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Chris' '90 Toyota Celica All-Trac Turbo (aka "The Shuttle")
Autronic SMC Feature: Flat Shift
Updated: August 20, 2021

Problem: Increased performance by decreasing the latency between full-throttle and achieving full boost.  At present, it takes about .25 - .3 seconds to regain full boost after each shift.  This delay is clearly observable via the SMC data log   And, considering there are three shifts in the 1/4 mile, I can decrease my 1/4 mile time-slips by simply regaining boost quicker after each shift.  Some people use a boost-controlled shot of nitrous to quickly regain boost pressure, and this certainly works well. However, before resorting to using nitrous between each gear, I am implementing a feature of the Autronic SMC called Flat Shift, and it works like this.

Solution: A momentary switch is installed such that it makes when the clutch is depressed.  This signals the SMC that a gear-change is occurring.  When the SMC sees this switch go active with TPS indicating 100% throttle (i.e. the foot is still planted to the floor), the SMC engages a mode very similar to a very mild anti-lag, in that it keeps the turbo spooled while simultaneously preventing runaway engine speed.  So, once the gear-change occurs and the clutch is lifted, the engine resumes normal operation, and boost pressure is not lost.  That's the theory.

Road Test:  OMG, this is this sh!t!   Running 1.0 bar, boost drops to about .85-.9 bar during the shift but immediately resumes 1.0 bar after the shift.  No more waiting for boost to rebuild.  And, while I used to occasionally chirp the tires in 2nd gear, now they are more like howling on the 1-2 shift.  This is awesome. 


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