Fred X50

Hi everyone,
Well I am back from Gumball and going to get my car tuned. My car will be at <a href="http://www.rennwerks.com" target="_blank">Rennwerks</a> and they have a <a href="http://www.rennwerks.com/Dyno.htm" target="_blank">Dynapack Dyno</a> .

It is a two wheel dyno. Does anyone see any problems in me dynoing my car with this type of dyno? Do they need to do anything to my car as my car is all wheel drive?

Thanks,

Fred

HBdirtbag

They will need to disconnect the drive shaft to the front wheels from what i've read.

But I have a question for you, you are just now getting back from gumball? <img border="0" title="" alt="[Wink]" src="wink.gif" /> Damn it took you forever to get back from florida

where is your gumball right up man!!!!

GuyR

Yep, they just need to disconnect drive to the fronnt wheel (by removing the propshaft), or (not recomended) they can raise the front wheels off the ground and remove wheels.

My Skyline GTR tuner here in the UK has a 4wd DynaPack (four boxes). I've got 831bhp at all four wheels so far on my R32, but only 600bhp at wheels on my R34 (we hit 99% injector duty so could only run 1.2bar.)

Fred X50

thanks guys, greatly appreciated !

Soon2be, I stayed in Miami and extra weekend and just got my car back. Ran into a little delay in the shipping. I will soon post pics and videos.

and GuyR, you need more HP ;-) J/K

KPV

Hey Fred,
Welcome back! I thought I would insert a post I made on fco a short time ago. Use the information as you wish.

Copy of FCO Post:
In regard to the nature of dynamometer testing of the 996TT, I wish to offer the following:
This is an exact excerpt from page 54 of the owner's manual:

Dynamometer testing procedure

Some U.S. states and Canadian provinces conduct emissions inspection/maintenance testing involving the use of a two-wheel dynamometer.
A two-wheeled dynamometer is a treadmill type device upon which a single axle of the car, the driving axle of the vehicle, rotates to simulate vehicle operation on the road while the vehicle remains stationary.
Your 911 Turbo has a full-time four-wheel drive system which cannot be disabled. Severe damage to the powertrain can result if tested on a two-wheeled dynamometer.

Warning!
To avoid severe powertrain damage and a possible unexpected movement of the vehicle.

Your 911 Turbo vehicle must never be tested on a two-wheel dynamometer.

Advise the emission station of this warning before testing the vehicle.

AWE (Where dyno day took place) uses an all wheel drive dyno utilizing mechanically coupled front and rear rollers. This insures "apparent road speed" is maintained. From the car's standpoint, this is absolutely no different than driving on the road since the tangential velocity of the rollers at the front and rear are identical which is the case during normal driving. If it wasn't the front wheels would be turning at a different rate than the rears. This is also the very reason why it is imperative to maintain the same factory front and rear tire diameter ratio when changing tire sizes. If the front and rear diameters differ, the variation in tangential velocity between the larger and smaller wheels would need to be taken up in the viscous coupling.

From an engineering perspective, I would not find fault with GuyR's approach. <img border="0" alt="[bigbye]" title="" src="graemlins/xyxwave.gif" />

Fred X50

Ok, this is not helping. So far right now it is 2 votes yes and 1 vote no.

Anyone have more input as I am doing this in the next couple of days. Maybe I will take it to ATP <a href="http://www.vwturbo.com/services/" target="_blank">http://www.vwturbo.com/services/</a> They did it before but didn't know how to measure torque. Does anyone have instructions for them on how to gage the torque?

thanks

Fred

KPV

Fred,
Read the article on page 26 of the May 2003 issue of Panorama for a write-up of the torque/horsepower relationship. It may help you.

I want to add my THOUGHTS concerning the awd vs rwd dyno debates. This narrative disregards the pros and cons of the various 4 wheel dynos (mechanically coupled front and rear drums vs computer controlled front and rear drums).

In the end, the basic difference between a 4 wheel vs 2 wheel dyno is the sum of the losses due to friction. A 4 wheel dyno requires the engine to drive front and rear drums thereby incurring more friction loss through the front drivetrain (from the VC forward). A 2 wheel dyno only requires the car to drive the rear drums thereby substantially reducing or even eliminating the friction loss from the front drivetrain. The degree of friction loss depends on the method of removing the front drivetrain from the equation (Wheel removal vs driveshaft decoupling). Driveshaft decoupling will result in less loss (i.e.: higher apparent hp readings on the machine) since the front driveshaft, diff., halfshafts and hubs do not need to be turned.
It is my humble opinion that a rwd dyno's direct machine results will be slightly unrealistic when compared to an awd dyno WHEN USED FOR HP DETERMINATION AT THE WHEELS. The difference will be in the amount of horsepower loss through the front drivetrain. If the appropriate friction loss factors are applied (very difficult to quantify and different for each type of dyno and each type of car) a comparison may be made between the two machine results.

I trust you are thoroughly confused

Geoffrey

A dynapack dyno in 4wd or 2wd is a great dyno. I have used the 2wd version on my 930 and seen a number of 993TT and 996TTs dynoed on this machine with the driveshaft removed. The dynapack is very popular in Japan where AWD cars are tested all the time. Give them a call <a href="http://www.dynapack.com." target="_blank">www.dynapack.com.</a> They are great to talk to and can help you understand how they work in 2wd and 4wd modes as well as a AWD car on a 2wd dyno.

The company is from Australia and the AFR tool is actually a MoTec Professional Lambda Meter (PLM) that has been integrated into the Dynapack software.

sharkster

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Fred X50:
<strong>Ok, this is not helping. So far right now it is 2 votes yes and 1 vote no.

Anyone have more input as I am doing this in the next couple of days. Maybe I will take it to ATP <a href="http://www.vwturbo.com/services/" target="_blank">http://www.vwturbo.com/services/</a> They did it before but didn't know how to measure torque. Does anyone have instructions for them on how to gage the torque?

thanks

Fred</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Fred I would REALLY reconsider taking it there. Yes it's one of only two AWD dynos in california but my front diff blew out on it (loaded wrong? i don't know) so just be aware that they are a) not familiar with how our cars work and b) don't risk the diff. Drop the front drive shaft and go to SCarGo or the Racer's Group or something. I like Rennwerks too, those guys seem nice...

PorschePhD

I have done a ton of dynos on both the 993TT and the 996TT and all you need to do is disconnect the driveshaft. The codes will fault and clear when hooked back up. The codes are not resident and will not harm anything. Simply re hook it back up and you are set. <img border="0" alt="[typing]" title="" src="graemlins/yltype.gif" />

sharkster

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by cjv:
<strong>Fred, I think you are being a little too trusting. They are great people with BMW's. You might check into their track history with Porsche's before you proceed. </strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Yes indeed if there's one thing that came out of my experience, it's a clear warning sign... Drop the drive shaft like Stephen says.