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post #41 of (permalink) Old 04-28-2019, 06:10 PM
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Originally Posted by smelonas View Post
I understand the perfect transmission doesnt exist for these trucks. The OP just stated he was saving for firepunk setup. Wanted to give him some potentially useful insight is all.

The ideal transmission is an auto, and does have a neutral clutch for every time the vehicle stops. Locking the TC upon the first shift.

I was aware that autos in gear use a lot more fuel than just idling in neutral, I've always thought that was a way to save a lot of fuel. In neutral my CTS2 shows 0% load, in drive sitting still, it shows 5%.

Back draining the torque converter at a stop would lessen the load dramatically, but that would be like driving a space shuttle at that point. Your truck would be impossible to drive for anyone else.

So many things about transmissions to gain and you see it in modern cars. They gain more efficiency from playing with the TCM than with the ECM. Fact.

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If only we could improve the efficiency of them to come close to mid- high 90 percentile range like manuals. If I remember correctly a good automatic (planetary type) is still at most around mid to high 80 percentile. Cvt would be an improvement over planetary types, but making one durable enough and cost effective would be the issue. I know playing in the tcm is good for around 1.5mpg on the autos. In the data I have 12% is the difference in manual vs auto. So at cruise getting 25mpg in a manual that would drop to 22.3mpg. I'd be curious how that could be improved by going to a 2.90 rear end and eliminating the double overdrive as that is a backwards gain for efficiency. Obviously, that choice was determined by the bean counters and not engineers or they might have forgotten the basics.

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2009 2500 CCSB G56 4x4, 3.73-Self tuned w/WARP 552HP & 1225 lb-ft
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