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Discussion Starter · #1 ·
Hello,
I understand Gen II Cayman equipped with PDK plus SC will not shift before hitting the redline when ib the sprt mode. Is this true to start with? How does it affect the engine on the long run, if true? How is that different from a manual equipped Cayman hitting the redline?
:thanks:
 

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I would assume this is in "auto" mode. You have the ability to change gears via the steering wheel buttons at will.

In a manual Cayman when it hits red line the car will automatically limit/cut the fuel thus causing the revs to reduce, I've done this on the odd occasion. ;)
 

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Any trip into the RED zone is logged by the DME unit.
Zones 1, 2 and 3 are generally accepted to be OK but 4 , 5 or 6 and you may have warranty issues should you blow an engine at any time.

All in all it's best to shift prior to the red zone, power is dropping off anyway.
 

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Hello,
I understand Gen II Cayman equipped with PDK plus SC will not shift before hitting the redline when ib the sprt mode.
Half true - the computer will shift at redline in Sport+ mode. In Sport mode the shift algorithm is more aggressive than normal, but will shift well below redline depending on your throttle at the time.

Is this true to start with? How does it affect the engine on the long run, if true? How is that different from a manual equipped Cayman hitting the redline?
:thanks:
Shouldn't affect much. You can't really overrev a PDK transmission. Even if you're shifting manually in a PDK, the computer won't let you downshift if it figures you'll overrev.
 

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Excuse me guys (and correct me if I'm wrong) but I thought that you (or the car in case of pdk) would shift at the highest torque for optimum performance, right? If so it should shift to a higher gear at 6000 rpm, right?
 

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Discussion Starter · #9 ·
I am not concerned about overrev while shifting down; my concern is while shipfting up and hitting the redline. How is hitting the redline in a pdk equiped with SC while shifting up different from hitting the redline in MT cayman in terms of long term effects on the engine, etc.? Hope this clarify the issue.
In other words: is hitting the redline so frequently a problem?
:thanks:
 

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Excuse me guys (and correct me if I'm wrong) but I thought that you (or the car in case of pdk) would shift at the highest torque for optimum performance, right? If so it should shift to a higher gear at 6000 rpm, right?
I always thought (perhaps naively) that when you upshift for maximun performance, the gear you shift into should be at maximum torque. Does it depend upon the shape of the torque curve? Have I been under the wrong impression for the last 40 years? At least, before I die, let me get something straight!
 

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I always thought (perhaps naively) that when you upshift for maximun performance, the gear you shift into should be at maximum torque. Does it depend upon the shape of the torque curve? Have I been under the wrong impression for the last 40 years? At least, before I die, let me get something straight!
Now we both seek an answer... and this was on my mind few days back! Let's hope we hear from those track junkies ;)
 

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HassanAbdeen said:
Excuse me guys (and correct me if I'm wrong) but I thought that you (or the car in case of pdk) would shift at the highest torque for optimum performance, right? If so it should shift to a higher gear at 6000 rpm, right?
I always thought (perhaps naively) that when you upshift for maximun performance, the gear you shift into should be at maximum torque. Does it depend upon the shape of the torque curve? Have I been under the wrong impression for the last 40 years? At least, before I die, let me get something straight!
I remember reading in another post a few months ago that the transmission would (and should in the case of a manual) shift at red line not at highest torque because the multiplier of the lower gear still made more power in the lower gear above maximum torque all the way to red line than it would by shifting before red line into the higher gear. This makes sense to me and it was explained more eloquently by the original poster.

:)
 

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Excuse me guys (and correct me if I'm wrong) but I thought that you (or the car in case of pdk) would shift at the highest torque for optimum performance, right? If so it should shift to a higher gear at 6000 rpm, right?
Sorry, but you asked to be corrected (and you are wrong - a common misconception). The objective is to keep the motor as close to the power peak for as long as possible (not the torque peak). It's true that the redline is a bit past the power peak, but you need to consider the rev range that the car assumes after an upshift too. If you were to shift at the power peak, then the engine would be well below the power peak in the next gear after the upshift.

So, the fastest way to drive is to shift at redline, which will result in being close to an equal amount below the power peak in the higher gear as you were above the power peak in the lower gear.
 

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Sorry, but you asked to be corrected (and you are wrong - a common misconception)....

So, the fastest way to drive is to shift at redline, which will result in being close to an equal amount below the power peak in the higher gear as you were above the power peak in the lower gear.
1) Thank you for correcting me.

2) With my FVD flash I assume then that for best performance I better shift to higher gear at 7500 rpm instead of 7000 rpm, right?
 

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Redline is a term used to describe the red line set on a tach to denote the highest possible shift point while the "limiter" is where the ecu will cut fuel and spark to protect the engine. The gear spacing is what determines the optimal shift point of a vehicle, the aim to keep the engine at the highest point on the power curve while allowing meaningful time in gear between shifts.

A separate question for those with PDK. If you are in manual will the transmission upshift before hitting the limiter on its own or will it allow it to bounce of the limiter and stay in gear?
 

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1) Thank you for correcting me.

2) With my FVD flash I assume then that for best performance I better shift to higher gear at 7500 rpm instead of 7000 rpm, right?
Since an 06 Cayman S has a redline of 7,200 (power peak around 6,500 I think) and your car has a modified redline of 7,500 that makes for an interesting question.

Do you know where the power peak is for your modified software?

I would say the optimum shift point is at least 7,200 but it's possible that 7,500 rpm will be a bit too high (unless the software has moved the power peak higher and not just the fuel cut-off point higher).
 

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Since an 06 Cayman S has a redline of 7,200 (power peak around 6,500 I think) and your car has a modified redline of 7,500 that makes for an interesting question.

Do you know where the power peak is for your modified software?

I would say the optimum shift point is at least 7,200 but it's possible that 7,500 rpm will be a bit too high (unless the software has moved the power peak higher and not just the fuel cut-off point higher).
I just emailed Florian from FVD... interesting point!
 

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I remember reading in another post a few months ago that the transmission would (and should in the case of a manual) shift at red line not at highest torque because the multiplier of the lower gear still made more power in the lower gear above maximum torque all the way to red line than it would by shifting before red line into the higher gear. This makes sense to me and it was explained more eloquently by the original poster.

:)
Sounds rational but can you show us some numbers?
 

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Sounds rational but can you show us some
numbers?
This is the post I was referring to. No numbers but it makes sense.

originally posted dec 21, 2009 by Downshift

Ideal shift points are usually discussed with engine torque in mind. Engine torque peaks at a certain rev and drops off after that. The thought is that you want to shift at such a point so that you utilize as much engine torque as possible, e.g. not go too far past the torque peak before upshift, but not upshift too soon or you will be too far below the torque peak.

This discussion is well and good, but it does not account for the torque multiplier called the transmission. You have far more torque in 2nd at 4,000 RPM than you do in 3rd at 4,000 RPM. This is due to the torque multiplier effect of the transmission. You will always get the most torque if you maximize the use of the lower gear as much as possible (e.g. shift at redline). Even if torque drops off a bit before you get to redline, you will have far more torque in 2nd at redline than you will at 3rd, at any RPM.

This is why the PDK shifts at redline when in SC+ mode. The engineers at Porsche know this.
 

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I agree. I'm going to see if I can figure out the math on my own. Peak torque does not equal peak power and you definitely don't want to put yourself on a poor power point with your upshift. Seat of the pants tells you this is true.:cheers:
 
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