bfellows

Is there a good procedure for running an auto on a dyno?

dr bob

You'll want to get a good run in just one gear if you want a realistic result. Easiest way to do that is to disconnect the TV (downshift) cable at the throttle quadrant. This is the outermost connection, the one with the little wire hairpin clip retaining the cable on the ball. If your kickdown switch under the pedal is working, you'll want to unplug that too. Make sure the throttle is actually open all the way when the pedal is on the floor too. On the rollers, choose gear 3 for your run so you don't overspeed the dyno. You'll want to get some directions from the dyno operator too. They may give you some good hints, since they've probably done one or two cars prior to yours.

bfellows

Hi Dr Bob, When you say "choose gear 3" I take it you mean manually select position 3 using the shifter?

bfellows

Also, just to be sure, is it 1, 2 or 3 that gets disconnected?

IcemanG17

2 gets disconnected (not 100% sure though) but I think 3 is the cable that runs to the throttle body under the intake, so if you disconnect that you'll only have idle.....

Also unhook the kickdown switch under the gas pedal....then use 3rd gear....that will give you a good run

the flyin' scotsman

Bert #2 is the one you need to disconnect.

The cables from closest to the intake are:

the accelerator pedal
the throttle body
the gearbox
the cruise control

This config is what my '88 auto has; its LHD but I cant see how/why Porsche would change it for RHD.......stranger things have happened though.

bfellows

Thanks all. Now fate has decided that I going to keep the car I need a baseline hp figure ready for my next project, so time to hit the dyno and see if things are good, bad or ugly......

IcemanG17

Bfellows
Most well running S4 automatics tend to dyno around 250-270whp depending on the dyno used.....with most right around 260whp.... If you have a problem (say like a bad hall sender like I have) then you will loose substantial amounts of HP...

rawky

So, to clarify;

- Remove Throttle Cable No.2 from the picture above
- Unplug the kickdown cable
- Get on the dyno, select 3rd gear
- Floor it from idle to redline, don't (overspeed?) the dyno.

Is that right?

atb

I would suggest manually shifting to third gear so you aren't second guessing yourself as to what gear you are in at the beginning of your run. Since the wheels are already turning on the barrels, if you go straight to 3 there may be question as to what gear the car is starting in - 1st or 2nd. If you then give it gas to shift automatically through the gears, then you're left to assume the car started in second and your now in third, or you wait around for it to shift again just incase it started out in first. Sounds silly but it will go a lot quicker if you walk it through the gears to Third as follows:


Pull the stick down to 2, which will manually select 1st gear in the S4. Do the 2-3-2 shift and you will feel the car shift to 2nd. Then select third and wait for the tranny to shift to 3rd. Good to go.

Darien

Like this...

http://s151.photobucket.com/albums/s...560DynoRun.flv

Now go give it hell

RngTrtl

From my understanding of what the bowden cable does I do not think it wise to dyno a motor with it disconnected. This cable tells the tranny how to adjust internal pressure of the fluid that controls the shifts. So by disconnecting it, you are basically telling the tranny that you are at idle/low throttle and to shift softly when it is time for a shift. So if the tranny happens to downshift while you are WOT, you will likely damage the tranny. I know for a fact that this is how Ford AOD tranny work and I would think that is how our trannys work. This was discussed in an earlier thread that I started about a month ago, do a search and see if anything pertains to you. I maybe wrong on this whole idea of mine and would like for one of the tranny gurus to chime in to this thread or one of the other threads about dynoing an auto tranny.

Doc GTO

What S/C kit do you have? Looks like a Vortech head unit.

bfellows

Its a 928 motorsports stage 1 kit with a vortech unit.

hacker-pschorr

It's a Stage 1 Murf 928 Surpcharger kit sold by 928 Motorsports