1 2
4/5/19 12:38 p.m.

hey guys Im actually fabricating a solution for this currently.  Im using the "vacuum" style valves that open as you get into boost or whatever; point is, they are mechanical and have a swing arm that actuates the valve.  Ill try to add some pics of my drawings so far but they arent entirely what I want to do as of now.  Essentially ill be using this vacuum valve: https://www.ebay.com/itm/2-5-63mm-Exhaust-Control-Valve-Vacuum-Actuator-Closed-Style-Cutout-Downpipe-/173730225325?oid=264262182870

And I ripped the vacuum chamber off and will be making a bracket and spring assembly to except Lokar's universal parking brake kit: https://www.summitracing.com/parts/lok-ec-80fu/overview/ 

And i looked around for some type of parking brake lever that was bolt on, but I couldn't find any winners so I guess ill have to build my own ratchet style pull lever.  Space is VERY limited in the cab (2012 Charger r/t) so ill have to play it by ear as I go.  Oh also ive already "been there done that" with electronic bypass valves (QTP low profiles) and they are way too slow and not really what i wanted which is the main reason why im doing this in the first place.

Im not really going to be on this website again so heres my email, jsolish@sandiego.edu if ya got any questions or suggestions about it!  Also my instagram is @jacobcharged ill pe posting updates about it there.

Robbie UltimaDork
4/5/19 12:48 p.m.

^ Cool!

I also realized recently that many sportbikes have "throttle plates" integrated into their stock exhaust systems after the header that the ECU controls to keep the exhaust optimized. (I don't know the theory behind it, just that the device is there). 

stock headers are all over ebay for like $50 and some even have pretty large exhaust "TBs" that could be used. I think the one on the 08 ish GSXR 1000 is over 2 inches in diameter. I can take a measurement if anyone is interested since I have one in the garage. 

So that could be used and for $50 you'd get to keep the rest of the titanium header as well!

jsolish New Reader
4/5/19 12:57 p.m.

Heres my setup, its a 2012 Dodge charger r/t (5.7L).  In terms of exhaust,  I have shorty headers to mid-pipes all off a stock 2017 challenger scat (6.4) but they bolt right on to the 5.7 heads.  Currently i have a garbage exhaust that ill be changing out once i finish fabbing up the manual valves.  So heres the plan: After the mids ill be stepping up from 2.75" to 3" (just because of muffler availability) which will continue to a standard x pipe.  After the x pipe i plan on putting in the Y pipes which on one side go to some mufflers and resos, and obviously the valves on the other side.  I was thinking of incorporating the  1/4 pipe aka the J pipe resonator as the capped off  y pipe (when the valves are closed) could emulate the effects! but after some research I found that the valve side of the Y pipe would have to be around 2 feet long which wasn't entirely practical. 

My plan is tp have a 3" perforated tube style muffler/resonator exhaust that's super quiet.  So I should say now that i'm only after sound here; I don't expect any power increase with this mod.  With that being said, the valves are only 2.5" so im hoping that the back pressure of the entire 3" exhaust is somewhat equal to the back pressure of the bypass through a 2.5" outlet.

jsolish New Reader
4/5/19 12:59 p.m.

In reply to Robbie :

pretty cool!  I wonder how its actuated.

dean1484 MegaDork
4/5/19 2:43 p.m.

My RX7 with a racing exhaust (from Mazda of Japan) would set off car alarms and it really was not all that loud.  I think the resonant frequency is much more important than the volume if your goal is to set off alarms.  

Keith Tanner
Keith Tanner MegaDork
4/5/19 2:57 p.m.

We have active exhausts on our NDs. We use vacuum-activated butterflies that are from some of the OE manufacturers. Something similar to this although I can't comment on that specific unit. They're basically instant.

The simple control method is to hook it to intake manifold vacuum. That way it'll open the bypass as you get into the throttle, and it has a nice organic feel to it. Quiet when you're behaving, LOUD when you're on it. This works best with bigger engines than small ones, because you find yourself into loud mode more often.

Next step is to use a solenoid to change the vacuum source. You can trigger the solenoid with a switch or even a little remote control. It can switch between two of the following three modes: active (intake manifold pressure), quiet (brake booster) or loud (ambient pressure). If you want all three, then stack two solenoids and get into a little logic.

Final step is CAN integration where we send signals to open the solenoid depending on what we want to do, such as a combination of throttle percentage and a switch/dial/mode selector. 

Stefan MegaDork
4/5/19 4:32 p.m.

The Focus RS has a factory cutout, operated by a solenoid, controlled by CAN.

Not hard to find from folks getting rid of their stock exhaust systems.

Actuate it with a stepper motor driver, controlled by a button on the dash, a throttle switch, etc.

Stefan MegaDork
4/5/19 4:37 p.m.

There's also this:


Seems like a solution worth trying.


mke Reader
4/5/19 5:49 p.m.

I have these vacuum units and they seem to work in the limited testing I've done.  All SS and could easily be converted to cable.

Keith Tanner
Keith Tanner MegaDork
4/5/19 6:39 p.m.

I don't understand why you'd want to convert them to cables. If you want them switchable, just put a solenoid in the line. Silicone hoses and wires are a lot easier to run and mount than push-pull cables, and more reliable in the long term.

Vigo UltimaDork
4/5/19 10:09 p.m.

Mke, what's the source of those items? Looks promising!

jsolish New Reader
4/5/19 10:55 p.m.

Reasons why I'd like to go cable (at least for my case):

Ive dealt with electronic cutouts (QuickTimePreformance) before and they weren't exactly what i wanted.  I had them for about 2 years before i got seriously tired of them.  Which ever motor (or gearbox that matter) was being used had about 2 degrees of rotational freedom when not clamped closed (aka loud mode) which translated to quite the airy flutter sound when they were opened.  I have a few other reasons but point is they weren't for me.

So the next practical choices are vacuum style (and all variants), bolt on plate, manual pull, or some type of solenoid system(thanks Keith i didn't know anything about that!).

I went with the cable pull style as it was the most simple in my opinion.  I wanted the entire system to be separate from the rest of the car as not to cross over any reliability issues.  The valve could be actuated as fast as I'd like, without using any voltage or pressure/vacuum source.  With that being said, i would like to be able to leave the valves open or closed when I leave the car (just like a parking brake laugh) just so that I can remote start loud or quiet hehe

 I dunno i guess I just have a more tactile approach to it as seeing something physical move and lock just does something for me that nothing else can.

Vigo UltimaDork
4/6/19 12:00 a.m.

I've had only one car stolen. Out from under me while i was sleeping. If it had a loud exhaust or a cutout i left open when i turned it off, who knows if i'd still have it. Just a thought. 

mke Reader
4/6/19 6:21 a.m.

In reply to Vigo :

It seems like the place I got them was like quality tuning or similar in greece I think it was but a quick search found then here:

3" exhaust valve

Look down below at related items....they come normally  100% closed or open and there is a 20% open option too.  I bought normally open thinking my quiet mufflers don't have the flow to make for the throttle to be open very far but should be perfect in town....but if the valve fails the engine would be stuffed up badly and run quiet but horrible so fail sfe is fail open. I also though I might get lucky and just hooking it to manifold vacuum might give the result I'm after....open at when the throttle is open, still haven't tested that idea and I have a little vacuum check valve and solenoid vacuum switch standing by for manual or ecu operation.


While searching I found this with more options:

exhaust cut article

The ebay ones posted above also look good but they didn't come up when I was searching a few years back.  Any or they could be switched 

SVreX MegaDork
4/6/19 7:05 a.m.
Shiftinwithoutliftin said:

In reply to Skervey:

Check out this new design from Cuthroat Exhaust Systems. What a simple but perfect idea! https://youtu.be/3Ch4hCTPTZw

Cutthroat canoe

Strizzo PowerDork
4/7/19 9:31 a.m.

So, why reinvent the wheel when you can get something like this?


pontiacstogo New Reader
4/7/19 11:08 a.m.

My Camaro has this unique bit of engineering goodness mounted after the rear axle and before the pipe goes into the rear crossflow muffler.  Not sure what the valves original purpose was, but it looks like it came from a turn-of-the-century steam engine or something blush

I've yet to get under there and open it up, but I suspect the neighbors wont approve;

 photo 820B122F-B224-4360-9FF9-B327D9AB6AF4_zpsvkpbvh66.jpg


jsolish New Reader
4/19/19 3:04 a.m.

some updates:

jsolish New Reader
5/20/19 12:01 a.m.

welp, the exhaust side is done.  Can't upload any videos but it actuates pretty well.  Clamping force seems somewhat equivalent to the vaccumm valves that were removed.  Now its time to figure out the actual lever

jsolish New Reader
5/20/19 12:03 a.m.

1 2
Our Preferred Partners