Exhaust Bypass?!? What?!?!

"TwoFortified" (twofortified) 01/09/2014 at 16:07 • Filed to: Automation

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...Thanks alot Automation, now I'm gonna have to add this, because it's just too badass (and I'd never heard of such a thing)

Laird Andrew Neby Bradleigh > TwoFortified 01/09/2014 at 16:13

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You have much to learn young padawan. ;)

Yowen - not necessarily not spaghetti and meatballs > TwoFortified 01/09/2014 at 16:20

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It's commonly referred to as 'Cut-outs'

They are pretty awesome in the right application.

They come in different flavors
-ones that you have to unbolt yourself, usually with wingnuts
-ones that open electrically
-ones you can open and close with a cable (like bicycle brakes)
-ones that open in certain conditions (rpm's, boost pressure, exhaust pressure)

Yowen - not necessarily not spaghetti and meatballs > TwoFortified 01/09/2014 at 16:22

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How are you liking automation? I'm having so much fun with it.

Created a 244 horsepower 9200 rpm 2.0 liter I4 yesterday. It has insane compression (over 12:1 I think) and it doesn't reach peak horsepower till 8400 rpm, lol.

I was going for an S2000-esque engine, I still have to compare my specs to the S2000 specs to see how close I came, lol.

jariten1781 > TwoFortified 01/09/2014 at 16:24

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Cutouts are illegal in a lot of places and can fail inspections in places where they're not. Be aware.

They do make a badass sound though.

Yowen - not necessarily not spaghetti and meatballs > jariten1781 01/09/2014 at 16:32

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They really are? I thought the great thing about them is that you aren't forced to be all noisy on the streets and can open them up when it is legal.

Either way, here in Michigan they don't care :D I want to get them one of these days.

TwoFortified > Yowen - not necessarily not spaghetti and meatballs 01/09/2014 at 16:33

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Lovin that game

TwoFortified > jariten1781 01/09/2014 at 16:35

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My car is older than inspection at this point anyway.

I've been thinking about how I could achieve the cutout by using boost pressure (like, 5 pounds of boost or more and it's open, otherwise it's closed)...Maybe I could repurpose a cheap wastegate...wait, no, that would cause a boost leak.

Hmm. Gonna keep thinking about it.

jariten1781 > Yowen - not necessarily not spaghetti and meatballs 01/09/2014 at 16:38

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Yup...

Here's VA's statute:

§ 46.2-1047. Muffler cutout, etc., illegal.

It shall be unlawful to sell or offer for sale any (i) muffler without interior baffle plates or other effective muffling device or (ii) gutted muffler, muffler cutout, or straight exhaust. It shall be unlawful for any person to operate on the highways in the Commonwealth a motor vehicle equipped with a gutted muffler, muffler cutout, or straight exhaust.

(Code 1950, § 46-306; 1950, p. 54; 1958, c. 541, § 46.1-302; 1964, c. 628; 1989, c. 727.)

I know plenty of people in Texas who failed visual inspections for them and had to go bribe a dude to get passed.

Yowen - not necessarily not spaghetti and meatballs > jariten1781 01/09/2014 at 16:55

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that's messed up, who cares if they know when to keep it closed, haha.

I guess if you want them you'd have to make a little bolt in pipe you could put in when it's inspection time and explain that you bought the car with them on there or something and found they are illegal so you replaced them with a little bolt-in pipe.

jariten1781 > Yowen - not necessarily not spaghetti and meatballs 01/09/2014 at 17:00

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Little known fact all, non-factory exhaust systems are illegal in VA in a separate statute though it's not enforced unless you somehow piss off the cops. Some other states have laws like this too.

46.2-1049. Exhaust system in good working order.

No person shall drive and no owner of a vehicle shall permit or allow the operation of any such vehicle on a highway unless it is equipped with an exhaust system in good working order and in constant operation to prevent excessive or unusual levels of noise; provided however, that for motor vehicles, such exhaust system shall be of a type installed as standard factory equipment, or comparable to that designed for use on the particular vehicle as standard factory equipment. An exhaust system shall not be deemed to prevent excessive or unusual noise if it permits the escape of noise in excess of that permitted by the standard factory equipment exhaust system of private passenger motor vehicles or trucks of standard make.

thereisnospork > TwoFortified 01/09/2014 at 18:17

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If you have an electronic cutout you could use a Hobb's switch + relay to actuate based on boost pressure.

TwoFortified > thereisnospork 01/09/2014 at 18:42

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There we go! That's what those are called! Very cool.

Yeah, that's where my thinking ended up. The idea of, say, using the pressure to open the baffle seems like a REALLY bad idea (i.e. would it close properly when boost is relieved? Even if it does today, would it close in 5 years?). An electric baffle seems like the way to go. A lot of them seem to be operated by a switch in the cabin, but that seems kind of strange when we have access to things like Hobb's switches (of course, this idea only works on cars with forced induction. Unless you wanted to, like, invert the switch such that the baffle is open when you're under .1 psi of vacuum or something...which also seems like a bad idea).

Guess you could use the TPS as an alternative ("If the throttle is open at least 75%, open the baffle"). That way, idling or cruising at speed wouldn't be too loud, but hard acceleration would be good.

Zoom > TwoFortified 01/09/2014 at 19:16

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This was on a 500ci SRT Grand Cherokee that stopped by the dealership one day. Dash switch controlled.

TwoFortified > Zoom 01/09/2014 at 19:18

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Um...Grand Cherokee? Really? I mean, don't get me wrong, 500ci, SRT, all nice, but...on a Grand Cherokee?

Anyway, pretty cool to see the setup. I'm sure anything I could come up with on the fly would be pretty ghetto (if cheaper).

Zoom > TwoFortified 01/09/2014 at 19:22

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I know, right? But with awd and plenty of motor, this fucker launched like it came from a cannon. The motor cared not about the weight. I think it ran 11 flat.

And, you don't need it from the dash. '60 Super Stock cars came from the factory with bolt on covers. Three bolts, no Makita.

TwoFortified > Zoom 01/09/2014 at 19:27

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A JGC running anywhere near the 10's is...well...counter-intuitive to say the least. Good on that guy though.

Also, the 60's were clearly a different time in cars. A more primal time. A more badass time. A time without Catalytic converters (err...I don't know if that last part is true...). After I get the Skyline all buttoned up (in the hopefully not TOO distant future), I think American muscle is in order. I'll even resist the urge to Tokyo Drift it (While most of my engine knowledge revolves around EFI, I wouldn't mind learning a thing or two about Carb'd V8s).

Andrew Lamb > TwoFortified 01/09/2014 at 19:40

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Yeah, they're common on Ferrari's and such, also known as "Active Exhaust"

Zoom > TwoFortified 01/10/2014 at 10:23

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Unless nostalgia is required in your case, an mpfi system is still the way to go, even on an old big block. Carbs are a tuning bitch. No o2 to watch, mostly guesswork, unless you have a dyno and a probe.

Good luck.