Dyno tomorrow - things I should know?

[JeremyD]

Been trying to read all the dyno threads -

Car in 4th gear...

Trunk open or closed?

Make sure she's secured well - that's a given.

Dynojet Dyno - so'll I'll save my files and ship to Steve W to work his magic.

Anything else I should know - do, etc?

[Porsche Doc]

Hey Man!
Looks like your ready
Engine lid open.
Make sure you mat it all the way.
GooD LucK Man

[autobonrun]

Engine lid open. They also placed a large cooling fan in place to account for no movement generating necessary cooling.

[madmmac]

Correct tire pressure.

[Jeff Alton]

Can't wait to see the results!


Have fun!

[DW SD]

Check to make sure your throttle opens all the way.

Check to make sure your WOT switch (at engine throttle plate assembly) is working properly. I believe the switch closes at WOT (before WOT, actually).

You probably know this, but: 3.2 motronic is in open loop at WOT.

Doug

[carrera1975]

make sure you are actually there in person, in case something happens, the dyno run should go up to 7200rpm for a period of time.

[911teo]

Is this the 1st dyno since your rebuilt? That is so cool! Good luck and have fun. Can't wait for the results!

[don911]

7200rpm?? Not if you have a stock motor in the 87. 6300rpm is factory red line I think. I try not to go over 6400rpm even tho my Steve W chip has 6500 as redline.

At the end of the run, gas off, shift into neutral. I saw a guy in a dodge truck shift into reverse at the end of the dyno once....it sounded like an expensive day for him.

[JeremyD]

Originally posted by carrera1975
make sure you are actually there in person, in case something happens, the dyno run should go up to 7200rpm for a period of time.

Oh, I'll be there in person - and there isn't much stock about my car...

[Steve W]

Jeremy, lots of good advice here. To best tune the fullest range of your air/fuel ratio, start your WOT run from as low a RPM as possible, i.e. 1500 out to around 6800 rpm. With your ARP rod bolts, your chip's rev limiter is set at 7000. With the engine lid open, have the dyno fan placed behind the car and blowing down directly over the engine compartment to keep it cool. Have the dyno operator check his wideband filter and clean it out and empty out any water it may have collected, that is unless he screws the wideband sensor in place of your O2 sensor. Dynojets typically use a long probe up the tailpipe, that take a sample of the exhaust through a high speed air pump. If there is an air leak or filter contamination, the AFRs will usually be out of wack or read lean. Of course, make sure you have full throttle and that the WOT microswitch activates. I have been sent many dyno plots from owners for tuning where it obviously shows the switch is not activating - the car still running closed loop. Bring a floppy disk or USB memory stick, and save the dyno .drf or 00x files onto them to email to me. Best of luck!

[charleskieffner]

hey did you get the PCA/PIR pics??? good luck on the dyno w/the cabri-o-lei(a hawaiian porsche brutha). cant wait to hear your results and see pics from your next track day spanking the pants off of coupes and targas. aloha! doing it right the first time.............WELL............. AINT AN OPTION!

[dd74]

In my mind, the cooling fan aimed directly on your engine is most important, provided, of course, that your car is anchored down properly and the guy running your motor doesn't blow it apart.

Don't do too many runs: dyno runs are sort of hard on engines, even 911 motors.

Also, don't be disappointed if things don't turn out as you planned. Dynos are used for tuning. They give you a good opportunity (depending on climate) to exercise the most out of your motor.

Good luck!

[JeremyD]

Thanks Steve - will do...

[JeremyD]

I'm really doing it for the tuning anyway - If I was really into the #'s I would have done a pre build dyno run and an after on the same Dyno... that way I could say look my HP increased 4%

[Craig 930 RS]

Even more important than fan aimed at engine:

Fan up front, right at the oil cooler

[Craig 930 RS]

You can juuuuust see the green rotary fan in front of the car



Rear

[Craig 930 RS]

The HUGE fan is to draw OUT the fumes from the shop

[Wil Ferch]

Also...ask the tech to run the chart using "SAE-corrected" figures. If not, he might post "Raw data" figures.

SAE-correction assumes sea level elevation ( approx 14.7 psia atmospheric pressure) , and I think 50% relative humidity and about 68-70 degres F temp. A "CF" or correction factor will appear at the bottom of the sheet.

This way, a car done at mile high Denver on a hot day can "compare" its results to a New York City car. I've assembled a few graphs myself on what are supposed to be indentical cars at such various locations and I am amazed at the consistency as long as SAE-corrected runs were made...at least via a DynoJet 248C.

- Wil

[Carrera3.5L]

Jeremy,

The vast majority of dyno operators know what they are doing as they do these on a daily basis and probably have hundreds or even thousands of runs of experience.

I would really hesitate walking in with a "to do" list and telling these guys how to do their jobs, only if something is obviously wrong would I speak up and suggest an alternative. You won't be the one running the dyno nor will you even be in the car (unless you are in the passenger seat)

I don't think you will run into a heat soak situation, since I am assuming that you won't be in a position to make any changes. The dyno operator will warm the motor up to temp, make a pass, wait 1-2 minutes and than make another pass. Unless you are making programming changes, I don't know why you would need to make any more runs than 3 total (at the most).

Most Dynojet operators will use SAE corrected numbers...

Since your basic 3.2L mods were the same as mine (SW chip, Dansk pre & final mufflers) your motor was most likely in the 200-205 range on a 248C. While not a substitution for your actual motor's results, it will at least give you some idea as to where you were before and where you will end up tomorrow.

I've got over 30 dyno runs on my 3.5L motor in about 15 months, from chip tuning to testing various performance "improvements" such as mufflers, air filters, MAF/HFM's etc. It will be too bad that Steve isn't riding shotgun with you and can program right than and there rather than having to send eproms back and forth. It sure makes it easier!

Good luck tomorrow, I hope you surpass my numbers! You have better cams and better gas to make it happen!

Ralph