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Supercharger lag ?

 
Old 03-14-2019, 09:24 PM
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Corvette farmer
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Default Supercharger lag ?

I recently came from a Grand Sport to a Z06 and while it is noticeablely faster it really has annoying lag time before it puts the power down. The naturally aspirated motor had zero lag and was very predictable if you needed to pass in a hurry. The Z is not as predictable because of the lag and then blasts off when you punch it. You guys that have the Zs is this normal for supercharged cars?
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Old 03-14-2019, 09:40 PM
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rrsperry
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There is no lag. You have a positive displacement Sc, not a turbo. You may have engine management or traction issues that seem to be lag.

Even a centrifugal sc has no lag. It just doesn’t make full boost until redline.
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Old 03-14-2019, 09:46 PM
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That should be your TCS or other nannies kicking in to keep you from going sideways when you stomp it, not lag.
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Old 03-14-2019, 10:16 PM
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It may help to understand that the power delivery of a positive displacement supercharger is linear; that is, it is not peaky and delivers the same amount of boost throughout the RPM band.

A positive displacement supercharger pumps a fixed amount of air per revolution. This is just like an engine. An engine pumps air linearly. If an engine displaces 1 unit of air at 1,000 RPM, it displaces 2 units at 2,000 RPM. A positive displacement SC does the same thing; it moves a linear amount of air with RPM. Also, the boost is constant. If the SC produces 10 psi boost at 2,000 RPM, it produces 10 psi boost at 4,000 RPM.

In this way a positive displacement SC is just like having a bigger engine. It produces more power and has zero lag.

(Turbos have lag as they are driven off of the exhaust. Thus, there has to be exhaust pressure to spool up the turbo. There is little exhaust pressure until the RPM rises. Thus, the turbo does not get spinning until the RPM rises, resulting in lag.)

Last edited by Elk; 03-14-2019 at 10:18 PM.
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Old 03-15-2019, 09:18 AM
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Nothing to add to the already good responses other than I have a 2019 Z06 and there is no lag. Jump on it and it is gone just a matter based on your gear and rpm how much tire spin and rear end sway you get. No lag at all.
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Old 03-15-2019, 09:05 PM
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It’s belt driven. No lag
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Old 03-16-2019, 10:18 AM
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Originally Posted by Elk View Post
It may help to understand that the power delivery of a positive displacement supercharger is linear; that is, it is not peaky and delivers the same amount of boost throughout the RPM band.

A positive displacement supercharger pumps a fixed amount of air per revolution. This is just like an engine. An engine pumps air linearly. If an engine displaces 1 unit of air at 1,000 RPM, it displaces 2 units at 2,000 RPM. A positive displacement SC does the same thing; it moves a linear amount of air with RPM. Also, the boost is constant. If the SC produces 10 psi boost at 2,000 RPM, it produces 10 psi boost at 4,000 RPM.

In this way a positive displacement SC is just like having a bigger engine. It produces more power and has zero lag.



(Turbos have lag as they are driven off of the exhaust. Thus, there has to be exhaust pressure to spool up the turbo. There is little exhaust pressure until the RPM rises. Thus, the turbo does not get spinning until the RPM rises, resulting in lag.)
“Well said”. Perfect explanation.
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Old 03-16-2019, 02:13 PM
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Thanks for the reply’s. Just getting used to everything it just seems different. Sure is a hoot to drive and will put a grin on your face every time. That is as long as I can keep the blue lights out of the rear view. Lol
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Old 03-16-2019, 02:56 PM
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Gearing has a lot to do with it. Your GS had lower gearing than your Z06.
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Old 03-16-2019, 05:53 PM
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Yes I have noticed that as well. I guess with that much horse power they figured taller gears were needed.
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Old 03-16-2019, 05:56 PM
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Originally Posted by Corvette farmer View Post
Yes I have noticed that as well. I guess with that much horse power they figured taller gears were needed.
Yes hitting damn near 90mph in 2nd is no joke. The cars get up and go.
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