996 GT2 dyno run on Maha LPS 3000
Discussion
Car is running an exhaust, air filter and extreme map. I'm concerned with drive train losses!
The maha works by calculating wheel power from torque from tractive effort. Then calculates drive train losses, rather than using a 17-19% rule of thumb for 2wd.
Which then in theory gives a true flywheel fig.
Am not really interested in the flywheel hp, as wheel power is the true measure of a car. But how am I losing the 180 drag power. My theory is clutch, but it is not noticeable hugely on road at mo. The car pulls v hard in low gears, not always so hard in higher gears.
The maha works by calculating wheel power from torque from tractive effort. Then calculates drive train losses, rather than using a 17-19% rule of thumb for 2wd.
Which then in theory gives a true flywheel fig.
Am not really interested in the flywheel hp, as wheel power is the true measure of a car. But how am I losing the 180 drag power. My theory is clutch, but it is not noticeable hugely on road at mo. The car pulls v hard in low gears, not always so hard in higher gears.
Kurgen_ said:
Car is running an exhaust, air filter and extreme map
...The car pulls v hard in low gears, not always so hard in higher gears.
...The car pulls v hard in low gears, not always so hard in higher gears.
sry cant see the graph assuming from above post its 600bhp...
if you're acheiving 600bhp just by overboosting (can standard k16 even get close to that?). BANG. who did the map?
but if its not pulling hard in higher gears
its not 600, infact its probably not even 500
Kurgen_ said:
The GT2 has the same turbos as X50 (K 24). The map is a Revo map.
If the clutch is slipping the car would pull hard in low, but not high gears.
will try and scan and post a better graph.
If the clutch is slipping the car would pull hard in low, but not high gears.
will try and scan and post a better graph.
my mistake re turbos. duh. if the clutch was slipping you'd feel/smell it surely? have you asked mitch what the map should produce as he did it?
Mitch has seriously tweaked the car, we have spent some time on road mapping.
I can smell a slight burning smell when booting car, and it does not always pull as hard in high gears.
Car has been dyno'd at Welt and Allan has told me clutch is slipping, car made similar wheel power (420-430) but their dyno back calculates using a Porsche 2wd formula. This gave 520 bhp flywheel based on 18-19% losses assuming drive train was in tact.
It doesn't matter if car is making 1000bhp at flywheel, if it only makes 430 at wheels.
My concern is whether clutch is knackered.
I can smell a slight burning smell when booting car, and it does not always pull as hard in high gears.
Car has been dyno'd at Welt and Allan has told me clutch is slipping, car made similar wheel power (420-430) but their dyno back calculates using a Porsche 2wd formula. This gave 520 bhp flywheel based on 18-19% losses assuming drive train was in tact.
It doesn't matter if car is making 1000bhp at flywheel, if it only makes 430 at wheels.
My concern is whether clutch is knackered.
There looks to be something wrong with the losses number, 180hp is way to much for a RWD 911..... 460RWHP is typically about 520hp flywheel in my experience....
What do the numbers in the bottom right corner mean -what is "Rotating vehicle mass" -does the values of these numbers affect the "drag power" number.
Someone is not operating this dyno properly !
What do the numbers in the bottom right corner mean -what is "Rotating vehicle mass" -does the values of these numbers affect the "drag power" number.
Someone is not operating this dyno properly !
Divide the rear wheel HP by 0.85.
In your case 430 / 0.85 = 505 hp at the crank. This is probably what your engine is making. It is fairly reasonable assumption for a RWD car.
Historically, this has always been a huge topic for arguments. THe fact is, real engine HP can only really be measure on an engine dyno. But, many, many people have empirically compared engine and rear wheel dyno figures and come up with 15% losses for a RWD car as reasonably accurate. It will no doubt vary, and tyre slip etc etc all has an effect.
For a good read go to:
www.pumaracing.co.uk
scroll down to the bottom and read some of the pages on coastdown losses etc.
Bloody good read.
For those who really want to believe that 30% losses are real, the easy way to check is to weigh your car and do some foot to the floor, straight line acceleration test with a data logger. With accurate figures for vehicle mass, gearing and tyre size, any decent simulation software will very accurately calculate the HP needed to produce the acceleration you measure.
If, on the other hand you just want to tell people at the pub you have a 600 HP car, just tell them.
In your case 430 / 0.85 = 505 hp at the crank. This is probably what your engine is making. It is fairly reasonable assumption for a RWD car.
Historically, this has always been a huge topic for arguments. THe fact is, real engine HP can only really be measure on an engine dyno. But, many, many people have empirically compared engine and rear wheel dyno figures and come up with 15% losses for a RWD car as reasonably accurate. It will no doubt vary, and tyre slip etc etc all has an effect.
For a good read go to:
www.pumaracing.co.uk
scroll down to the bottom and read some of the pages on coastdown losses etc.
Bloody good read.
For those who really want to believe that 30% losses are real, the easy way to check is to weigh your car and do some foot to the floor, straight line acceleration test with a data logger. With accurate figures for vehicle mass, gearing and tyre size, any decent simulation software will very accurately calculate the HP needed to produce the acceleration you measure.
If, on the other hand you just want to tell people at the pub you have a 600 HP car, just tell them.
stevesingo said:
Powerstations rollers by any chance?
Their powertrain losses for 2wdare way too high IMO. My M3 Evo3 (238bhp stock) put out an alleged 258BHP (190 @wheels) after a change of engine managment and nothing else. 30% is way too much to loose.
Steve
Their powertrain losses for 2wdare way too high IMO. My M3 Evo3 (238bhp stock) put out an alleged 258BHP (190 @wheels) after a change of engine managment and nothing else. 30% is way too much to loose.
Steve
Powerstations rollers always give high losses.
The losses depend entirely upon the gear used and the dyno. 15% is a fairly good number to use on some dynos, but others (such as the dyno dynamics, use nearer 19% which seems to work fairly well. I would say that car has around 520bhp going from the wheel pwr. Also depends if the intercoolers where cooled on the dyno, because Porsches pull timing as soon as the intake temps go up even a bit. We don't have the fans, so won't do turbo porches.
I would take it to Weltmeister or Parr who are both equipped with the correct fans to do the job.
GuyR said:
My car has the 590bhp Ruf package
The easiest way to settle it is to race mine against yours and the winner keep the losers car......
GT2 Jedi Master Guy, I bow to your superior powers and knowledge..
I am but an impudent upstart, who desires to comprehend the true power and awareness of the GT2 force!
Yours unworthy,
Robbie
like the idea of racing for pink slips though.
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