B&B resonance help - muffler questions

Jgordon · 06:31 AM

Hey there. I just installed a B&B setup on my car - rundown is as follows:

Mahle 3.4 P&Cs, 964 cams, raceware springs, arp rodbolts, B&B headers, currently B&B muffler (2/2, capped on passenger side).

The resonance is awful. Literally painful up to 3k rpm, and then it disappears. I'm not exagerating at all - it hurts your head to be in the car. Not a "hey, that doesn't sound as good as it could" - I had a kicking headache after driving for an hour. Couldn't keep it above 3k enough.

So I'm looking to get this fixed this weekend. I've heard a lot of advice for the Dynomax and the flowmaster. Advice seems to be for the dynomax (moses suggests a super turbo model 17725):

As for flowmasters, people have mentioned the mustang/firebird crossflow design?

And I just read that a simple solution might be to get piping that narrows from 3 inches to 2 inches? would this really cure the resonance?

Thanks very much - I'm not looking forward to getting in the car at this point to go to the muffler shops, and that's saying a lot.

Also, if anyone knows a good muffler shop in the NYC area, I'd love to hear about it - Bill V, how far north are you, and how was your experience getting your flowmaster welded up?

89911 · 12-02-2005, 07:56 AM

I've had good luck using a Magnaflow. Prior I had a Borla that had a little Resonance. It's a hit of miss thing. My brothers GHL rings my ears at idle and just above. This Maganaflow has absoulutely no resonance. None. I'm very happy with it on my 3.4.

Magnaflow Custom muffler made for SSi's and Dual outlets.

I kept all the inlets and outlets 2.5 and used some adaptors only at the SSI exit. Everything else is 2.5".

Jack Olsen · 12-02-2005, 09:34 AM

Quote:

Originally posted by Jgordon
And I just read that a simple solution might be to get piping that narrows from 3 inches to 2 inches? would this really cure the resonance?

Yes. It's the simplest path. Any muffler shop should be able to do it.

The downside is that the B&B muffler will fall apart (at least, mine did) under any kind of hard use.

mb911 · mb911's Garage

The internals of all fo mentioned are very similar However I believe the magnoflow has fiber packing. The drone/resonance is typically no existant in a single out muffler as you have capped one side.. Good luck

Jgordon · 12-02-2005, 09:51 AM

Well I have called a muffler shop that seems pretty confident that they can do it. I was trying to get pricing over the phone for a bent narrowing pipe - I'd rather have a price in hand before they see what car it's going on, but I'm not sure that that's an option.

I have another muffler shop that has a dynomax like the one moses describes waiting for me. I guess I'll try the pipe first, and go with the dynomax if that doesn't work.

I also have what B&B calls a "limerock tip" as my exhaust pipe.

This is what it looks like - capped off at the end with a "knight's helmet" type opening. Do you think this could be causing/contributing to the resonance?

My thought is, first cut the limerock tip to a slash opening. If that doesn't work, get the narrowing tip. If that doesn't work, change the muffler. This just seems like a long, expensive process.

mb911 · mb911's Garage

what heat exchangers do you have?

Jgordon · 12-02-2005, 10:33 AM

B&B heat exchangers, B&B two in, two out mufler. Passenger side is capped with a pineapple can (don't ask).

Jack Olsen · 12-02-2005, 10:36 AM

I had normal outlets on mine, and the resonance was terrible. This is a picture of mine once they were reduced. The muffler is upside down (don't ask), but it didn't have the resonance any more.

Jgordon · 12-02-2005, 10:40 AM

Hmm.

That's actually the orientation my muffler's in as well. The B&B collector->muffler tubes (3-bolt flange) wouldn't fit otherwise. So I'm pretty sure you have it right.

Are you saying there's no resonance even with both sides open?

Jgordon · 12-02-2005, 10:54 AM

And do you guys think that cutting the tips open (like this) would help, or should I just get the new tips and sell these?

Bill Verburg · Bill Verburg's Garage

I like my Flomaster but folks that have done side by side comparisons like the Dynomax better.

W/ either, all you need are 2 flanges 2(prefereably) ss 2.5" U's, tips of your choice and the muffler itself

Beginning

End

Jgordon · 12-02-2005, 12:34 PM

Bill, Thanks for chiming in. I'd rather keep this as low budget as possible for the time being. I'm trying to think of ways to modify what I have or start out small. If it comes to it, I'll obviously have to rethink the new muffler and collector tubes, but I'm hoping to get away with what I have in hand.

Bill Verburg · Bill Verburg's Garage

Like Jack I had a losing battle w/ B&B mufflers, IMO they are cr**, that fall apart annually if not sooner.

MysticAlpaca · 12-02-2005, 01:18 PM

Along with changing the piping size could you modify the baffles on the inside of the B&B muffler or add packing?

Fabspeed has a great video showing the B&B. While the video is designed to make them look better, I think it fairly representative of the facts.

I just got the Fabspeed set up and its solid. No resonance and when you knock in the muffler with your knuckles its like knocking on a solid hunk of steel.

Too bad they dont offer a less bling model for cheaper.

Fabspeed 911 Muffler Versus B&B & GHL 911 Muffler Comparison video

Fabspeed Exhaust from Pelican

Jgordon · 12-02-2005, 01:24 PM

Thanks guys.

Ben, do you (or does anyone else) have any thoughts as to an order of operations here? If you tell me the B&B is hopeless, I'll just go pick up the dynomax tomorrow morning. Otherwise I'll be tempted to play with the muffler on the car before giving up.

Jack Olsen · 12-02-2005, 03:19 PM

Some people have had the B&B's hold up fine. They made some manufacturing changes along the way (gussets on the outlets, I think, and maybe other changes).

In your shoes I first reduced the outlets, and was happy for a while.

Joe Bob · Joe Bob's Garage

The big bucks mufflers are bling bling....I have used a good local muff shop on two-three applications and recently 993 heat exchangers on my 3.6....VERY happy and I know who to go an beyotch at it if there's a problem....

Jgordon · 12-02-2005, 03:42 PM

Ok, my first stop will be at the local muffler shop to see if they can just throw some narrowing tips on. If they inflate the price due to the car, I'll go buy the muffler and try somewhere else. Mike - I hear you, just not sure where to go around here. NYC area is very low on DIY support businesses.

Thanks - I'll let you all know how it goes.

Joe Bob · Joe Bob's Garage

Go to a small town .....

mb911 · mb911's Garage

Ok B&B mufflers look great and you asked so I will give my feed back on muffler etc.

B&B look good cost allot=not so good in quality however they make really nice headers.

Best bang for the buck is definatly the flow master/or dynomax. This will cost 100 bucks or so and will work well.

The tail pipe size and shape do make a huge difference.

I must point out when I started my business I looked at several things

weight:
Why would anyone want something that weighs that much just for exhaust and then start thowing out the seat/door panels/sound insulation etc

fittment:
How much Bs intsalling and how well will it fit.

cost:
Why spend 900-1500 for a muffler when you can build one (flowmaster) for about 100 or so

Sound:
I think the claim that if you tap on the muffler and it is solid then it won't resonate is BS Any and every muffler that has dual outlets will resonate just depends on how much and at what range will it be an issue.

I did Start with a flow master on my 911 it was just to loud for me. I think I have a good solution for you ! PM if interested