[Z06] Lag/Delay at Full Throttle?
Thread Starter
Racer
Joined: Jan 2007
Posts: 297
Likes: 17
From: El Paso, TX
Lag/Delay at Full Throttle?
Anyone notice the very slight but noticeable delay in immediate acceleration when one presses the accelerator at full throttle from a rolling start? I heard that turning traction control off may eliminate this delay...is that true? And yes, I'm talking about mashing the pedal instantaneously and not squeezing it.
Race Director
Joined: Aug 2000
Posts: 10,649
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From: Central Florida
Anyone notice the very slight but noticeable delay in immediate acceleration when one presses the accelerator at full throttle from a rolling start? I heard that turning traction control off may eliminate this delay...is that true? And yes, I'm talking about mashing the pedal instantaneously and not squeezing it.
If your pre-determined intent is to accelerate strongly, in preparation, press and hold the console button for 5-seconds. "Competitive Driving" will appear in the Driver Information Center. This mode turns off Traction Control, giving you full control of the rear wheels and allowing wheel spin, but keeps Active Handling available to help you maintain control of the car, should the rear end get loose.
I made all my C5Z drag strip passes in Competitive Driving mode.
Finally, if you want max acceleration in a C5Z, whether it's stock or modded, you will do better by learning to squeeze the throttle to minimize wheel spin.
Ranger
Le Mans Master
Joined: Oct 1999
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Anyone notice the very slight but noticeable delay in immediate acceleration when one presses the accelerator at full throttle from a rolling start? I heard that turning traction control off may eliminate this delay...is that true? And yes, I'm talking about mashing the pedal instantaneously and not squeezing it.
If I mash the throttle I am usually moving with no power drop. when I had bad tires they would go up in smoke a good while before trac control kicked in.
Le Mans Master
Joined: Oct 2005
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From: Macon, GA
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 32
From: Central Florida
That must be what I'm feeling in my '03. Even when not power shifting, (just good old fashion fast as you can without trying to break it shifting) between 5500-6200 RPM when I shift, the car suddenly noses over for a split second before resuming haul-*** mode. When I turn off TC, it doesn't do that. Kinda weird that my buddy's 2000 FRC and 2007 C6 Z51 doesn't do that. What's different about the Z?
The TC/AH system was revised in 2001. That difference is likely what you sense when riding in your buddy's 2000 FRC compared to your 2003Z.
Ranger
Le Mans Master
Joined: Oct 2005
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From: Macon, GA
That's what I thought, but his 2000 doesn't do this. Is it just the power difference and the computer sensing wheel slip? I can see it slipping the tires in the 2-3 shift, but it's very hard for me to believe that it's trying to break the tires loose during the 3-4 shift and envoking the TC.
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 32
From: Central Florida
That's what I thought, but his 2000 doesn't do this. Is it just the power difference and the computer sensing wheel slip? I can see it slipping the tires in the 2-3 shift, but it's very hard for me to believe that it's trying to break the tires loose during the 3-4 shift and envoking the TC.
It will do the same on a strong 4-5 shift at 140-144. You can do that test too, if you've access to an abandoned runway.
Ranger
Le Mans Master
Joined: Oct 2005
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From: Macon, GA
OK I take your word for it. One last thing though. On the last run last night, I had my friend drive the car while I watched the dash for any warning lights during the "lag", but nothing popped up warning of impending doom. It just dies for a nano-second. Almost like fuel shut off or something. Who knows. 
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Race Director
Joined: Aug 2000
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From: Central Florida
No DIC message, but short power delay on the shift = wheel spin.
Listen to the audio of the 1-2 shift in this pass, recorded inside the car. The rear wheels spin for a bout 20 feet. TC-Off (retains AH).
If you place the cursor right after the launch on the progress-bar, you can replay the 1-2 shift segment by repeatedly clicking the mouse. Listen to the engine while the wheels spin; watch the rear wheels snake to the left. You can see the spin marks in the track surface. It's brief. But that sound is accompanied by a momentary loss of acceleration. I suspect, that may be what you are sensing in your car.
Ranger
Last edited by Ranger; Aug 7, 2007 at 09:25 AM.
Race Director
Joined: Aug 2000
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From: Central Florida
Le Mans Master
Joined: Oct 2005
Posts: 9,429
Likes: 44
From: Macon, GA
Nice run Ranger. I didn't notice the lag as much in the video as you mentioned, but I'm sure if I were in the car I would feel it. I'll try to take some in car shots with my video camera soon. Maybe that would help nail things down.
Advanced
Joined: Jul 2007
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Also Ranger if he is power shifting the car he may be getting into the 6700rpm range for a split second and we all know what happens then. It only takes a nano second at 6650 rpm to shut fuel and recovery time may be what he is feeling.
Race Director
Joined: Aug 2000
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From: Central Florida
This circumstances allow the engine to rev 300-400 beyond the limiter without invoking it, assuming the clutch-in duration is brief. The duration of the over-rev is brief, less than 150 milliseconds. The reason is likely just latency of the signaling and resulting mechanical actions.
That's the way it works on a C6Z, when I make fast shifts with 100% throttle lift, as I've learned from data-logging the engine during passes. The engine will hit 7400-7500 without the limiter cutting fuel.
Behavior is different if the driver runs head-long into the limiter before clutch-in.
Ranger
Last edited by Ranger; Aug 7, 2007 at 12:24 PM.
Melting Slicks
Joined: Jul 2006
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From: The 7th layer of hell - Western Washington
I didn't think I was shifting that hard, but I was getting power reduction after the 3rd to 4th shift during this lapping day. Once I looked at the video I could hear that I was breaking the tires loose, I couldn't hear it inside the car when driving...
Race Director
Joined: Aug 2000
Posts: 10,649
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From: Central Florida
Will do it too on the 4-5 at 140-144, spinning the wheels enough to activate the TCS.
That's why Competitive Driving mode is the preferred setting when the driver expects some wheel spin and doesn't want to pay the TCS power-lapse penalty.
Thanks for posting that vid.
Ranger
Team Owner
Joined: Sep 2003
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From: Raleigh / Rolesville NC
Great smooth line. Yes could hear that chip as you shifted.
Melting Slicks
Joined: Jul 2006
Posts: 2,094
Likes: 5
From: The 7th layer of hell - Western Washington
Also I run HAWK HP+ pads which are a streetable race pad, and NAPA rotors which are cheap and high quality.
Basically I show up, slap on a number and go like hell!
Le Mans Master
Joined: Nov 2003
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From: NJ
Believe you'll find that when the clutch pedal goes in before the rev-limiter is invoked, the engine retains upward momentum and the fuel-rails still contain pressurized gas.
This circumstances allow the engine to rev 300-400 beyond the limiter without invoking it, assuming the clutch-in duration is brief. The duration of the over-rev is brief, less than 150 milliseconds. The reason is likely just latency of the signaling and resulting mechanical actions.
That's the way it works on a C6Z, when I make fast shifts with 100% throttle lift, as I've learned from data-logging the engine during passes. The engine will hit 7400-7500 without the limiter cutting fuel.
Behavior is different if the driver runs head-long into the limiter before clutch-in.
Ranger
This circumstances allow the engine to rev 300-400 beyond the limiter without invoking it, assuming the clutch-in duration is brief. The duration of the over-rev is brief, less than 150 milliseconds. The reason is likely just latency of the signaling and resulting mechanical actions.
That's the way it works on a C6Z, when I make fast shifts with 100% throttle lift, as I've learned from data-logging the engine during passes. The engine will hit 7400-7500 without the limiter cutting fuel.
Behavior is different if the driver runs head-long into the limiter before clutch-in.
Ranger
I also see significant wheelspin with hot etstreets at 10 psi on the 3-4 shift on the data logger. My car is heads and cam with 4.10's but I still never expected much wheelspin on the 3-4.
I can show both of these things happening on a logged pass if anyone wishes to see.