Macca

Here is the track map and sectors then a track map showing minimum and maximum times for each sector if that helps some folk visualize the lap better.

996tnz

That's good scene setting. Any chance still of that earlier throttle position and revs lap analysis again, but after toggling the time/distance button?

Macca

Post #36839 has the time bar on the bottom. Did you want the same with distance?

996tnz

Oh, sorry Mark, I'd missed that one at the bottom of the previous page. More time for that horsepower difference to work than I thought! My own estimates at the time were for HD, with its tighter, slower infield, but even there I reckon I must have underestimated the full open throttle proportion per lap with my 20%. Though I'm pretty sure I worked off a video on roadies back then as a basic Solo/Smartycam doesn't capture throttle position.

On further reflection, I suppose that what probably limits the time savings from horsepower as much as the open throttle percentage, is that air resistance rises with pretty much the square of the speed, which is why the faster you're already going to start with, the less added acceleration that any given amount of extra horsepower can deliver. Hence why a Veyron may have twice our horsepower but little more than a third extra top speed.

We think a lot about power to weight ratios, but at track speeds power to drag ratios may start mattering more for those full throttle sections, pushing us closer towards diminishing returns?

Macca

Hi Walt. All good. I looked at a lap at HD at the beginning of the year. This was just over 12s and 28s on 100% so 39%. Yes you are right about the hp vs speed thing. Ive often been surprised even in the GT3 how slow it can be to catch up to cars with 100 bhp deficit such as Nigel in his 996 GT3. It feels like an eternity to catch him on a straight.

996tnz

Know the feeling. Kind of like patience... patience... finally, yes got him! None of this will be news to you, but I actually had to think it through some years back, as follows.

If he's ahead when leaving the previous corner, he's further along in his acceleration of course so initially enjoys a decent speed advantage. Sure you're accelerating faster than he was (and is), but that better acceleration first has to happen for long enough to kill off that initial speed deficit. Until then the distance between you has still been growing, so you've been winning time but losing distance. But once past the point of matched speeds, your superior acceleration should see that gap shrink exponentially before you finally blast past at considerably more speed - even if sometimes only as you're closing in towards the next braking zone.

Actually, it was noticing lower powered cars pulling away from me out of corners that got me to think about it.

Macca

Well described. It also explains perfectly the phenomena I used to feel when being overtaken by Nigel in his GT3 when I was driving my 993. Like I was standing still lol!

shiraz

Getting a bit shaky up your end of the woods, Mark - also off California coast. All ok at yours?
Cheers - D

Macca

Hi mate. Thanks for asking. All good in the "shaky Isles" thanks. 7.8 off Sollies 5am this morning local time. We are 600km south so didn't feel it but got the Tsunami warning (now retracted).

Seems like a lot of seismic activity around at the moment. What's next, Auckland?

PS how you holding up down there? How is the family? I'm guessing the novelty for everyone has worn off now and the reality sets in which is when you need to stay busy and chin up and stay focussed on the simple things in life and the pleasure they can give...

cbnz

Macca, do you also have a braking map? From my observations on the sideline over the past 10 years, a lot of time is made up under braking, and it's how you brake that makes the difference, not just when. Also, tyre type and pressure is also a big factor, eg from Michelin to Pirelli slicks the difference is up to 2s/lap.

gt38088

http://www.pistonheads.com/news/ph-g...r-coffee/35422

The arms race continues a 7.10 lap is effing quick - would be a bargain vat free out of UK?

shiraz

Life has become an endless round of meetings - 2 days in Chch this week. Paua industry has agreed amongst ourselves to close down the immediate area, this is a 50% reduction & may be lasting some years. Steven J was in town again, so got to spend some time with him.
Family all good - daughter got junior (yr 10/form 4 for us oldtimers ) dux last night at high school prize giving ,held at trotting club because school gym is a bit 2nd hand. The world's not all negativity.
Took car for a "get fluids up to temp " run, need to slow to walking speed 3-4 times / km
Cheers

Macca

...

Macca

Craig. Brake table above for the same lap at Manfield. 19s or 26% of the time on the brakes. This could be reduced into T7 (sweeper) where Im using a big dose of trail braking (the 991 GT3 repsonds well to trail braking) into the double apex. Ive only been a couple of times to this track with the GT3, I think if i could get a bit more time there I could get on the brakes harder for shorter at the beginning, but currently I dont have the confidence/experience in terms of how much speed that will scrub off. With a bit more practice Id say that would reduce 3s a lap off the brakes. Also my max brake pressure is low at 107 psi. The cup cars will brake harder in the 120s-140s for less time. In the 993 I would be under ANS into T1 end of front straight regularly, in the GT3 I havent gone there often but need to build up teh courage to stay on teh gas around 0.4s longer on the straight and then harder into the brakes to gain a few tenths. More for next time I guess...

The word on the street is the Pierelli slicks last year were around 2s a lap faster at Taupo than the prior Michelin ones. I was surprised by the difference, but looking at the data from 2013/14 and 2015/16 does support an improvement in times with the new tyres...

Macca

I caught up on this this morning. Quite incredible isn't it. 13 seconds faster than a 991 GT3RS and a fair bit cheaper too.

Porsche are going to need the GT2RS to set thing right and need it soon too.

Like the Giulia Quadrifoglio with a 7.32 Ring time on road tyres (driver estimated 7.28 on TrofeoR - 3secndd slower - itcteslly begs how Porsche will keep up with the GT3 without turbos?