944 DYNO RESULTS!! PICS!!
11-22-2004, 01:08 PM
#61
When the shop can't set up the dyno right or scale the graphs (not to mention loops on graphs are impossible), I don't know if I'd even trust the dyno charts at all - you have no idea how reliable/unreliable those numbers are.
11-22-2004, 09:46 PM
#64
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Anybody find it funny how Dad and Ashton were posting less than a minute apart almost. I'd love to sit and listen to the dinner conversation at their house!!!!!!!!!!!!!!!!!!!!
11-23-2004, 12:17 AM
#66
Why are loops on a graph impossible? Can't RPMs decrease?
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11-23-2004, 12:18 AM
#67
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Great discussion! Thanks for emailing the manufacturer, Matt... I'm eager to see what they have to say about this. I knew my 944S couldn't have ONLY 140 at the wheels! 
11-23-2004, 12:23 AM
#68
Ian, the only thing I can think of is that the dynapack somehow places a load (you can control the speed manually, from the operators buttons), the irony is that the reason people are high on the dynapack is that there is no rolling resistance.
I read alot about dynos today trying to find the answer. Finally, got bored, tried calling but Dynapack is HQ in Australia and the time change had me screwed up so I let them an email with a note that I would post the response, unless they specified otherwise. If they dont want it posted, I will paraphrase it for all of you.
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I read alot about dynos today trying to find the answer. Finally, got bored, tried calling but Dynapack is HQ in Australia and the time change had me screwed up so I let them an email with a note that I would post the response, unless they specified otherwise. If they dont want it posted, I will paraphrase it for all of you.
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11-23-2004, 09:25 AM
#69
Anyone who was there, can you tell me the operators name?? I am in contact with Dynapack and they are interested to know. Additionally, what is the name of this place you were at?
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11-23-2004, 07:15 PM
#71
Stoogemoe, how are you going to spin the wheels on a dynapack? This is a hub dyno (i.e. the wheels come off and the hubs are bolted to the machinery). I.e. not possible.
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11-23-2004, 07:23 PM
#72
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I completely forgot the operators name.....dangit
the place was motor werks racing.
but the guy with the dyno was from a shop next to that one....
the place was motor werks racing.
but the guy with the dyno was from a shop next to that one....
11-23-2004, 07:32 PM
#73
11-23-2004, 07:33 PM
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Motor Werks Racing would like to say thank you to everyone who attended our open house and truly hope that you had a good time. This day was designed in appreciation of our customers allowing them the opportunity to obtain a dyno base run for their Porsche at no charge. Motor Werks Racing, an exclusively Porsche shop, deals with 99.9% track cars and very little with street cars.
In keeping with the theme of the day, we wanted to offer all attendees an opportunity to do a dyno run. With that in mind, minor adjustments had to made to accommodate everyone that attended. A true Dyno session requires extensive setup using optical tachometer, TDC markings, ports tapped into manifold for boost on turbo cars and vacuum on N/A cars and lots of practice. In order for all who attended to participate in the free dyno runs we were unable to attach the optical tachometer, vacuum lines and other various items to obtain a smooth and accurate reading. Although the readings appear erratic, the numbers obtained during the free dyno are very close to absolute numbers.
Jim Burke, the owner of PFM Engineering, graciously supplied the dyno for the event and has addressed, in conjunction with DynoPack, the questions presented on this thread.
Gear Ratio:
The DynoPack dyno reads the wheel RPM and calculates engine RPM using the gear ratio. If the actual gear ratio (transmission ratio * differential ratio) is known, this number is entered. Alternatively, the dyno operator can set gear ratio by using the vehicle tachometer.
In the interest of time at the Open House the vehicle tachometers were used to determine gear ratio. For serious dyno sessions, the engine RPM is measured using a calibrated optical tachometer.
Loops in Dyno Sheets:
The DynoPack dyno uses hydraulic force controlled by valves to apply torque to the axles. If the engine suddenly loses power for whatever reason, the computer may not be able to release torque quickly enough to allow the engine to smoothly accelerate. When power loss is severe, the RPM decreases before continuing the sweep. This produces a “loop” in the horsepower and torque curves. The driver also has to smoothly bring the RPM up to the initial RPM and then apply full Power in a controlled manner.
5252:
I don’t know where this urban legend got started, but torque and horsepower curves on graphs only cross at 5252RPM under one special condition!!! Unless the scaling is the same for both torque and horsepower the curves will NOT cross at 5252. By the Way, 5252 is the constant to compute horsepower when torque is expressed in Ft-Lb and speed in rev/min.
Excessive Engine Loading:
This is a problem I have discussed with DynaPack. Engines with low torque at low RPM are difficult to dyno on the DynaPack 3000. Running in a lower gear usually solves the problem, but a poorly tuned or sick engine will not get past the residual torque of the dyno.
As stated before, the dyno base runs and the Open House presented by Motor Werks Racing were meant to be a fun gathering for Porsche enthusiast. As far as the head and exhaust work on the N/A 944 absolutely other mods were performed. Although- stock rods and pistons were utilized as well as compression ratios. This is an ongoing project and not unlike other accredited engine builders, certain proprietary information will be protected. After all, absolute peak power is less important then the overall power under the line. We appreciate your input and welcome any questions you may have concerning our Open House or any of the vehicles that appear on this post.
Thank you
Motor Werks Racing
Exclusively Porsche
(770) 886-0686
In keeping with the theme of the day, we wanted to offer all attendees an opportunity to do a dyno run. With that in mind, minor adjustments had to made to accommodate everyone that attended. A true Dyno session requires extensive setup using optical tachometer, TDC markings, ports tapped into manifold for boost on turbo cars and vacuum on N/A cars and lots of practice. In order for all who attended to participate in the free dyno runs we were unable to attach the optical tachometer, vacuum lines and other various items to obtain a smooth and accurate reading. Although the readings appear erratic, the numbers obtained during the free dyno are very close to absolute numbers.
Jim Burke, the owner of PFM Engineering, graciously supplied the dyno for the event and has addressed, in conjunction with DynoPack, the questions presented on this thread.
Gear Ratio:
The DynoPack dyno reads the wheel RPM and calculates engine RPM using the gear ratio. If the actual gear ratio (transmission ratio * differential ratio) is known, this number is entered. Alternatively, the dyno operator can set gear ratio by using the vehicle tachometer.
In the interest of time at the Open House the vehicle tachometers were used to determine gear ratio. For serious dyno sessions, the engine RPM is measured using a calibrated optical tachometer.
Loops in Dyno Sheets:
The DynoPack dyno uses hydraulic force controlled by valves to apply torque to the axles. If the engine suddenly loses power for whatever reason, the computer may not be able to release torque quickly enough to allow the engine to smoothly accelerate. When power loss is severe, the RPM decreases before continuing the sweep. This produces a “loop” in the horsepower and torque curves. The driver also has to smoothly bring the RPM up to the initial RPM and then apply full Power in a controlled manner.
5252:
I don’t know where this urban legend got started, but torque and horsepower curves on graphs only cross at 5252RPM under one special condition!!! Unless the scaling is the same for both torque and horsepower the curves will NOT cross at 5252. By the Way, 5252 is the constant to compute horsepower when torque is expressed in Ft-Lb and speed in rev/min.
Excessive Engine Loading:
This is a problem I have discussed with DynaPack. Engines with low torque at low RPM are difficult to dyno on the DynaPack 3000. Running in a lower gear usually solves the problem, but a poorly tuned or sick engine will not get past the residual torque of the dyno.
As stated before, the dyno base runs and the Open House presented by Motor Werks Racing were meant to be a fun gathering for Porsche enthusiast. As far as the head and exhaust work on the N/A 944 absolutely other mods were performed. Although- stock rods and pistons were utilized as well as compression ratios. This is an ongoing project and not unlike other accredited engine builders, certain proprietary information will be protected. After all, absolute peak power is less important then the overall power under the line. We appreciate your input and welcome any questions you may have concerning our Open House or any of the vehicles that appear on this post.
Thank you
Motor Werks Racing
Exclusively Porsche
(770) 886-0686
