Nickshu

Wow you can really see the difference in how quick it accelerates out of the turns with the 4:1. Higher in the rev range at roughly the same speed throughout giving more torque available on demand vs. waiting for it coming out of corners. That's my issue with the stock gearing.

spiller

My pleasure, it's been great to be able to experience the difference between a very "cup" road going GT3 and a true cup car. The conclusion for me is the two cars are more similar that one would think, but I guess it shouldn't come as a surprise given how much they share in common. I am not phased by driving LHD, I actually think it's the better side of the car to sit on for a clockwise circuit as you get a slightly wider view of the apex on the mostly right hand turns. Getting used to shifting with my right hand has been a bit of a challenge as the h-pattern demands accuracy and the cup car REALLY does not tolerate slow shifting but I don't yet have the skills to bang through the gears with the right hand - I need to get better with this.

As for the set up, on a proper course my GT3 was definitely set up for oversteer but some of those turns are so tight that I was purposely taking a shallow line to avoid the rear end slipping in an attempt to keep up momentum. From memory my road car was full stiff on the front bar and one notch from full stiff on the rear. I also had very heavy springs, somewhere in the range of 1100/1300. The cup car is set full stiff front and rear is a little more neutral/understeer but I'm yet to fully understand the slip angle of slicks vs r-compounds and haven't driven the car on fresh rubber (or even matched compounds front to rear) yet so my goal is to get back to more of an oversteer bias once I work out what the car does on fresh rubber. I much prefer the oversteer set up but the slicks (in my limited experience with them so far) don't work as well with this as the r-compounds did. Or maybe I need bigger ***** LOL.

Yep, not ideal with our 996 cars given their lack of torque compared to the 3.8 and 4.0 cars! These things need to be singing from 6-8 at all times or it's a little frustrating.

Rootwitch

There's a concrete barrier on the right, the one at for example 1:51-1:52 on the cup car video.
Coming out of that corner, the street car is into 3rd gear well before the end of that wall, whereas for the cup car it's well after, a very noticeable difference.
Timing the laps, the cup car looks to be 0.5 second or so faster per lap.

Great videos!

What are the tire sizes on the two cars?

spiller

Overall fastest lap in the cup was 3 tenths over the road car but on average about 5 tenths so good estimation! 991 GT2RS was 1.9 sec quicker . The street car was on Yokohama A050 235/40/-18 front and 295/30-18 rear (brand new soft compound at the time). The cup car is running hankook 240/640-18 front and Pirelli 305/680-18 rear (old, and miss-matched). I think with fresh slicks the gap would have been another 7 tenths or so. As pointed out by GT Gears, the big rear tire on the cup car further lengthens the gearing and this probably outweighs the benefits of more rake on such a tight track. It would have been interesting if I was able to run the r-compounds in the road car sizes on the cup on the same weekend to see what was quicker.

GTgears

I want to add something to think about to this conversation. The reason that the street car 3rd gear feels long, even though it is the exact same ratio, is because of 2nd. It's not because of the final drive as people tend to assume. It's about the RPM drops. The 2.15 2nd gear versus a 2.00 is a HUGE gap. This is why going down to a 1.600 or shorter 3rd on a GT3 regear is so common.

Something I think people need to think about these days is long term cost. Historically people only ever regeared a car once. However, in this day of Chin and country clubs where someone might get 40-50 days annually, gearboxes have become a maintenance item in the same way that an engine is. People are wearing out and needing to replace both 2nd and 3rd gears.

2nd gear on the street car presents its own unique problem which is that the dogs aren't serviceable and it's part of the mainshaft. This means if you **** 2nd, you're buying a 1-2 kit. 2nd slides on and off on a Cup mainshaft, so it's replaceable. Of all the 6spd mainshafts Porsche has made in recent years, the only offer a 2nd gear service part for one of them, the 996TT. Why? Because they had the 2nd gear popout recall issue and in the middle of that fiasco they started selling 2nd gear idlers.

It turns out to be a 2 birds with one stone approach that Ray used. The turbo 2nd is 2.06 instead of 2.15. So it's now closer to 3rd, improving your rpms drops. And the taller 1.56 3rd gear has a longer life than any of the 1.60 or shorter 3rd gears. For long term service of a track car, Ray's approach is the cost effective way to do it. It may leave a tenth/sec per lap on the table in the hands of a pro, but for most of us mere mortals it won't matter. Hell, at a track day, traffic can kill your hot lap at any time. It's not racing and there's no qualifying laps. I've set up a lot of people with what Ray did, or maybe something just a tick shorter in 3rd like a 1.579.