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Flat shift, synchro H pattern

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I watched the webinar on flat shifting, but I still have some questions that hopefully can be answered here.

I am using an H pattern stock Audi gearbox, main goal is to keep the boost while changing gears, I am using a pedal switch that is installed at the very top of the clutch (cruise control switch).

The car is on Ecumaster EMU and I'm trying to experiment with ignition angle cut when changing gears.

So here are my questions:

1. How much fuel enrichment should I use and why? Can more fuel enrichment cause louder explosions in the manifold thus keeping the turbo pressure better, if yes, this makes me think that it will significantly reduce turbo life.

2. How much ignition retard? Speaking in absolute values, what is a good starting point and how much retard I can go?

3. Gear cut time - maximum value here is 1000ms, I'll be honest, I am not Toretto from fast and furious, and I think that I should start with highest value here and adjust based on log data?

4. Should I experiment with these settings at 3-4000 rpm? The car is pulling after 4k rpm, since it's a big turbo.

What would be a good step-by-step guide to experiment with these settings without damaging the gearbox?

Thank you


My experience with setting up shift cut is that all car/engine/gearbox/fuel/driver combinations are different, and what works well for one, will be considered to be poor for another.

Setting up a Flat Shift system is an iterative process, that is massively helped by having good logging at a fast rate.

I now have some good starting files (as well as knowledge about what setting to change to resolve an issue) for the ECU's (MoTeC M1) and typical vehicles that I work on, but even then they are just starting points, and each one of them has required fettling to get the suited to the conditions that the driver will be in. For example, a vehicle that is going to be used for Rally work (either tarmac or gravel) will require a lot of work on the power on up and down shifts to accommodate the driver pulling a lower gear under load (like braking under antilag operation) compared to a circuit car.

For a car that I haven't done before, I would extend the times for the different stages of the shift cut and put more cut into the ignition and fuel (if used) cut tables than would be needed. I would then send the driver out to do some shifts and report back on the feel, I would look at the logging to see how long the shift is actually taking and then reduce the cut time to be about 10% longer than this. I would also look at how much the engine speed has dropped under the shift cut, and its response out of the cut and start to reduce the amount of cut needed. You make these changes and then get the driver to do another test and report back.

This is much easier to do when the ECU has closed loop operation of the shift cut functionality, as you can put longer times in and have the ECU automatically reduce the time that the cut is active for based on the shift position.

Steven has covered about everything.

Only comment I would make is, if this is for 'drag strip' use you incorporate a manual switch somewhere to turn it off for normal driving, as I expect you'll find all the timing is going to be off for that, making it a horrible driving experience - Steven would be better qualified to comment there, though.

Oh, and the placement of the cut-out switch, if using a clutch placement, may also need some adjust ment - I would expect you would need it closer to the engagement point. It will also potentially cut the ignition/injection when stationary and the pedal depressed to select a gear, at stop lights, etc. This is why it's usually triggered from the gearlever - again, Steven can better comment.

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