I'll try to cover everything I mentioned in the other thread that was too wide for most to read easily.

torque/hp:
<a href="http://members.rennlist.com/adrial/dyno1low.jpg" target="_blank">http://members.rennlist.com/adrial/dyno1low.jpg</a>

torque/air fuel ratio:
<a href="http://members.rennlist.com/adrial/dyno2low.jpg" target="_blank">http://members.rennlist.com/adrial/dyno2low.jpg</a>

boost:
<a href="http://members.rennlist.com/adrial/dyno3low.jpg" target="_blank">http://members.rennlist.com/adrial/dyno3low.jpg</a>

what it shows in the manual:
<a href="http://members.rennlist.com/adrial/dyno-factory%20manuallow.jpg" target="_blank">http://members.rennlist.com/adrial/dyno-factory%20manuallow.jpg</a>

Then we BS'ed a bunch about SAE vs. DIN hp and I think we came to the conclusion (or at least I did) that they are within 2% of eachother nowadays. SAE is the american standard, DIN is the euro standard.

Then 951porsche said:

[quote]<strong>Hey guys,
I run a Dynapack dyno out in Colorado. The dyno's raw torque #s are calculated from the hubs, and those #'s are run though the SAE correction factor to show SAE corrected HP. This takes into account baro. press, temp, humidity. Dynapack dyno's don't correct for torque as there is not an SAE correction factor for torque, as I was told by Dynapack. Important things you guys should know is the TC (correction factor), and how they did the calibration for hub to rpm. It would also help if someone could get the dynapack files for all your dyno runs, that will have a text file with all data captured during the run. I somewhat doubt the curves would like the same as what porsche has released as that was done on an engine dyno and not a chassis dyno. Chassis Dyno values vary enough between dyno types, let alone comparing engine vs chassis plots. The dynapack is a great tuning dyno as it is load based and not a inertial dyno. Anyhow, if you get the .pts files from Rick I can tell you guys a bit more about your pulls. If you have other specific questions, let me know...

Pete</strong><hr></blockquote>


I said:
[quote]<strong>
This is very interesting...I asked Rick if it was correcting based on the temp readings and such and he said no. The temp monitor was right by the computer monitor and was reading 90 degrees F. If torque is not corrected and HP is, then it would make sense that my HP would be so much higher than torque...However this does not explain why this doesn't hold true for everybody else...

What is the formula for SAE correction?? The calibration for hub to RPM I believe they plugged in the gearing...they may have done more but not to my knowledge...but I didn't ask. I'll see if I can get the .pts file... The TCF as shown on my dyno charts is 1.00.

EDIT: I did my own little SAE correction test. I plugged in various torque and rpm values from the graph...and all the hp values I got from doing this were 5-10hp lower than what I got on the graph. When I plugged hp into the formula and did a backwards calc, i got similar results...5-10lb/ft of torque that would have had to exist for me to get those hp values, uncorrected.

OK, so we found where 5-10 hp came from...what about the other 20-25?

thanks!!

Oh, and I figured out how to test if I have stock chips or not. If I get an MBC and crank up the boost I should see the overboost protection right? Well if they are actually not-stock chips...I won't see any overboost protection!
<hr></blockquote></strong>

So, personally I am still searching for the remaining lost HP and of course any thoughts in general are welcome.

 

I'd also like to know why the torque peaks don't match up. The stock chart shows the torque peak at 4000rpm while yours shows it at 5300rpm?

 

OK here we go. The dyno IS correcting to SAE except for Wheel torque #'s. The SAE correction factors happen for AMBIENT air temp, humidity, and pressure. I really can't/won't explain whats right or wrong with any of your pulls unless you can get me the raw dynapack files. There are just too many unknowns without seeing the raw data. With those plots I can see for sure what what was happening and being calculated for your printouts. The dynapack does the correction based on it's inputs and outputs both a raw and corrected HP number.

The TCF does show 1.00 but i'd still like to see the .pts to confirm whats going on. I recently dyno'd a 944 turbo track car and had no issues with it bucking. I've not experienced what you guys are talking about with the dyno bucking, I hope you guys got a raincheck or something because that many cars having issues sounds like a dyno issue IMO.

The RPM values may be skewed if they wrong ratios are entered which may explain the 968's torque being offset. Get me the pts files and I can tell you....

Adrial, I'm not sure what you think is wrong with your car. Do you want to know where the extra HP #'s are coming from? Or missing HP? Please clarify...

 

If you find your missing horsepower, let me know. Maybe mine is lurking there as well!

 

951porsche,

I followed what you meant about hp being SAE corrcted, but torque not being.

I'm trying to find where the extra hp is coming from. There's an extra 20-25. I know who both of the PO's of my car are and have all records and it doesn't seem likely that either of them would have done internal engine work. SO I'm trying to find out if the car really has the extra power, or if its dyno BS.

Danno, I think the reason my torque peak is so high is that the boost hit so late on the dyno. If you compare mine to a 951 dyno'ed same day with a k26/6 and bypassed cycling valve...you see that his boost hits more where it belongs.

<a href="http://members.rennlist.com/adrial/image001.jpg" target="_blank">http://members.rennlist.com/adrial/image001.jpg</a>
<a href="http://members.rennlist.com/adrial/image002.jpg" target="_blank">http://members.rennlist.com/adrial/image002.jpg</a>
<a href="http://members.rennlist.com/adrial/image003.jpg" target="_blank">http://members.rennlist.com/adrial/image003.jpg</a>

Finally, the bucking on the dyno we were told was a result of clutch slippage. Some cars hooked up (4 of em), some didn't (3 of em). Luckily, mine hooked up. It wasn't really bucking...just the exhaust rattling all over the place because of the clutch slipping. The guy driving the car said the clutch was slipping on the dyno.

thanks,
Adrial

EDIT: I'm also wondering if my boost curve is characteristic of a stock 951 on a dyno. On the street I know the boost hits earlier, much earlier...around 3700rpm I see FULL boost. What I don't understand is that my car isn't being put under enough load to spool up the turbo earlier, but that other cars are being put under enough load to slip the clutch on the dyno when it holds perfectly on the street?? Even Tony's 951 (the dyno charts up above), he has an MBC and he doesn't see full boost on the dyno until 4000rpm...on the street I know he sees full boost earlier.

 

I haven't read any replys on my post from saturday but here goes again.

My car bucked on the dyno, nad i was told my clutch was slipping. Both my 944S2 and Dave's 944NA started bucking around 3,000-3,200 rpm. we were told the clutch was slipping.

I punch the gas pedal and as soon as the motor starts revving the tach starts moving and the car moves. Whats slipping?

PETE - on the drivers side of the dyno there was a lever like a jack handle. I think it was taken off on one car, and left in when my car ran. Do you have any suggestions other than a clutch problem?

Thanks.

Adrial, I think that extra HP you found is Damians. He's looking for about 30 that are missing from his car!!!

 

Tom,
Your clutch may be slipping and you just may not notice it since you don't generate enough load to cause it to slip. The way I used to notice was on a steep hill starting in first or second. That exaggerates load for the car and would be the first indicator for a slipping clutch. I don't know if you guys really have slipping clutches or not.
The handle on the Pods is to move the hub up and down when aligning it to your car. We usually take them out after the car is setup as the stick out and hurt when you bang your chin into them.

Adrial,
I wouldn't obbess to much over the HP #'s. Dynos are tuning tools without an original baseline run on this dyno when your car was new there are just too many variables. One thing to keep in mind is that Porsche has been known to underate their engines. They do that for sure on the 996tt. Other things are the SAE correction factor, The mystery chips in your ECU, etc...
The dynapack does generate a fairly heavy load, which should have gotten your car to spool up faster, so I'm not sure whats up with that. I don't know how much load, but if you're looking at dynojet runs they put 3600lbs of interial load. I can tell you more if you get the raw files...

Pete

 

Well, my new clutch is in, so I'll let you know what the dyno says today (on Saturday I was slipping at 200 hp, so we know I'm at least good for that much hp!).

Look's like I'm back on schedule for Watkins Glen DE on wednesday & thursday. Right now I plan on leaving for the Glen tomorrow afternoon (hope to arrive before dark).

Richard
'87 Carrera-3.6L

 

Good luck, 87' Carrera with a 3.6? Thats a fun setup at sealevel I bet!