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Old 11-24-2019, 03:50 AM   #3 (permalink)
EcoModding Lurker
Join Date: Oct 2017
Location: USA
Posts: 16

Accord - '12 Honda Accord sedan EX-L
90 day: 25.99 mpg (US)
Thanks: 1
Thanked 1 Time in 1 Post
Huh, I did not realize that taller tire would have less rolling resistance!

I just tested it out and in 5th @ 46mph with TC locked my car turns 1500rpm.
When TC unlocks because of an incline (cruise control for accuracy) it flares up anywhere between 2200 to 2600.
I was thinking 1.5% more rpm @ 1522 won't be as bad as unlocking the torque converter every other hill I encounter.

I also have an Acura in the family which shares many component with the Honda, but with slap shift so I can select which gear I want to be in, and using OBD port my car was actually getting 10-15% better mpg in 4th with TC locked compared to 5th unlocked, going up same hill, same speed, similar wind (tried back to back). And 4th locked was turning 300-500rpm more than 5th unlocked.
Now I cannot do that in the Honda, I may have to look into wire-rigging the gear selector, but I digress.

I usually let the speed fall about 5-15mph going uphill, to recover on the downhill.
And the car likes to hold it in 5th once I hit 42+mph and down to around 32mph. But half the times I can accelerate it back to over 40 while holding the TC locked but other times it's TC unlock and with some head wind, car shifts down to 4th with TC unlocked and exceeds 3000rpm.

I also do mixed city/highway driving that my actual MPG is 1-2 above EPA mixed rating(27-28 vs 26mpg). I may not be very good at coasting but I do try to use as little gas pedal as possible by looking far ahead and using hills to my advantave, and don't drive over 65mph.

Would you say the 1.5% more torque & rpm making a positive difference in city driving is insignificant?

Sorry I'm just throwing my thoughts out there, too tired after work but I tried my best.
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