The petrol used was fine (EU 98 RON), the weather was perfect, the dyno is trustable (indipendent entity that even takes care of periodic car inspection in CH)
The result was not the one I was expecting.
Any thought, comments, ideas?

 

This is what was expected by looking at the tequipment on porsche website

 

It appears that you have confused horsepower at the crankshaft with horsepower at the rear wheels. Take take the rear wheel power and divide it by unity minus the assumed fraction of drivetrain losses. For a two wheel rear wheel drive, 15% is frequently assumed.

The graph shown is unclear and difficult to read. Torque in foot-pounds?

 

I would however,assume that drivetrain losses on a 911 to be minimal, as there is no driveshaft running fore to aft. I dont personally see anything wrong with that result, but perhaps a tune up would bring out a few more horses.

 

Sorry. I was mainly referring to the "potenza motore" (horsepower at the crankshaft) and "potenza corretta" (adjusted horsepower) that was supposed to be 280kW (381hp).
"Potenza ruota" is horsepower at the rear wheel while "potenza persa" is horsepower drivetrain loss.
So...
horsepower at the crankshaft: 347hp
horsepower at the rear wheel: 291hp
horsepower drivetrain loss: 56hp

"Coppia" is torque and it's measured in Nm.
390Nm should be 287 foot pounds

 

HI there

I have run my car on a MAHA dyno, they are great as they actually tell you engine power, so power at the flywheel and are generally accurate.

My car got 368BHP and 305lb/ft.

My car is a 2006 C2S with X51 manifolds, BMC air filter, so not full X51 car like yours.

As such your car is either not healthy or the specific dyno you ran on is in need of a calibration.

 

That's why doing dyno tests on a vehicle for anything other than comparing before and after installations is a total waste of money/time. It doesn't change what you have and can only set you up to be disappointed. Mine without dyno confirmation is (in my head) around 1,000 HP stock. No need to chance that I'm wrong.

 

That day I had too much spare time

 

Ale,
I would consider perhaps cylinder leak testing at this point, as you are right, those are very disappointing numbers. You might try another dyno run at a different date. Also, on installation of the X51 (aftermarket right?) did the installer flash the ECU with the new program required for the flaps to take advantage of the new airflow dynamics? (this might be redundant since the ECU "learns" over time anyway)

Mike

 

Hi Mike,
no, it's not aftermarket. The X51 has always been there. All car has been properly checked by Porsche Zurich in order to get the pre-approval for the mot needed to import the car.
They found a small leak (fixed under warranty) but nothing else.
Since when I bought the car I found out that the previous owner changed shocks and springs to PSS9 I was wondering if maybe he did not go for some chiptuning that messed up the original ECU. Unfortunately I cannot contact him.
I am wondering if Porsche dealer during normal porsche approved checks may notice it (it never happened in the last two years) and/or if I should ask them.
Numbers apart, car really runs fantastic

 

What kind of leak?
Yes, aftermarket tuning software not made specifically for an X51 tuned engine will alter performance. I had a GIAC flash that was wiped out by the dealer installation of the X51 kit - when I went back to GIAC to enquire about reinstallation, it was a BIG hassle. They can't flash through OBD port because the ECU doesn't have a stock identifier anymore after the Porsche upgrade. They have to "manually" tune variables which involves pulling the ECU out of the car. A PIWIS scan should tell if the ECU had been messed with, but this could void warranties.

Back to the cylinder leak down (static test - engine not moving) vs compression testing (dynamic test) concern; if you don't notice any flat spots in the power curve and seems to be running great, just enjoy and don't worry about the likely faulty dyno reading like DenverSteve said.

Best
Mike

 

This is my fear and this is why I'd rather be clear with the dealer if they can help.

This is what I am doing Anyhow I made it try to a friend with a GT3 MKI and he told me: "shut up, it runs great"

 

was this test done in switzerland...maybe in the alps? altitude factored in might affect the output,

 

Tessin... not north enough.
500 meters on the sea level. 1640 ft.

 

Ale,

I'm in Geneva (CH) and have a 997.1 4S. Would be happy to compare the cars if you happen to drive by. The X51 horsepower upgrade is significant enough to notice a difference if you drive the cars back to back.

Dyno numbers only mean something when you compare the output before and after a modification to the same car. Or another way to compare: I would want to know the output of a stock non-X51 997.1S on that specific dyno to compare your car to it.