This is exactly what I've been doing as at higher RPMs it will just break loose with the DSC off, and with it in trac mode it will kick it in to easily which ruins your track out. Although it saved my butt on the banking once so I'm not complaining. So my tactic has been using lower revs as a "traction control" and applying power as the grip allows, while unwinding the wheel to track out. I'm usually at or near full throttle soon after the apex if I turned in correctly and at the right speed. But I gotta get faster but safely

 

The advantages of staying at higher RPMs are NOT ONLY more power but, much better handling control. Just try the differences between going through a corner at 2500 vs 5000 RPMs. Night and day in control. You will pick up seconds in cornering by staying with higher RPMs.

Certainly, you will have to control the accelerator with much more care at high RPMs due to the extra power delivery and the much tighter connection between the engine and the wheels. As I said so many times; treat the gas pedal as if you you were stepping on eggs without breaking them.

The few times I have driven my XRK quickly on winding roads I had kept my RPMs in the upper ranges that the car handled beautifully there. If I let the RPMs drop the car would understeer badly and try to get away from me in the corners. Winding up the RPMs give you a second, fine steering control - with you foot.

 

Thank you and you may have just answered my question as to the understeer. I steer with the gas, its hard to see in that video as its dark but once steered into the apex I make adjustments with the gas. Off the throttle to pull it in, neutral throttle to maintain speed and the arc, then slight on if I'm a hair too close to the apex.

One thing I dislike about the car in Dynamic Mode is the throttle response, its WAY to sensitive. I wish there were a way to tune this out, its really annoying on the track especially at the edge of adhesion when you're unwinding the wheel. I've forced myself to drive in Trac DSC and if I can keep it from kicking in I'm pretty close to where I need to be, its sort of a throttle shock collar.

On the other hand Trac DSC intervenes a bit too much in corners. This may be where the brake overheating is coming from as I can hear a "hydraulic purring" if the car pushes in a turn. Once I get back in line it stops. I'm going to experiment with the higher revs this Sunday and post some more videos for you guys to take a look at.

I really appreciate all the comments and suggestions!

 

MaximA,
What tires are you running and their sizes.
Thanks....

 

Max:

Reviewing your dyno data sheet, it looks like if you can keep the rpms in the 5000-5200 range you will notice significant improvement in launch speed coming out of center of the apexs. You will be just short of full potential HP.

I understand your car red-lines at 6600, so I see no problem in running your engine in the 5000-5200rpm range. You will need to potentially use lower gears to bring up the rpms. At 5000-5200 rpm your dyno shows your pulling 460-480 HP. At 5200 your maxium torque starts to decline. So there is no need to push the car to the extreme rpm limits, as torque declines after 5200 and you may have to pay a price with engine stress to achieve the higher HP pushing the rpm any higher than 5200.

In the dyno the 530HP printed at around 6500 RPMs, very close to red-line so you know the dyno machine pushed your engine to the limit for this test. So the 5000-5200 range looks like an idea range to run your car on the track.

Try this a few times, on a track your comfortable with. Continue to test this method lap over lap. In due time, you will increase track times, and overall the car will handle well. Of course it is up to the driver to control speed and overall control of the car.

Hope this might help.

 

Thank you Rich, I missed last weekends track day due to business but will be back at Homestead in the next few weeks then Sebring on 8/23.

 

Max,

While the engine's torque curve is quite flat, the use of a lower gear's ratio multiplies the torque at the wheels. The XKR's powerband, with hp basically rising to redline indicates that the optimum shift point for acceleration is at redline in each gear. Your car will always accelerate the fastest when shifted at redline, and operated in that top part of the rev range. The correct gear selection for corner entry would be the one that reaches red line at a point late enough in the corner exit where an upshift won't upset the balance of the car.

I'm at a similar point with the new Viper where I'm still kind of avoiding the meaty part of the power/acceleration band in most corners, and using a higher gear and lower revs party as a traction control technique, but really more as a throttle response dampener. Where I knew I was on the tire's limits of grip a lot of the time with the XKR on street tires, and I found the electronic throttle response dangerously aggressive when at the limit, whereas with the Viper I really haven't found the rear tire's limit, and concerned about what will happen when I do find it

It's all about seat time, and the confidence that comes with having probed the limits in familiar and controlled ways. I did two days at VIR recently, started probing cornering at higher revs once I had become more familiar again there, and found it to be much more controlled than I thought it might be. Hopefully you will find it to be the same.

 

Bruce and Rich,

Thank you again for the advice I really appreciate it!

You're right I must keep the revs up and turn off the TRAC DSC as its intervenes to easily on corner exit and just cuts the throttle abruptly. This has caused me to drive within its limits which are too low for the track.

During the Jag Performance academy the stock cars were fine with the factory DSC and I rarely hit the limit, but with all the mods I've done I'm nearing 1.2G which throws the computer into a frenzy as it starts to "correct" the car mid corner when I'm actually trying to get it to rotate faster. That has been whats frying my rear brakes.

I'm turning off the baby sitter for this next track day and should have the brake ducting done as well.

 

Sounds like a plan. I'm at 1.5 g and that's throwing my brain into a frenzy. What have you other guys found in actual race cars?

Btw, a track friend took his just broken in '14 C7 Stingray with Z51 package for a shake down track day before heading to VIR with me. He completely wore out the rear pads from the Performance Traction Control applying rear brakes all day in the corners. Also overheated the coolant and transmission, ruined the front runflats and siezed both valves in the exhaust system that function as part of their 8>4 cylinder deactivation. That's GM's idea of a "stress tested and track ready" Vette.

 

WOW 1.5 in a street legal car is great! Some of the race prepped RSRs are pulling around 2Gs but aren't that fast in the straights(lower HP and drag). In the banking at Homestead they are missiles. I'm around 110 MPH pulling 1.4 in banking and they fly by me like I'm sitting still.

I can't believe your friend as fried a C7 Z51 they are supposed be track ready. I can understand the rear brake issue mine are fried again after two months. You try to get the car to rotate and instead the computer keeps telling you to go straight by applying brakes to the outside rear. All this while you are starting to accelerate out of the apex, it just eats your pads and rotors.

I've owned corvettes but they are no Porsche GT3 or Viper on the track. They have way too many pedestrian compromises.