Amfab

Ok sometimes I think my 1.75 LPMMs pipes are just a little loud, and I dont want to spend 600+ dollars on a solenoid actuated valve. So I was thinking, when I was putting my Big Ovals on, I can very easily get to the bottom of the bypass pipe with the car on the ground. What if I fabbed up some sort of valve that could open or restrict the LPMM, It wouldnt have to be supper tight fitting , just something that could close it down in a couple stages.

Id do the by pass out of 2in pipe , so the 1/4 inch shaft would stil leave 1.75 inches of bypass. The valve would be at the outlet end for easy access. I scetched up the idea, what do you guys think?

FisterD

Nice drawing !
The only thing for me, personally, is the mod sounds so good, why would you ever want to turn it off. Just my .02

axl911

I would love to have that adjustability!

Air Kuul TT

I'm with Darin.

But at the same time... having the option to restrict the bypass would be great.

Nice work!!

RallyJon

A little more than half that: http://www.dmhperformance.com/ecutout.htm

Amfab

hmm $320........ hmm Thanks John SO I would just have to weld on flanges

Kigiin

Huh, I find mine to be too quiet. Admittedly I came from supercups and the exhaust does have a decent growl, especially when cold, but never- ever loud. I too am using 1.75"

I had my mechanic do them sight unseen - haven't even bent down to look at the welding job. Is there any variation in the configuration of the pipe that could lead to one being louder than another, assuming the same size pipe is used?

Rob

InTheAir

Andrew -

<all in good fun-ON>

How's that OCD treating you?

(btw, I like the idea and drawing.)

cowtown

Nice graphic. I've been thinking about doing butterflies like that for about a year. I keep taking my bypass mufflers on and off because I love them for a while then get tired of them on my 25 mi-per-day commute 993.

I'd like to build a little controller box that reads the throttle position sensor and adjusts the butterflies to open on throttle and closed throttle, and then closes them up at cruise. Just trying to find the time....

Amfab

I dunno Rob. Everyone loves the 2inch and I was scared and so I went 1.75, I did cut the holes in the inlet and outlet holes really close so there is no little flange sticking out inside.
I did put the bypass pipes only about an inch from the body of the muffler, where most people put it like 2 inches out.

I mean they arent insanely loud, just sometimes I want to take off on the freeway on ramp and get up to speed quickly and not have to draw that much attention.

Maybe Ill just shut up and drive. They do sound cool .

They do substantially affect the gas milage though.
Now I drive everywhere at a higher RPM and with the windows down and top open

Colin, yeah, Im in the same situation, 25 mile commute. I dont have a problem when cruising though, only under hard acelleration. The sound comes on loudest from 3500-4500 RPM at WOT, then thins out a little higher up. Cruising under partial throttle at 3k to 5k its not bad at all, almost stock

DBYT

Andrew,
I know what you mean about the LPMM affecting gas mileage...mine has certainly increased since the mod...always trying to stay in higher RPM range...it sounds very very sweet.

Mike J

I like these products but when I looked into it I could not see how to put this valve in where the bypass pipe is...its too tight from what I measured. But it would be the ultimate solutions...hit a button and dial in the noise you want!

Cheers,

Mike

RallyJon

Oh, that's too bad. But thanks for doing the measuring!

brucec59

Take a look at post #23 in this thread: https://rennlist.com/forums/993-forum/258976-very-interesting-switchable-ruf-exhaust-ebay.html Bruce in Seattle actually bought electric valves but they did not fit. Some other good comments in that post to consider, too.

Bruce SEA 993

Yeah, this thread is Deja Vu all over again!

I incorrectly thought mine would be too loud for the day to day street driving so I wanted the valves. I could not figure out a way to get the valve and all the stack of flanges and gaskets to fit. I am happy it didn't work as I really like them all the time and am not tired of them.

If we think we are loud...listen to the Harley crowd. I was having lunch in Old Colorado Springs on our South West trip to bring home the BMW and we could hardly hold a conversation with all the straight pipes going by...

Andrew, your design looks good and very compact. If you have the fabrication skills it would do the job. There might be some exhaust leakage through the shaft though...prolly not a big deal.

Cheers