quick question: how to dyno the TDI

[ZuberSpeed]

ya, this seems like a total newb question, ive seen someone post before, but i cant find it with the search.

so, how do you get a proper reading to get an accurate dyno?

 

[major-poser]

i second that, i don't know either, where to hook up the RPM reading

 

[dieseldorf]

Gary had a hand-crafted a pick-up that clamped on a metal fuel line to pick up pulses and that provided the RPM input for the calculation. I'm not certain what others have done but there is probably another method..or two.

 

[jackbombay]

Diesel dyno shops plot roller speed to your tach rpm at several points before the actuall run then they have the RPM info for the pull.

-Jack

 

[je]

If you're going to the Dyno Day I'm thinking of, find flair.14, as he's going too, and has dyno'd in the past.

 

[GoFaster]

An optical pick-up can also work.

 

[IowaA4TDI]

Try to find a Mustang or Superflow (or loadbearing dyno), they will use an optical trigger on a crank pulley, and they'll also offer more useful information. And more accurate numbers. Make sure the operator keys in the correct atmospheric conditions to determine proper density altitude, and you should get an accurate, correct HP/Torque plot.

 

[ZuberSpeed]

bump!

 

[peter pyce]

So, we got the optical pick-up (Thanks Gary and Jeff) and it would be nice if someone would tell us little bit more about how exactly to operate the car so we all get comparable numbers. Which gear shall we dyno? I read everyone here says 4-th, but then our dyno guy uses 3-rd.... is that OK? I would much prefer the 3-rd as it may be easier on the clutch, but then do not want after to hear things like "your pull is not valid as it was not on 4-th".... Also, any other tricks we can use? not to cheat, but to make sure we get as accurate data as we can. Our Dyno day is this Saturday, so it will be nice to get some info before that. Thanks everybody....

P.S: I do not doubt that Ray is going to do the whole thing right, I just would like that we all here agree on how dynos should be done, so we all post later accepted by everyone results...

 

[dlai]

Actually, the auto tranny is dynoed in 3rd, locked up, and the stick cars are dynoed in 4th, as I recall, and this is how I remember this shop doing our dyno on Sat does it...

 

[GassinGerhard]

Last time I did mine in third. I think it doesn't really matter if you're in third or fourth. The trick is to maximize the turbo boost.

 

[ZuberSpeed]

how do you lock a tranny in a gear?...out of curiousity, even though i have 5spd

 

[dlai]

Some auto trannies have the ability to lockup the t/c in whatever gear. I've seen some Cummins trucks with this, but don't know about other vehicles...

 

[dlai]

Directly from the Dynojet Manual:

Making a Run - 4TH Gear Roll-On
Use the following steps to make a run. This run
is a fourth gear roll-on.
Step 1
Release the dyno brake, put the vehicle in 1st gear
and start the drum rolling. Shift up to 4th gear
and accelerate to the desired starting RPM. A
good starting RPM is when your engine is
running at the lowest RPM where there is no
hesitation when you floor the accelerator (usually
between 500 and 1500 RPM).
Step 2
Push the sample button on the hand held pendant or the <ENTER> key to begin
sampling.
Step 3
Floor the gas pedal all the way and accelerate to
redline.
Step 4
Finish the run
• Let off the gas pedal and press the sample
button.
• Take the vehicle out of gear and press the
dyno brake button.
Step 5
Press the <ENTER> key or the sample button to
continue.
Step 6
Press the <N> key to return to the “Make Run”
dialog.
Congratulations! You have just made your first run.

On the rpm/optical sensor, below is lifted from an old dzljet post:

As for hooking it up, you'll see how to set it up by taking out the side skirt for the belly pan. Remove the right side front wheel to access it. The belly pan should also be off.
Take off the silver dollar looking clips that hold side skirt (one in wheel well, one harder to find up by intercooler) one 10mm nut if I remember right is a retainer for lower ic hose will have to be removed and then I'm pretty sure you can pull it out to access drive shaft area. On the TDI, this method is a grueling ordeal, since there isn't an easy way to locate the optical pickup. We either use reflective tape or white nail polish, and then use the optical pickup to get engine rpm reference.