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Author Topic: should i change gear arlier on the 1/4mile  (Read 1916 times)

Offline Janner_Sy

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should i change gear arlier on the 1/4mile
« on: May 17, 2011, 12:18:30 am »
looking at my dyno graph you can see the power peaks at 5000rpm and tails off gradually to 200Hp at 6500rpm.  

This isnt a big drop in power by any means and very likely wouldnt even notice the drop off in real life.  However the difference in torque between 5000rpm and 6500rpm is around 45lbft and surely 45lbft you would notice.

Now what im thinking is would it be better for me to change gear at 5000rpm just after i reach peak power (210Hp/180lbft), the revs will drop to say 4250rpm which is around 205hp/250lbft

so changing gear earlier im essentially staying in the power peak power AND peak torque for longer as its not dropping off at all.



Also id be ragging the engine much less which is of course a big plus.

Thoughts guys as ill be taking it on the 1/4 very soon????
« Last Edit: May 17, 2011, 01:34:50 pm by Janner_Sy »

Offline Weston

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Re: should i change gear arlier on the 1/4mile
« Reply #1 on: May 17, 2011, 08:20:23 am »
Seems to me you need DSG  :signLOL:
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Offline Janner_Sy

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Re: should i change gear arlier on the 1/4mile
« Reply #2 on: May 17, 2011, 12:14:42 pm »
Good job i have 7spd DSG then :booty: :booty:#

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Offline Richn83

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Re: should i change gear arlier on the 1/4mile
« Reply #3 on: May 17, 2011, 12:38:38 pm »
I have no experience of quarter mile driving but the logic seems sensible if you can drop 5 bhp by shifting or gradually lose 10bhp by holding the gear then with DSG so instantaneous shifts and no loss of drive then I reckon shifting will be your best bet, only othere thing is to consider traction on 1st to 2nd gear shift if holding longer will reduce the chance of losing traction then you might do better to run first gear out then shift at 5000rpm for the later gears.

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Offline Weston

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Re: should i change gear arlier on the 1/4mile
« Reply #4 on: May 17, 2011, 01:25:24 pm »
Oh no  :sad1:
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Re: should i change gear arlier on the 1/4mile
« Reply #5 on: May 17, 2011, 03:54:44 pm »
Tails off??.......... you mean falls away into the abiss  :signLOL:

Offline Hurdy

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Re: should i change gear arlier on the 1/4mile
« Reply #6 on: May 17, 2011, 04:18:15 pm »
With a power/torque profile like that, I'd be shifting no later than 5k rpm. :happy2:
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Offline rich83

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Re: should i change gear arlier on the 1/4mile
« Reply #7 on: May 17, 2011, 04:24:23 pm »
Peak power seems to be quite low down

Offline Janner_Sy

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Re: should i change gear arlier on the 1/4mile
« Reply #8 on: May 17, 2011, 04:48:52 pm »
its a trait of the engine.  pretty much all of them start dropping power after 5k unless they have an intake and full exhaust system.  Its just like what happens on the K03 TFSI which also normally loses power after5.5k unless its got extensive mods and mapping
With a power/torque profile like that, I'd be shifting no later than 5k rpm. :happy2:

that was my thoughts.  I have a forge intake sorted now, but i dont expect the overall curve to change that much, just to flatten out a bit more.  will get it dyno'd @ JKM next month once fitted

Offline Richn83

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Re: should i change gear arlier on the 1/4mile
« Reply #9 on: May 17, 2011, 05:01:55 pm »
Peak torque is nice and low down though as well with 7 speed DSG and a small car must be a very nice daily driver, any traction problems?

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Offline Janner_Sy

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Re: should i change gear arlier on the 1/4mile
« Reply #10 on: May 17, 2011, 06:45:47 pm »
no worse than i had on my S2+ octavia tbh, once i mod the suspension add a rear arb and put some better boots on it, there will be no issues with traction i think

Offline Poppa Dom

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Re: should i change gear arlier on the 1/4mile
« Reply #11 on: May 17, 2011, 09:34:48 pm »
Short shift 1st to 2nd, change up at 5k, jobs a good un  :happy2: Though I don't know the characteristics of spool and wheel hop (power/torque) in first and whether there is call for an early change to 2nd.

Dom