996 turbo dyno

[Vixpy1]

So, I guess it's fairly well known, certainly amongst my customers, that i won't dyno turbocharged rear engined pork. I get asked alot to do it, but because of the various drivetrain and heat related issues, I've always declined. If you can't do it properly, don't so it all has always been my motto, in the case of the dyno anyway

I got my 911 tubby a few weeks ago, everycar I have ever owned has been on the dyno, some having had many runs. However 3 weeks after getting the tubby, it had been nowhere near the dyno. It was as fast as i was concerned fast enough. :



However, after a chat last week with my good friend Adam, (Anyone who uses fearnsport may have met him) He told me to stop being a poof and get the bloody thing on the dyno.

So, Sat afternoon after all the customers had left, with it pissing down with rain. My friend Dan and I loaded the 911 onto the dyno:



(Dan being the poser in the photo)

So after getting the car strapped down and the fans on, and after giving Dan orders to keep spraying water down the intercooler ducts, off we went.

2002 Turbo, Fearnsport remap and diverter valves, design911UK exhaust. The work was carried out about 3 years ago by a previous owner (whose 993 turbo is ironically in Fearnies at the moment)



Quite pleased with it tbh, we got a good few pulls out of it. There appears to be a hole in the power curve at the higher end, the car could have been pulling timing, or it could be the exhaust or Adam said that particular map was a fairly safe one. The car is running just above 0.9 bar boost

And no, I'm still not doing rear engined turbo engined pork on the dyno

Ps, i'd like to give a massive thankyou out to Matt at Fearnsport who has been an absolute legend over the past few weeks answering my inane questions!

Edited by Vixpy1 on Monday 31st May 21:27

[Mr Freefall]

Vixpy1 said:

So, I guess it's fairly well known, certainly amongst my customers, that i won't dyno turbocharged rear engined pork. I get asked alot to do it, but because of the various drivetrain and heat related issues, I've always declined. If you can't do it properly, don't so it all has always been my motto, in the case of the dyno anyway

I got my 911 tubby a few weeks ago, everycar I have ever owned has been on the dyno, some having had many runs. However 3 weeks after getting the tubby, it had been nowhere near the dyno. It was as far as i was concerned fast enough. :



However, after a chat last week with my good friend Adam, (Anyone who uses fearnsport may have met him) He told me to stop being a poof and get the bloody thing on the dyno.

So, Sat afternoon after all the customers had left, with it pissing down with rain. My friend Dan and I loaded the 911 onto the dyno:



(Dan being the poser in the photo)

So after getting the car strapped down and the fans on, and after giving Dan orders to keep spraying water down the intercooler ducts, off we went.

2002 Turbo, Fearnsport remap and diverter valves, design911UK exhaust. The work was carried out about 3 years ago by a previous owner (whose 993 turbo is ironically in Fearnies at the moment)



Quite pleased with it tbh, we got a good few pulls out of it. There appears to be a hole in the power curve at the higher end, the car could have been pulling timing, or it could be the exhaust or Adam said that particular map was a fairly safe one. The car is running just above 0.9 bar boost

And no, I'm still not doing rear engined turbo engined pork on the dyno

Ps, i'd like to give a massive thankyou out to Matt at Fearnsport who has been an absolute legend over the past few weeks answering my inane questions!

What gear was that in??? 3rd like TVR runs

Mr F

[Vixpy1]

3rd Mr F

[Mr Freefall]

Vixpy1 said:

3rd Mr F

Come on Charlie, get some fans!!!! Do some pork, Can be that hard can it???

Mr F

[ZeroH]

Vixpy1 said:

3rd Mr F

You have a 4wd Dyno Dynamics rr or just 2wd ? If 4wd whats the issue running 4wd 911s?

[Vixpy1]

ZeroH said:

Vixpy1 said:

3rd Mr F

You have a 4wd Dyno Dynamics rr or just 2wd ? If 4wd whats the issue running 4wd 911s?

There are camps out there that insist the propshaft should be disconnected on the 996 turbos when dynoing, however there are those that say the 996 is fine and that its the 993 thats the problem.

Its 4wd

[Nano2nd]

What difference does it make in third?

[Vixpy1]

Nano2nd said:

What difference does it make in third?

Keeps the runs short, Mr F is making an old gag from his TVR Cerb days

[Nano2nd]

A right, had my 4i dyno'd last year in third, every other time has sways been in fourth

[williamp]

yes but do you dyno rear engined Pork??

[ZeroH]

Vixpy1 said:

ZeroH said:

Vixpy1 said:

3rd Mr F

You have a 4wd Dyno Dynamics rr or just 2wd ? If 4wd whats the issue running 4wd 911s?

There are camps out there that insist the propshaft should be disconnected on the 996 turbos when dynoing, however there are those that say the 996 is fine and that its the 993 thats the problem.

Its 4wd

Not sure I understand. Disconnecting the propshafts is necessary for 2wd dynos yes, but not 4wd ones, thats the whole point !

Or am I missing something ?

I've seen literally a dozen 996turbo's dyno'd on 4wd dyno dynamics no issues... seen a few 993turbos done also, again, no issues.

[Vixpy1]

ZeroH said:

Vixpy1 said:

ZeroH said:

Vixpy1 said:

3rd Mr F

You have a 4wd Dyno Dynamics rr or just 2wd ? If 4wd whats the issue running 4wd 911s?

There are camps out there that insist the propshaft should be disconnected on the 996 turbos when dynoing, however there are those that say the 996 is fine and that its the 993 thats the problem.

Its 4wd

Not sure I understand. Disconnecting the propshafts is necessary for 2wd dynos yes, but not 4wd ones, thats the whole point !

Or am I missing something ?

I've seen literally a dozen 996turbo's dyno'd on 4wd dyno dynamics no issues... seen a few 993turbos done also, again, no issues.

Some people say you can damage the 4wd system running them in 4wd on the dyno. Not sure i agree.

My major issue has always been cooling, as they are so sensitve to intake temps

[ZeroH]

Vixpy1 said:

ZeroH said:

Vixpy1 said:

ZeroH said:

Vixpy1 said:

3rd Mr F

You have a 4wd Dyno Dynamics rr or just 2wd ? If 4wd whats the issue running 4wd 911s?

There are camps out there that insist the propshaft should be disconnected on the 996 turbos when dynoing, however there are those that say the 996 is fine and that its the 993 thats the problem.

Its 4wd

Not sure I understand. Disconnecting the propshafts is necessary for 2wd dynos yes, but not 4wd ones, thats the whole point !

Or am I missing something ?

I've seen literally a dozen 996turbo's dyno'd on 4wd dyno dynamics no issues... seen a few 993turbos done also, again, no issues.

Some people say you can damage the 4wd system running them in 4wd on the dyno. Not sure i agree.

My major issue has always been cooling, as they are so sensitve to intake temps

Indeed, they are cooling sensitive, so you need to be happy that you can accomodate. CHeers.

[Ultra Violent]

I'd say something isn't right there. That hole is almost certainly ignition being pulled, or a back pressure problem. Ask FS what changes were made to the Map, from that dyno looks like a simple boost increase that hasn't sat well with other parameters.

[TB993tt]

Broken record I know but (particularly on our Porsche turbos) even the Dyno Dynamics runs have to be taken with a pinch of salt.
They can capture maximum power quite accurately as long as the AIT is controlled, I monitored it for the run below using Durametric and the AIT was reasonable. For the next attempt the AIT went off the scale and the run was worthless.



I have a useful and unique perspective here since following the run above the exact same engine was tested on an engine dyno with proper AIT control and the peak power was within 2.5PS. The rest of the curve was very different rendering and analysis to be done lower down the scale as pretty meaningless.

I think the scaling was also out on the run above making it even more meaningless.

[333pg333]

Is this to the crank or whp? Also I notice it's in 'Shootout Mode'. That will give a higher read than when not in this mode.

Must be a hoot to drive nevertheless!!

[Sunnysidebb]

As you will know the 996tt is not real 4 wheel drive. There is no direct drive from the gearbox to the front diff.
To give an example . Any Cosworth has a centre differential. Its got planet wheels/gears/cogs etc.It also has a limited slip differential in the form of a viscus coupling. There is always a mechanical link to the front or rear diff.
On the 996tt there is a fixed link to the rear diff and a viscus coupling to the front. There are no cogs/gears or any form of mechanical connection to the front diff. Even Porsche say its not a true 4 wheel drive but there for driving dynamics.
Another eg. WE have a steep drive, when it snows the rears will spin but the front wont because.... there is no drive to the front just torque going through a viscus coupling. Have you ever seen a 996tt light up the front tyres. The back yes but never the front. A Scoob, Evo or Cossie can light all 4 tyres if given enough power.

So why remove the front prop on a dyno, because if the rear tyres turn at a different speed to the front by only a small margin the fluid in the viscus coupling will get hot, boil and turn into black gunge. No more viscus and no torque to the front tyres.
You can get viscus coupling upgraded, ZF, Quaife, R&D or Getrag. The fluid viscosity is changed and the diff revalved. Makes a huge difference in a Raly car, if the rears spin more torque is sent to the front. Its a combination of centre mechaniocal differential internals and viscus cupling.
I beleive the 997tt has a mechanical cluth type viscus which will lock ( or vary its load) if necessary so there would be no difference in wheel speeds between the front & back ?

Frank

[996ttalot]

Sunnysidebb said:

As you will know the 996tt is not real 4 wheel drive. There is no direct drive from the gearbox to the front diff.
To give an example . Any Cosworth has a centre differential. Its got planet wheels/gears/cogs etc.It also has a limited slip differential in the form of a viscus coupling. There is always a mechanical link to the front or rear diff.
On the 996tt there is a fixed link to the rear diff and a viscus coupling to the front. There are no cogs/gears or any form of mechanical connection to the front diff. Even Porsche say its not a true 4 wheel drive but there for driving dynamics.
Another eg. WE have a steep drive, when it snows the rears will spin but the front wont because.... there is no drive to the front just torque going through a viscus coupling. Have you ever seen a 996tt light up the front tyres. The back yes but never the front. A Scoob, Evo or Cossie can light all 4 tyres if given enough power.

So why remove the front prop on a dyno, because if the rear tyres turn at a different speed to the front by only a small margin the fluid in the viscus coupling will get hot, boil and turn into black gunge. No more viscus and no torque to the front tyres.
You can get viscus coupling upgraded, ZF, Quaife, R&D or Getrag. The fluid viscosity is changed and the diff revalved. Makes a huge difference in a Raly car, if the rears spin more torque is sent to the front. Its a combination of centre mechaniocal differential internals and viscus cupling.
I beleive the 997tt has a mechanical cluth type viscus which will lock ( or vary its load) if necessary so there would be no difference in wheel speeds between the front & back ?

Frank

The VC fluid takes just under a minute to heat up first time you drive.
The normal result of the dyno of 996tt when there is a difference between rear and front is also new front diff.
The situation is even worse for a tip box because the TC will not lock properly at high revs.
So you are right, removing the front prop is a safer option is you really must dyno.

Edited by 996ttalot on Wednesday 2nd June 13:34

[Adam996tt]

well done charlie glad you got one, hope you are enjoying it. i have still not managed to get to the bottom of my crazy dyno print out from dms. your curves look nice and smooth. Adam surrey came down to you about a month ago with selection of cars including ultima tvr tuscan 348.