I want it both ways. I want the power of a free breathing muffler but I want to be able to temporarily quiet that thing when I want to. With the top off, the muffler is just too loud. After about 20 minutes or so you get ear fatigue from the low rumble (idle is actually worse than when the engine winds-up).

So I remember some thread on Pelican a while ago discussing putting motorcycle baffles in the sport pipes. What's the deal with that? I like the idea because it sounds like an easy install and easy to remove on the fly. I went to a Ducati/Honda shop in Sunnyvale yesterday and they had no idea what I was talking about. So, where do I get those baffles?

Also I found that some people have actually installed three pipes and run the sport pipes capped when they want quiet operation. See photos below.

So what do you think?

Second

Third.

The third pipe is stock. Easy to add back on... then cap the other two.

From what I gather.. Porsche did this on some of the GT's when they ran the cars on rallyes that entered city streets. This way they could cap them and uncap them when needed.


B

my brothers 1971 honda 175 had 'snuffer knots' . a circular disc with three holes in the end of the tail pipe. the disc had a throttle plate shaft with a spring to hold tension on the plates to hold them open or closed. they probably don't make them anymore, but an old carb out of a junk yard would have the parts to make some.

So Brad, you think the 3 pipe solution is the way to go? Can you recommend a muff-welder on the peninsula? I wish I were a muff-welder.

Douglas

Castro and Central Expressway (Michaels..they did all my stuff when I lived in Mountain View) They have done a lot of magazine projects for Hot Rod. From your office..turn left onto Castro (if you go right..you end up in front of all the food places)

Have them make a new tip for you and cut the current capped end off.

They where very reasonable on price.

B

Depending on the fit of the caps, I'd worry about it whistling or making odd sounds.

IMHO, good idea, but terrible execution...it just looks wrong

I'm not a fan of the look either... but it works and it IS what the factory did back in 1970.

B

The caps are not the tightest fit, but there is no odd noises from them. They are tight enough to need some persuasion to get them on and off.

I thought about putting in some gasket material, but decided otherwise. They look better now that I cut 6+" off the pipes.

I got the idea from Bruce Anderson's book, but couldn't find the original muffler. I had AJ USA build that one. It's just a sport with the side put back on and two aluminum caps machined. A bolt goes through the side to attach. It takes less than a minute to go from socially acceptable to down right obnoxious (sp?).

I will still build a true duplicate of the factory race muffler, but for not this one works.

Did you re-tune the motor afterwards?

Changing the length of the tubes is simialar to adding/removing discs on a SuperTrap muffler.

Yup, it was retuned afterwards. What I need to learn to do is to tune it when I go from caped to uncaped... or the otherway around. The car runs a bit rich with the caps on and I get some popping (lean?) with them off.

Does that sound right?

Ahh yes another good reason for injection.

Doug, you car will automatically adjust..

Oh wait.. you dont have the O2 hooked up... hum..


B

I was watching TNN (Hot Rod or Truck's, can't remember) one Sunday and they were installing a dual pipe system. It had a Y in the pipe, one pipe went to a muffler the other had an electric gate and it went to a straight pipe.
Flick a switch and you had a wide open header, flick it again to muffler.

Real cool, maybe try a Hot Rod shop.

Yeah, if you look at the Summit or Jegs catalogs, they have drag race mufflers that have a lever...open the valve and it's a straight pipe, close it and it's a muffler. Kinda cool.

I got black flagged once for too loud pipes....I used coke cans and screw clamps. They were good for about ten laps and they burned up....