one calculate power from several variables. So to claim that a dyno gives you the true flywheel hp rating is nothing but a lie. It is impossible to calculate driveline losses since they wary on the load - this basicly means that a 300 hp engine and a 310 hp engine will not have the same drive line percentage. Doing a coast down test will not tell you anything usefull.

Also, any roller type dyno out there can impossible be accurate since you have varying grip.

Dynos are great for baselines seeing how a car performs over time and for trouble shooiting. Great tool when tuning a car but to use it simply to measure power is useless if one aims to compare it to numbers measured differently.

Also, I believe that hp rating from Porsche is from during load at a steady rpm and not when doing a rpm sweep.

GT3 Rob

ATW fig for my RS was .. 351.3 bhp

TB993tt

Noticed in GT mag that the Cargraphic GT3 RS which did so well in the German Tuner GP ran 411PS on RS Tuning engine dyno, mods were full exhaust filter and of course the bespoke mapping - just makes the 420 measurement look a little unlikely ?

sweanders

With 19% losses I would advice that you release the handbrake before calcultating driveline losses..

GT3 Rob

lol

420 ATF
353 ATW

that reads 16%..

Maybe you should have spent more time at school..

you need help with your spelling as well.. !

Woodster

Sweanders, do you think the MAHA dyno is accurate at estimating
flywheel horsepower ??
Have you been spending too much time with that beautiful German
gal racer? LOL

MK

sweanders

16% is still way high, thank you for pointing out my math error.

Feel free to point out my spelling mistakes, I'll trade you the the same service when you need to write something in Swedish..