dyno tuning idea (part-throttle) - which dynos can do this?
 

I searched and posted on efi101 and I find it hard to believe I couldn't find anyone who's done this.

Can anyone confirm if they know any dyno software that can do this?

A reply on efi101 seemed to indicate that the Rototest will do it.

When one does WOT tuning on an inertial dyno (e.g. Dynojet), one will plot torque (y-axis) vs RPM (x-axis). What you are doing is plotting torque vs RPM at a fixed MAP. MAP is fixed by holding WOT. (assuming an NA or s/c car, or a properly functioning boost controller).
You examine the plot, change timing in a few RPM areas, repeat, and examine the change. This way you do one pull, then the plot lets you examine torque at different RPMs. You change timing at some RPMs, repeat the pull, examine results. You know you are at MBT at a given RPM if reducing timing drops torque and increasing timing doesn't increase torque.

What I'm proposing is to make the dyno hold RPM (at an RPM breakpoint in your ECU), then your foot goes slowly from light throttle to WOT, so as to sweep through different values of MAP. After you reach WOT, you lift and stop the "pull", then you examine a plot of torque (y-axis) vs. MAP (x-axis) generated by the dyno's log. You make some changes to the timing map at different MAP values, repeat, examine changes, tune for MBT at the different values of MAP.

Repeat for different RPM breakpoints.


Most tuners tune part-throttle by letting the dyno hold RPM and display a live torque readout. The tuner then adjusts throttle until a target MAP is reached. He then adjusts timing up and down and looks for MBT by watching the live torque readout. He does this one cell at a time. If the area being tuned is a 5x5 matrix, he needs to do this 25x.

The problem with doing it one cell at a time is that you need to hold your foot steady at the center of the MAP value. As you change timing and you watch the live torque reading, and your foot moves, you're screwed. In addition, as you change timing at part throttle, the turbo might change its output pressure and MAP changes. Again you're screwed - you don't know if torque went up because of the timing change or because MAP went up. You will then have to adjust your foot to get the target MAP value again. Another problem here is the heat soak. As you hold the engine at a rather high value of output power, if you are slow in changing the timing the output torque will continually drop, obfuscating the torque change you are trying to see.

If you sweep through the MAP values and plot it, you won't have this problem, and you can see the whole plot and tune timing in the same way one might do it with a WOT run on an intertial dyno. In the above example of a 5x5 matrix, one can examine the torque at 5 MAP values with each pull, saving time.


The plot of torque vs MAP will be approximately a straight line going up. Ideally for greater resolution, the dyno software can do some math, and plot (torque divided by MAP) vs. MAP to flatten the line so % changes in torque at low MAP will be more visible.

This is exactly what a load dyno is for isn't it? Load dyno will hold your RPM at whatever you set it so that you can tune different LOADS at that RPM. What is in your lemonade?

Neo,

Read my post again.

I am looking for a dyno what can plot MAP as the X-axis and TQ as the Y-axis.

I know for a fact a Dynapack will NOT do it. It won't let you select MAP as the X axis. It only allows RPM/time/distance/speed.

What's in YOUR lemonade?

Pee Pee

I have no experience with the software of like a dyno dynamics dyno. But If you had the raw data I'm sure you could create something to parse it and graph what you want.

Yes but spending the time to manually generate the graphs defeats the goal of saving time.

I can't believe the dyno designers didn't think of this method.

Write a program once that does it many times.

How do you quickly transfer the data from the dyno to your laptop after each pull?

Granted, it's not dyno tuning and with no feedback on torque, but this is exactly how I've been datalogging.

Travel at rpm that matches a column of the VE table, and go through as many load cells as possible without tipping AE. It's pretty easy to go through the full range of load with <200rpm of change in motor speed while going uphill.

I would think that any load dyno should be capable of this. It's the same tool, just a different method.

gospeed you are thinking of FUEL tuning with your wideband.

I am talking about tuning TIMING.

I was discussing the method, but I digress.

Cam timing? lol


Just use a Mustand or Dynodynamics and you'll understand what you're missing. I completely tuned my in about 1-hour and its tuned better than you'll ever tune, spending 3x the money on a ghetto dyno.

The DynaPack does at least show both the MAP and the load on the main screen at once, so it's pretty easy to hold your foot in one position while watching the readout. If you accidentally get more MAP, you'll know immediately.

Looks like it would take some programming changes to make the software give a plot, but the "if your foot moves, you're screwed" thing is a non-issue if you're using the dyno correctly.

Geez. I have been doing tuning on a Dynapack and it WILL NOT DO WHAT I AM SAYING.

Read what I wrote about one cell at a time vs. a fixed RPM pull which sweeps MAP.

Let me ask you this. When you did your tuning, over what range of RPM and MAP did you find MBT, how many cells was that, and how long did that take you?

Heat soak is another issue.
If your foot moves you will have to re-adjust it to hit target MAP, and in the meantime heat soaks in and torque drops. It is hard to see the torque change with timing changes.

With a sweep like I describe, you will save dyno time, save money, and have more consistent more precise readouts.

I selected a cell on every-ther rpm column and every other kpa row. It took me about 45-minutes to do those, I embraced the engine heat-soak because that way I knew it would be safe on the track, then did about 5-ramp runs and I was done.

I think the whole thing was over and done with in 90-minutes. Just pick your RPM column/load cell, pick your TPS/kpa value, change spark and be done. There is no sense in reinventing the wheel.

How many cells did you do cell by cell in 45 minutes? Why did you skip over RPM/MAP rows and do every other? Why have those breakpoints in the first place then?

And why did you do WOT pulls using ramp runs instead of the same cell by cell method, if not to save time? If you did the latter to save time, then you will understand why my proposal is meant to save time.

Jason, we go from steady state to ramp runs at high load for a couple reasons. The most basic reason is to reduce high stress run time. It's to save run time on the motor, not to save the operator time.* However, a less obvious but equally important reason is so that we can try to predict the next load zones before hitting them. So we take our ramp run, observe, and if necessary change not just the zone that we're in, but all of the areas above and next to our current area that we haven't hit yet. Predictive tuning. Meanwhile the car is cooling down, and by the time we're done rescaling, the car is ready to pull again.

Our dynapack has a mode very similar to what you're suggesting--it just doesn't display the data in the manner you're requesting, but in terms of operation is pretty similar.

*Bear in mind that most tuners get paid by the hour!

And what you describe above are all the same good reasons for doing a "MAP sweep" run like I want!

Another advantage as I mentioned is that when doing a WOT ramp pull, boost creep may cause MAP to walk across different MAP rows making tuning a PITA because the ECU is now interpolating between rows. If you fixed RPM and swept MAP, you would remain centered on the RPM column, and the plot would show you the effect on torque at the various MAP centers!

Another thing--
Holding RPM like that would be super hard on the transmission. I was watching the trans temp gauge on MegaManiac when she was on the dyno, and I could see the trans temp climb fairly dramatically during the 2 seconds the dyno held at our starting RPM before releasing to the ramp run.

We ended up having to reduce our hold time to 1 second. 1 second settle time on a car that breathes like that makes it difficult for the operator, but it's what the transmission needed.

On a well prepared, low boost, stout car with extremely good EBC, it would probably be possible to do what you want. Like I said, our dyno is pretty similar in steady state mode to what you are requesting. It just won't display exactly how you're asking.