Flat-shifting or Power-shifting G50

JohnJL · 08:24 PM

Strictly in a racing application to begin with...I've noticed my ECU has built in features to enable flat-shifting. It allows for multiple rpm bands and multiple rpm limiting (spark, fuel, mix) etc.

Before I starting slamming my new G50 into gears in experimentation, is is possible or necessary to cut power momentarily in order to achieve full-throttle upshifts? Anyone do this successfully? How about the downshift?

Others using this ECU have achieved it using a clutch switch or sensor on the shifter. When the ECU sees 1. RPM in the specified range (just below redline) and 2. throttle position above 95% and 3. the clutch switch or shifter sensor is activated then the ecu momentarily (and this is configurable in miliseconds) cuts either spark, fuel or both. The trick seems to be experimenting with the timings to get the motor to "pause" long enough to be matching speeds for the next-higher gear which you simple move the lever into. No clutch involved except where a clutch-switch is used and then it is only a "touch" to activate the switch and not fully disengaging the clutch mechanically.

thanks all

Mr9146 · 05-24-2009, 09:05 PM

Sounds like a sequential box would be right in your wheelhouse.

JohnJL · 05-24-2009, 09:28 PM

Yeah, but I just spent a bundle on a new shortened G50!

jcge · 05-25-2009, 01:53 PM

Some info on shift sensors

http://www.bosch-motorsport.de/content/language2/html/2892.htm

And power cut to shift (refer to the Bosch MS4 Function Sheet page 34 "%GEARCUT") which describes the specific implemetation in their MS4 ECU software.

http://www.bosch-motorsport.de/content/language2/html/3562.htm

Maybe try calling your local V8 Super Car team for a chat (seriously !!)

Sorry I have no personal experience to contribute.

Regards,
John

Dixie · Dixie's Garage

I see an expensive transmission rebuild in your future.

JohnJL · 05-25-2009, 02:34 PM

Thanks John. I know holder, nissan, subies, evos and toyotas which have this working.

I'm looking for anyone who has done it with a G50. Even if not a full implementation, perhaps still using the clutch but manipulating spark and fuel based on ECU inputs to faciliate quicker shifting.

Rob, do you say that because you have knowledge that this doesnt work? If so what configuration was that? Did you or they just jump in and try forcing gears 'cause thats not what I'm talking about.

Dixie · Dixie's Garage

I'm not saying it won't work. I am saying I doubt the helical gears and dog teeth in a G-50 will survive for long under such abuse. If time spent shifting was so important, I'd look into swapping in a true racing transmission.