Power loss after each full throttle shift?

[Tygen1]

Doing timed practice runs to get accustomed to shifting quickly during full throttle acceleration. Last night I was shifting just past 5500 rpm and it all went well. After reading that some have had good results shifting at 6500 rpm, I gave that a try tonight. I lifted the throttle during each shift, just as last night, but tonight the engine fell on its face, momentarily, after each shift. Is this normal?

 

[M-Sport fan]

Mine, still on factory turbo AND tune, almost feels like a FULL 'boost dump' when I hit red line on a WOT shift.

Some on here tell me that is just the sharp power 'drop off' at/near red line on the factory tune, but it feels A LOT stronger than that (and even stronger than a spark/fuel 'cut' as well), like a TOTAL power loss (not merely a 'drop off') for those few seconds, until the revs drop back below red line.

 

[slightlyslowst]

Mine, still on factory turbo AND tune, almost feels like a FULL 'boost dump' when I hit red line on a WOT shift.

Some on here tell me that is just the sharp power 'drop off' at/near red line on the factory tune, but it feels A LOT stronger than that (and even stronger than a spark/fuel 'cut' as well), like a TOTAL power loss (not merely a 'drop off') for those few seconds, until the revs drop back below red line.

also curious about that

 

[Tygen1]

I shift and as I press on throttle again, its like there is a flat spot, no deceleration, just flat, for a moment, then it picks up again.
Perhaps I was shifting too near fuel cut?

 

[M-Sport fan]

You did not raise the red line at all, and still on the full factory tune, correct?

 

[Tygen1]

100% stock

 

[Tygen1]

Just re-read your earlier post. Boost dump at redline would make sense. It would take a moment for the actuator to spring back and allow boost to build again. I will take a closer look...

 

[Hypergram]

I know that on a fully stock tune if you hit the rev limit the car just basically stop accelerating even if you're still on the gas. It doesn't bounce off it. Maybe that has something to do with it? Took the car stock to a drag race once and found that out. Beat a Civic coupe lol.

 

[LilPartyBox]

GFB+ and an OTS Stratified tune and that will mostly disappear.

 

[M-Sport fan]

I know that on a fully stock tune if you hit the rev limit the car just basically stop accelerating even if you're still on the gas. It doesn't bounce off it. Maybe that has something to do with it? Took the car stock to a drag race once and found that out. Beat a Civic coupe lol.

Yeah, this, as I was used to that 'stuttering' of the rev limiter when it was 'ridden' on my naturally aspirated, LS1 Z28. (Does that indicate a spark cut ONLY limiter?? )

Whatever this car uses as a rev limiter (anyone know for SURE?!), it is a HARD limit, with none of that stuttering effect, and with a 3" catback system, I will even get a pronounced pop happening most of the time just as it passes the limiter.

IS the wastegate programmed to open HARD when these cars hit the limiter on the factory tune?

 

[Se7eN]

100% stock

Don't do that, don't shift that high up in the RPM range with the tiny key chain turbo 5,500rpm is fine and well without tune Flat Foot wouldn't even really work.

 

[Tygen1]

I'm searching for the best shift point 🤓👍

 

[4sfed4]

I'm searching for the best shift point 🤓👍

Have you found it yet?

I have also noticed that between shifts (even on the factory turbo) there is a tiny bit of transient lag. I have heard folks say that replacing the factory DV helps with this, but I have not tried this yet as I haven't found it to be that big of a deal.

 

[FORZDA 2]

To the OP: You're hitting the rev limiter for SURE. The tachometer (and Speedo) lags just a bit when accelerating at WOT, so when you lift to shift you're already right on the rev limiter.

The relatively heavy flywheel keeps the engine accelerating even as you lift to shift, so it is already into the rev limit when you get back on the gas. There is about a 1/4 to 1/2 second delay before the ECU recovers after the rev limiter activates. If you're watching the tachometer and were shifting at 6k rpms, you were probably right on the money.

Most people can't shift quick enough to prevent the slight over-rev watching the tach which is the ONE advantage the dual-clutch transmissions have over manuals. If you really want to take the last tiny bit of the power, don't watch the tach. Get yourself a big bright shift light and set it to come on at about 3-400 rpms before you want to shift. Test your physical reaction time delay and adjust the shift light onset to allow your specific shift time.

You could replace the OEM flywheel with a lighter version, or do the light and flywheel for peak power useage.


Edit: One more thing, your tune(r) may have left the shift assist active which holds revs between shifts. Make sure it is disabled...

 

[Se7eN]

^^ the Cobb Accessport has shift lights FYI