Muffler suggestions for the V8 MG

I'm looking at the potential exhaust design for the LS1-powered MGB, and space (as always) is at a bit of a premium. The goal is to build a good little GT out of the car, something that's quiet and comfortable on long trips. I might install some cutouts for when Janel feels like being raucous

I'm thinking I can either fit two small diameter, longer round mufflers or one moderately-sized oval. Looking at the Flowmaster website, a pair of Hushpowers (4x5.5x18) or a single Delta 50 SUV (5x10x17) should be possible. The packaging of a pair of 2.25" or 2.5" pipes would be easier than a single 3" and should give more flow, although I'm honestly more concerned with sound than power in this car.

The reason I'm looking at Flowmasters is because they have a useful website, showing expected interior and exterior sound levels. Most muffler product descriptions are useless as they don't give any hard data, merely meaningless marketing fluff that talks about "hot sounds" and "performance rumble".

Thoughts? What's going to work out best? Personal experience? Suggestions?

I don't like the way most flowmasters sound - they kind of give a cheap header-esque sound, tinny. I have heard they don't do great when it comes to power, but I cannot vouch for this without data. Some are rated for flow at a given pressure - don't buy without that data if you're looking for something really good.

I'm partial to Dynomax super turbo mufflers. They're fairly quiet with a mellow sound.

I've never used the Hushpower line or the 50 series. I've used the Flowmaster Delta Flow 40 series on two vehicles. The Dakota wasn't bad with a single since it was under the bed of the truck. The pair under my wife's Challenger resonate so bad at 35-45 MPH your head wants to explode. But it is a mean sounding 318 2bb. Those mufflers are coming off this Spring.

I'm partial to the Dynomax Super Turbos. They are a modified turbo muffler design and have different case sizes and shapes available. They flow well and don't resonate like the Flowmasters. Plus they aren't terribly expensive. I'm running them on my Barracuda, and that's what's going on the Challenger.

When the 40 Series rusted through on my Dakota I replaced it with a Dynomax stainless Ultraflow. It's a little louder than the Super Turbo, but not anywhere as loud as the 40 Series.

If the Challenger has taught me anything, it's a closed car with lots of resonance isn't a fun car to drive.

-Rob

Magnaflow is all I'll ever buy. Flowmasters sound terrible to my ear, and apparently don't master flow at all. Magnaflow also has sound clips from a bunch of cars on their website, and a long time ago I found a thread on LS1Tech (I think) of someone flowtesting a bunch of mufflers and Magnaflows did very well.

Though whatever brand you're thinking about I'm sure somebody has posted a high-quality YouTube video of it.

lots of people sell their OE corvette cat-backs for pretty darn cheap when they install borla or other aftermarket. i'd rock a craigslist OE take-off.

Good call.

http://picasaweb.google.com/jaym67mg/67MGBGTV8CONVERSION?authkey=WcethjvABAw#

You following this conversion? Scroll down to the bottom. Exhaust looks good. Going to be loud I think?!

Lake-pipes FTW

Osterkraut wrote: Flowmasters sound terrible to my ear, and apparently don't master flow at all.

They master the flow alright... right into a wall in the middle of the box.

AngryCorvair wrote: lots of people sell their OE corvette cat-backs for pretty darn cheap when they install borla or other aftermarket. i'd rock a craigslist OE take-off.

Corsa muffler for a LS1 with their resonator or a good magnaflow resonator (skinny). Relatively quiet but expensive. Running a cat?

I think the LS vette mufflers would be great, bonus for the c-6 with built in cut outs however they are still expensive for take-off's. Also, I would think if you are looking for a single canister, a F-body muffler would be best. The 'vettes use two can mufflers and they are not small. I had 2 C5 mufflers on a tpi350 and it was relatively quiet, just bulky. I want two C6 mufflers w/cut outs but they are still going for $400 for take offs and are pretty big (but short).

Except Corvette take-off mufflers are the size of Miatas!

I have original Flow 40's on the P71 and they are great. You can see and hear the quality difference to new ones though, so I'm unlikely to ever use them again. I like a lot of Magnaflow's stuff. Their bullet mufflers are efficient and lowering dB without taking up a lot of room or power. The NHRA guys love them at the sound-controlled tracks. I'd look there first.

baffled tubes - makes the system your muffler

spin tech

I've got twin stainless cans - don't remember the brand - traded my stock mg crossmember for a pile of parts with an mg conversion vendor - they were in the pile.

Thanks for the feedback. Factory take-offs aren't an option. Note my dimensions earlier - I think I can fit a single 5x10x17, but that's going to be borderline. I could use the muffler from the donor Camaro but only at the expense of my gas tank. My entire gas tank. I can see a way around that, but it involves moving the tank into the trunk instead of under the car and relocating the filler - and I don't want to either lose the space or take the time.

One of the Flowmaster sound clips on the website does have a pretty hollow sound, I was hoping that wasn't typical. The Delta 40s are much louder than the 50 SUV model, as the latter is intended to be fairly quiet especially on interior resonance, that's why I was leaning towards it.

Personally, I'm not a huge fan of Magnaflows. I have one of their fairly large bullets on my Locost, and it's a running joke locally about how the car basically has no muffler at all. It's completely overwhelmed by a 1600cc four. We also did a bunch of exhaust testing a few years back with some hand-built mufflers vs Magnaflows, and the Magnaflow combined high sound levels with poor flow. But I'll take another look. I'll also see about the Dynomax super turbos - those look promising due to their construction.

Nohome, I'm not following anyone else's conversions. Thanks, I'll see if there's anything I can borrow from that. Looks a bit loud.

Stock MG crossmembers are worth something? I'd better tell the metal recyclers I can't even get rid of the rear axle from this car.

A number of years ago Car Craft compared a bunch of mufflers and they liked the Dynomax Super Turbo mufflers for flow as well as price. I would look there first myself.

The butt dyno told me the Dynomax Super Turbo is a winnah.

This article (I believe by David Vizard) also points to the Dynomax Super Turbo as a winnah:

Exhaust Science Demystified

I've run Dynomax Super Turbos on the Sinister Sentra and the Lethal Locost. I will be buying one for the Hideous Hardbody soon as well. The Fiendish Firefly will be getting two....

I vote Dynomax, too. That should keep it from being used

how about some sidepipes?

Seriously, I have heard good things about the Dynomax too

Hooker Aerochambers.

Someone did a big comparo using the same car, same engine, and swapped out only mufflers on the dyno to see what actually gave the best performance and sounded the best. Somewhere I have a copy of the CD they made of the recordings of the exhaust as they flogged the car on the dyno. The aerochamber had the flowmaster rumble at idle all the way up, without going tinny and sounding like a cheap glasspack the way the flowmasters do at high RPM. Pure awesome-ness.

edit; Found it! the cd is available here

Thermal Research and Development.

It's amazing how much these straight through mufflers dampen the sound. Had one on my 300Z back in the day, and also ran one on my S52 E30.

The E30 was equal length headers into a 2.5" catback, no cat or resonator. You could barely hear the car at idle or cruising on the highway, but it would scream when you floor it.

Although I don't know how much the headers were responsible for.

Thanks for the YouTube suggestion. Gold - lots of Dynomax Super Turbo exhaust clips on various 5.3l Chevy trucks, which is a pretty good match to my critter. Plus they have a couple of cans that look to be about the right size for my single muffler option.

Thermal R&D is one I should have thought of from the start - that's who makes all of the exhausts for Flyin' Miata. Fantastic workmanship. Still, my personal experience is that straight through mufflers are too loud for this application. Remember how I said I was more interested in sound control than outright power?

Lots of interesting options here. The mufflers themselves are cheap enough that I can realistically try a couple of different ones and see what works best. I like the fact there's no packing material in the Hooker.

I hear that turbos make really good mufflers.

zipty842 wrote:

Osterkraut wrote: Flowmasters sound terrible to my ear, and apparently don't master flow at all.

They master the flow alright... right into a wall in the middle of the box.

The Flowmasters might not be a restriction at all if the internal volume is large enough to create an effective exhaust box. This would vary from engine to engine, so its up to you to calculate and determine if it applies.

An exhaust box basically acts as if the exhaust dumps to atmosphere at that point. This means that anything beyond the exhaust box would not effect performance as long as it wasn't a restriction. The plus would be that you could add or delete mufflers/resonators after the box to tune the sound and as long as they weren't a flow restriction, they would not effect system performance. The location of the box would also determine total system length, so that by moving it forwards or backwards you could tune to a specific rpm.

something else to consider.. if it is too loud, get a resonated tip from ansa... good for a few db drop