Author Topic: More ramblings and musings....  (Read 5246 times)

Offline Organisys

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Re: More ramblings and musings....
« Reply #10 on: 23 June 2015, 12:33 »
Never brake, hauling the weight up to speed is a juice slurper.

Also avoid boosting too much. Somewhere on the internet there will be a rpm, AFR graph no doubt.

As others have said. Drag is a drag init. Lowering helps!

 :smiley:

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Offline Organisys

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Re: More ramblings and musings....
« Reply #11 on: 23 June 2015, 12:35 »
Well, then its the gearing for sure then :)

Closer and more ratios help.

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Offline NeilH

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Re: More ramblings and musings....
« Reply #12 on: 23 June 2015, 12:51 »
I guess that's why a 10 speed DSG has been rumoured. Better acceleration  :smiley: too and/or smaller engines. Makes you wonder what manual option they will offer against a 10 speed auto - if anything... :sad:

Neil.

Offline fredgroves

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Re: More ramblings and musings....
« Reply #13 on: 23 June 2015, 13:58 »
10 speed DSG will be more fuel/CO2 efficient for sure, however the top gear will always be set to whatever they consider to be the "typical maximum cruising speed" at whatever the most fuel efficient RPM value is (probably sub-boost RPM - I seem to remember that typically 70mph is about 1.5k RPM in 6th - thats probably around the sub-boost rev limit).

It seems unlikely that say 8th gear will be for 70mph and 9th and 10th are for effeciency at 80 and 90mph (for example)

What I would hope from 10 speed DSG though is that DSG will return the same CO2 figure as manual in the "approved test"... and thats all VAG actually care about!
Current: Mk8 GTI DSG, Adelaides, DCC, HUD, HK, Winter Pack, Rear Camera.. Aka "HMS Weasel"

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Offline NeilH

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Re: More ramblings and musings....
« Reply #14 on: 23 June 2015, 16:07 »
If the engines get smaller and possibly less powerful due to having 10 gears to play with then a six gear Mt would be far less flexible...

Offline corgi

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Re: More ramblings and musings....
« Reply #15 on: 24 June 2015, 12:31 »
I've noticed the same as you. I thought maybe the drag coefficients or weights would be the culprits but no, the Mk7 has the best drag coefficient out of the the Mk5, Scirroco and Mk7 and weighs less than the Mk5. Think the Scirroco weighs about the same as the Mk7? Not sure.

Other factor is frontal area (Scirocco  the smallest)? Mass makes no difference at a constant speed
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Offline fredgroves

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Re: More ramblings and musings....
« Reply #16 on: 24 June 2015, 15:18 »
If you like a bit of light(ish) physics try:

http://realworldnumbers.com/drag-crisis-the-coefficient-of-drag-is-not-a-constant/

Or this quite easy to read one which is talking about car fuel economy vs speed:

http://www.wired.com/2011/04/what-will-an-85-mph-speed-limit-do-to-your-mileage/

Although I suspect in a GTD and the speeds we are talking about it more to do with the boost being on than anything else.
Current: Mk8 GTI DSG, Adelaides, DCC, HUD, HK, Winter Pack, Rear Camera.. Aka "HMS Weasel"

Gone: 2017 Mk7.5 GTD,manual, NavPro
Gone: 2014 Mk7 GTD, manual, NavPro, DCC

Offline NeilH

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Re: More ramblings and musings....
« Reply #17 on: 24 June 2015, 22:19 »
You would have to assume that if manufacturers didn't have to maximise fuel consumption at set speeds for comparison purposes then some could actually be really innovative and build really economical ( and maybe performant) engines that were better than figures at the prescribed speeds.

Cheers, Neil