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Chris' '90 Toyota Celica
All-Trac Turbo
(aka "The
Shuttle") Autronic SMC Feature: Flat Shift |
Updated: September 25, 2017 |
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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