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Old 08-16-2013, 12:57 PM   #18
Fair
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Join Date: Nov 2012
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Update for Feb 4, 2011: After looking at my notes and in-car videos, I've compiled a list of ten observations about the 2011 Mustang GT and its on-track behavior. I've heard rumors of overheating, oil usage, and questions about the stock brakes. After our 2 drivers beat the crap out of our 2011 all weekend, one day in the dry and another in the wet, I figured I'd comment on the cooling, oil usage, fuel consumption, and track worthiness of the stock Brembo brakes (some of this might look familiar to one forum, but I've expanded this considerably since I posted that).



1. The water temp never got over "the middle of the gauge" warm. Sure, its a stock gauge, and I'll replace it soon with a trio of real oil/water/pres gauges, but so far I'm pleased with the results of the OEM cooling system (I may be singing a different tune around June here in Texas). It got a little warm outside on Saturday and Amy and I were running it in back-to-back sessions, for 8 total sessions on Saturday.

2. Oil consumption was minimal. We checked it after every other session and I added 1/4 qt of oil each day. That's minimal, and nothing like the 1 qt a day usage most of my LSx powered cars use on a typical track day. Not bad.

3. Fuel consumption on track was 6.8 mpg all weekend. On the street it has been averaging 19 in town, about 23 on the highway. Not bad, especially considering how I've been driving it (like it was stolen). On track consumption was not stellar, but it only drinks 93 octane, so it was cheap to fuel up at the track compared to the guys paying $8.75/gallon for Sunoco 98 or 110 octane. We accidentally let it get down to under 1/8th of a tank on track and it never fuel starved, not once. That's a relief.

4. The brakes were very impressive and confidence inspiring, and the ABS worked like a champ in both the wet and dry. They are bone stock other than the stainless braided lines we built for it. One of the other 2011 Mustang GT TTA guys had beautiful 2-piece ($800/pair) rotors up front, mostly for weight. He also had the CS lower valance on with ducting to the front rotors (see pics, below). Not a bad idea. Still, I think the stock rotors, pads and calipers worked fantastically at this track, at least for the current grip and power levels of the car. People that have driven with me say I am a pretty abusive to brakes (lots of left foot braking, trail braking, and late braking on track) yet I was pretty happy with the stock brakes all weekend. You'd think with 2 drivers running the car double duty we would have cooked the things, but the pads took a beating and kept diving deep into each corner. I complained once on video of a bit of smell from the brakes, but that was it. I don't know what pads these Brembo cars come with, but I like them. Minimal dusting, too.



5. Overall handling and balance was good with the AST 4100s and Hyperco rates we chose, but I had some trouble with rear traction. Many of the higher speed corner exits were tricky in 3rd or even 4th gear in the dry (and this is with the tallest available 3.31 final drive ratio), and we were running wider and stickier than stock 265mm Yokohama AD08s. I guess that's to be expected with a factory 380 whp. We've more than tripled front spring rate but rear rates went up only 63%: Hyperco 450#/in front, 200 #/in rear. The stock spring rates on the 2011 GT are 122 #/in front, and 154 #/in rear. The added front rate really cut down on brake dive and is helping control roll and heave from the over 1000# per front wheel. The relatively soft rear rate was chosen (with the help of AST-USA) to help rear traction. We have some more spring rates to test with (350# front, 250# rears), but I don't know if I want to lower the front rates much, and increasing the rear may make it have less corner exit traction.

Both track events we've run in the GT so far were noticeably bumpy: Harris Hill Road had several bumpy corners and straights and was wet, and MSR-H had lots of bumps going into turn 13 ("The Launch"), where braking would have been compromised without quality monotube dampers, especially in the wet. Once I figured out where to brake into T13, I was able to run down a lot of cars by staying in the throttle longer and braking later, whereas I noticed some other cars were skipping and hopping over the same patch of track. The shock valving we're testing with felt great and took only minor knob adjustment to get the car sorted.

This set-up still has a bit of understeer mid-corner, so we'll play with the set-up a bit more, but we haven't even added aftermarket swaybars yet, which should help us make quicker adjustments at the track.

continued below
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