[rlcowley]

I had a track event last week with my ZL1 and captured video and telemetry.
A friend also participated with his SS 1LE equipped with PDR.

I sync'd the laps in a video to compare and was shocked to see that our top speed was only a few mph difference.

I topped out at 124mph and he topped out at 122. Only a 2mph for having an extra 200HP?!

In the previous corner running up to the long back straight, we were exactly on pace with each: We both ran the kink flat out at ~102mph, shifted from 3rd to 4th and braked about the same time.

Is something wrong with my car? Should it have been faster?

I've heard about the intercooler problem but my IAT was 93F so I don't think the engine would have pulled power.

The timing started to pull back prior to the top speed however. It was at 18.5 degrees at 115mph and by the time I reached top speed, it had pulled back to 12.1 degrees.

Ideas? Thoughts? Am I missing something?

https://youtu.be/zkgwsR7qE_s

[viurniel]

First, I could obviously be the driver.

I would look into air in supercharger cooling system as the second suspect.

[bdavies11]

Originally Posted by rlcowley

I had a track event last week with my ZL1 and captured video and telemetry.
A friend also participated with his SS 1LE equipped with PDR.

I sync'd the laps in a video to compare and was shocked to see that our top speed was only a few mph difference.

I topped out at 124mph and he topped out at 122. Only a 2mph for having an extra 200HP?!

In the previous corner running up to the long back straight, we were exactly on pace with each: We both ran the kink flat out at ~102mph, shifted from 3rd to 4th and braked about the same time.

Is something wrong with my car? Should it have been faster

I've heard about the intercooler problem but my IAT was 93F so I don't think the engine would have pulled power.

The timing started to pull back prior to the top speed however. It was at 18.5 degrees at 115mph and by the time I reached top speed, it had pulled back to 12.1 degrees.

Ideas? Thoughts? Am I missing something?

https://youtu.be/zkgwsR7qE_s

Your car is fine. He simply gets through the last corner better and accelerates earlier and harder than you do. If you pause the video at 32 seconds you can see he's still around the apex of the corner but you're pretty much on the straightaway yet hes at 85mph and you're only at 78. Simply put, he just nails the corner better and accelerates earlier than you did. Obviously it takes time and distance but you eventually hit a higher top speed (since you have more power) at the end of the straight even though he held a much higher speed and accelerated earlier than you did in the previous corner. Looks like you got through the next corner a little better and you hit 98 at the end of the straight while he only hit 91.

Also, you realistically only have about 150 more hp than him once you factor in power to the wheels and your car is roughly 200lbs heavier which might be why you weren't able to corner quite as well.

[Stephen12ZL1]

Your car is fine he just gets back to the throttle way faster than you do

[angryBits]

Looks like you apex'd early and had to lay off the throttle until out of the turn.

He swung wider and apex'd later allowing him to get on the throttle sooner. This can be a good approach before a long straight.

[rlcowley]

I appreciate everyone's feedback.
I've done some additional analysis to try and articulate my position, because I still think the ZL1 should have been faster.

I've highlighted the area of the track and shown the trap speeds.
You can see that we both had the same apex speed (77mph) at the corner before the back stretch (Workout). Then we go thru the high speed kink (Scream) and we are both flat out, full throttle thru here. That's when the SS 1LE starts to pull the ZL1 (100mph vs 103mph). Then the long back stretch into Blackrock, the ZL1 finally catches up, but just barely. The ZL1 tops out at 125 and the SS 1LE tops out at 122. The total distance of that backstretch is 1,500 feet.

Maybe I'm up in the night but I think in that amount of distance, starting at basically the same speed (77mph), the ZL1 should have been a lot more than 3mph faster than the SS.

[Gunkk]

Sorry if this comes across a bit harsh, but it's not your car, it's your DriverMod.

This course is almost all turns, and you're 2-7mph slower in turns: 1, 4, 5, 6, 7, and 8 (red boxes in the pic below are his speeds). He's also using more road than you in a couple corners allowing him to carry more speed with his lighter car.

Brake later, carry more speed thru the apex, and get on the throttle sooner. Switching back to the stock GYSC3 tires may help here if you're having corner grip issues (i.e. if car control isn't an issue).

Good luck

[Vtor_ZL1]

The fix is easy, MORE track time.

[Dave-ROR]

Originally Posted by Gunkk

Sorry if this comes across a bit harsh, but it's not your car, it's your DriverMod.

This course is almost all turns, and you're 2-7mph slower in turns: 1, 4, 5, 6, 7, and 8 (red boxes in the pic below are his speeds). He's also using more road than you in a couple corners allowing him to carry more speed with his lighter car.

Brake later, carry more speed thru the apex, and get on the throttle sooner. Switching back to the stock GYSC3 tires may help here if you're having corner grip issues (i.e. if car control isn't an issue).

Good luck

This. Also the SS generally had better speed at trackout even in "Workout" where both had the same apex speed, the ZL1 track out speed is 78, because the ZL1 driver is scrubbing speed and not accelerating until basically track out. The SS is slowing, apexing then back in the gas so he's at track out doing 89.

So OP, your car is fine. Just need to work on your driving a bit and this comparison is actually a good way to do that. Just don't look at JUST the specific points you seem to be focusing on.

[angryBits]

Originally Posted by rlcowley

I appreciate everyone's feedback.
I've done some additional analysis to try and articulate my position, because I still think the ZL1 should have been faster.

I've highlighted the area of the track and shown the trap speeds.
You can see that we both had the same apex speed (77mph) at the corner before the back stretch (Workout). Then we go thru the high speed kink (Scream) and we are both flat out, full throttle thru here. That's when the SS 1LE starts to pull the ZL1 (100mph vs 103mph). Then the long back stretch into Blackrock, the ZL1 finally catches up, but just barely. The ZL1 tops out at 125 and the SS 1LE tops out at 122. The total distance of that backstretch is 1,500 feet.

Maybe I'm up in the night but I think in that amount of distance, starting at basically the same speed (77mph), the ZL1 should have been a lot more than 3mph faster than the SS.

Your exit speed was not 77 and your apex was much earlier than his.

I agree, more seat time.

[Zee_Ohh]

Your scrubbing a lot of speed, he’s not. I would try and get him in the passenger seat and have him show you his line. Or if your comfortable with it have him drive your car and shit shotgun for a couple laps.

[philpacs]

I agree with prior comments. It's amazing how much exit speed does to a lap time. The ZL1, IMO, is harder to track than the SS 1LE also. In the later you can use more of the throttle and it's lighter. In the ZL1 you manage a bit more weight and have to manage the throttle more which isn't as smooth as a NA car. As you get more comfortable trusting the throttle, and corner/exit speed you'll be faster. Even the in the hands of Randy Pobst he was only about 2 seconds faster in the ZL1. At Sebring I found a video of an SS 1LE a little faster than me...but not for long

[SSDan]

Originally Posted by Zee_Ohh

Or if your comfortable with it have him drive your car and shit shotgun for a couple laps.

Maybe you meant to type "sit" shot gun - or maybe not!

[Zee_Ohh]

Originally Posted by SSDan

Maybe you meant to type "sit" shot gun - or maybe not!

Gotta love predictive text. Shows how often I type one over the other.