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TDI Fuel Economy Discussions about increasing the fuel economy of your TDI engine. Non TDI related postings will be moved or removed.

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Old July 10th, 2020, 13:33   #31
devon1996
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Originally Posted by bigsexyTDI View Post
I gotta admit, I like seeing the newbies actually doing research on this...

Everything you seek is all here young man. You just might have to really dig for it...

I am becoming the Volkswagen master slowly lol.
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Old July 11th, 2020, 07:56   #32
PakProtector
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Ultimately, thermal efficiency is bounded by compression ratio( effective compression ratio, boost, or vacuum, or what ever). As just written about, the cost of creating this additional compression ratio with the exhaust turbine creating back pressure is costing more than it is worth. Not much of a surprise; read some of the efficiency measurements on VNT's...they kinda suck even if they deliver the 'right NOW' boost that is often desired.
cheers,
Douglas
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Old July 11th, 2020, 11:10   #33
MAXRPM
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Fuel Economy: 57 mpg driving like a granny on HWY-5 from LA to SF
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This is like if you drive like a granny you'd get up to 60mpg on the highway if you drive it like you stole your own car you would get 38 to 40, do the math, do you like to stump your car and go like a missle of course you'd take a hit, why do we bump up our cars to get better mpgs? No, we knew all along about this.

Fact is do you drive for mpgs or do you drive it and punch on the pedal all the time, for me I want both, I get it accomplished by 2 different ways,1) ECU with switchable programs where 1 will give me the most and the other restrict the limit on my car,,,, 2) drive it like a granny and I get 46 to 48 mpgs, so even leaving the ecu at ultimate setting i will accomplish the 46 to 48.
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Old July 11th, 2020, 14:57   #34
devon1996
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Originally Posted by MAXRPM View Post
This is like if you drive like a granny you'd get up to 60mpg on the highway if you drive it like you stole your own car you would get 38 to 40, do the math, do you like to stump your car and go like a missle of course you'd take a hit, why do we bump up our cars to get better mpgs? No, we knew all along about this.

Fact is do you drive for mpgs or do you drive it and punch on the pedal all the time, for me I want both, I get it accomplished by 2 different ways,1) ECU with switchable programs where 1 will give me the most and the other restrict the limit on my car,,,, 2) drive it like a granny and I get 46 to 48 mpgs, so even leaving the ecu at ultimate setting i will accomplish the 46 to 48.

Yeah I am pedal to the floor any time I'm accelerating. City mileage isn't great but my mostly highway commute is still 44-46 mpg going reasonably fast
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Old July 11th, 2020, 19:19   #35
atikovi
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So now the duty is about 30-45% while cruising so the vanes are open about 70% assuming it's linear. Cruising down the road I'm making about 1-2 psi of boost where before it was 6-10 psi. And based in the last trips the boost map paid off in dividends.
Changing the vnt to be less restrictive brought me up to 44-46 mpg. By changing just the boost basically I was able to gain atleast 10% more fuel economy. No driving changes at all.
No idea if this setup is like what I have on my '06 but the little hose to the turbo is off and plugged for other reasons and I average 55 mpg overall

and got 65 mpg on a 1,000 trip to Florida last week at around 70 mph.

Engine has a RocketChip tune which may or may not have anything to do with it.
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Old July 12th, 2020, 03:05   #36
devon1996
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It doesn't matter what the computer is telling the turbo to do if it's unplugged haha. So there it is if you have no boost ever you'll get 55 mpg with the vanes open all the way all the time.
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