Power Measurement in case of the Porsche 964



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(translation by Joachim Grueninger)

The following article was written by Dr.-Ing. Mario Schacht (eMail : mario@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 / Q&A database (german only).

Nr. owner / type / built in tuning measures test stand location test stand boundary conditions date time-of-day atmospheric pressure [mbar] temperature [C] gear used standard performance [kW] engine performance [kW] wheel performance [kW] drive chain loss [kW] max power at n= [rpm] max. torque [Nm] at n= [rpm] max. revs [U/min] standard performance [kW] / torque [Nm] at 3000 rpm standard performance [kW] / torque [Nm] at 4500 rpm
1 964 C2 standard; factory specifications - - - - - 184,0 - - - 6100 310 / 4800 6700 85 / 260 140 / 300
2 964 RS standard; factory specifications - - - - - 191,0 - - - 6100 325 / 4800 6700 85 / 260 150 / 320
3 MSCH / 964 C2 man.gearbox / 02.92 sports airfilter - nothing else! Maha, OPC Berlin 2-wheel-test stand 06.09.00 / 11:51 996 / 32 4. 199,0 191,5 155,5 36,0 6370 322 / 5090 6660 88 / 274 140 / 300
4 MSCH / 964 C2 man.gearbox / 02.92 sports airfilter; cup-pipe; FVD-Chip (removed afterwards) Maha, OPC Berlin 2-wheel-test stand 17.10.00 /11:53 997 / 28 3. 197,0 191,5 165,0 26,5 6230 326 / 5050 6960 85 / 260 140 / 300
5 MSCH / 964 C2 man.gearbox / 02.92 air mass sensor LM220; big throttle; sports airfilter; cup-pipe Maha, OPC Berlin 2-wheel-test stand; broken ventilation! 17.07.01 / 08:10 994 / 34 4. 204,0 195,5 159,0 36,5 6370 338 / 5020 6880 88 / 280 150 / 316
6 MSCH / 964 C2 man.gearbox/ 02.92 air mass sensor LM220; big throttle; sports airfilter; cup-pipe Maha, OPC Duesseldorf all-wheel-test stand; engine ventilated directly 22.08.01 / 10:38 1022 / 30 3. 216,0 214,0 174,5 39,5 6360 345 / 4860 did not run into revs limiter 90 / 285 153 / 330
7 MSCH / 964 C2 man.gearbox / 02.92 air mass sensor LM220; big throttle; sports airfilter; cup-pipe Maha, OPC Duesseldorf all-wheel-test stand ; engine ventilated directly 22.08.01 / 10:57 1021 / 31 3. 212,0 209,5 170,0 39,5 6470 344 / 5010 did not run into revs limiter 88 / 285 150 / 330
8 EK / 964 C2 man.gearbox / 12.91 RS-motronic Maha, OPC Berlin 2-wheel-test stand 06.09.00 / 11:42 996 / 27 4. 196,0 190,5 154,0 36,5 6290 331 / 5010 6670 85 / 280 150 / 315
9 KHB / 964 RS / - air mass sensor LM220, 3.8 RSR injectionjets+ pist+ barrel+ throttle+ intake+ cup pipe and factory exhaust SUN, Victor Guenther, Cologne 2-wheel test stand, engine ventilatetd directly 28.08.95 / 08:31 1001 / 17 4 238,0 236,5 194,5 42,0 6820 351 / 6040 6980 70 / 268 140 / 290
10 KHB / 964 RS / - air mass sensor LM220, 3.8 RSR injectionjets+ pist+ barrel+ throttle+ intake+ "Fäp-Rohr" and factory exhaust SUN, Victor Guenther, Cologne 2-wheel test stand, engine ventilatetd directly 01.09.95 / 09:31 1007 / 17 4 245,5 245,5 204,0 41,5 6870 361 / 6080 7120 79 / 280 145 / 298
11 MG / 964 C2 / 1993 air mass sensor LM220; big throttle; sports airfilter; Cup pipe Maha, PC Berlin 2-wheel test stand 12.07.01 / 10:09 992 / 31 4 202,0 194,0 161,5 32,5 6060 337 / 4970 6880 89 / 285 154 / 320
12 MG / 964 C2 / 1993 air mass sensor LM220; big throttle; sports airfilter; Cup pipe Maha, PC Berlin 2-wheel test stand 17.07.01 / 09:43 993 / 31 4 204,5 197,0 163,5 33,5 6420 342 / 5000 6880 92 / 287 155 / 325
13 MG / 964 C2 / 1993 air mass sensor LM220; big throttle; sports airfilter; Cup pipe; sport-KAT Maha, PC Berlin 2-wheel test stand 10.09.01 / 09:29 990 / 31 4 209,5 203,5 167,5 36,0 5920 349 / 5030 6930 92 / 287 158 / 335
14 NN / 964 RS / 1992 air mass sensor LM220; big throttle; sports airfilter; Cup pipe Maha, PC Duesseldorf 4-wheel test stand; very good engine ventialtion 06.02.01 / 13:44 964 / 24 4 222,0 210,0 165,5 44,5 6170 365 / 5110 did not run into revs limiter 93 / 299 160 / 341
15 NN / 964 RS / 1992 air mass sensor LM220; big throttle; sports airfilter; Cup pipe Maha, PC Duesseldorf 4-wheel test stand; very good engine ventilation 06.02.01 / 13:55 975 / 20 4 227,0 218,5 169,5 49,0 6180 367 / 4830 did not run into revs limiter 93 / 299 160 / 347


Remarks and conclusions from the measuring results listed :

Nr Remarks
4 In my opinion the effectiveness of chip tuning shows, but the performance and torque increase should mainly come from a noticable increase of the allowed max rpm. In order to deliver a secured evaluation, further measured values are needed.
6, 13 The tuning measures "air mass sensor LM220;big throttle;sports airfilter;Cup pipe" result in a noticable increase of torque in medium and high revs.:
  • + 27 Nm at 3000 rpm
  • + 35 Nm at 4500 rpm
  • + 39 Nm at 5030 rpm (Mdmax)
    		•
    6, 13The tuning measures "air mass sensor LM220;big throttle;sports airfilter;Cup pipe" result in a noticable increase of power, especially at high revs.:
  • + 7 kW bei 3000 U/min
  • + 18 kW bei 4500 U/min
  • + 32 kW bei 6360 U/min (Pmax)
    		•
    9, 10The tuning measure "capacity increase to 3,8 l + sharp cam + intake optimization" show that a quite big increase in engine power can be achieved (+ 53 kW for a 964 RS) at very high revs. However at medium and lower revs the torque and power stay standard.
    6, 7 und 14, 15 measurements, even if only briefly (30 min.) apart, show dispersions:
    • Max. performance can strew up to 5 KW.
    • Max. torque is achieved at numbers of revolutions differing by approx. 200 rpm.
    4, 7 When reving up (the engine on the test stand) the power output is measured directly at the wheels. This is not quite what we are interested in. What we are looking for is "just" the engines power output, even if you cannot get this onto the road. The engine power output is reduced by some power losses untill it actually reaches the rear wheel and the test stand, where it's measured. This drivechain loss between clutch and test stand roll is measured after you depress the clutch (after the actual power measuring) and has to be added to the power output figures measured before. This way you get a figure giving you "true" engine power output. Finally the output has to be converted to standard conditions. The drivechain losses depend on the test stand and the conditions of the measuring. This means they vary from test stand to test stand, but also depend on a number of other factors:
    • downforce on the driven wheels when securing the car (strapping it down),
    • tire pressure,
    • surface (and resulting slip) of the role,
    • unfortunately also on the examiner (however that is another history).
    You can measure in different gears, all it really does (in higher gears), is bring the revs of the wheels up and therefore increase the drivechain losses (approximately linear to the revs).

    The big differences between Nr 4 and Nr 7 can be explained. The way the car is tied down as well as the surface of the roller are very different, this results in big differences in the drivechainn losses. I'd like to illustrate this with a brief comparison: measuring Nr 4 (3rd gear) <-> measuring Nr 5 (4th gear) results in a difference of 10 kW. measuring Nr 6 (3rd gear) <-> measuring Nr 15 (4th gear) also results in a difference of 10 kW. Unfortunately I lack results of the same car measured in the PC Duesseldorf in 3rd and 4th gear, but even though comparing "apples with pears" **NO CLUE HOW THAT TRANSLATES** you get the point.

    Recommendation from MAHA (manufacturer of the rolling road test stands): measure with the car in 3rd gear and avoid to brutally hit the revs limiter every time. The overall lower revs of the wheels will save your tires and the car stays calmer on the rolling road. Also the car should be tied only lightly (guess that means don't overdo it).
    5, 7, 13, 15 If the rolling road has insufficient ventilation with fresh air, you might as well forget the results. You can tell the difference if you compare measurement Nr 5 (bad air situation) and measurement Nr 7 (perfect ventilation). Measurement Nr 13 was carried out on the same bad ventilated rolling road. The power output up to 5000 rpm is better than average and very promising, but doesn't go together with the result given for max. power output. I assume, that due to the quickly raising temperature (31°C) the motronic just has adjusted ignition timing and thus reduced the power output. Best Practice at measuring Nr 15. Additionally here the temperature sensor has been placed outside the actual intake area (stuck to the rear window), to simulate normal drive ventilation situation (= a constant temperature) to the electronics. As this trick is used to overcome the bad ventilation of the rolling road setup, it shouldn't create false or optimistic results and therefore should be ok to use.

    (c) translation by Joachim Grueninger

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