I am sure GM wanted the "cool" factor and to also have the car quite for the people that wanted it quite. Those are the only reasons. I have a few videos on my site www.nakidparts.com with exhaust open and close with and without headers
The OP's speculation is well founded. It is a fact that higher exhaust back pressure at low rpms builds power and reduces high rpm power.
Same principle as large volume intake runners are good for high rpm power but rob low end power
Many motorcylce exhaust systems use valves and they are not there for sound. Other cars use two set of intake runners and use a valve to direct the intake air depending on rpm.
Now after saying all that, I believe in the case of the vette that it is a sound and wow device.
I would have thought TQ would have been lower at lower RPM w/flaps open. I've had several liter bikes and as Blazone said, they weren't there for sound, which is why I asked the question...
I'm not looking to change the exhaust just yet on my 08, as I like the OEM exhaust sound, but wondered if there would be significant loss of TQ at low RPM's. I was considering removing the fuse or installing the remote bypass...but don't want to lose any low end grunt in doing so. All the reading on this has given me mixed results on the TQ question so far.
I would have thought TQ would have been lower at lower RPM w/flaps open. I've had several liter bikes and as Blazone said, they weren't there for sound, which is why I asked the question...
I'm not looking to change the exhaust just yet on my 08, as I like the OEM exhaust sound, but wondered if there would be significant loss of TQ at low RPM's. I was considering removing the fuse or installing the remote bypass...but don't want to lose any low end grunt in doing so. All the reading on this has given me mixed results on the TQ question so far.
take the fuse off....drive it for a while - you WON'T notice the difference as far as "torque" goes...and, who cares what happens below 3,500 rpms anyway? 7,000 is where it's at!
LOL, I'm not doing track days with the Z...it's mostly for when I'm too lazy to get on my ZX14 (Ninja). I just like to whack the throttle often, but I'm used to bikes that 1/4 in the 8's...and though a Z won't quite get the insane feeling of acceleration in comparison, I sure don't want to lose whatever's there now in low end TQ.
LOL, I'm not doing track days with the Z...it's mostly for when I'm too lazy to get on my ZX14 (Ninja). I just like to whack the throttle often, but I'm used to bikes that 1/4 in the 8's...and though a Z won't quite get the insane feeling of acceleration in comparison, I sure don't want to lose whatever's there now in low end TQ.
It'll be minimal, if much @ all, really. Nothing you should be able to pick up in the SOTP. I drive my car in both modes & am not able to pick up any noticeable difference.
Enjoy it
__________________
George B.
* '90 ZR-1 SGC built 368ci 'Factory Black Motor' (421 Stroker coming!) (11.0 @ 130.2 & 11.2 @ 132.4) w/ the 368--sprayed 120 shot...
July 2000 feature & February 2001 article in'Corvette Fever' 448 RWHP on motor, 560+ RWHP on the spray (SAE #s)
* '08 JSB Z06 11.4 @ 126 on EMTs, 490/460 SAE--some bolt-ons (Sold )
* '09 Nissan GT-R--SCCA ASP/SM & Time Attack Weapon10.63@131+ 561whp--Mods in full swing...
I pulled my fuse to the flappers today but didn't like the interior resonance around town. So I'll try some B&Bs soon. I couldn't detect any difference in low end torque. I am also used to zx-14s and now have a 08 Busa with full ti system and dyno tuned . I bought the Z06 last weekend and my bikes have been sitting, which speaks volume for this car. I am head over heels with this ride.
I pulled my fuse to the flappers today but didn't like the interior resonance around town. So I'll try some B&Bs soon. I couldn't detect any difference in low end torque. I am also used to zx-14s and now have a 08 Busa with full ti system and dyno tuned . I bought the Z06 last weekend and my bikes have been sitting, which speaks volume for this car. I am head over heels with this ride.
If you didn't like it with the fused pulled.You won't like B&B's for sure.Have fun with your new ride.
If you didn't like it with the fused pulled.You won't like B&B's for sure.Have fun with your new ride.
I'm not sure that I can agree with you about that. When I pulled my fuse, I was severely disappointed because the drone at some [lower] RPMs was worse than any aftermarket drone I have ever heard. That is what bothered me. I liked the Borla Stingers on my C5 a lot better than the pulled NPP fuse on the C6Z.
I pulled my fuse to the flappers today but didn't like the interior resonance around town. So I'll try some B&Bs soon. I couldn't detect any difference in low end torque. I am also used to zx-14s and now have a 08 Busa with full ti system and dyno tuned . I bought the Z06 last weekend and my bikes have been sitting, which speaks volume for this car. I am head over heels with this ride.
Oh man -- not what I wanted to hear...LMFAO -- I live bikes...and the Z was only for the lazy-don't-feel-like-gearing-up-for-a-ride-day. Here we go now -- so, what's faster, the 08 'Busa or the 08 ZX14? LOL -- kidding Steve and thanks for the input...
BTW, I went down one on the front and up 2 on the rear on the ZX, with a full Brock Gen III (flies out, mapped, 6" over, and +4 advance @193 RWHP)....I play with Vettes/Ferraris, etc and eat em up without as much as a single downshift at any speed now, still, the Z06 is a real thrill!
I'm not sure that I can agree with you about that. When I pulled my fuse, I was severely disappointed because the drone at some [lower] RPMs was worse than any aftermarket drone I have ever heard. That is what bothered me. I liked the Borla Stingers on my C5 a lot better than the pulled NPP fuse on the C6Z.
This is why I didn't pull my fuse. In 5th and 6th at certain lower RPM's the drone is intolerable with the flaps open.
Oh man -- not what I wanted to hear...LMFAO -- I live bikes...and the Z was only for the lazy-don't-feel-like-gearing-up-for-a-ride-day. Here we go now -- so, what's faster, the 08 'Busa or the 08 ZX14? LOL -- kidding Steve and thanks for the input...
BTW, I went down one on the front and up 2 on the rear on the ZX, with a full Brock Gen III (flies out, mapped, 6" over, and +4 advance @193 RWHP)....I play with Vettes/Ferraris, etc and eat em up without as much as a single downshift at any speed now, still, the Z06 is a real thrill!
Umm....yeah I would hope so...you're driving a 530lb machine with a power to weight ratio of .3058..
Mean bike though!
Cheers.
Last edited by 09 Cyber Grey Z; 09-02-2008 at 12:07 AM.
The flaps OPEN definitely improve both horsepower and torque below 3.5k. See the difference in my car here (only look at the pre-3.5k, not the gains above, as that didn't come from the exhaust, but rather from the tuning):
The flaps OPEN definitely improve both horsepower and torque below 3.5k. See the difference in my car here (only look at the pre-3.5k, not the gains above, as that didn't come from the exhaust, but rather from the tuning):
]
Why do you assume the gains down low aren't from the tune? We would need to see a stock to stock to gather any conclusions.
Why do you assume the gains down low aren't from the tune? We would need to see a stock to stock to gather any conclusions.
Because I tuned the car! I know what it gained and what it didn't. Those ARE the gains down low. There's rarely any changes in power down low from just tuning alone. From a stock longblock comparison, the real gains start above 4k in the tuning process.
Besides, this is OLD news. You must be a late bloomer to this crowd. Tell you what, look below. Are you happy now?
Local friend and customer's 2008 Z06 before and after between the exhaust flaps opened and closed, both with the same tune.
Corvette Store
Exhaust flap -- dual purpose?
)
This is why I didn't pull my fuse. In 5th and 6th at certain lower RPM's the drone is intolerable with the flaps open.
