What exhaust systems are people with 4EFTE's running?

Mine has a noticeable drone at freeway speeds 100km/h+ kind of like a hmm hmm hmm hmm hmm hmm and gets annoying after 20-30min.

It's fine around town and even at freeway speeds if you are accelerating it goes away, it's just under slight load with i'm guessing back pressure.

My system is just a straight through 2.5in system with a cat.

Should i look at putting a silencer in?

I dont want to sacrifice huge amounts of power but if there is nothing in it i would rather sort it out.

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Starlet Conversion:
http://www.ausmini.com/forums/viewtopic.php?t=15484

There's nothing specific about the drone peculiar to the car and engine you have...so I might throw something in.

It's often a harmonic that is set up in the silencer or the body panels around it. You might try dampening it by putting in sound deadening into the floor space above or below the panel. Sticking it on will dampen the noise and reduce the vibration, just having it there will only dampen the noise a little.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

As said the drone may be harmonic... Try and get rid of it. Harmonics can make even the strongest things crack at the right frequencies...

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If you want more inches, stroke it
Life's a garden.... Dig It!
http://www.ausmini.com/forums/viewtopic.php?t=20746

I had this issue in my old car (not a Mini btw) and was fixed by adding a Hotdog (resonator) in between the cat & muffler and the drone dropped right away. The drone was still audible but the headaches I'd get cruising down the freeway were gone

Ironically, my last Mini only had a single Hotdog in the entire exhaust - no actual muffler was ever installed.

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-Alan
I blame my dad for my love of minis. I think I was conceived in the back seat of one
I also blame my Dad for me being 6' 1" - not really the optimum height for driving a Mini.

Josh,

Definitely sounds like harmonic resonance to me.

Try interrupting the flow, or make the pipework either shorter ot longer.

Some 4x4's have a rubber damper welded onto the piepwork to cancel this out, that may help as well.

Cheers,
Tricky

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"Not Speeding Officer..........Qualifying"

I have a slight drone with mine aswell but not enough to cause any trouble.
I have a hotdog then a straight through muffer and my system is only 2 1/4"

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4efte powered Clubman
supercharged 998 race car

Also where exactly does your tip finish, if its well under your beaver panel it can set up a harmonic vibration through the boot space, if its just past the lip of the beaver panel the harmonics have a much better chance of dissipating sideways, also check your exhaust mounts , if their hard mounted to the body it might be worth seeing if you can fit one or two rubber washers.

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Just turn up the tunes man!!!

Nah seriously, I've got 2.5" - High flow cat - almost straight through (with a bend) muffler and side exit tail pipe and mines pretty quiet really. I do have an extra foot of exhaust length though!

I drove From Kal to Perth and back and didn't really notice any droning and I have hardly any sound proofing in the van.

As said above: Try changing the resonance frequency of the exhaust or surrounding body work. Probably the easiest way would be to try a different muffler. Can be straight through still, but maybe longer or shorter, or use one a straight through muffler with an internal kink. Lukey make some real good ones.

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-James.

Toyota 4EFTE Powered Minivan.
102 Kw @ The Front Wheels....Oh What a Feeling!