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Old 06-03-2013, 02:43 PM   #1 (permalink)
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At which RPM to shift ?

(I hope this is the right thread) Max torque on my Peugeot is 120 Nm (88 lb.ft) @ 2800 rpm, i usually shift at 2000-2100. My question is when to shift ? At 2000, or near the highest torque ? And how does lower and higher torque affect the consumption ?

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Last edited by kegel; 06-03-2013 at 02:56 PM.. Reason: I posted in wrong thread maybe
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Old 06-03-2013, 04:35 PM   #2 (permalink)
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One "rule-of-thumb" is about 70% of the max-torque rpm, so roughly 2,000 rpm:

1,960 = 0.7 2,800 ~ 2,000 rpm
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Old 06-03-2013, 04:41 PM   #3 (permalink)
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Old 06-03-2013, 04:49 PM   #4 (permalink)
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Quote:
Originally Posted by Old Tele man View Post
One "rule-of-thumb" is about 70% of the max-torque rpm, so roughly 2,000 rpm:

1,960 = 0.7 2,800 ~ 2,000 rpm
I have an Infinity 635 6MT and its max torque occurs at 4800 RPM; that would make the suggested shift point approx 3400 - does that sound high to you (it does to me)? I usually shift much lower than that - using Infinity's suggested speed/gear.

Thoughts?
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Old 06-03-2013, 05:51 PM   #5 (permalink)
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Not necessarily, because the goal is to accelerate as fast as possible UP to your 'goal' cruising speed--without going into WOT enrichment--while simultaneously minimizing the time in doing so.

Sorta like an EcoModder's version of Goldilock's porridge, "...fast enough, but not too fast..."

Of course, once you're AT your 'goal' crusing speed, the goal switches to keeping the engine at it's lowest rpms, in it's highest gear, without lugging it, ie: in the BSFC "sweet zone," which is typically between 1K-2K rpm.

Last edited by gone-ot; 06-03-2013 at 05:58 PM..
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Old 06-03-2013, 05:52 PM   #6 (permalink)
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Quote:
Originally Posted by Old Tele man View Post
Not necessarily, because the goal is to accelerate as fast as possible UP to your 'goal' cruising speed--without going into WOT enrichment--while simultaneously minimizing the time in doing so.

Sorta like a EcoModder's version of Goldilocks porridge, "...fast enough, but not too fast..."
Well, I know what I'll be trying out ...

And, thank you.
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Old 06-19-2013, 04:00 PM   #7 (permalink)
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Hello,

i take a "Muscheldiagramm" (i had no word for it) to find out when i shift.
A normal gasoline Engine has a diagram like that: http://www.spritmonitor.de/sc/pics/v...eldiagramm.jpg

The best motor efficienty are between 2000 and 4000 rmp about 80% of the maximium torque. The motor mangagement system of my old car use a fully load injection in these areas -> bad efficienty
So i take them out (blocked the throttle flap to max. 72) and is all good.
accelerate in these areas and you safe fuel

My car: Volkswagen Polo 2F (builded 1990!) with 55HP Monoinjection engiene and bad cw (0,36) takes 4,4l/100km (53mpg). evaluated over 20000km.
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Old 06-19-2013, 04:17 PM   #8 (permalink)
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BSFC Chart

It looks like Muscheldiagramm is called a BSFC chart in the USA.

It stands for Brake Specific Fuel Consumption.

Those are ideal to have to help one find the sweet spots in different gears and speeds.

Old Tele Man has great advice regarding the rule of thumb if one doesn't have a copy of a BSFC chart for their vehicle. Soemtimes they are hard to find.


http://ecomodder.com/forum/showthrea...html#post14985

Brake Specific Fuel Consumption (BSFC) Maps - EcoModder
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Old 06-24-2013, 06:05 AM   #9 (permalink)
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I've somewhat recently started shifting at 3100 rpm; up from 2500. No noticeable change in fuel consumption, plus I get to where I'm going faster and with a little more fun.

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