Shift points

[CatmanV2]

Not sure if this is 100% the right area, but...

So yesterday was the first time I'd managed to get anywhere near the red line repeatedly, with enough time for the answer to the question 'What next' to be anything other than 'braaaaaake'

So what's the best RPM to upshift?

Cheers

C

 

[2b1ask1]

On the road I tend to short shift first but all the others about 250 RPM off the limiter!

 

[TridentTested]

So yesterday was the first time I'd managed to get anywhere near the red line repeatedly, with enough time for the answer to the question 'What next' to be anything other than 'braaaaaake'

It comes quickly doesn't it?

Yesterday some neighbours where I'm staying persuaded me to take them to the beach so they could ride in the QP. I wasn't looking forward to it because the route is mostly busy 50 kph urban roads made worse with Saturday afternoon traffic.

We took the longer way and went onto the town's bypass. As I wound down onto it by the 270° slip road I kept the car in second and floored it once we were pointing straight. The bypass was empty. Having enjoyed the redline in 2nd it was too tempting to leave my foot planted and let it redline in 3rd. Whao, how intoxicating.

I didn't even dare look at the speedo before easing off for the roundabout at the end of the bypass, and as you say 'braaaaaake'. It reeled in the horizon very quickly.

 

[Chrisbassett]

I was trying to shift at about 7k yesterday, but it gets there and passes through soooo quickly that I was hitting the limiter at times.

 

[Emtee]

I was on the red line pretty much all the time yesterday and the car didn't grumble at all, well not for that anyway. The brakes grumbled like h3ll

Wouldn't be anywhere near the rev limiter on the road mind you. THere's just no point; may as well save a bit of petrol and short shift.

 

[mjheathcote]

Last time I was on track I was initially changing gear near the red line. I then had some tuition and then I found myself one gear higher going around the circuit, and not red lining half as much!

 

[Felonious Crud]

Yesterday I was trying to shift at the top end of the yellow. A couple of times, though, I hit the limiter before I'd had time to shift. Generally on the road I shift between 2 and 3k if there's another car in front of me. As Miles said, the brakes were more grumbly yesterday. Actually, they didn't grumble, they just couldn't really be ar5ed. The tyres had a whale of a time though - the fronts are scrubbed to h3ll, slightly more so than the rears, which suggests that I need to get better at more elegant cornering.

 

[Andyk]

I was trying to shift at about 7k yesterday, but it gets there and passes through soooo quickly that I was hitting the limiter at times.

I hit the limiter every change when I drove yours around Chris.....................................Only joking mate you know I would take care of her.....They do tend to rev well and you have to keep an eye on the counter.

 

[Emtee]

Last time I was on track I was initially changing gear near the red line. I then had some tuition and then I found myself one gear higher going around the circuit, and not red lining half as much!

There's some logic in that, given the torque maxes out at 4.5K rev's. I guess it's a case of balancing a slowing rate of acceleration against the time taken to get to maximum torque in the next gear. Depends on the situation I guess, but anywhere between 4K and 7K and you'll be getting the best out of the engine.

 

[QP4Me]

Hi,

In my drag racing days I constantly changed up only when hitting the redline.

Until I was shown on a dyno that in fact, peak power output was actually reached before that point. A rev limiter was fitted and resulted in fasted times. I am not sure of the profile of the power output of our V8, but it may produce some interesting results?

Pat.

 

[RW3200]

My take on this is to get used to driving by ear and feel rather than revs.
The optimum shift point will alter due to many factors including surface, conditions, grip levels, gradient etc....

From what I know the car will make power right through the range but the rate of increase will drop after a certain point. Torque will max out at a point and from then on, while the car continues to power on, traction and stability levels will drop off.

As its been said its about balancing it all out, but there's nothing like a red line dash to get the sense of speed even if it may not necessarily be the quickest method.
In my experience an engine used to its potential runs stronger than one that never reaches it.

Ru

 

[CatmanV2]

There's some logic in that, given the torque maxes out at 4.5K rev's. I guess it's a case of balancing a slowing rate of acceleration against the time taken to get to maximum torque in the next gear. Depends on the situation I guess, but anywhere between 4K and 7K and you'll be getting the best out of the engine.

So mostly these types of responses are backing up what I felt. On the road, it's a different story, but at Brunty I was heading for the red. On that long straight though, it became apparent that hitting the 140+ was as much due to what gear and when. It seemed that it would pick up much faster from 110-130 (in 6th) than 100-110 for example. Which made me think I was actually revving too high.....

C

 

[MAF260]

So mostly these types of responses are backing up what I felt. On the road, it's a different story, but at Brunty I was heading for the red. On that long straight though, it became apparent that hitting the 140+ was as much due to what gear and when. It seemed that it would pick up much faster from 110-130 (in 6th) than 100-110 for example. Which made me think I was actually revving too high.....

C

110 in 6th? I wasn't changing up to 5th until 120....

 

[Grinzzz]

Quite a flat torque curve on these things. I'd hazard a guess that peak torque is around 5 - 5.5k, with peak power kicking in at around 7k. Best point to change is going to be around 7k, but your not doing anything overly wrong anywhere after 6.5k. Sometimes you can be faster by changing up early and killing wheelspin; sometimes changing up earlier makes you more relaxed in a corner and hence able to carry higher speeds (although shouldnt be a problem with these cars - changing is not a chore!)

Hitting high speed on the straight was more a function of power and exit speed from the chicane. If you come out of the chicane 10mph faster youd end up 10mph faster at the end of the straight (these things dont appear to suffer significant drag effects until 160-170).

Bennys car surprised me, those pipes of his have freed up at least 15bhp more from the engine. I was overhauling him coming out of the chicane, but foot to the floor he then managed to slowly match my speed and then pull away down the straight. These engines, unlike many modern ones, appear to like as little constriction as possible on the exhausts.

 

[QP4Me]

On the question of exhausts, I recently fitted remote controlled flaps to open or close the exhaust (to the open air), before the back boxes. When open fully (along with a modified free flow x-pipe), there is a reduction in torque/acceleration from stop or low speeds. But there is a positive increase in higher end power output when accelerating from higher speed/rev range's.

 

[2b1ask1]

Grinzzz,

Benny had the group remap done in 2011 and got a custom map created lifting his limiter by 250 RPM and also de-restricting max speed I recal! I'm sure he will expand upon the details

 

[BennyD]

I was red lining and beyond for most of the day. Once got close to 8.5k before I realised and changed up. Mine seems to pull right through but I wasn't changing gear at the optimum point for maximum acceleration, I was hanging on to the gears because I love the noise it makes just before the valves start to bounce! I might have to put the 'Le Mans' exhaust back on for next year. Too much is never quite enough!

 

[Grinzzz]

Ahh that explains it! Should have seen the look on my face as you pulled away, the only other things getting away were the GTRs! It sounded fantastic as well at high revs. Guess you've got an extra 15 -20 bhp judging by the way you pulled away.

 

[CatmanV2]

Thanks, all. I shall bear it in mind for next year

And get some more tuition!

C

 

[ENZ525]

Lesson learnt for next time...must try harder!!
I was no-where-near the red line for any of my runs,
mind you, I kept getting the 'bonnet open' warning light flash up on the dash,
so will have to strap that down properly I guess