Hi, I was wandering if anyone knows the answer to this question. I removed the fuse for the dual mode exhaust. Sounds good but I noticed alot of carbon in the two pipes with the gate. Does the car perform any different with the fuse in or fuse out??? Will you lose bottom end???
Thanks Rick

 

Hi Rick

Well....I saw your post earlier and thought some of the experts would chime in, but maybe they figured the answers were obvious. Since nobody else has responded, I'll give my thoughts.

I don't know much about the NPP on an LS3, but I guess it's pretty similar to the Z06 exhaust.


Considering the valves normally close when you start the engine, and don't open again until 3,500 RPM (3,000 in Comp mode - at least in the Z06), unless you're tracking the car, or driving around on the street at fairly high RPM, the valves are pretty much closed most of the time and no exhaust goes out that pair of exhaust pipes so not much black exhaust residue.

So....if you pull the fuse and the butterfly valves are open all the time and exhaust is exiting those pipes, of course they'll get black.


Without the NPP option the spec on the LS3 is 430 hp. With the NPP it's 436 hp.

However, with the fuse in, the valves open automatically when the engine starts to get into the power band. I've got a progressive shift light on my Z06, and after reviewing many dyno charts I decided the power really starts to come on above 3,500 RPM, so I set the first light to come on at that RPM. It has 7 lights that come on at even intervals up to where ever you set your upper RPM for your shift point, then all 7 lights start flashing. I set the upper limit at 6,800 (the LS7 has a 7,000 redline). When I get slow in traffic or a corner and see that only 2 or 1 lights are on then I downshift to keep the RPM in the power band.

So....I don't think the car will perform any better with the fuse out - you're not into the power band until about where the valves would open anyway if you had the fuse in.


What do you consider "bottom end"? As I said above, on the track I try to keep the RPM above 3,500 (but the Z06 has such fantastic torque I'll often just leave it in 3rd gear even if the RPM gets down to 2,800-3,000 because the shifting gives up more time than a little bit lower RPM).

So....I don't think you're gonna lose any bottom end with the fuse in or out because even if it's in the valves will open at around the minimum RPM you'll be maintaining anyway if you're really worried about staying in the power band.

In addition to running it on the track, my car is a DD and long range GT road trip car. With the valves open at highway speed (1,400 to 1,600 RPM in the Z06 at 70-80 mph) there is a very annoying throbbing drone.


BOTTOM LINE 1: I don't think pulling the fuse will do anything to harm or help performance. Even with the fuse in the valves will open when you get into the power band and give you that extra 6 hp that GM advertises. I think the only thing you get with the fuse pulled is more noise at low RPM (and black exhaust pipes!)

BOTTOM LINE 2: GET A REMOTE EXHAUST CONTROLLER!!! I have one, and I open the valves when I want them open, and for highway cruising I close them up.

I have a checklist that I run when staging for a track session (ratchet seat belt tight, A/C off, data-logger on, video camera on, etc.), and one of the items is to use my exhaust controller to open the butterfly valves.

Get an exhaust controller(mild-to-wild switch, or m2w) and you'll have the best of both worlds!!!

Here's a link to forum vendor Sunset Orange Creations "Exhaust Commander" controller:

http://forums.corvetteforum.com/c6-c...-gas-card.html


Bob

 

I've got the MTW foot switch, mounted in the dead pedal about where the old style dimmer switches were placed. It's easy to activate but don't hit it by accident. I love it!

 

Hello,
I just bought my first Corvette, a 2008 Z51 with the Dual Mode Exhaust. I ordered the Exhaust Commander Switch fron Sunset Orange Creations and recieved it three days later. I am not mechanically inclined in any way but was able to install my switch in less than ten minutes. It works very well and I am completly satisfied with the operation.

 

well I have an 08 z51 with npp and when I got it dynoed they wanted the flaps open not sure why other than it's more power I have the exhaust comander also and love it but I don't see how you will loose low end power with the flaps open maybe if you had some 1 7/8 headers and hi flow cats maybe but I dought itnor will it be anything you can feel.

 

yep I got the same thing, I used to have the wireless one , but like the dead pedal more.