Exhaust.

Gary820

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So I don't hijack Chris's thread....
The 80 is going in for a stainless system shortly but I'm very undecided on its exit point. Either rear where it should be, rear but tucked up a bit more or side exit behind the rear wheel.

What have those who've got a custom system done? Looking for ideas/inspiration.
Noise depending I might be able to get away with only the main silencer and ditch the small rear one. Bearing in mind it's a petrol.
 

Shayne

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Chas has a stainless exhaust with side exit if i recall - if Chas ain't broke it then it truly must be indestructible :lol:
 
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Gary820

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I get what you mean where it's routed, it'll be getting a 2.5" cat back system.
I've built my own in the past but on diesels and I thought I'd save myself the hassle lol.
 

stumog

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i have losr the rear silencer on my diesel and it made no differance to mine. i dought it would make that much more on the petrol. i am tempted to see what mine would be like with a straight throw main box?
stu
 

clivehorridge

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I was told the HDJ didn't really need a silencer, 'cos the turbo does a lot of silencing itself.

My HZJ has no turbo so I have a single fat box under the RH seat.

The tailpipe is straight out the back with a slight droop.

IMG_1312.JPG

I was also told that the turbo version is good at 3" dia but for normally aspirated with priority power band 2,800 - 3,500 RPM, less would be better (62mm) to get sufficient "vacuum" in the system.

The petrol version may benefit from that.

I had a thread which may be useful...

http://www.landcruiserclub.net/forums/showthread.php/49180-New-SS-Zorst

My advice is to get one made using the original mountings, otherwise you may have some difficulties when the mountings fail in years to come (the s/s exhaust should have a lifetime guarantee).

Good luck :icon-biggrin:
 
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Chris

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Petrol engines are a bit different though aren't they? They actually need back pressure. Diesels don't really need an exhaust at all. I don't have any boxes in mine from one end to the other. On a petrol, there may be a little more science to it.
 

stumog

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you need back pressure in a petrol. my old golf gti lost the exhaust from ylthe down pipe amd was considerably slower. i would say it needs some thing.

chris what did you mount the middle off? i thought about just cutting the middle box out and putting some flexing in to see how it picked up. is it worth trying.
stu
 

clivehorridge

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Petrol engines are a bit different though aren't they? They actually need back pressure. Diesels don't really need an exhaust at all. I don't have any boxes in mine from one end to the other. On a petrol, there may be a little more science to it.
I'm told turbo diesels don't Chris, but normally aspirated do. That's why I didn't go for 3" and why I needed a silencer too!

I would have thought the petrol would be more similar to my normally aspirated diesel.
 

Chris

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Err, can't remember. But I don't want to hijack Gary's thread after he kindly started this not to hijack mine. I took a std system and just chpped the boxes out. Replaced with straight pipe and welded the hangers back on. Wans't exactly rocket salad.
 

Dave Burgess

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I think I have been told that the only engines that need back-pressure are the BMC 'A' Series and 'B' series with siamese centre ports and they needed it for scavenging out the exhaust gases from nos 2 & 3 cylinders, this leading to the well known Long Centre Branch tuned manifold for the Mini, MIdget, B, etc (and the less well known and expensive Longman 8 port heads). An engine is an air pump into which fuel is introduced and burnt, any back pressure will reduce the flow and therefore the capacity to burn fuel and release its energy. Where some engine benefit from an exhaust is in the sort of 'chimney draw' that a good manifold, collector and pipe will produce (probably why the Golf was flat with a broken pipe.

Silencing is a different subject and will almost always introduce a pressure, even if only by turbulence in expansion chambers and 'free-flow' boxes. You can't have cake and eat it, noise is free flowing air pulses, if it is quiet its been restricted. Noise does need to be controlled to live with it and to keep the law (and neighbours) happy.

Turbo chargers are a good free flowing silencer, simples. When I had the flex pipe break, it didn't sound too bad ( I quite liked the whistle) wasn't too noisy and actually ran better (certainly better fuel economy)! Noticeably different in sound an performance with the 2.5in Longlife Stainless system on it now.

One important role of the pipe on any vehicle is to keep the fumes from the intakes of vents and engines. Fumes entering the cabin can be a serious issue, so making sure the pipe exits into a suitable area outside the perimeter of the outline is essential.
 
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Gary820

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Yeah it needs back pressure more then a td does. 2.5" isn't much bigger then stock diameter. Already re welded a hanger back onto the main box so before it breaks it's having a shiny one.

Chris feel free to hijack as its all exhaust related. Didn't wanna add a load to your thread as its not in context of your build ;-)
 

Gary820

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Had a look underneath this eve, depending on a rear silencer being needed or size of one, there's scope to have it either side exit or out of the way but exit at the rear I'd think
Will have to see what's suggested when it gets done.


Or turbo it a dump the silencers :icon-twisted:
 
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Chas

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I dropped over a rock once and flattened the rear exit pipe so when I had a 3" S/S exhaust made by Charlie at Prospeed I got him to side exit it through the bumper.

20140104_205803.jpg
 
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