Sunday, March 6, 2011

Z06 Exhaust

I have been looking for a different exhaust for the corvette, the factory exhaust is extremely quiet for the type of car it is. After researching numerous options and deciding that sound was not justification for paying 1,200.00 to 1,800.00 at this point in time I had basically given up, until I read about the NPP and Z06 multimode exhausts. The NPP is a factory option that has exhaust cutouts built into the mufflers, they are vacuum operated and controlled by throttle position and RPM through the ECU.

The option was 1,195.00 and added 6 horsepower to the base coupe 430, buying just the mufflers alone is over 1,200.00 new and 600.00 to 800.00 used. That eliminated NPP as an option, the Z06 multimode mufflers though came on all Z06's and sell from 250.00 to 400.00 used. They have a deeper tone and larger tips than the NPP's.

I found a set of Z06 mufflers for sale on a corvette forum and the seller was located in Phoenix. Tania and I drove up two weeks ago to pick them up. The tailpipes on the Z06 mufflers are 3" in diameter versus 2.5" for the stock pipes, so I had some adapters made which once everything was apart didn't come close to fitting.

Matty decided he wanted to help me and during the removal I got a call from work, by the time I was off the phone he had almost the entire stock exhaust off all the way to the downpipes.

Being late in the afternoon and seeing the adapters were not going to work, I cut the tailpipes off the factory mufflers and welded them to the Z06 mufflers. This actually worked fairly well since the Z06 mufflers reduce down to 2.5" at the inlet of the muffler.

Now all that is left is to hook up the vacuum lines to the exhaust cutouts. They default to open but this causes a bit of a drone at low RPM freeway speeds. I have found a remote control relay that I can use to control a vacuum solenoid, adding a small accumulator to the system will allow me to open and close the exhaust valves at will.

In the picture above you can just see the vacuum actuators and linkage that open the valves in the center exhaust tips. When they are closed the exhaust is very quiet.

The old exhaust not only was very quiet but very restrictive, note the small diameter of the pipe leading into the dual tips. The new Z06 exhaust has individual pipes going to each tip.

The sound of the Z06 exhaust is very similar to what flowmasters sound like and makes the car sound like it should have when it was new.

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