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86TOYO2k17 · 06-23-2020, 07:58 PM

Since it was bumped, might as well add my experience.

Disclaimer: This is for general all purpose fun spirited driving (if you are tracking/autox specific then deciding on an FD has a specific method to align gear/rpm with the track and specific usage to get the most benefit from it, but i wont go into further detail in this post)

2017 AT
When i was NA full bolt ons, custom tune, full drag reduction, 100+lbs weight loss, etc... Switching from 4.1 to 4.56 was up there with ace header / custom tune in terms of performance and acceleration feel. header/tune and then FD swap in that order is what i would do for NA. Highly recommended for NA. Personally i wouldn't go more aggressive though, if i was MT i would probably do 4.44.

Then i went FI probably at around 285whp/220ftlbs. and 4.56 was just too short now. Traction in 1st was an issue, 4th (1-1 gear same as MT 5th gear) topped out around 114mph which came up way too quickly, always wishing for a little more gear. If i was cruising at 75mph+ (common cruising speed since FI) and floored it, it would either only shift to 4th because it was too close to topping out 3rd (83mph) it wouldn't bother shifting to it, or i would shift it to 3rd but then about 1/2second later it would top 3rd and shift to 4th, so the start of my pull was either wasting time shifting back and forth or trying to pull in 4th at lower rpm. NA wasn't a big deal since it pulled slower the time between downshift/upshift was longer and i usually cruised around 70mph instead of 75mph. (that low end torque makes your foot heavy...)

Then i swapped back to 4.1 and went from a 225 tire to 255 tire at the same time which solved my 1st gear traction problem (still couldn't launch at all though) and i liked the higher MPH per gear but not the slower acceleration feeling despite the power pulling to almost 130mph in 4th now (with 255 tire) felt kind of slow. so Finally settled on a 4.3FD. Can still hit 120mph in 4th (1-1 gear), 3rd gear with the 255 tire shifts at about 89mph so i am not just double shifting or bogging down at start of pull. and the 5% more mechanical torque to wheels made acceleration that much better. 40/60-120mph pulls are awesome now. Seems perfect for 250-300whp range on an AT.
I would probably stick to 4.1 with MT at 260whp-300whp range, maybe 220-260whp a 4.3 would be great. Below 220WHP a 4.44FD. would pair well. Again all for general purpose fun spirited driving.

06-23-2020, 07:58 PM	#42
86TOYO2k17 Senior Member Join Date: Jan 2018 Drives: 2017 toyota 86 Location: PNW Posts: 2,131 Thanks: 336 Thanked 1,189 Times in 781 Posts Mentioned: 16 Post(s) Tagged: 0 Thread(s)	Since it was bumped, might as well add my experience. Disclaimer: This is for general all purpose fun spirited driving (if you are tracking/autox specific then deciding on an FD has a specific method to align gear/rpm with the track and specific usage to get the most benefit from it, but i wont go into further detail in this post) 2017 AT When i was NA full bolt ons, custom tune, full drag reduction, 100+lbs weight loss, etc... Switching from 4.1 to 4.56 was up there with ace header / custom tune in terms of performance and acceleration feel. header/tune and then FD swap in that order is what i would do for NA. Highly recommended for NA. Personally i wouldn't go more aggressive though, if i was MT i would probably do 4.44. Then i went FI probably at around 285whp/220ftlbs. and 4.56 was just too short now. Traction in 1st was an issue, 4th (1-1 gear same as MT 5th gear) topped out around 114mph which came up way too quickly, always wishing for a little more gear. If i was cruising at 75mph+ (common cruising speed since FI) and floored it, it would either only shift to 4th because it was too close to topping out 3rd (83mph) it wouldn't bother shifting to it, or i would shift it to 3rd but then about 1/2second later it would top 3rd and shift to 4th, so the start of my pull was either wasting time shifting back and forth or trying to pull in 4th at lower rpm. NA wasn't a big deal since it pulled slower the time between downshift/upshift was longer and i usually cruised around 70mph instead of 75mph. (that low end torque makes your foot heavy...) Then i swapped back to 4.1 and went from a 225 tire to 255 tire at the same time which solved my 1st gear traction problem (still couldn't launch at all though) and i liked the higher MPH per gear but not the slower acceleration feeling despite the power pulling to almost 130mph in 4th now (with 255 tire) felt kind of slow. so Finally settled on a 4.3FD. Can still hit 120mph in 4th (1-1 gear), 3rd gear with the 255 tire shifts at about 89mph so i am not just double shifting or bogging down at start of pull. and the 5% more mechanical torque to wheels made acceleration that much better. 40/60-120mph pulls are awesome now. Seems perfect for 250-300whp range on an AT. I would probably stick to 4.1 with MT at 260whp-300whp range, maybe 220-260whp a 4.3 would be great. Below 220WHP a 4.44FD. would pair well. Again all for general purpose fun spirited driving.