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.2RS release date

 
Old 08-02-2016, 08:51 PM
  #46  
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Originally Posted by Macca View Post
It also "rev holds" on upshifts using sport mode.

We ran a loose experiment at our local track with a GT4. Using sport mode it gave away 0.4-0.5s a lap to my GT3 due to 3 upshifts per 1.4 mile lap. My 993 gives away 1.2s on 6 upshifts same lap (Lower gearing). It's a relatively tight track. Turning sport mode off the same driver in the GT4 will loose another 0.3-0.4s a lap, not so much from the auto blip downshifts although they aid stability much like PDK but in the rev hold on upshifts!

The secret to the manual GT4 lap times on track is twofold. Tall gearing for less upshifts with similar torque to 911/GT3 but also the BIG factor is rev hold on upshifts.

In sport mode the GT4 is acting more like a PDK than a true manual.

If you want to try this yourself ask a mate at the track who times his laps and is competent and consistent to turn sport mode off and see what it does to his lap times. I 100% guaranty they will be slower. No matter how good he is at heel and tie he cannot emulate the "rev hold" benefits on up shift.....

This is one reason why the delta on track between GT4 and GT3 is relatively small. The rest is down to the GT4 superior dynamics and slightly lower weight.

Many wax lyrical about GT4 manual transmission being so involving. But they only use sport mode especially in the track. Having driven all of them my opinion is an air cooled manual is a vastly different MT experience. It's slower, move involving and it doesn't help you. Of course this can work against a poor MT driver who doesn't know how to H&T...
I don't own a GT4 but I've driven one. I didn't notice anything extraordinary about the upshifts. What does the rev hold actually do?
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Old 08-02-2016, 09:49 PM
  #47  
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Most people dont know its there. On the track is where its much more apparent (i.e. shifting at peak rpm under load on a straight). A track buddy with a GT4 didnt believe me either till he switched it off.

Under load on maximum throttle when you up-shift with a traditional manual the revs will drop off very quickly. No matte how fast you physically shift the engine will loos a few thousand revs before you engage the clutch on the next gear. The function built into the sport mode holds those revs for approximately 2s till you select the next gear and pull the clutch out. It makes a difference to the data traces - you can see and feel the effect immediately...
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Old 08-02-2016, 10:04 PM
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Originally Posted by tqevo View Post
I understand. That's my gripe with it. You can't turn off rev matching and have sport mode on.
No, I don't think you understand.

Sport mode in GT cars is Rev-matching and only Rev-matching. There is no other function with Sport button. Sport Exhaust and Sport Suspension have separate buttons. In non-GT cars, you get sportier throttle and PSM with Sport. This is not true in GT cars - PSM has two separate buttons for dual stages of deactivation and the throttle is always in sportiest setting.
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Old 08-02-2016, 10:09 PM
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Are you saying that under normal circumstances without this feature the revs would drop below where the next gear engages? I would think with the longer gearing of the GT4 that there should be plenty of time to shift before the revs drop that low.
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Old 08-02-2016, 10:11 PM
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Originally Posted by GrantG View Post
No, I don't think you understand.

Sport mode in GT cars is Rev-matching and only Rev-matching. There is no other function with Sport button. Sport Exhaust and Sport Suspension have separate buttons. In non-GT cars, you get sportier throttle and PSM with Sport. This is not true in GT cars - PSM has two separate buttons for dual stages of deactivation and the throttle is always in sportiest setting.
I thought the sport function in the GT3 allows a higher slip tolerance for the ESC. Does it not do that in the GT4?
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Old 08-02-2016, 10:29 PM
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Originally Posted by tqevo View Post
Are you saying that under normal circumstances without this feature the revs would drop below where the next gear engages? I would think with the longer gearing of the GT4 that there should be plenty of time to shift before the revs drop that low.
It's nothing to do with long gearing. It's just a fact of physics. Time is lost as the engine builds back the revs. The traces flat spots on upshifts are longer. The reason it rev holds is to reduce these. PDK does the same but shifts the gear even faster obviously.

Take a GT4 to the track and put in your best lap with sport on and repeat with sport off. The difference will become immediately noticeable. You can try it on the road, just accelerate dip the clutch and watch the needle then turn the system off and try that again...
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Old 08-03-2016, 09:40 AM
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Originally Posted by tqevo View Post
I thought the sport function in the GT3 allows a higher slip tolerance for the ESC. Does it not do that in the GT4?
No, it doesn't do that in GT cars. The default setting has a high tolerance for slip. Then there are two buttons to disable the Stability and Traction controls.
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Old 08-03-2016, 02:05 PM
  #53  
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Originally Posted by GrantG View Post
No, it doesn't do that in GT cars. The default setting has a high tolerance for slip. Then there are two buttons to disable the Stability and Traction controls.
It's stated to make the shifts snappier in the GT3 though. And what if I want the rev hold without the rev matching on downshifts?
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Old 08-03-2016, 02:18 PM
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Originally Posted by Macca View Post
It also "rev holds" on upshifts using sport mode.

We ran a loose experiment at our local track with a GT4. Using sport mode it gave away 0.4-0.5s a lap to my GT3 due to 3 upshifts per 1.4 mile lap. My 993 gives away 1.2s on 6 upshifts same lap (Lower gearing). It's a relatively tight track. Turning sport mode off the same driver in the GT4 will loose another 0.3-0.4s a lap, not so much from the auto blip downshifts although they aid stability much like PDK but in the rev hold on upshifts!

The secret to the manual GT4 lap times on track is twofold. Tall gearing for less upshifts with similar torque to 911/GT3 but also the BIG factor is rev hold on upshifts.

In sport mode the GT4 is acting more like a PDK than a true manual.

If you want to try this yourself ask a mate at the track who times his laps and is competent and consistent to turn sport mode off and see what it does to his lap times. I 100% guaranty they will be slower. No matter how good he is at heel and tie he cannot emulate the "rev hold" benefits on up shift.....

This is one reason why the delta on track between GT4 and GT3 is relatively small. The rest is down to the GT4 superior dynamics and slightly lower weight.

Many wax lyrical about GT4 manual transmission being so involving. But they only use sport mode especially in the track. Having driven all of them my opinion is an air cooled manual is a vastly different MT experience. It's slower, move involving and it doesn't help you. Of course this can work against a poor MT driver who doesn't know how to H&T...
I guess it depends on your definition of involving. Whether I have the sport button on or off, I find the manual transmission to be much more engaging than PDK. While performing H&T yourself is more engaging, I would not equate driving a GT4 in sport mode to a PDK. The GT4 still needs clutch modulation and input to put the car into the correct gear. You can stick a pdk in automatic and my 70 year old mom can drive it.

Last edited by drdonger; 08-03-2016 at 02:35 PM.
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Old 08-03-2016, 02:22 PM
  #55  
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Originally Posted by tqevo View Post
It's stated to make the shifts snappier in the GT3 though. And what if I want the rev hold without the rev matching on downshifts?
I'm talking about rev-matching in GT cars with manual gearbox. The PDK-S in the GT3 rev-matches whether in Sport or not. In the GT3, the Sport button provides a different function.
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Old 08-03-2016, 02:32 PM
  #56  
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Originally Posted by GrantG View Post
I'm talking about rev-matching in GT cars with manual gearbox. The PDK-S in the GT3 rev-matches whether in Sport or not. In the GT3, the Sport button provides a different function.
Again, it looks like the sport button in the gt4 does more than just rev-matching, as someone said it opens up the cooling radiator earlier and rev holds. What if I want these things without the downshift rev-match feature? There should be a separate button to turn it off, just like on the GT3 there should be independent controls for ESC+TC off (i.e. you cannot turn off TC by itself while keeping ESC on).
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Old 08-03-2016, 03:01 PM
  #57  
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Originally Posted by tqevo View Post
Again, it looks like the sport button in the gt4 does more than just rev-matching, as someone said it opens up the cooling radiator earlier and rev holds. What if I want these things without the downshift rev-match feature? There should be a separate button to turn it off, just like on the GT3 there should be independent controls for ESC+TC off (i.e. you cannot turn off TC by itself while keeping ESC on).
Right, I was the one in this thread who mentioned the radiator. This is a non-issue, just makes the car warm-up slower. Once you are driving hard, the radiator is cooling whether you have Sport on or not.

The reason you cannot turn TC off while leaving ESC on is because when traction control is disabled it allows for wheelspin and wheelspin causes yaw angles and yaw angles are prevented by ESC. It makes perfect logical sense if you think about it (ESC would act like TC anyways).

The GT4 has as many independent buttons as one could ever want or need (some would say too many). I assure you it's not an issue when driving (you have as many options as you will need - use Sport or don't, use Firm or Soft Suspension, use Sport Exhaust or not, drive with PSM on, or just TC on, or PSM totally off). If you can't get over not being able to separate Sport upshifts (very subtle difference that I never notice) from Sport rev-matching downshifts, you are way more OCD than I am

Last edited by GrantG; 08-03-2016 at 03:34 PM.
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