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Rev Limit

  • Thread starter Thread starter Drummer
  • Start date Start date
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Drummer

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I understand there is a rev limit of 6500 rpm on the 2003 Z06. What exactly happens when the car is moved over the 6500 limit?
Is the engine turned off or are the rev's pushed to zero or what?

Thanks.
 
Boom? If your car doesn't have a rev limiter or governor of some kind (Which I think it doesn't) your going to basicly BLOW your motor. The Connecting Rods will collapse, the valve train will bind then following that your going to see a cloud of bluey steam coming from your tail pipes. This is steam from coolant hitting the block or firing chamber as a result of a busted head. Also combine a little oil blow by in there to create the nice blue effect. But we better check our block because a pushrod may have gone A-Wall through the wall's!

:L

Scared ya?

Yes this can all happen etc.. but unlikely unless you take her up to like 8000+ (DON'T TRY IT) The Redline is GM's way of saying if you take the motor past this point we are not responsible. For the actual tach YA it'll keep going and going past red.

Besides redline doesn't mean your car is putting out more HP or Torque. It is simply a gauge that tells you factory engine capabilitys. For instance my car my redline is around 5400 RPM however my MAX power is at 4400. After which I start losing power. (The engine can't keep up with airflow and fuel) So to take it up to 5400 is simply a personal vendetta against my own engine.

:J

Hope that answers your question
 
Welcome To The Corvette Action Center Drummer!

A rev limiter is placed in the electronic circuitry to prevent the engine from over-reving. At a pre-set rpm, say 6,500 rpm, the rev limiter engages. Once the engine reaches 6,500 rpm it interrupts the signal to the coil, alternating on/off, slowing the firing sequence, and preventing the engine from rapidly shooting up in rpms. Factory rev-limiters are generally set at low rpm levels.

Electromotive Engine Controls claims their total engine management system, the TEC3, has dual rev limiters with "Triple Smooth Technology"
  • 1st step retards timing to a negative -12º degrees
  • 2nd step cuts coil current in half
  • 3rd step coil current and fuel are cut-off
...all three steps occurring within milliseconds.

Hope that helps you. :w
 
The C5 and the C4 shut the fuel off at the redline, if they just shut off the ignition, fuel would still be introduced by the injectors. That wouldn't be good.
Now on to redlines...
One of the reasons there is a redline, (not to be confused with a cut-off RPM), is due to valve float at high rpms. At very high rpm the valve springs have difficulty closing the valves quickly enough to keep up with the high RPM. To compensate for this, the design engineers have to plan for higher valve spring rates, but this also creates higher internal friction in the valve train. Overhead cam engines can get away with higher RPM because there are less reciprocating components to contend with. Remember the more components in a given system the more reciprocating weight must be changing direction.
So, in a pushrod design engine, starting at the camshaft, the lifters are moving, the pushrods are moving, the rocker arms are moving and finally the valves are moving. At 6500 RPM the cam is rotating at 3250 RPM, that means each cylinder's valve train (assuming an 8 cylinder engine) is moving at 406.25 cycles/minute in a four cycle engine. This means that each cylinder's intake and exhaust valve is opening and closing at 203.125 cycles per minute, or 3.38 cycles per second. If I did the math correctly.
All those components between the camshaft and the valve are moving at the same rate or cycles / minute. So it's very easy to see why the pushrod design engine does normally have lower RPM limits than it's overhead cam cousin, and why redline limits are so important.
Remember the valvetrain problem is just one stumbling block in the road to engine design, there are many more that affect operating RPM limits also.
vettepilot
 

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