At minute 2:38 of this video: http://videos.streetfire.net/search/...B545DC5535.htm you can see what HKS describes as "The exhaust system is also equipped with an adjustable valve system which can control the exhaust noise." And they got a pretty shot of the controller and the valves in action Does anyone know anything further about this product? This was the first I've heard of it...

The only other company I know that makes such a device is Apexi, with their Exhaust Control Valve (ECV) (http://www.apexi-usa.com/product_exh...=251&pageNum=1). They say, "The ECV was created as an alternative to the standard silencer typically fitted in the tip of performance exhaust systems to lower the sound output. The ECV (Exhaust Control Valve) is a spring loaded butterfly valve that can be installed to the main piping of an existing exhaust system. The angle of the valve can be modified on the fly from within the cockpit to provide complete control over exhaust decibel output." I believe this was very similar to the system used on the VR4, and on the current Z06. Much better than a traditional silencer, since it will negatively affect power levels the whole time it's installed.

~Ramy

 

Sorry, don't know anything about that exhaust silencer thing. But could that be part of the exhaust valve timing thing that are testing there also?

Besides, that video is awsome. I really liked that 4 wheel drift near the end.

 

No, but I want that car.

 

The video flat out doesn't want to load for me. Other videos on Streetfire work fine - wonder if it's hosted somewhere and the host is down?

I dug through HKS Japan's website, saw NO mention of a exhaust valve anything. I almost wonder if it's the Apexi product and they just goofed up.

Dale

 

Possible... but you saw the clip of it in motion, rite? While they were at standstill/idle?

Dale, darmn...I was hoping you'd see it and comment hehe. I went through the website too, and couldn't find it. And no, this is completely different from the Apexi one. If you manage to view the video (on a diff computer etc), you'll see how stark the diff is. The Apexi one is essentially a butterfly flap/valve. The HKS one is a collapsable cone-like part.

~Ramy

 

That is HKS's customized car, it may be a custom made part seeing as the car itself is buult by HKS. Maybe?

 

Just got off the phone w/ HKS, and they said it's the EVR exhaust, and is a R34 Skyline application only I guess Apexi's the only option...

~Ramy

 

Man, you were dedicated to this! LOL.

 

Na...I just took the easy way out

 

http://www.hks-power.co.jp/products/...r/evr/evr.html

Finally saw the video - there's the page on it. It's a Skyline-only system, cat-back with the variable deal installed. Considering the price is nearing $2k, it wouldn't be worth buying it then hacking in onto an FD .

Apexi ECV/DECS seems like the way to go for exhaust sound tuning.

Dale

 

Glad you got to see the video. And good find (although of course, it was easier once I found out the name of the product...cheater )

You're one step ahead of me haha. Already knowing what I was gonna check

Sure does. I'll hopefully try this out myself within the next 6 months I don't know anyone else on the forum who has...

~Ramy

PS: I found a nicer pic of it (than the crappy one on Apexi's website) along w/ some more info here: http://www.prostreetonline.com/news/apexi_decs_ecv/ Apparently the valve itself is the ECV, and the controller is the DECS.

 

One more...I read this "It can easily reduces the exhaust loudness level by a maximum of 10dB by varying the butterfly valve in the ECV" here: http://www.xtremeautos.ie/apexiexhausts.asp. Is 10dB that much of a difference? Ie would it make the difference between "illegal 4" exhaust" and "quiet 4" exhaust"? (In VA, sound is the issue, not the design).

 

One more... a different product but similar to Apexi's... http://www.hyperflow.com.au/techaes.html

 

Rami your right about all what u have said...

HKS made this only for the GTR34 Skyline and we already have a car here in Jeddah with that type of exhaust. as the police here is being verrrrrry picky with load car noises !

 

Picky in Jeddah? I thought Jeddah was pretty laid back...and Riyadh was where they were uptight? (I remember seeing the mutawa3een there too hehe)

 

10db is quite a sound difference - going from, say, 100db to 90 makes a big difference. The big thing is taking the "bite" out of the exhaust - if you can get rid of the deep, bass tones that really carry, that makes a huge difference.

I'm still thinking about trying that setup myself sometime. Electronic gizmos are fun!

Dale

 

Yamaha sportbikes have been using an electronically-controlled valve in their exhaust for years. The purpose is to adjust the amount of backpressure depending on engine RPM and throttle position, in order to gain some low-end torque. Yamaha calls it an EXUP valve, and I know that Suzuki motorcycles use a similar system (with a different name).


Those are both non-turbo applications, however. I'm really not sure what effects you'll see if you install an ECV on a turbocharged rotary. On another note, I wonder if it will be able to withstand the heat that our engines produce; I'd be sure to install that sucker as far from the turbo(s) as possible!


-s-

 

hmmm

 

Scott, thanks for the info, and good point re: the heat. The Apexi EVC is supposed to be mounted after your cat (ie between the cat and exhaust pipe), and I'd hope that that's far enough away, whether you're running a cat or mp? Guess there's one way to tell...

In my search, I found a guy on the RX-8 club who pulled out his entire exhaust system (dp to catback), and basically hacked it up and welded new pieces in place to make the exhaust system as straight as possible, and he posted that he's going to be running the EVC. I'll be keeping an eye on that...