Yeah, thanks. I might need it, even coming from you. You held so little regard for the muffler in the first place, because I'm not an acoustical engineer and all. I just meant it will not be torturing your finely tuned ears for quite a while. What I meant by "in a way". I know no rotary owner would wish anothers car not to run, that is just bad karma.

 

Frustration, understood. Again, good luck.

 

Call it whatever you want. I wasn't recanting, just re explaining. And again, thanks.

 

needs a rebuild, because of a broken exhaust stud? Is that the only reason? Doesnt sound like you need a rebuild, more like stud removal and replacement?

 

It's broken off flush to the block, if you think you can do it drive on over and do it It also broke off twice, and broke a stud pulling tool. I'm going to take it to a rotary friendly local guy, and see what he says. I don't hold much hope, as at the VERY least, it needs to be drilled and heli coiled. I haven't found a drill bit or drill short enough to do a good job yet, so more than likely the engine has to come out.

 

Bad luck with the exhaust stud I'm sure you can fix it fairly easily.
I snapped an aluminium speedflow fitting in my front cover the day I was ready to take my fresh home rebuilt engine on its first testdrive. That set me back another week. Its just a slight setback. You'd be surprised what you can get out, we snapped a ring gear to carrier diff bolt with permanent strength thread lock on the bolt, and my mates dad still got it out pissed as a fart at 10pm after working 10 hours that day.


purple82

when you talk about computer simulation, are you talking about FEMLAB? I have FEMLAB 3.1, and some slight knowledge in computer modeling, do you know how to test these theory's and maybe even model this muffler to show its performance?

I know you would need to use approximations but it would still be good to see.

 

well you can ship me the muffler, and i can tell you how it will sound.. i mean, i will put it on my car and make clips of it...

 

FEMLAB looks like a potential tool for the job, I've not used it myself. You'd need information on geometry and boundary conditions to do an accurate enough simulation to be useful. Then you'd need to know what you're looking for and what you're looking at when the simulation is complete.

Like I said though, even the best simulation won't be 100% accurate so prototypes are always needed.

 

How about those low profile drills that are available from Harbour Freight?

http://www.harborfreight.com/cpi/cta...emnumber=92956

Anything to save pulling that motor out just for a broken stud... Have you juiced that bad boy with PB?

I wish you the best of luck....
Scott

 

When you do get the stud out... Since you've obviously got the fab skills, why not pick up a couple 90 or 180 degree mandrel bends and cut them in pieces as needed to weld up your own exhast? I did this for a custom exhaust on my '7 and it turned out quite nicely for a fraction of the cost. Another benefit is the mandrel bends verus the regular restrictive crimped bends that a muffler shop will make when they bend something up for you. Ex: a 2.5" pipe bent normally will become a 2-2.25" pipe for the length of the bend -- definitly something you want to avoid if you're aiming for performance.

great work on the muffler btw

 

+1... muffler shops will ruin everything. Settle for nothing less than mandel bend exhaust. If you decide to use prebent it is also nice to have a pipe expander. This way you can expand the recieving tube and create a smooth transition. This also reduces the requirement for precision cuts as with butt welding. The overlapping tubes makes blowing through the tube less likely. Makes mockup easier too. Just not too easy with anything thicker than 16GA.

Good luck.

 

Ya, and you wanna use AT LEAST 16ga tubing. The heavier the better with a rotary. You'd be surprised what a thin ehaust tubing can do to the sound.

 

Damn, once again no email notifications. Figures. I dropped it at the shop today, and they said they'll "try" it. We've begun to save the money for a new engine from Mazda. About $2700 from what the shop said. They do rotary car repairs as a specialty, so they probably have the connections.
We're selling a luxo van that is in the garage not being used, so that may give a big boost to engine
cost.

 

It's done!! The shop drilled it out and helicoiled it. It's a "little bit" louder than I was hoping for, but it does sound pretty good. It's very low at idle, but it does fart a little in higher rpms, say above 5-6 thousand. There's a straight section of pipe between the muffler and cat, so I will try putting a shorty glasspack in there. Or,,,,I may build a small diameter muffler with a baffle or two in it. Funny thing is with the tips on, it's quite a bit quieter. Must be the extra pipe past the muffler, or the pencil tips cancelling out some of the high tones. It's almost boomy up close, hehe. You can feel the pulses in your chest. So all in all it's not a total loss for an experiment.

The exhaust shop also used VERY thick tubing. It was least 16ga, probably thicker. Almost 1/8" by finger gauge.

 

Sweet man. Post some vids or sound clips

 

Hmm. Where can I host a sound clip? I can record it tomorrow and post up a clip for reference. I will be quieting it down some more though. One way or another.

 

I say photobucket is probably your best luck

 

I have an account already. You can host sound clips there? Sweet!

 

I'm pretty sure you can. You just have to check it out

 

try putfile.com

 

With no tips, straight muffler from about 4-5 feet.

http://s114.photobucket.com/albums/n...=RX7notips.flv

With 2 inch pencil tips stuffed with SS wool. Sounds like an big angry chainsaw on steroids. I think I'm going to install an Imco glasspack a couple of feet in front of the muffler. It should knock it down some I hope??



http://s114.photobucket.com/albums/n...v?t=1166379873

 

I cut about 3 inches of the tips, and then used a smaller somewhat tighter wad of SS wool stuffed a bit deeper into the tips. It made a pretty big difference. If it burns out I have enough SS wool to last 15 years. It's even quieter now, with a more mellow exhaust tone. I think I found the solution, to pass inspection anyways. the only time it has a bad tone is when it is building RPM's rapidly. When at steady RPM it is bearable.


http://s114.photobucket.com/albums/n...snstuffing.flv

 

Oh well, I guess I'm talking to myself at this point? The car is loving the new exhaust system, though the neighbors probably don't. It gets rubber while shifting to second without too much effort. Before it chirped, now it is a longer duration. More like a quick squeal. I can still hear the
Holley pump, so it's not that loud I guess. No droning to speak of. Mostly all the noise is at the
tailpipes.

 

 

Nuck Chorris!! Suhwheat! lol!