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Flexi exhaust pipe


FridgeFreezer

Flexi exhaust systems  

17 members have voted

  1. 1. Are they a good idea on an off-roader?

    • Yes
      2
    • Well...
      3
    • No
      12


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Perhaps getting a bit ahead of myself, but when my truck eventually fires into life I'll need a custom exhaust system. A full SS system was my first idea, but they're pricey and I'd cry if I ripped it off on a tree.

The flexi hose stuff can be bought for relatively little money, and rather obviously you can bend it to whatever shape you want (and if you bend it on a tree stump you just bend it right back again).

So, bearing in mind it's a Land Rover not an F1 car, is there any reason not to plumb an exhaust system using flexi pipe?

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Loads of reasons not to …………………………. Flexi being convoluted (sp) will create loads of turbulence to the gases, which is not exactly what you want with the V8 ……. Nice smooth bore pipes that clear the gases quickly are the order of the day. Long lengths of the flexi are also difficult to secure properly and will require loads of extra bracketry.

However, the gas disturbance due to the convolutions does tend to knock out any harmonics, although that statement is more application to air intakes – pre airbox ;) .

Ian

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What about just a few short lengths of flexi? Get some good quality stuff - random I know but my old Primera GT had a flexi joint about a foot long between the frontpipe and the exhaust and it couldn't have been that bad for power as the engines were tuned to 150bhp standard which is a fair bit for an old 2.0 16v.

Failing that I guess you could route it through the bulkhead and along the transmission tunnel inside the cab.. keep you warm in the winter!! ^_^

EDIT: I think it's worth mentioning as well that the flexi pipes were I believe rubber inside with a braided outer so they were smooth. Not the ribbed type as seen on your tumble dryer -those would cause daft amounts of turbulence which you really don't want as Bull Bar Cowboy mentions!

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Joseph - nowt wrong with primeras B)

Ian - assuming the pipe is of decent bore, does it really make THAT much difference? I've got SS tubular manifolds so the first metre of gas flow is down nice smooth tube to the 4-1 collector, plan after that is a balance toob and then out either side of the vehicle for the full stereo surround sound :P

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Cr^p idea.

Either pay the money and have something made Jon, or buy an off the shelf and modify it so as to fit properly.

With the 4.6 you have don't mess it up with a Chav exhaust system

There are a whole load of exhausts bits to cobble about, just a bit of tweaking and welding, 3.9 front end and 300 tdi rear system is a quick and close system

Nige

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Joseph - nowt wrong with primeras B)

Ian - assuming the pipe is of decent bore, does it really make THAT much difference? I've got SS tubular manifolds so the first metre of gas flow is down nice smooth tube to the 4-1 collector, plan after that is a balance toob and then out either side of the vehicle for the full stereo surround sound :P

Fridge, do the job propperly! With all the work that's going into your vehicle you might as well do a decent job with the exhaust. If its designed properly it won't get caught up unless your very unlucky. Remind me on Thursday night and I'll give you the number of someone to talk to.

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I did a short section (about 400 mm) in 75 mm bore flexi when the SUS system I had made for the Mazda 3.5 SLT didn't match up down pipe to the first box between clamps, worked fine on and offroad.

Never experienced cracking of the down pipe which is not uncommon with diesels & SUS systems.

I got a standard 2M length from the local Bosal distributors warehouse at trade (taking the full length) for a little over 8 quid, the remains I still use for directing exhaust out under the garage door years later. :D

I found that if you carefully twist it against the wind of the spiral it will open up a few mm, and can be twisted back again for a tight fit with some gasket paste and finally U clamps. It was completely gas tight. If I was doing it again I think I would use the wide circular clamps for neatness and no other reason.

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Will - there's a very nice toob bender in the workshop with dies up to 2.5", for a twin-exit system that should do it, it's just the lazy factor of flexi that appealed...

If that's BT's Tubela bender - it wont bend exhaust tube without kinking it.

You could try packing it with sand and sealing the ends.

I've got a short piece of flexi on the Ibex, never given any trouble, but its not something I'm proud of.

I'd do it properly.

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Perhaps getting a bit ahead of myself, but when my truck eventually fires into life I'll need a custom exhaust system. A full SS system was my first idea, but they're pricey and I'd cry if I ripped it off on a tree.

The flexi hose stuff can be bought for relatively little money, and rather obviously you can bend it to whatever shape you want (and if you bend it on a tree stump you just bend it right back again).

So, bearing in mind it's a Land Rover not an F1 car, is there any reason not to plumb an exhaust system using flexi pipe?

my comments.

1. flexi stuff is not good for gas flow - convolution and stuff. I don;t know how many horses you loose, ptobably not many. if it were that great, why don;t they fit them on production cars?

2. flexi stuff is thinner so probably won't last as long.

2. how many times have you heard of peole ripping the exhausts off? I've not heard of any but I have heard of the tail pipe getting crushed.

3. how do you propose to unbend the convoluted exhaust? most likely it will crush before bending. to open it out you somehow need to get inside it - I can't see how you can do that.

perhaps look at fitting thicker tube in the vulnerable area(s) and give some thought to routing it. maybe fit bash plates = the latter will be the cheaper and easier option.

BTW I cry too when I see the prices for S Steel free flowing ehxuast + tubualr manifolds. :(

Edited by 02GF74
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Niall - that's a nice price for an exhaust system B)

my comments.

1. flexi stuff is not good for gas flow - convolution and stuff. I don;t know how many horses you loose, ptobably not many. if it were that great, why don;t they fit them on production cars?

2. flexi stuff is thinner so probably won't last as long.

2. how many times have you heard of peole ripping the exhausts off? I've not heard of any but I have heard of the tail pipe getting crushed.

3. how do you propose to unbend the convoluted exhaust? most likely it will crush before bending. to open it out you somehow need to get inside it - I can't see how you can do that.

perhaps look at fitting thicker tube in the vulnerable area(s) and give some thought to routing it. maybe fit bash plates = the latter will be the cheaper and easier option.

BTW I cry too when I see the prices for S Steel free flowing ehxuast + tubualr manifolds. :(

1) They do, as has been mentioned a lot of cars these days have a flexi section from downpipe to system.

2) You can get SS flexi, and at £8 a length I wouldn't mind replacing it more often.

2 (the 2nd one)) I've crushed my exhaust a few times, but if it'd been flexi it would have moved out of the way instead.

3) Spend £8 and replace it :D

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Niall - that's a nice price for an exhaust system B)

1) They do, as has been mentioned a lot of cars these days have a flexi section from downpipe to system.

2) You can get SS flexi, and at £8 a length I wouldn't mind replacing it more often.

2 (the 2nd one)) I've crushed my exhaust a few times, but if it'd been flexi it would have moved out of the way instead.

3) Spend £8 and replace it :D

was only trying to help :( don't know about modern cars; the youngest one I drive is 11 years old.

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