Building an exhaust for my 318is. What size?

[harv]

What size muffler? I was going to go with 2 1/2 but what size (outer dimension) fits in the stock location? I'd also like to get a new flange to start after the cat. Anyone know the size of that? I'd like to order the stuff from Summit while I'm away at work. Exhaust muffler broke while I was driving to the airport.

John

[harv]

Well I ordered this muffler.

http://www.summitracing.com/parts/SUM-630125/

I also ordered a couple of mandrel bends and the female 2.5 ball flange.

We will see.

John

[harv]

I should NOT have gotten the one with the center inlet or outlet. I should have gotten this one: http://www.summitracing.com/parts/SUM-630225/ I think I can still make it work but the center inlet is close to the half shaft. (the offset outlet is required if you want the outlet lined up with the cutout in the valence). Get the one that is offset inlet and outlet. Also, this muffler is a lot smaller than the original. Could have been a lot longer and still fit. If I was going to throw more money at it I might be tempted to try this one http://www.summitracing.com/parts/MPE-12577/

John

[harv]

So I finished it today. Idle is wonderful. But when you get on it at all,,, RAAAAAAASP. So my thoughts of a larger muffler would be spot on. Problem is that in my Summit catalog, there aren't any that are simply longer. I could go larger and get a Flowmaster but we all know how much noise they make. I think the other problem is the fact I went with 2 1/2 tubing. Maybe 2 1/4 would have worked better. Looks like I'm going to have to add a glasspack right after the cat. This one might do the trick, http://www.summitracing.com/parts/SUM-630805/

Maybe I should just add a turbo. I'm sure that would quiet it down.

John

[Hey_You]

I vote...Yes

[harv]

So looking in the factory first muffler after the cat, the lovers are open to the exhaust flow. I ordered a Summit glass pack with lovers also. On the glass pack, there is an arrow saying the direction of flow. This is with the ramp facing the flow (opposite from what the factory had) I'm thinking of installing the glass pack backwards for the best sound deadening. Any thoughts? Maybe this would just pack the glass sooner.... Hmmm Maybe I should just put it in the way its supposed to go.

John

[ak-]

Thanks for documentating.

But darn, there is a thread about this somewhere buried explaining the differences in which way the ramps in the glasspack face. I can't find it.
Maybe try m42 club in the exhaust section for tips.

[harv]

Found this in a hot rod forum.

A straight through glasspack really doesnt have a flow direction...That said there are a couple small points to consider with the direction of the louvers.These louvers are really designed to allow high end sound waves to enter into the fiberglass packing.When these sound waves enter this fiberglass the sound waves are trapped and therefore stop moving thus canceling the sound produced by these sound waves .If you place these louvers with the packing faced twords the collector you will be exposeing these louvers to a little bit more heat , sound waves , water ( a natural by product of combustion ), carbon , air flow ect ect. In that direction you may get a decible or two more quieting than if faced in the other direction but the muffler life may be a small amount shorter as the packing is exposed to abit more of the exhaust blast then if faced in the direction of the tailpipes.... Either way the real problem with these types of mufflers is that the fiberglass does a great job of collecting and holding water... this is the main reason most glasspacks have reletivly short lifespans compared to non packed mufflers.

John

[harv]

Thanks for documentating.

Well, someone's gotta do it. I see questions about this every once in a while (emphasis in the h)

John

[ROLLingKING]

yea this is much appreciated. ive thought about trying to build my exhaust from these..wi a sound clip be up at the end?
subscribed.

[harv]

I installed a 12" inch long Summit Glasspack and it quieted it down a little. I drove it today on a 45 min each way trip on the highway. I think the glasspack has broke in a bit. It might be a little too loud for me but like Billy Sports being a little too stiff, I;m just going to deal with it and enjoy the ride. If I were to make another exhaust I'd go with the 24" glasspack and go from there into a Super Turbo.

Other than that, the car simply flies! and at 80+ in 5th it sounds awesome.

John

[harv]

OK,

Too Fing ricey sound! There, I said it.

Ordered this...... WLK-18406 SOUND FX MUFFLER 1Z045WV80364995820 Here is the link. http://www.summitracing.com/parts/WLK-18406/

Cut the Summit super turbo off. Welded on the new one.




No change in rasp sound! F!

After a few days of driving, It has broken in better and is quieter. If I were to do it again, I'd do it with 2 1/4 instead.

John

[TimKninja]

did you ever find out the stock diameter of the exhaust?

Similar situation, cutback has disintegrated , stock one shipped is $250, but i think i can get a muffler shop to throw some pipe and a muffler on there cheaper.

[harv]

I would do the same size out of the cat. No bigger than 2 1/4. Make sure you get a resonator and not a glasspack. I think if I had done this it would be quieter.

John

[idickers]

I'm getting ready to build a 2.25" exhaust for my 318is. Did you find a decent resonator?

I've been debating the same issues; I'd like as much performance as I can get, but don't care for a loud exhaust. I've been thinking of using the longest 2.25" free-flow muffler with offset in/out that I can find for the rear muffler, and either a glass pack or round resonator after the cat. I'm thinking of the Heartthrob HVM for the rear muffler, but haven't a clue for the resonator.

Did you ever find a source for the flange to mate up to the cat?
Ian