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      09-11-2014, 02:41 PM   #1
kseyfi86
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N54 shift points when roll racing/drag racing

I know all the dynos for our motors show power tapering off past 6400 but I still see all videos on YouTube of high speed runs w/ well modded A/T's redline through their gears, leaving me a bit confused. Has the early shift strategy been debunked as insignificant? Sorry if it's been discussed here before, I couldn't seem to find a straight answer.
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      09-11-2014, 03:00 PM   #2
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What I have gathered from reading the forums is that the peak power is achieved around 5600 rpm for AT. You can shift early if you want but you won't get the most of the HP.

I'll let some of the professionals give better advice,
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      09-11-2014, 03:05 PM   #3
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I am also wondering the same so I can set my shift light at the right point. I have a 6mt
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      09-11-2014, 03:07 PM   #4
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I believe this would have more to do with the turbo setup you are running, rather than the engine itself.

Stockers run out of steam around 5500ish.
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      09-11-2014, 03:10 PM   #5
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If you are on stock turbos and 6at, shift around 6100-6200.
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      09-11-2014, 03:12 PM   #6
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That^ or just let the trans shift itself at redline.

the theory makes sense if you look at a dyno sheet. Power falls off at a certain RPM; where if you shift, you'd be making more power at that rpm VS. letting it run to redline.

It may make sense for some, though i just let the car shift itself at the drag strip.
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      09-11-2014, 04:11 PM   #7
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Interesting question which I asked myself several times.. but you cannot simply say "when HP drops, there is the place to shift"

For acceleration horsepower, torque and transmission ratio have to be taken into count.. maybe someone who's into physics could explain it for us
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      09-11-2014, 04:28 PM   #8
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I shift around 6200rpm with N54 and 6MT.

That's where I "feel" the car running out of steam.
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      09-11-2014, 04:38 PM   #9
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Quote:
Originally Posted by Miller335 View Post
I shift around 6200rpm with N54 and 6MT.

That's where I "feel" the car running out of steam.
Yup, same reason I shift around there too. I'd love to see a side by side race w/ same mods to test the shift point advantage, if there is any.
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      09-11-2014, 04:55 PM   #10
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Take it from a track junkie, you want shift just before 6k RPMs
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      09-11-2014, 05:42 PM   #11
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I shift right at 6k, stock turbos mt. I don't like the feeling of the car Falling on it's face I get after 6k.
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      09-11-2014, 05:57 PM   #12
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Quote:
Originally Posted by Jklad View Post
I shift right at 6k, stock turbos mt. I don't like the feeling of the car Falling on it's face I get after 6k.
Yup, I have my shift lights set for 5900. So by the time I react it's probably at about 6100
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      09-11-2014, 06:02 PM   #13
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How about guys with aftermarket dual hybrid setups with fbo? I'm good stock with a tune but I'd like to know for my new setup. Thx
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      09-11-2014, 06:13 PM   #14
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IMO run them to redline. You should see what your tuner says. it Depends on how they set the tune to taper off boost at redline.
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      09-11-2014, 06:14 PM   #15
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Quote:
Originally Posted by idrift4wd View Post
IMO run them to redline. You should see what your tuner says. it Depends on how they set the tune to taper off boost at redline.
Cool. I'll do that. Was also going to install a two step controller when I upgrade the clutch.
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      09-11-2014, 06:48 PM   #16
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Take it to the track and see what goes faster.
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      09-11-2014, 06:54 PM   #17
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you don't need to be at peak power

when you shift at peak, your next gear engages way down the power band

you want to shift at whatever RPM it'll be so that when you engage the next gear, you'll be at the same HP
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      09-11-2014, 06:58 PM   #18
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Here's an example... say shifting from 2nd to 3rd we drop "X" rpm (simplified, but it helps illustrate the concept. please excuse my inability to spell RPM. lol)

Here's an HP curve, with different HP points plotted.

See how shifting at 250 drops us to 150, so your next gear will start slowly. But if you overrun the peak hp and drop to 200, you'll already be at 200 in your next gear, netting you a faster overall acceleration.

Make sense?

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      09-11-2014, 07:26 PM   #19
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Quote:
Originally Posted by tc535i View Post
Here's an example... say shifting from 2nd to 3rd we drop "X" rpm (simplified, but it helps illustrate the concept. please excuse my inability to spell RPM. lol)

Here's an HP curve, with different HP points plotted.

See how shifting at 250 drops us to 150, so your next gear will start slowly. But if you overrun the peak hp and drop to 200, you'll already be at 200 in your next gear, netting you a faster overall acceleration.

Make sense?
One must also take the massive amounts of torque I into consideration that our cars make though. Which we make huge amounts before 3000rpm.
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      09-11-2014, 07:36 PM   #20
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Quote:
Originally Posted by DuDai View Post
One must also take the massive amounts of torque I into consideration that our cars make though. Which we make huge amounts before 3000rpm.
Agreed. I'd say apply the same idea to torque not hp. Tq makes the world go round.
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      09-12-2014, 07:58 AM   #21
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Shift at 5900rpm....you get full boost around 3500rpm

N54s start tapering boost around 5700rpm
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      09-12-2014, 10:21 AM   #22
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Tq gets you started, but hp keeps you accelerating. Shift based on hp calculations, not tq.
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