Muffler options?

[wmontoya]

Hoping to make my Caterham/Crossflow a quieter and a bit more stealthy in general, and seeking experienced Seven-ers input on viable muffler options.

It's a LHD w/ modestly built 711M Kent motor and as close as i can tell it has the Caterham catalog listed "MUFFLER - Crossflow competition (and Rover race

Any suggestions for something readily available/mountable which would reduce dBs and not screw up back-pressure/flow too much (so as not to require a ton of re-jetting*)? or "that's not possible, not a good idea or not available?"

 

TIA and regards... WM

 

(i'm a two-stroke guy when it comes to tuning experience/knowledge and the Webers are a bit daunting.)

[s2k7]

Use this one with patented noise reduction

http://img85.imageshack.us/img85/6356/hushpower2.jpg

 

Pretty quite at idle but alive in HI-RPM

[scannon]

Use this one with patented noise reduction

http://img85.imageshack.us/img85/6356/hushpower2.jpg

 

Pretty quite at idle but alive in HI-RPM

I'd like to lower the sound level on my Caterham as well.

 

I went to the Hushpower website and cannot find that muffler by searching on the part number nor "slimline". A Google search didn't yield any results either. Any further info? Where did you buy it?

[Ian7]

I went to the Hushpower website and cannot find that muffler ...

 

Is this close?

http://www.flowmastermufflers.com/searchfmm/search_cat.php?cat=1&sub=75&sc1=&sc2=HP-2%20Series&sc3=&sc4=

[super7guy]

Ian et all,

 

You may be thinking of a spiral muffler. The concept is patented, but both Jegs and others sell them as race mufflers. Our dyno testing shows negligable hp loss. That being said, you still need a muffler with volume. To be really quiet, you need a muffler with a street rating, not a race rating. We have to run under 93 db wide open throttle at 50 ft.

 

Wayne

[scannon]

Is this close?

http://www.flowmastermufflers.com/searchfmm/search_cat.php?cat=1&sub=75&sc1=&sc2=HP-2%20Series&sc3=&sc4=

That's a different muffler and not available with the 3" inlet and outlet I need for my system. I tried the original part number on the flowmaster site and got nothing.

 

The one pictured above looks perfect for my car, right diameter and length.

[s2k7]

I'd like to lower the sound level on my Caterham as well.

 

I went to the Hushpower website and cannot find that muffler by searching on the part number nor "slimline". A Google search didn't yield any results either. Any further info? Where did you buy it?

 

The muffler is the new product designed for a car like "seven" & "cobra".

This statement came from the Hushpower engineer. Actually, he gave it to me for a test ---- I like it.

 

I will search my old email from hushpower. I will let you know who you should talk.

[bsimon]

You may be thinking of a spiral muffler. The concept is patented, but both Jegs and others sell them as race mufflers. Our dyno testing shows negligable hp loss. That being said, you still need a muffler with volume.

 

I fully agree. most of the baffled or split flow mufflers attempt to mix sound waves traveling different distances to cancel each other out. The internal distances are tuned to cause this canceling effect at the loudest part of the noise frequency spectrum.

 

This all sounds good on paper, but as the frequency spectrum of a engine is rather wide, lots of sound at the un-tuned frequencies still escapes.

 

If you want quiet without backflow restriction, it takes a packed/wrapped type straight through muffler with lots of internal volume.

 

To get below 95DB WOT at 50ft. with a big exhaust flow engine (Duratech, VX, ported Zetec, etc.) count on using 2-3 feet of 7" zorst packed with e-glass.

[pierats]

Possible bulk buy here: http://www.californiacaterhamclub.com/chat/showthread.php?p=10683#post10683

[super7guy]

Hi Guys,

 

I had to quiet down a BDA. Used the spiral muffler and two big Ultraflow mufflers to get the job done. Also did the intake side by making an enclosure using 1/8" alloy and picking up cold air from the heater opening. It all worked together well.

 

Wayne

[randy g]

what dia. are you guys using, I race my car and currently have a 2" system. Currently up grading zetec with webers and stage 3 cams and p&p head,was thinking about going to a 2,5" system. Any one else using 2.5"

Randy

[WestTexasS2K]

I was using a 3". I think a 2.5 is enough for a NA Zetec.

I like the Hushpower II round canister with cool shell technology. It sounds good at cruise talks to you when you have the pedal down but the shell stays a reasonable temp. It gets warm, but it wont burn you to the bone if you touch it for an second.

[jbt56]

Hello, gentlemen, I happened across this forum due to a Google alert here at work (Flowmaster). As long as the mods don't mind, and since it's been mentioned, I'd like to let you know the best person to talk to here would be Lee Thompson. He can be reached by calling 800-544-4761 and asking for extension 716. That's our Special Projects Department. They have built mufflers for a huge variety of street and race vehicles, with dramatic sound reductions and no power losses vs open pipes. We recently got a McLaren CanAm car from 115db to 94db using Hushpowers with (according to the driver) NO loss in performance. Anyone interested can call; we'll be happy to work with you to develop a muffler for you.

 

Mods, if this is out of place or out of line, please accept my apologies; I won't be a regular here at all, I just thought I could furnish some needed information.

Thanks.

 

Jeff Thomas

[bsimon]

Welcome Jeff,

 

Any input you might have to this discussion would more than likely be received graciously.

 

Just a few things you should probably know about Seveners and their thoughts about exhaust cans;

 

1) Weight is a big concern. The typical Seven weighs in under 1300lbs. Ideally we would want a zorst to tip the scales under 1 lb. Obviously, this is not a practical vision and more than likely a complete fantasy. That being said, if you could offer something under 10lbs., we'd probably be rather content.

 

2) The 95 dB limit at WOT raises it's ugly head at many track venues. More and more tracks are adopting this standard everyday as urban crush encroaches on our hallowed ground.

 

3) Many of these engines pump great volumes of gas. High RPM and/or ported heads play a great part in maximizing horsepower from these pea shooters. Engine builders tend to use rather large pipes (2"-3") for the typical 120 cubic inch engine. On most cars, the entire exhaust tract is under 6 feet long from exhaust port to the tip of the blewey pipe. There's only about 30" of space in that tract reserved for a can. On some cars, a more elaborate 4-2-1 collector systems may limit this space to less than 24".

 

4) Cost is a big concern as well, although I'm sure you've heard that before. There are great exhaust cans available from the UK that meet these requirements, but most of us are a bit reluctant to shell out 900 clams for a stinking muffler.

 

I know it sounds like a big order, but we'd certainly like your input and suggestions.

[jbt56]

Thanks for the welcome, Bob. We've had experience building mufflers for a huge variety of race vehicles, from diesel sled pullers with 1200+ pounds of torque to 1500 HP drag racers. As someone mentioned above, we developed a muffler specifically for the 427 Cobra that not only controls sound amazingly, but also eliminates the 'snake bite' leg burn that those side pipes are famous for. We've had excellent results on the Trans Am (we were the spec muffler for the 'old' T/A series)and Can Am cars, and were also the spec muffler for Indy Lights.

I would encourage anyone to call Lee at the number in my last post. With all the specs (physical size, engine size/output, sound level current/desired, etc.), he and his team will be able to build a muffler just for the Seven. Some time back we did a bit of work for the Ariel Atom (when Brammo was building them), so small, lightweight mufflers are nothing new for us.

Cost-wise, production Hushpowers list at $130-180, so no worries about insanely priced parts, as the custom mufflers won't be that much more, in my experience. Lee can tell you more about that, as well.

Another plus to ours is that it will be, for all intents and purposes, a lifetime muffler. Even the Hushpowers will never wear- or blow-out, so technically, they'll never need replacement.

To see more, please check out both http://www.hushpower.com and http://www.flowmastermufflers.com . There are 100+ videos up of all sorts of different exhaust setups on many different vehicles (race and street).

[s2k7]

Jeff,

Who is Dan Johnson at Hushpower?

He was the guy that adviced me to get this one: http://img85.imageshack.us/img85/6356/hushpower2.jpg

At that time, he said this muffler still at the lab and not in the inventory.

 

As I mentioned, the muffler is quite at idle and low rpm. However, at hi-rpm

like a Honda s2000 (9k) a bit different story. The muffler can no longer hide

it's sissyness (lol: wonder if there's word).

 

Can you give us an input?

What happened to this 0221081 part number?

 

I had a few enthusiasts asking me this part # but they can't find in the list.

[jbt56]

Dan is one of our Customer Service Reps, and works with me here. For some reason the link you provided is at best excruciatingly slow- it's been 2-3 minutes and it seems to have stopped trying to open.

 

No luck... It won't open for me. If you're referring to our 'Cobra' sidepipe muffler, it isn't a production part but is available as a special order through the phone extension above.

I'm out of time today, but will check in tomorrow AM. I'll see what information I can gather, as well.

[scannon]

Jeff,

 

The link worked almost instantly for me. I copied the picture and here it is below. I am one of those looking for this particular muffler although I could use it an inch or two longer.

 

I'm running an 1,800cc Miata motor with turbo, 3" exhaust with a redline of 7,400 RPM so it will probably work for me.

 

Does this muffler have the thermo shielding?

[s2k7]

Yes! it has a thermo shielding.

You can run the engine and actually touch the muffler, even the engine is running for a while & hot....no need for muffler cover.

 

 

However, I put a cover on mine for looks and for extra shielding.

[jbt56]

Jeff,

 

The link worked almost instantly for me. I copied the picture and here it is below. I am one of those looking for this particular muffler although I could use it an inch or two longer.

 

I'm running an 1,800cc Miata motor with turbo, 3" exhaust with a redline of 7,400 RPM so it will probably work for me.

 

Does this muffler have the thermo shielding?

 

Hmm... Our internet can be a bit odd from time to time. Anyway, the muffler pictured is a prototype. It (or almost any variation) can be built with no problem; it's simply not a production item. If you need it a bit longer, shorter, fatter, etc., our guys can do it.

Once again, I would have you call our Special Projects people; they are the ONLY people who can make this happen for you- I can't do much, as these aren't production mufflers. Give us a call after 7:30 AM (Calif time) at 800-544-4761 and ask for extension 716. Whether you need one muffler or 100 built to the same specs, they'll be able to help you out.

 

*That muffler, like all Hushpowers, does incorporate Cool Shell Technology. Typically, after running under load, a muffler's case will measure about 600* F; Hushpowers will be at about 200*F. This makes them ideal for sidepipe applications. Check out the Cobra video linked from our website; note Bernd's (Bernard? Can't remember his name! Works for Leno) leg resting against the muffler while running the car on the dyno. Try that with any other sidepipe!