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Old 04-02-2008, 09:38 PM   #21 (permalink)
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I think the discussing needs to be quantified between standard and automatic transmission.

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Old 04-02-2008, 10:22 PM   #22 (permalink)
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Mileage sucks until you're in top gear. There is an optimal acceleration rate and it might be surprisingly quick on some vehicles for what the owners might actually think it is.

I still haven't tested this. A accelerate at a LOD of 50 or so, although I'm using LPH instead but it really gets impacted by the cold. I need more than 1!
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Old 04-16-2008, 09:28 AM   #23 (permalink)
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In terms of simple physics, one would assume that the extra energy needed to propel at a higher velocity, within a short time frame would be exceptionally costly, but maybe I'm incorrect.
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Old 04-16-2008, 03:39 PM   #24 (permalink)
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Quote:
Originally Posted by Lazarus View Post
I think the discussing needs to be quantified between standard and automatic transmission.
I agree -- without full control in an automatic, one would expect to get to the desired speed at a high load / lowest RPM possible -- or relatively quickly. Depending on the engine. I'd need to see the BSFC, but mine is about half of where max torque is made (5200/2 = 2600) 2500-3000 seems to be the best operating range.

Of course tests are required to confirm.

So how about a slap-shift auto? On the TSX I can force upshifts in the 2300 RPM range and keep the accelerator mashed (not fully, but 75% or so). I almost always drive with the manu-matic -- prevents the unexpected downshift until it computes that it absolutely has to based on speed.

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Old 04-17-2008, 10:10 AM   #25 (permalink)
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Quote:
Originally Posted by Lazarus View Post
I think the discussing needs to be quantified between standard and automatic transmission.
http://forum.ecomodder.com/em-fuel-log.php?vehicleid=16

Dang .. you've got that thing tweaked!
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Old 04-17-2008, 12:43 PM   #26 (permalink)
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Originally Posted by Harpo View Post
http://forum.ecomodder.com/em-fuel-log.php?vehicleid=16

Dang .. you've got that thing tweaked!
I guess I will change the name on that. It's a bike not a car

Done.
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Old 04-25-2008, 04:52 PM   #27 (permalink)
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Here is what I learned from my last car, which I got quite a bit into both mileage and performance enhancement, was an AWD Turbo, this should pertain quite a bit to you:

Open-loop = horrible, horrible for mileage. I got anywhere from 2-6 mpg in open loop at WOT (wide-open-throttle). Turbocharged cars, especially older ones can go very very rich (8:1 was possible) under open loop, which kills mileage in a hurry. This is the easiest way to save (and also waste) fuel.

Somewhat counter-intuitively, low throttle position = bad for mileage. The throttle plate is a restriction to the engine. The pistons have to work hard to suck air through a closed throttle plate, which leads to large parasitic losses. This is a big reason why diesels get better mileage than gasoline engines - no throttle plate. The less resistance to movement you can get on the engine, the better. This includes things like a more open intake and exhaust to get rid of the pumping losses, windage trays in the oil pan to get rid of oil slinging around the crank, using good oil, etc. The easier it is for the engine to turn, the more efficient it is. This is difficult to do, because usually open throttle = open-loop, which ends up being less mileage overall, see above.

The trick is finding a balance between open-throttle and closed-loop. If you can use external methods to force both of these conditions, that's optimal for mileage, but can come with problems of its own (turbocharged cars run rich under wot for a reason, to protect the engine from knock).

The turbocharger also improves efficiency (theoretically). You are scavenging otherwise-wasted energy from the exhaust gas. The problem is, as stated above, that when the turbo spools up under WOT, the car runs rich to keep everything safe, which takes any efficiencies the turbo gives you and throws them on the ground angrily.

What I was just starting to get into on my last car before it broke was a way to have the throttle fully open, the turbo fully spooled, but yet running extremely lean so I didn't keep accelerating. It was technically open-loop, but I was manually keeping an eye on the EGT, the knock, the temps etc, and running way leaner than 14:1 (which is where closed-loop keeps you). Didn't have time to get much into it before an unrelated event broke my car and I decided I was sick of it.

My 3 cents.

-Jesse

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