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Old 11-18-2010, 03:37 PM   #17 (permalink)
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Originally Posted by euromodder View Post
I'm not surprised by it (only slightly so by the speed where it happens).

I have a hard time getting decent FE @ 90kph/56mph in 5th (top) gear, and it's the same with anything below 60kph/37mph in 4th.
The (smallish) engine revs low at these speed/gear combinations, barely 1600rpm.
I suspect it simply doesn't have the power to cope with the high loading.
A little bit faster, and it goes straight into its FE sweet spot around 100-105kph/62-65mph

Coming out of a deceleration phase and ending up in these situations, mpg will be OK. But any incline, or any attempt to accelerate will instantly result in a massive drop in mpg.
I've recently started to go back to 4th rather than stay in 5th, to come out of a tunnel on my commute and it seems mpg on the climb is better (or not as bad) in 4th.

I think I'm going to go ahead with an ECU remapping that gives more power and torque at lower revs.
I could use the odd extra 50 Nm around 1400-1600 rpm to bring the rpm down by 200-300 rpm - and drive in a higher gear.
As it is, the car needs a fair bit of throttle to get going smoothly.

HP and torque diagram of the Rica E-power remapping :
right, I would assume somewhere around 40-50 mph would get best mpg as this would be approx speed of high gear . But in that first graph of 2006 Toyota Corolla 1.6L Auto it gets best at 24 mph, no way it is in high and as noted above the next bump is probably the high gear one .

I am just surprised it can get such good mpg, even besting high gear speeds .
If the engine is to small for gearing and weight, I would assume best would just move up on rpm scale, not go down in speed .Yes I realize most small engines peak there TQ at like 4-5k rpm which doesn't help real low rpm cruising .
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