During discussion on the Sharktuner thread, or tuning '85/'86 928, we talked about some of the performance measuring devices, other than dynos, that might be used to help tune ignition timing. I mentioned a couple that I had used and wasn't too impressed. Rick Carter brought up the MrDyno variety that he had but hadn't used yet. Rick sent his MrDyno to me for evaluation. I received it yesterday and tested it today.

I tested MrDyno and another accelerometer based unit called DynoPlus. First thing you notice about the MrDyno is the large 64 page instruction manual and it's small size with small 7 segment digital display. Both alpha and numeric data is displayed on the 7 segment characters so you get the much despised mixture of upper and lower case letters more or less which you can almost sometimes guess at what it is supposed to be. To compound the frustration, when a message is to be shown that is longer than the 8 characters that are displayed, it scrolls horizontally. Scrolls so fast you have no clue as to what it is trying to show. It also has 4 pressure sensitve keypad "buttons" with which you navigate through menus for setup and use. I didn't count all the menu choices, but there are probably close to 200 layered several deep. This is one complex device and it takes several hours to just figure out the basic setup. All the configuration data must be entered into the unit before you can do anything with it. It would take another 64 pages just to detail everything that has to go in. Just a summary is, vehicle data (up to 4 vehicles), weight, speed/mph in each gear, test window (min mph & max mph), for both acceleration as well as deceleration. The deceleration is to map the vehicle loss so a better approximation of RWHP can be determined. Current weather information, temp, humidity, altitude, atmospheric pressure. The data entry is somewhat simplified by the MrDynoLab program that runs on a computer. You connect MrDyno to the computer with a serial cable. By entering data in the MrDynoLab program on several screen, you can download it to the device. The download process isn't easy either because you have to go 3 layers deep into the indecipherable menus to find where it is. Some help is available in the computer program so only 3 or 4 tries were all it took to download all I could before actual testing. You really have to take your computer with you so you can download the current environmental information when you are testing. You should be able to load that in directly but you have to contend with the insufferable menus to find it and try to figure out the weird scrolling upper/lower case alpha numerics. I took the laptop with me. BTW, if you want to load data in this at home, drag out your trusty 12v power supply with lighter power adapter so you can plug MrDyno in. It does have a built in 9v battery, I think all that does is keep memory alive, or something. It won't work without being plugged in to a lighter adapter. +12v will burn it out so you have to use a special adapter that outputs +7.5v. That adapter is supplied.

Today, I load up the car with laptop, 12v/120vac inverter to power my laptop because the battery is near gone, Lighter socket power splitter for the laptop & MrDyno power, altimeter, outside air temp probe, MrDyno with windshield mount, serial cable, power cable, note pad, duct tape, and my DynoPlus which is a self contained box about 4"x2"x1".

I found a smooth road that was almost level and about 1/2 mile long with light traffic and hopefully no cops. First, I tried the DynoPlus. It's pretty simple. I strapped it down with duct tape to the drivers door arm rest and leveled it by jamming a popsickle stick under one end until the "zero" LED lit. With the car stopped, I switched the switch from "on" to "record" and made an easy start in 1st, shifted to 2nd, and opened the throttle until I got to 6000 rpm and shut down. I turned theswitch from "record" back to "on". That got me to about 72 mph and just where the road began to have a slight rise. I turned around and went back to the starting point and did this two more times. It took maybe 10 minutes max.

Next I tried the MrDyno. I had to input the weather info, so fired up the laptop and MrDynoLab prog. Entered the weather info in the laptop prog, and figured out how to download to the MrDyno device. Next was to try to go through the menus to do an acceleration run. You've got the choice of an acceleration run, 1/8 mile, 1/4 mile, 0 to 60, or continuous data logging. I found the acceleration menu and had to go through a few more sub menus after selecting that. You have to zero the accelerometer which means sitting there in the road stopped, working the menus, and slightly moving the device in the suction cup windshield mounts until it reads zero G, then press the "enter" key pad while trying to not move it. The unit says "ready" in it's window, or something you might imagine is "ready". As with the DynoPlus, you start in 1st, move to 2nd, and open the throttle. I had previously set 20mph as the start speed and 70 as the stop speed. When 70 was reached, the unit flashed "done", and then the elapsed time for the 20 to 70 test. If you want to use the arrow pads to move through more menu choices, it will display power peak (hp), average hp, distance traveled, and I think some more information. I did that two more times. It probably took 30 or 40 min to do that test sequence.

Then I went home. I downloaded the data from MrDyno into the computer while I was still in the car because it had to be powered from the lighter socket.. More dealing with menus to get the data out of MrDyno. It's pretty easy with DynoPlus. You connect the serial cable, turn on the switch, and after starting the software on the computer, click on "connect" and when the "connected" message shows, click on "read". Do that for each of the runs you made in this session.

The MrDyno runs were all there in the database and were easy to display by selecting the run and clicking on the "Show in new window" button. To overlay another run on the same graph, select the run in the database and click on the "Display in same window" button. Both runs show in the same graph. The graph properties can be set to show torque and hp, time, or speed. I noticed that the hp/tq seemed quite low and the displayed rpm was high. I didn't turn theengine much over 6000, yet the top rpm showed 7000. I saw that the vehicle data showed a wrong value in the rpm/mph config data. I don't know why this was that way. I checked the .ini file for the vehicle and it was ok. No matter what I did, I couldn't change it. MrDyno is supposed to show a graph of an average of several runs. I could never get that feature to work. I did not do a deceleration test because I didn't have enough level road. I would have had to accelerate to 5mph above my top test speed, in this case that would be 75mph and let the car coast down to 20 ro 30. So these runs didn't have a correction for vehicle loss. The MrDyno unit has you enter all data into the device and it does the calculations internally. Apparently the run database contains this data and the computer program just displays it. If you mess something up in data entry into the unit, you are pretty screwed because you can't alter parameters later. Maybe this isn't the way it is, but I only spent all last evening and nearly all day today trying to figure this thing out, and I may have missed a small point.

The DynoPlus works differently. It records raw accelerometer data and downloads that into a file to your computer. The computer program has you input enviromnental data (same as MrDyno), vehicle gear ratio you used during the test, final drive ratio, wheel size, tire size (such as 245/45), and which gear you used for the test. The computer does the calculations. It also wants vehicle Cd and area. It calculates vehicle loss from that. The results wern't much better. Hp/Tq were low. This time the RPM was lower than it shouldhave been and the torque curve fell off a lot at the upper end which MrDyno didn't show. The DynoPlus computer program can't display more than one curve on the same sheet. It does output in a .txt file and a .csv file. It has inputs for four 0 to +5v analog inputs too. Normally this S4 makes about 310 lb ft tq, and 300 hp +/- at the rear wheels on several dynos.

What's my conclusion? Neither of these is adequate for tuning because there is too much variation between runs. You have to have a measurement tool that will show several runs right on top of each other with accurate rpm data before you can determine if you've made an actual improvement, or just measurement error. DynoPlus showed a couple runs with very close peak tq & hp, but differences in other parts of the chart. Would you really know if you made an improvement, or made it worse, at 3500 rpm with these charts when actually nothing was done? Most tuning improvements come in small increments. It takes some time to do each set of runs especially with the MrDyno. I didn't like doing it on a public road even though I live in a very rural area.

I've made screen shots of the graphs. The top one is from MrDyno, and the others are from DynoPlus. Even though I made three MrDyno runs, one was garbage so I didn't use it.

https://rennlist.com/forums/attachme...id=87667&stc=1
PowerCharts1024.jpg

 

Very interesting, Louie ! The search continues....

Regards

 

I think I know the answer. A real dyno

 

Louie-

That's some great information. Thank you for your candid evaluations.

 

Much frustrating work, not a lot of good results. I wonder if the vendor can fix the rev issue (maybe a hidden setting or such).

 

"What's my conclusion? Neither of these is adequate for tuning because there is too much variation between runs." - Louie928 -

To be expected! Good "toys" for a 1st year high school auto shop, i.e. "tools" to avoid.

 

I highly doubt a first year auto shop kid could figure MrDyno out. I have mine lying here, unused, as it is just to cumbersome to use. Very techinical, but cumbersome. So much easier to use the G-tech pro.

 

Louie
Have you tried any of the Gtechs? I was surprised to see how low the HP numbers were compared with the actual dyno #'s?

 

I have a GTech Pro. It isn't one of the newer graphing types. It did give fairly consistent 0 - 60 times and maybe 1/4 mile too. It was no use for tuning, but to give an overall number after everything was done. I did check out and contemplated purchase of the new GTech with the graph display and ability to download to a computer for further analysis. From my perspective the display is too small for serious data display. Getting the configuration and car info inputted is a pain too. I talked to others that had them and downloading the data was no real help either because of the same variation between runs problem. I think Escort has a similar unit, but I haven't tried one, nor do I know anyone who has.

My power may have read low on both of these units yesterday because the road I used was very slightly uphill. The freeway, about 6 miles away, is flat, but I figured it wasn't the place to be doing this. I was mostly after repeatability of the device, not exact hp/tq readings. The RPM reading does have to be accurate if you are going to use that to make adjustments in an ECU map, and neither of these units recorded RPM very close to accurate. The DynoPlus was closer than MrDyno.

 

Louie,
It sounds almost like I put you through torture with Mr. Dyno. Here's another one to look at, I don't have one. Have you heard of it?
http://www.dynorad.com/index.php
Rick
85 32v modified

 

No Virginia, there is no Santa Claus.
Great work Louie, we're all now just a little further in your debt.

 

I suppose you could manipulate the vehicle information to get the RPM closer to actual. Depends on how much time you want to mess with it. In both units the RPM is calculated from velocity which is calculated from G & time. The MrDyno uses an RPM/Speed variable to get RPM. You can either get this from your speedo and tach, or from the vehicle data. Both my tach and speedo are not right on so I didn't use that. I used the RPM vs. speed in each gear chart in the S4 owner's manual. I have stock tire size and wheels. If that chart is off, then that would be an error possibility. The DynoPlus does about the same thing except you enter wheel size (16"), tire cross section (45), and width (245). It also wants the transmission gear ratio that you are doing the test in (2.714 for 2nd gear), final drive ratio (2.2). It also wants which gear is used for the test. In my case, 2nd. It wants that because it won't begin to display data on the chart until after the 2nd zero G point. You have zero G at the start, zero G when you dis-engage the clutch to shift to 2nd, then the display of data starts. If you were to use 3rd gear, it would begin data display after the third 0 G point. There are other ways to display the data, and if you want, you can see the whole run including gear changes. Yes, there is no acceleration when you change gears on a 5 spd.

 

Ok. I can see that this might be useful. I saw graphs where they compared one DynoRad run to Dynojet runs, but I didn't see two DynoRad runs laying on top of each other. At least they are doing it in a better way with a wheel speed sensor and an RPM sensor. You would have to be sure of no wheel spin, but for most 928's 2nd or 3rd gear would work. For others with big torque, and/or small tires, it's back to the same old dilema of where to test where you can go to 120 or 140 without getting thrown in the hoosgow.

I'd like to try one of those and at ~$200, the price isn't too bad.

One last thing was apparently the unit in the car only saves the last run internally. That means you'd need to take your laptop and download each run after you did it. If you are tuning, it's not bad because you could make changes and do another run and download that. Still looks like an all day job to do what you can do on a dyno in an hour or two.