Power Measurement in case of the Porsche 964

The following article was written by Dr.-Ing. Mario Schacht (eMail : ma@schacht-berlin.de) in case of questions or if you have additional information please contact him directly.

Important Note : Detailed information about the CUP PIPE, SPORTS AIRFILTER and the LM-220 TUNINGKIT from CARTRONIC as well as experience reports about them can be found in my FAQ database (german only).

Tuning for the 911 is a very widespread topic, about which you can, no doubt, discuss a lot. However, the quality of this discussion is often quite comparable to a political discussion in the pub and terms like "feels much better...", "has much more power in low revs..." etc. are not very substancial or measurable.

I started gathering and putting together all impotant, measurable and relevant data concerning this topic in an Excel spreadsheet. It's content is attached below as a html table.

In order to keep the approach small enough to be handled I've focused just on the Porsche 964.

Some remarks concerning the table and the given values:

- All measuring was done on rolling roads from one manufacturer called MAHA. I figured that if I start to include results gathered on other makes of rolling roads, the comparability of the measurements would be entirely gone.
- Even with that limitation, the influences of the technician measuring and the general circumstances under which one measures are very big. If e.g. you don't allow for enough air circulation, you can (as you can see further down) forget any results beyond approx. 5000 rpm , as the motormanagment reacts to the quickly raising motor temperature and adjusts the timing of the ignition, which makes you in effect loose power in the upper revs.
- The value for maximum power does not necessarily reflect the effectiveness of the tuning measures taken, since these benchmark figures can strew strongly.
- additional to the maximum power values I have decided to add a value at 3000rpm and at 4500rpm as these are the revs (at least I) use my car a lot at. These values should give you a more practical idea of how much you can win - in every day live - from a tuning measure taken.
- As far as I'm concerned I would mainly trust the given torque values.
- I have my doubts about the given drive chain losses, the values from the Porsche Center Berlin and Porsche Center Düsseldorf show very different amounts here. As the drive chain loss is an important value in the overall engine power calculation I have to be sceptic about all the resulting values. As much as I want to, I just don't believe my 964 has 293 PS (hp).

I would be pleased about your feedback (and if available your own measuring results).

kindest regards

Dr.-Ing. Mario Schacht
eMail : ma@schacht-berlin.de

(translation by Joachim Grueninger - jo_list@magicon.de)

Click the following links to read the test results :

964er Leistungsmessung : (30.03.2008)
http://www.jarke.de/porsche/964/964-leistungsmessung.xls
964er Drehmoment : (31.10.2002)
http://www.jarke.de/porsche/964/964-drehmoment.xls
964er PS-Formeln : (31.10.2002)
http://www.jarke.de/porsche/964/964-ps-formeln.xls