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Day 1 on track with the GT4 is complete! I was asked to post my thoughts and I will keep it short and sweet (for once):
What I want:
- 30 to 40 more HP. Not to sound like a whiny driver but waaaaaahhhh...I could keep a modified 991 GT3 at bay in the infield but on the banking he left us; I don't like that!
- I need more front grip so I am about to add front wheel spacers and lower the front end of the car because I'm sure it has that lovely factory toe setting of zero and we know it needs more camber. Lowering the front of a 911 or Cayman will generate more static camber and toe out.
- Did I mention I want 30 more horsepower? My 981 PDK with the GTS mapping, X51 throttle body, X51 manifold and filters generated the same 160mph terminal velocity as the GT4. I think the aero, side scoops and larger front bumper are creating more drag and holding us back.
- Can I have less rear wing angle?
What I don't want:
- a shorter 2nd gear. As I suspected, 2nd is almost too short in the slow corners when you carry the appropriate min speed. A shorter 2nd would be way worse. All 3 GT4 owners here agreed. Obviously the car doesn't need to be geared for 190mph so 3-4-5-6 could be shorter but (see below).
In conclusion, for this thing to start at $86K and to be as good as it is out of the box, it gets too much criticism. No current day factory is going to produce a car without some understeer. If you track the car and find it pushy, adjust the setup and purchase some bits. I think though that the car gets a lot of negative feedback when people need to chill out and accept it for what it is.
MattTheBoatMan got a full day of my riding shotgun and yelling at him! He's doing just fine! Here's his baby in the garage!
After I make these changes for tomorrow I will adjust the bars for Sunday.
... for this thing to start at $86K and to be as good as it is out of the box, it gets too much criticism. ... I think though that the car gets a lot of negative feedback when people need to chill out and accept it for what it is.
...
- Can I have less rear wing angle? ...
...
What I don't want:
- a shorter 2nd gear. As I suspected, 2nd is almost too short in the slow corners when you carry the appropriate min speed. A shorter 2nd would be way worse. All 3 GT4 owners here agreed. Obviously the car doesn't need to be geared for 190mph so 3-4-5-6 could be shorter but (see below). ...
...
After I make these changes for tomorrow I will adjust the bars for Sunday.
Do you think the rear wing is really slowing you more on the straights than it is helping you in the corners? I know the car understeers, but it seems time can be gained even in that situation on high speed bends because you can really lean on it with enough rear downforce.
I think what sets apart the C7 Corvette Z06 Z07 package (or whatever it's called ) and new Viper from european cars with similar power to weight ratios is their aero packages. And it doesn't seem to take a lot of power to use better aero either, case in point Jack Olsen's streetcar '72 911 with a 300 hp 964/993 engine. It did a 1:26.88 at big willow, its secret: good aero with a lot of downforce. (for completeness, here's a fun video of the comparison
I wonder if more front downforce is what's needed... dive planes? (To back up your point though, sport auto did run the high downforce config in the front with tunnels open, and the rear wing in the low downforce config being more flat for their nurburgring run)
Your 2nd gear comment makes sense: Potter's 1:58.2 lap at thunderhill only used 2nd for turn 11.
I can't wait to hear more as you get the car dialed in!
I wonder if more front downforce is what's needed... dive planes? (To back up your point though, sport auto did run the high downforce config in the front with tunnels open, and the rear wing in the low downforce config being more flat for their nurburgring run)
IIRC correctly their test car had PCCBs and therefore needed it to balance the std setting rear wing because the rotors are larger and therefore didn't have the flow-thru necessary. Plus if you recall PAG was there to assist in setting up the car.
IIRC correctly their test car had PCCBs and therefore needed it to balance the std setting rear wing because the rotors are larger and therefore didn't have the flow-thru necessary. Plus if you recall PAG was there to assist in setting up the car.
Right, I remembered the rotor difference in front downforce, but didn't consider it in terms of balance. Interesting.
I assume they tested at Daytona since BGB mentioned banking. I'm curious what the GT4 lap times are compared to a Continental Tire Sports car contender. If the CTSCC car is hitting higher top speed than the GT4 than we know the aero is impacting top speed. Then we need to look at corner speeds. If the GT4 is slower in the corners than the drag is severally impacting the overall performance. Curious to know if BGB has any input on this thought.
Great to hear you got the GT4 on track and the feedback you give is great. You are saying exactly what myself and my 2 other GT4 owner friends are saying about the car. We want the extra HP to keep up with the GT3's. We also need to sort out the front end grip as this is the only issue we currently have not been able to tackle with just tire pressure and sway bar settings. I am waiting anxiously for your feedback on lowering front and toe settings and how it reacts on track.
Thanks for the feedback guys...I will just paste in some notes as it what I'm thinking and see if I can address everything via the iPhone because I can't multi-quote.
- We are here at my home track which is sort of like a big dyno / drag test because you reach more terminal MPH here vs anywhere. It helps determine if you are not slippery or aren't making big power. To be fast at start/finish though you need to roll big speed through the bus stop before going back into the banking which is really just a big straightaway. Aero helps a lot through there because we are doing 80mph at the slowest point. More front grip would generate more exit speed as it's the front that I'm waiting on more vs. the rear. I think I'm focused solely on improving front grip to try and generate more MPH. We have already proven that horsepower can be bolted on to this car.
- We can all agree that an optimal track setup requires more camber and I still think so. I am just trying to do things sequentially and experiment with baby steps before I put on required parts because I figure it's valuable to folks starting out.
- the 4mm per corner of wheel spacer I added last night is not going to do squat in my opinion. The issue I have is that the "snout" that's on the GT3 upright (which is a very nice upgrade for wheel centering) only leaves enough room to run a 4mm spacer (will post a photo later). I wanted to try a 7mm. I went to the shop to get something meaningful that has a hub centric ring but I have not added studs and am forced to use aftermarket bolts. The spacer is 14mm so it's going to be meaningful. I'm just hesitant to trust aftermarket wheel bolts when we don't have a lot of room to spare.
- the ability to re-set tire pressures on the instrument cluster for changes in race track cold pressure settings is rather cool in my opinion.
- I will try and tinker with the bars this afternoon; we are waiting on the track to dry out.
12-04-2015, 06:02 PM
) and new Viper from european cars with similar power to weight ratios is their aero packages. And it doesn't seem to take a lot of power to use better aero either, case in point Jack Olsen's streetcar '72 911 with a 300 hp 964/993 engine. It did a 1:26.88 at big willow, its secret: good aero with a lot of downforce. (for completeness, here's a fun video of the comparison
