DIY exhaust change

DIY exhaust change

Author
Discussion

jagawd

Original Poster:

10 posts

91 months

Monday 20th February 2017
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I have a jaguar x type 2.5 with a rusty exhaust. I've been meaning for sometime to put something louder on it. The stock exhaust goes from two manifolds and joins together at downpipe into one pipe then splits into twin mufflers. My plan is to go from the downpipe straight to a performance muffler. So the end of the exhaust will be midway of the car (roughly below gear stick). I know this will be irritating for most drivers due to the droning/vibration. Apart from that, will there be any safety issues? There's a fixed hanger for the back box. I'll be shortening nearly 2 meters of exhaust and exchanging two crappy stocks exhaust mufflers for something a bit more free flowing.

GreenV8S

30,406 posts

289 months

Monday 20th February 2017
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You planning to have a side exit exhaust, or just stop the exhaust pipe somewhere in the middle of the car?

jagawd

Original Poster:

10 posts

91 months

Tuesday 21st February 2017
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It will stop in the middle of the car for now. I'm not to worried about the noise inside the car. Just wondered what over issues I might occur engine wise.

mike_e

588 posts

268 months

Tuesday 21st February 2017
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Don't believe there's an issue with the exhaust under the car, I think it needs to be a certain distance away from doors and exit behind the front wheels. My concern would be gasses entering the cabin. Airflow under the car won't be smooth as the floor isn't flat so gases will swirl around and could get inside. Where's the exit in relation to the fuel tank? Not a good idea to blow hot gasses over that.

jagawd

Original Poster:

10 posts

91 months

Tuesday 21st February 2017
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There should be roughly 1 meter distance between exhaust and fuel tank. I'll probably try to re adjust the angle of the exhaust so that it's not directly blowing fumes towards fuel tank. Although fuel tank is tucked away with a fair amount of protection around it.

liner33

10,755 posts

207 months

Tuesday 21st February 2017
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jagawd said:
There should be roughly 1 meter distance between exhaust and fuel tank. I'll probably try to re adjust the angle of the exhaust so that it's not directly blowing fumes towards fuel tank. Although fuel tank is tucked away with a fair amount of protection around it.
Where did you find that info? As far as I recall as long as the system exits clear of the passenger compartment and is leak free its ok

jagawd

Original Poster:

10 posts

91 months

Tuesday 21st February 2017
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So could having the exit gases exiting below the car midway be a MOT issue? My new back box is on its way from japan today, so have time to plan design

Simpo Two

86,617 posts

270 months

Tuesday 21st February 2017
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jagawd said:
So could having the exit gases exiting below the car midway be a MOT issue?
I'm no expert but can't imagine you can just hack 50% off your exhaust and expect it to pass. I'd check with an MOT bod first. What about the slipstream circulating fumes into the car?

jagawd

Original Poster:

10 posts

91 months

Tuesday 21st February 2017
quotequote all
I'd never really taken the fumes into account. I'm have a re think. I've read the mot handbook and there is nothing saying you can't do it. Although they can fail car if they can't perform emissions test.

stevensdrs

3,221 posts

205 months

Tuesday 21st February 2017
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Has a car ever come off a production line with an exhaust system that terminates under the car? NO it hasn't. There is a good reason for that so don't do it.

PaulKemp

979 posts

150 months

Tuesday 21st February 2017
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I had an exhaust leak about where your planning on exiting yours
I could taste it after a few minutes
It is not a good idea to exit fumes under a car
I have 2 kit cars and both exit in front of the rear wheels, one fully external exhaust and one in the side pods I cannot smell either but boy can I hear them.
My personal opinion is that if you do what your planning to do the result will be both smelly and uncomfortably noisy but then if you gas yourself you probably won't be worried about that

liner33

10,755 posts

207 months

Wednesday 22nd February 2017
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Construction and use regs on exhausts

http://www.legislation.gov.uk/uksi/1986/1078/part/...

jagawd

Original Poster:

10 posts

91 months

Wednesday 22nd February 2017
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Interesting read. Not sure if it says it's OK or not. Definitely a issue with noise though

ruaricoles

1,181 posts

230 months

Wednesday 22nd February 2017
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Doesn't sound a good idea to me, regardless of the potential noise

You're certain to get some fumes (/CO) into the cabin under some driving conditions

At high engine loads you'll have hot exhaust gas blowing out into who knows what underneath - fuel lines, brake lines, wiring

Even at low engine loads at low speeds like in a traffic jam you'll get heat building up under there

Get a proper full-length system for it

liner33

10,755 posts

207 months

Thursday 23rd February 2017
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It has to exit clear of the passenger compartment so to the sides ie Lake or side pipes , to the front ie stacks or to conventionally to the rear

jagawd

Original Poster:

10 posts

91 months

Saturday 25th February 2017
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I'll fit my new muffler at the rear. Bought some flexi pipe, clamps and new hanger. Going for a jap look.