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2JZ S15 anti lag between gears


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Hey Legends

Im trying to now focus on keeping boost from falling off between gears.

H pattern synchro R154 gearbox.

2jzgte 655hp S15 silvia

Bosch 82mm DBW 


Can i use anti lag to help keep boost between gear shifts? And if so could i get some info on the setting this up correctly?

I can upload my Tune to adjust for the Anti lag between gears



ALSO, Can "no lift shifts" be set up on the this style of gearbox and ecu setup? so still using the clutch between gears but tuning the dbw throttle between gears to keep the throttle completely open and adjusting the ignition etc to unload the gearbox etc?

may need a strain gauge on or clutch switch


Thanks team 


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Ive never set up or used anti lag before so im interested to see what the results are for changing gear quickly and keeping torque and boost between gears.

I always thought it was used for with launch control to help an AWD car launch very hard off the line. 


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You can use Antilag or gear cut, but they have conflicting requirements so you really need to decide what you want.  Antilag needs a mostly closed throttle, Gear cut needs a mostly open throttle.  Antilag is generally used more in rally where there is lots of On/Off throttle action.  You also want a mechanical pedal box or electric vacuum pump for the brakes with antilag as your engine will no longer make vacuum. 

Yes gear cut will work ok with a synchro gearbox and a clutch switch, the clutch switch needs to be set up so it switches somewhere shortly after the pedal first starts to be pressed.

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Ok thanks for that, I do have a switch mounted at the top of my clutch pedal, it’s not in use at the moment so I could use that for the flat shifting.


basically im just trying to reduce the lag/drop in power between gears.


would you suggest “flat shifting” would be preferable over the two? for what I’m trying to achieve

i have had a look at the settings for the “gear shift control” 

all reasonably strait forward with the “start and end modes” on the clutch switch digital input, but I’m unsure of the “driven up shift” tables (x4) and the base setting I should put in them so I can start testing on the road and see how it performs.

could you have a look at that for me with some base numbers to start with? 

this is new territory for me haha 

appreciate your time 




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Boost pressure is good between the gears on this run but im interested to know what this dip ive got on all my gear changes is? As it shows, its happening inside the clutch activation time. 

Is there a way to smooth out the dip? not let the rpm drop as far as it does etc

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hey mate, ive tested dropping the driven upshift cut% from 90% to 80%. looks and feels good.

ive attached the log of the new settings, second part is of log is where i was testing the flat shift. 

By the logs, should i be adjusting any more settings to dial it in further?


the photo is from the log above flat shifting 1st, 2nd, 3rd


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In all 3 of those shifts your cut is active for 500ms.  This is the max shift time we have set.  So in other words the cut has timed out before you have actually let your foot off the clutch.  Especially the last shift you can see the clutch is held down for quite a while after the shift.  This is not normal - the "max shift time" setting is generally just used as a safety and usually the gearshift would be complete long before that time was reached. 

So that may possibly be the clutch switch position not quite right or just driver training.  I have seen other synchro cars with shift times down around 250-300ms so there is room for improvement I suspect. 

I suspect the clutch switch position may need to be adjusted to it gives a better indication of the engage/disengage point.

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legend mate, appreciate the video, helps so much.


i've adjusted the clutch switch and removed some slack in the pedal travel.  about 20mm of travel.

What effect does adding in ignition trim to the upshift do? I'm assuming it effects the 20% of the shift cut i'm not using (80% setting), but what effect on performance does it have 

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  • 3 weeks later...

Hey mate, could i get some clarity on two settings with the torque reduction % and introduction time. Im a bit confused with what gear to change the settings on to get my desired outcome.


If i wanted to increase my torque reduction amount (driven up shift cut %)  going from 2nd gear into 3rd gear, would i change the 2nd gear column from 75 to 80% ? 

If i wanted to reduce (driven up shift)  torque introduction time going from 1st gear into 2nd gear would i adjust the 1st gear column or second gear column? From 30sec to 40 sec 





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  • 2 weeks later...

Thanks for the response mate.

I guess i'm still confused with the "torque INTRODUCTION" side of things. I understand the settings for torque REDUCTION, as that is associated with the gear thats being shifted out of. But the torque INTRODUCTION is to do with the new gear being shifted into.

So are we to change the setting for torque introduction in the new gear being selected?

i.e   If changing from 1st gear into 2nd gear, we change the settings on the number two column to get desired torque introduction results 


hope that makes sense and you can see the confusion 



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On 11/6/2021 at 8:14 PM, Adamw said:

The gear settings reference the gear you are shifting out of (or more correctly the gear that it was in when the "start shift" conditions were met).

This includes torque re-introduction.  


3 hours ago, Phil2JZ said:

 If changing from 1st gear into 2nd gear, we change the settings on the number two column to get desired torque introduction results 

You are changing out of first so the gear 1 settings apply to all parts of the gear shift.

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