I just installed a Mild2Wild switch in my 2008 LS3 Coupe and it seems like there is a power loss at low speeds when the exhaust is open has anyone else had this issue. this also messes with the shift patterns in the transmission( Automatic)

Is there a fix?

 

Are you sure you don't have a vacuum leak in your system?

Elmer

 

Honestly,when I had mine and opened it I felt the same thing in the 08.I Tried a couple of different times to see if it was just me,but nope,the car felt bogged down somehow.I left the baffles alone after that.On my latest 08,I won't be installing that item.

 

Did you check for a vacuum leak?


Seriously. All you have to do is put your finger over the hose and block with your thumb. Do you feel a vacuum on your thumb? Does the engine change pitch/idle/performance with your thumb on or off the vacuum line. A cracked hose, loose fitting, leaking bellows on the flaps, can give the symptoms you both are describing.

My open/close of the NPP only results in a sound change. No change in idle or performance with the NPP open or closed.

Elmer

 

The Corvette engineering team really knows their stuff. A certain amount of back pressure is good for power production at lower RPMs, evidently. At the higher RPMs, they have found that less back pressure creates more power.....thus the flap that opens at higher RPMs.
I've also noticed a drop in gas mileage when leaving the flaps open all the time.
The real benefit, to me, of the M2W switch is the ability to have more exhaust rumble at lower RPMs. And being able to get that snap, crackle, pop on decel.
Love my M2W.

 

You experience a loss of torque with the exhaust open and lower back pressure. Same as conundrum with the header installation: larger diameter pipes or smaller, the smaller produces more torque at lower rpm's while the larger produces more hp at higher rpm's.

 

You have to think of it like this... The M2W when open gives you more flow. At low speeds it doesn't offer the back pressure so you kind of do lose power as you don't need that much flow. When you get on it ie. high speeds you'll notice the HP increases. (Less restriction at WOT will give you better HP). As for low speeds its for folks that want their corvette to sound like a corvette and not much more.

 

 

While true, does back pressure change affect the A6 shifting as the OP mentions? I don't think it does. I do think a vacuum leak would affect the A6 shifting.

 

It's all in your head!

loud car will "feel" less powerful than a quiet car. But it's not, it's just a mind trick. That's because the exhaust sound makes you "expect" power and speed. With a quiet car you sense the power in your body but aren't notified of the effort by the exhaust sound. In a way, you're surprised to feel the power, and you think to yourself that the car is fast without even trying (because you don't hear the effort)

Try this if you really want to prove it to yourself. Go for a ride in a high end luxury sedan, step hard on the gas, it will make you think that the car is faster than your C6 because you won't hear much from the engine or exhaust, but you'll feel more than you expect.

or, another example... ever see a Harley make more noise than a jet yet it seems to be going very slow? Same thing - you expect the rumble to coordinate with the speed, but it doesnt and the bike seems slow...

 

I don't know enough about the motor/ tranny to give you an educated answer on this one. Maybe one of the Tuners/ motor folks can answer this.

 

I believe the A6 is electronically controlled unlike the automatic transmissions of the past.

 

I demand before & after dynos

 

X 2.

 

I agree that it "feels" just a little bit less torquey when fully open (wild) at low-rpm and light throttle.

Anyway, it's louder than I like fully opened. But too quiet fully closed.

So, a few weeks back I installed collars that keep it slightly open all the time. Very pleased!

The collars are easily adjustable... I set it ~1/4". The sound is perfect for me. And it feels the same as stock.

With the engine off...


Slightly open at idle...

 

I have dyno'd the differences in my 08. No change to the upper curve, but with the valves open it was good for 6 rwhp; stock, under 3500 rpm. (When they will open anyway)
With a cam and Novi blower, it was good for about 20.

It was a couple years ago, so if you're dying to see the graphs, you'll have to look them up in my old posts. :P

 

While I try to respect all opinions voice herein and respect their knowledge, I am hard pressed to believe that the very little difference in exhaust back pressure that exists between your open and closed butterfly valve is causing you power loss - at least sufficient power loss that you can discern by the seat of your pants.

There are dozens and dozens of exhaust variants for Corvettes. There are multiple butterfly systems and methods for opening and closing the same. If having your muffler butterfly open, with a M2W or whatever, caused discernible power loss at low speeds, this Forum would be overrun with screaming complaints. Can you even begin to imagine the Vette owners on here buying exhaust butterfly control devices by the thousands and being satisfied with the associated loss of power ??!!!

I would respectfully submit that those who have suggested the power loss you are discerning is attributable to your use of a exhaust butterfly control device and subsequent loss of exhaust back pressure are wrong. There must be another or subsequent issue.

I'm no expert or engineer. And if I am wrong I will stand up to admit being wrong. But I think this 'loss of exhaust back pressure is the root of your problem conspiracy theory' is all smoke . . . .

Plenty of room for any who can demonstrate otherwise to post the Dyno sheet here.

 

I watched my buddies Z06 being dynoed Monday and you can see the torque rise sharply right around 3500 rpm, which I assume is at least partially due to the valves opening there.

I can tell you that on my boosted car the difference in back pressure is enough to cause kr when the valves are closed, when its tuned with them open.

 

that's a Jedi mind trick

 

found some dyno sheets from a thread, sounds like a big witch hunt in this thread and i find it funny. Look, if anything more toqure with them open under 3500.