From: Marc Thomas [mmthomas@ix.netcom.com] Sent: Thursday, October 19, 2000 8:12 PM To: 928 Subject: [928] Lets standardize dyno pulls so there is comparative data Folks, I am glad to see everyone getting interested in dyno 'ing their 928. By dyno'ing your car and utilizing sound protocols, one can determine the best course of action for maintenance and modification. To date, we have over 2500 dyno runs, and in some cases over 100 runs on one car in one day! In an effort to create a database that maintains the integrity of the data, I suggest we all follow one protocol for the actual dyno session.. As mentioned in an earlier post, there are ways to "extract" some extra power from a 928 engine that one person may know and another be unaware. This really does not help create a good database. As such, I am offering the protocol that we use for dyno sessions. The following is a method for dyno sessions: pre-requsite - DynoJet Chassis Dynamometer if the car is warm: once on dyno, let idle for three minutes, do one run to make sure that all is well (we will go to 5500rpm just to make sure), wait 1 minute at idle, then do three runs with no more than 20 or so seconds between each run. Just enough time toreset the dyno. if the engine is "cold" once on dyno, let idle for five minutes, do one run to make sure all is well (we will go to 5500rpm just to make sure), , wait 1 minute at idle, then do three runs with no more than 20 or so seconds between each run. Always use the second run as the reference curve/numbers as it is more representative of a fully warm engine, not too cold, not too hot. This keeps everything apples to apples, and it helps make good for a good database with relative results. I really like the coding, although I would leave out the estimated crank numbers as they are very misleading and subject to much debate. Another item that might be of additional use is the 80% torque range number....over what rpm range does the engine product 80% of its maximum torque. This number tells you the overall efficiency of the engine and is a way of telling the difference between two engines that make the same peak numbers. A good example is a 85 euro vs. a 85 us engine. both make about the same peak numbers, but he curves are very different. Let me know your thoughts. Marc -- Marc M. Thomas DEVEK 650-592-5287 phone 650-610-0557 fax http://www.devek.net From: Tom Middleton [midlman@seanet.com] Sent: Tuesday, December 05, 2000 8:01 PM To: 928 Subject: [928] Re: DYNO run 101 Hi Tony, Based on the runs we did up here in the Pac NW. you should disconnect the kickdown under the gas pedal (so you won't lose the dash by pulling the fuse), and also disconnect the kickdown linkage under the hood. Also, make your run in 3rd (tranny will shift normally by just pushing the shifter). I did a couple in D and ended up killing the data acquisition since the dyno stops recording at 200mph (which is what you will be doing at 5800rpm in D with a 2.2 rear)... The dyno can give accurate details even in 3rd. maybe even try a 2nd gear run just for comparison.... Aside from that, let us know the results... Later, Tom. From: Tom Middleton [midlman@seanet.com] Sent: Thursday, August 16, 2001 2:36 PM To: 928 Subject: [928] Re: Dyno notes/questions??? Hi Jay, We have run quite a few dyno days out here in the Pac NW and are using the Devek protocol. For the automatics, you will need to disconnect the kickdown switch under the gas pedal, pull off the kickdown cable at the intake (top outside(towards drivers side) cable) to keep the car from downshifting. Make the run in "3" so you don't exceed the 200mph limit of the dyno (I've been there before). Louis Ott constructed a fan that directs air directly through the rad, but the real goal is to keep the fans from kicking on during the run and possibly biasing the run and also to keep things cool. All other equipment should stay as normal including intake tubes etc...but with the hood open Once you get the car on the dyno rollers, make sure everything is up to temp including oil, diff oil, tranny fluid etc...but not hot as if you were sitting in traffic. Also, if you can, get the car rolling on the dyno and run up the revs to where you feel comfortable a couple of times to get things circulating. Once you are ready to run you will need to get up to around 2000 rpm and when the operator flags you, you will floor it until 6000ish (how high depends on you) and then let off and let the operator brake it down to 2000 rpm.... Ideally you want to get 4 back to back runs (ie. once he gets you down to near 2000 and sets up the next run you will floor it again...and then again until the 4 runs are done).Try to get the runs as quickly together as possible. Toss out the first and then plot the next three together. If you have access to the Air/Fuel ratio sensor on the dyno go for it.. Couple of cars at the Devek dyno day were running lean and it was very obvious from the graph.... Getting your car on the dyno is a blast and isn't only for people that want to modify their cars. As a matter of fact, each time we set up a dyno day, we end up finding someone with a failed flappy.....very good diagnostics tool. later, Tom midlman@seanet.com 87S4 AT(302ft-lbs and 284hp)