Looking forward to receive advise on what to do, so to best dyno my 4-speed automatic. This as very soon I will make a local appointment so to be able to get before- and (than after a few days) after-modifying results (as I'm very interested in the delta, less so in the absolute numbers).

Just put it in D an floor it, or making some prepations or...?

The dyno will be of the type that is directly attached to the wheel-hub, so not the more tradtional rollers type of dyno.

 

Unplug the kick down switch under the gas pedal.

Take off transmission bowden cable at the throttle quadrant

Let the dyno guys do the rest.

 

So would that be the older "water brake" style dyno?

 

Thanks Sean for yor immediate reply, much appreciated!

Eh...I'm a total 'noob' regarding dyno's (hence my question), the dyno tester is of this type's: http://www.rototest.com/

 

thats the ticket.....I have dyno'd more automatic 928's than just about anyone here.....

Also run the test in 3rd gear......4th (2.20) is far too tall for most dyno's....my 84 with its brutal 198whp pegged the dyno at 195mph.....

If you have a 3 speed then 3rd is fine since its the 2.75 and will "only" hit 160ish mph

 

I think forced 3rd gear is needed or dynos speed limit is reached before redline even with 2.54:1 diff. Will selecting 3rd do the trick together with killing kickdown switch and cable to the gearbox? I'm also interested as my automatic GTS and maybe some other 928 automatics will go into same dyno eventually.

 

Yep, that's the way to do it :-)

 

Just..let the dyno guys do it.

It'll walk up to 3rd..and then they will floor it.

No hassles...no kickdowns..nothin.


Painless.

 

Very interesting... Not to side track the original question, but what gear should you dyno a 86.5 - 5 speed?

Thanks,

 

I recall reading in the WSM that diagnostic testing of the 4-speed auto and kick-down system should result in the 'box changing down from 4th to 3rd if kick-down is activated at speeds up to about 215 kph (130 mph) or so.

There is a similar bit about kick-down causing a 3rd to 2nd down-shift at anything less than some lesser speed, but I don't have the actual numbers handy.

Without the kick-down disconnected, I am tipping that the 'box will downshift if you floor the throttle at typical dyno run starting speeds.

I am guessing that two gear shifts (3 to 2, 2 to 3) through a dyno pull would invalidate the readings somewhat.

 

Having a 1994 with dynamic kick-down and going for my base dyno-run tomorrow 10th August 2012, is it better to also remove the dynamic kick-down relay XVII?

I have been checking the electrical wire diagram for MY 1994 on this, however not entirely sure - so any further advise of those of you who have done dyno-run's with MY 1994 or 1995: much appreciated!

 

Normally 4th ≈ 3rd in auto ≈ 160 mph top speed.

5th manual/4th auto would be better, with a 1:1 ratio, but you are getting close to 200 mph.


Make sure your tires are in good shape! Flat tread, no alignment problem wear.

 

Or simply pulling fuse 39 (which takes care of: Instrument control lamps, Kickdown, Warning Lights, Switch for rear window wiper)?

 

And the answer is: pull the dynamic kick-down relay XVII (as well as the already earlier advised taking off of the transmission bowden cable at the throttle quadrant), do NOT pull fuse 39 (because then you also loose all Instrument power, apart from all other items mentioned above ).
No need to also unplug the kick down switch under the gas pedal, as that is in series with the dynamic kick-down relay switch.

I will open a separate thread for my dyno-shop findings (having just returned from it): that was fun and I learned several things!

 

remove roger box, install 5 speed..... :-P