RE: 911 RSR debuts at Silverstone

[anglophile]

I just think that those floor pivoting pedals are what every proper motorcar needs

[Joe911]

Dr Clive said:

"Automatic clutch"? - No, with paddle shift the clutch remains engaged, on the upshift the ECU cuts the ignition momentarily whilst the current gear disengages and the next one engages, so no need to come off the throttle either ("flat-shift"). On the downshift the ECU uses inputs from revs and road speed to blip the throttle to match the revs when the driver requests the change with the left paddle. Not disengaging the clutch sounds brutal, but the dogs are made to take the strain.

I'm sure you're right, I was avoiding the fine details as I'm not aware of them.

However (not disputing what you say but looking for more detail) - how can the throttle be 'blipped' with the clutch still engaged?
To achieve a blip surely the clutch must be at least partially engaged - or the gearbox be between gears? If it is the latter surely it's not between gears long enough for the blip to be effective?

[zebedee]

k-ink said:

Does this imply the 991 is not up to the job?

No, it means they have worked very fast to get the GTE and cup cars out first, the GT3 is bound to be next on the agenda.

[chuntington101]

Why cant they make the road cars look this striking? Stunning looking bit of kit and sure it will be blindingly fast also.

[RacerMike]

Joe911 said:

However (not disputing what you say but looking for more detail) - how can the throttle be 'blipped' with the clutch still engaged?
To achieve a blip surely the clutch must be at least partially engaged - or the gearbox be between gears? If it is the latter surely it's not between gears long enough for the blip to be effective?

Knock your car in to neutral from a gear without using the clutch and you'll have no problem blipping the throttle. If you get it right, you can also force the next gear in without the clutch. Not a good idea in a normal road car box, but a dog box actually works better without use of the clutch. All the auto blipper does is rev the engine whilst in between dogs and bangs the next gear in when the speeds match. No clutch required.

[Joe911]

RacerMike said:

Knock your car in to neutral from a gear without using the clutch and you'll have no problem blipping the throttle. If you get it right, you can also force the next gear in without the clutch. Not a good idea in a normal road car box, but a dog box actually works better without use of the clutch. All the auto blipper does is rev the engine whilst in between dogs and bangs the next gear in when the speeds match. No clutch required.

Yes indeed - but the between gear time needs to be tiny - how is that enough time for a blip (even an electronically activated one)? I assume they are looking to complete a downshift in, what, 0.1s?

[Dr Clive]

Joe911 said:

RacerMike said:

Knock your car in to neutral from a gear without using the clutch and you'll have no problem blipping the throttle. If you get it right, you can also force the next gear in without the clutch. Not a good idea in a normal road car box, but a dog box actually works better without use of the clutch. All the auto blipper does is rev the engine whilst in between dogs and bangs the next gear in when the speeds match. No clutch required.

Yes indeed - but the between gear time needs to be tiny - how is that enough time for a blip (even an electronically activated one)? I assume they are looking to complete a downshift in, what, 0.1s?

As RM says, the blip occurs in the time between one set of dogs disengaging and the other set engaging (don't recall what sort of time we're talking about). These days with mostly fbw throttles it can be achieved very quickly, though. Even when cable/mechanical throttles were still being used (as was the case until recently for LMP2 cars, when fbw actuation was denied by the ACO Regs) it was still possible to achieve a mechanically-actuated blip using a solenoid or pneumatic "prod" on the throttle assembly. Not having a blip isn't really practicable as a downchange could otherwise cause a rear-wheel lock-up under braking, which isn't generally a good thing.

In F1 they've used so-called "seamless-shift" 'boxes for some time now, which perform the changes in the order of ms, and they still manage to perform a blip on the downchange.

DC

[RacerMike]

Joe911 said:

Yes indeed - but the between gear time needs to be tiny - how is that enough time for a blip (even an electronically activated one)? I assume they are looking to complete a downshift in, what, 0.1s?

It's unlikely to be that short. Downshifts can be done at a fairly leisurely pace as there's no benefit to be had from downshifting as fast as you can upshift. Whilst the upshifts on a race sequential are now in the region of 50ms (or 0.05s), a downshift could well take 200 to 300ms (0.2 to 0.3s). Added to that, the fact that the ECU can blip the throttle considerably quicker and more accurately than the driver, and the fact that a low inertia race engine revs at a rate that's like to be >10,000rpm/s, then even 0.2-0.3s is plenty of time.

Remember of course that for a number of years in F1 now, the control systems are able to calculate the position of the gear teeth on meshing gears and fire them in at the right moment. Add to that in the last 5 or so years systems that engage two gears at once to help speed up or slow down the input shaft to match the wheel speed and you can see that simply applying a blip whist in neutral between gears on a decent sequential is a fairly straight forward task.

Have a read of this: http://www.geartronics.co.uk/paddleshift.htm on the Geartronics website about their paddleshift system for race sequentials. It's got some very good, un-marketing like explanation about how it all works

[Obiwonkeyblokey]

RacerMike said:

Knock your car in to neutral from a gear without using the clutch and you'll have no problem blipping the throttle. If you get it right, you can also force the next gear in without the clutch. Not a good idea in a normal road car box, but a dog box actually works better without use of the clutch. All the auto blipper does is rev the engine whilst in between dogs and bangs the next gear in when the speeds match. No clutch required.

Many moons ago I drove my R5 GT Turbo from Reading to Henley On Thames when the clutch cable snapped using this method. Traffic was fun.

[mat205125]

I love the way that the inner edges of the rear tyres start at the widest point of the cabin's glass house.



Even if this is largely due to the natural shape of the standard car, I can't help thinking about this from that view.

[mat205125]

anglophile said:

I just think that those floor pivoting pedals are what every proper motorcar needs

Nothing like that signature cramp in the calf holding the car on the start line

Floor hinge is always the best IMO too.

[SD and P]

Obiwonkeyblokey said:

Many moons ago I drove my R5 GT Turbo from Reading to Henley On Thames when the clutch cable snapped using this method. Traffic was fun.

This brings back memories of the late 80's - I had a broken clutch cable a couple of times in my R5 GT Turbo too and became practiced at changing gear without a clutch. Such a great little car - when it worked.

[Housey]

mat205125 said:

Now we are talking, these were epic, I do miss seeing these race

[VonSenger]

SD and P said:

This brings back memories of the late 80's - I had a broken clutch cable a couple of times in my R5 GT Turbo too and became practiced at changing gear without a clutch. Such a great little car - when it worked.

lol, brilliant, so did I!!! At least 3 times, once I went from central London to Surrey with no clutch. didnt do the starter motor any good though when pulling away from lights.

Oh the good old days

[chuntington101]

Quick question, how effective is the diffuser on the 996/7 with the rear mounted engine? there looks to be naff all room for a good sized one!