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Old 06-13-2018, 10:38 PM   #10 (permalink)
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Join Date: Jun 2016
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IGL - '04 Saturn Ion
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Originally Posted by California98Civic View Post
Ah. I also don't have a map for my specific engine, either. But I always do pulses at 75%-80% load in the best gear to keep me 1700-2200 RPM (sometimes 1500 and sometimes 2500). There is a general lesson from reading multiple BSFC maps for NA gasoline engines and that is that the 75% load, maybe 80%, from 1700 RPM, maybe 1500, up to maybe 2500 RPM is the area of best BSFC. And if that is not the exact best in my car, it would be damned close. Then I can experiment.

I think the general lesson might be that you could be leaving some potential untapped with the 40-50% load, high gear acceleration you described. On the map I posted above--and some others--50% load at 1000 rpm is in the 325 band, whereas if you down shifted and hit 75% load at maybe 2500 rpm you would be in the 250 island. That is maybe 20% more efficient. I got that right, yes?
I only intentionally limit load when under 1000RPM in 5th gear, as the engine doesn’t seem to like it and just shakes/vibrates... sometimes when I’m losing speed on a hill in 5th, with foot on floor, I’ll let it drop to 900 or so, IF I’m close to the top and I know I’ll be able to let off soon... sometimes when taking off really gently downhill, I’ll be in 4th gear as early as 10-12mph(600RPM) but I limit load st that low of engine speed

Anytime else that I’m accelerating and over 1k, I usually flatten the pedal, and UG reports 78-82% load...yes I do know that if I backed off a little I could accelerate in closed loop... sometimes I go the extra and can get better mileage hit usually I don’t
My current Ecotec project...

My last Ecotec project...

Last edited by 19bonestock88; 06-13-2018 at 10:45 PM..
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