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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
my setup is Kooks 1-7/8 into X-Pipe into the Akropovik slip-on.
Car has a tune, but stock cam.
The problem is that even after working with Akropovic and adjusting the throw on the NPP values to the maximum I have significant drone.
(the akropovic's were sold as certified by Akropovic as build as intended, but had been returned due to sound).
I love the way the car sounds & the weight reduction is nice as well.
BUT, I can't take it on long road trips anymore due to the remaining drone.
6th gear becomes unavailable => 5th gear => really hot tunnel => very unhappy passenger.
I'm at a point where I will consider high flow cats, dynamat or replacing the axleback again. (stock w/ muffler mod, others?)
Yes, I love the vette, but the passenger makes her worth it.
Akros sound horrible, and drone like crazy. One reason I never even considered them. You can try to add resonators in line but hacking the system up in hopes that helps would be rough. If you don't like the sound, I would replace it with something that doesnt' drone.
B&B Fusions which could still have slight drone, but less then Akra's. Or stock mufflers w/muffler mod, or even easier just find a used set of '09+ ZR1 mufflers or 2011+ Z06 mufflers. You may be able to work a trade with your Akra's...
Drone is eliminated with some back pressure. On the stock system the unvalved outlet is very small, about 1 3/4". Several years ago I measured the back pressure and it wasn't very much, about 1/10 psi. I installed Magnaflow single outlet mufflers and got drone. So I did a test and partially blocked off the single 3" outlet and that mostly eliminated the drone. One of these days I'm going install a valve in the outlet. Did you see the C7 mufflers? The valve is now ahead of the muffler. When closed the exhaust has to pass through 2 small holes in the valve.
I had Corsa with headers no cats and had zero drone, sound great, higher pitch and loud as hell WOT but very tame in the lower RPM. Ironically, I just sold them and bought the Akraprovic, wanted to try something new, no doubt with headers you experience drone in the open and closed position in the lower rpm range. I truly enjoy the exhaust note so I just drive around it, on the highway I'll go 6th gear 80mph higher, below I leave it in 5th gear. In my experience, the stock system will also drone with npp open in low rpms, especially with headers. Corsas maybe a good option for you if drone is a deal killer for you.
I bought a Corsa and it was way too loud for me, but it didn't drone. I returned it and purchased a B&B Fusion and it is the best for me. As quiet as stock with NPP closed and almost as loud as Corsa with NPP open.
I debated on the Akro when I bought the Corsa, but the deal breaker for me was the drone. I will never buy an exhaust that drones no matter how good it sounds. At the end of the day I like to drive my car and my 1st modding rule is not not do anything that won't allow me to enjoy driving my car.
Take the Akro back and by the B&B. You will be very happy with it.
I can't figure out how a car that will go almost 200 mph in 5th gear why people are going down the highway and trying to use 6th gear. If you had a pickup truck and were going down the road in 6th gear going 60 mph it would bog down and spit and carry on. Cruising at 70 mph in 4th gear, my car is at 3 or 4 grand with little to no drone and if I close the NPP there is none and even the wife is happy. I love love love my system, but I guess if I didn't I'd send it back or sell it too. I will agree that at 1500 rpm's in 6th gear blood starts dripping out of my ears, so I stopped after the first couple times.
Thanks for all the input.
yes, I can drive in 5th all day long.
but the fiancée likes to go on road trips, and she's sensitive to the heat...
she remembers no issues the first time we took one (4500 miles in 10 days) and now everything has to meet that standard.
in terms of back pressure.... is there an easy way to insert a blocker?
something that twists into place and is easily removed?
Thanks for all the input.
yes, I can drive in 5th all day long.
but the fiancée likes to go on road trips, and she's sensitive to the heat...
she remembers no issues the first time we took one (4500 miles in 10 days) and now everything has to meet that standard.
in terms of back pressure.... is there an easy way to insert a blocker?
something that twists into place and is easily removed?
if that's all it needs, I can make that work.
Not worth the hassle, if its even possible. Why hack a system you'll have no issues selling? When you're cruising at low RPM, the valves are closed on that system, so its about as quiet as that system is going to get...unless you lose the LT's.
I just install the Akrapovic's on my 08. Love them. While we had the exhaust down we wrapped the torque tube with this http://www.ebay.com/itm/394mil-60-x4...BYIXFd&vxp=mtr enough to do two cars. Added a insulated tunnel plate and now the heat from the headers is almost non existent. Where the MGW shifter arm used to get too hot too touch, it now stays cool.
I had my long tubes and x pipe ceramic coated and that almost eliminated the tunnel heat. You need to play with car and engine speeds to find the sweet spots that don't drone. 6th @80 almost no drone
My HCI Z06 with LG Super Pros noncatted headers with Corsa Sports, has less drone than when I had the stock NPP with the fuse pulled.
My interior heat was pretty uncomfortable for me after 30 min of driving. I would never be able to put anything in the console. Also, after 30 min of driving, I'd have to turn the AC on to keep the cabin heat down because it felt like the heater was on 80*. Then I added a thermal tunnel plate and that reduced the heat in the cabin overall. Now I can drive for hours with the windows closed and place things in the center console.
I must have some wierd miracle car because I've never had heat issues. Ever. Console/etc has never got hot. Never noticed any heat in interior from tunnel. No added insulation. Done 14+ hour drives in the car with uncoated headers and nothing. Makes me wonder if it is a tune/timing thing or some other contributing factor to hot tunnels.
Mine was hot for the first 1.5 years of ownership. Stock other than Halltech cai and Corsa axle backs. Everything cooled down after all the other work was done. Maybe I notice heat more because my Norcal coast weather of typical 50-60* weather? I don't know if it was exactly 80* Temps inside, but it definitely wasn't 50-60* like outside Temps.
I must have some wierd miracle car because I've never had heat issues. Ever. Console/etc has never got hot. Never noticed any heat in interior from tunnel. No added insulation. Done 14+ hour drives in the car with uncoated headers and nothing. Makes me wonder if it is a tune/timing thing or some other contributing factor to hot tunnels.
You live in AZ, therefore you have decreased sensitivity to heat. That's my theory...
Ya see those black frame rails 2" from the exhaust? Well guess what something black does. Absorbs heat. Paint em white, silver or use some heat reflecting tape.
03-06-2017, 04:22 PM
How to kill drone w/ Akropovik Exhaust
