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Old 03-21-2014, 12:12 AM   #5 (permalink)
Master EcoModder
Join Date: Jan 2012
Location: United States
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spyder2 - '00 Toyota MR2 Spyder
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As someone with a car that's faster than most of the cars on Ecomodder as well, something to consider:

Your engine runs faster than my engine on the freeway with the same displacement. On the freeway my engine runs at ~20 in Hg vacuum while idle is something like 24. That means my engine is producing something like under 15% of its available torque, and yours even less, whereas peak efficiency arrives at ~80%. From idle up to 80-90% peak torque output, your efficiency is increasing at a slower and slower rate with respect to change in torque. 60% load might be >90% as efficient as 80%, but 40% load is probably only 75% as efficient as 80% load, typically.

If you step hard on the gas, you'll accelerate pretty quickly, and then end up running your engine at high rpm with low load for marginally longer if you are cruising. If you step less hard on the gas and only use 60% of the available power, your efficiency will be slightly lower but you will have much more time to reach your desired speed. If you're going to pulse and glide, using less power will mean less speed fluctuation to piss other drivers off, and if you have a hill it might be better to hold 50-60% load than to try to accelerate up it and increase your aerodynamic drag.

On the flip side the higher the engine rpm, the more friction and so the peak efficiency point moves higher, and especially on cars like yours and mine where running well over 3000rpm is normal, that could be a substantial difference.

My personal method is P&G when I am not feeling lazy, I pulse at 80-90% load over 3000rpm, ~70% at 2500rpm, 50% at 2000rpm, if it's a moderate grade I use ~60-70% at 3000 to only slightly accelerate. In gears lower than 5th, drop those numbers by 10-20%, since it's very easy to accidentally go too fast and then brake.

Last edited by serialk11r; 03-21-2014 at 12:20 AM..
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