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pannawonica



Member Since: 21 Nov 2010
Location: Clackline Western Australia
Posts: 568

Australia 
Do Decat pipes cause surging problems.
I was looking into the purchase of a good quality decat , however I have heard that they often cause 'surging.' Could you please advise on this matter. Very Happy
Post #168297 14th Sep 2012 7:54am
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The Boy



Member Since: 28 Aug 2008
Location: East Northants
Posts: 1459

United Kingdom 2009 Defender 110 Puma 2.4 XS CSW Rimini Red
Mine has run so much better since geting rid of the cat. It's one of the best mods I have done.
Post #168299 14th Sep 2012 8:04am
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defender4



Member Since: 22 Jun 2011
Location: South East London
Posts: 411

United Kingdom 2007 Defender 90 Puma 2.4 XS CSW Java Black
Ditto. No hint of surging, in fact, a much smoother power curve.
Post #168318 14th Sep 2012 9:11am
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jst



Member Since: 14 Jan 2008
Location: Taunton
Posts: 8341

 2011 Defender 110 Puma 2.4 USW Stornoway Grey
what other effects have people seen

smoother seems common.

i had not heard of surging, any one had any? Cheers

James
110 2010 XS Utility
130 2011 M57 bespoke Camper
90 2010 Hardtop
90 M57 1988 Hardtop
Post #168469 14th Sep 2012 10:13pm
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JWL



Member Since: 26 Oct 2011
Location: Hereford
Posts: 3443

England 2002 Defender 110 Td5 SW Coniston Green
You don't think that some people are mistaking surging with turbo response Question
Post #168498 15th Sep 2012 12:11am
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pannawonica



Member Since: 21 Nov 2010
Location: Clackline Western Australia
Posts: 568

Australia 
[quote="JWL"]You don't think that some people are mistaking surging with turbo response Question[/quote]


Well to be honest I think you have hit the nail on the head. The suggestion of 'surging' came from a quite relaible and genuine person, however they have a big turbo and intercooler with reputatable tune. There actually could be some underlying fault/problem that is not related to tuning. All logic around decats suggests that there cannot really any downsides for the engine. Many thanks. Very Happy
Post #168506 15th Sep 2012 5:13am
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Thud



Member Since: 21 Jul 2012
Location: London
Posts: 667

United Kingdom 2008 Defender 90 Puma 2.4 SW Zermatt Silver
The cat by it's very nature is everso slightly restrictive, slowing down the air flow and everso slightly causing the turbo blades to slow down with the extra pressure.
Get rid of any air flow restrictions and the turbo will be able to do it's thing faster.
If you are feeling a surge, that surge should have been there in the first place.
Post #168512 15th Sep 2012 8:05am
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The Boy



Member Since: 28 Aug 2008
Location: East Northants
Posts: 1459

United Kingdom 2009 Defender 110 Puma 2.4 XS CSW Rimini Red
Quote:
The cat by it's very nature is everso slightly restrictive



and some Thumbs Up
Post #168516 15th Sep 2012 8:15am
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Lorryman100



Member Since: 01 Oct 2010
Location: Here
Posts: 2686

Do you know who made the decat pipe on the surging vehicle? Also who did the remap? Throttle latency is evident on certain earlier OEM fuel files, so what software is the Puma running? Also the supplier of the remap file can tweak the throttle latency. Back to the decat pipe, did it come from a tuning company or is it a generic copy?

Removing the cat does allow the turbo to spin faster as the back pressure is reduced, however if the decat pipes diameter is to constrictive or overly large this can cause more issues. If the pipe is overly large in diameter it reduces the velocity that the exhaust gases are released, and if the pipe is too constrictive it will reduce the exhaust flow and result in more back pressure than the originally fitted cat. Proper piping diameter provides an optimal level of exhaust flow and velocity with minimal backpressure allowing an engine to reach full potential and efficiency.
Backpressure constricts exhaust flow. Backpressure also dirties the clean air/fuel mixture injected into engine cylinders during combustion. Backpressure is ever present in vehicles engine/exhaust, but harmful when excessive. A running petrol or diesel engine produces a lot of exhaust and heat that needs to be removed from the engine to allow it to run properly. A blockage of exhaust in the engine can cause a back flow of exhaust into the engine, causing the vehicle to be sluggish. Some back pressure is needed in an engine and the catalytic converter and muffler provide that; too much back pressure, however, can cause problems as can too little.
So to me it sounds as if the surging issue is to do more with the electronic side rather than with the decat pipe.

Brian.
Post #168525 15th Sep 2012 9:35am
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T1G UP



Member Since: 08 Dec 2009
Location: Bath
Posts: 3101

England 2011 Defender 110 Puma 2.4 XS CSW Orkney Grey
hence the reason i want to de cat a standard pipe. I'll be picking mine up next week.
Post #168526 15th Sep 2012 9:45am
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JWL



Member Since: 26 Oct 2011
Location: Hereford
Posts: 3443

England 2002 Defender 110 Td5 SW Coniston Green
Ah the beauty of a Td5, just roll back to a pre cat downpipe Whistle
Post #168528 15th Sep 2012 9:56am
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T1G UP



Member Since: 08 Dec 2009
Location: Bath
Posts: 3101

England 2011 Defender 110 Puma 2.4 XS CSW Orkney Grey
JWL wrote:
Ah the beauty of a Td5, just roll back to a pre cat downpipe Whistle


yep! £25 for 1999 td5 front pipe, straight swap and you'l get £40 for the cat Thumbs Up
Post #168529 15th Sep 2012 10:01am
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JWL



Member Since: 26 Oct 2011
Location: Hereford
Posts: 3443

England 2002 Defender 110 Td5 SW Coniston Green
I bought a new one from the motor factor neighbour next door at £32 and with a 2 year guarentee!

So what do they actually guarentee? I mean it's just a bit of pipe, if it gets bent then most probably it's your fault driving over that rock. It isn't going to rust away in 2 years, it's under a Land Rover getting dripped on euth finest quality oils! If it comes detached from the rest of the system it's because you didn't fit it properly. So all in all it's like a Britpart warranty, as much use as one of their parts in the first place Whistle
Post #168543 15th Sep 2012 10:55am
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mk1collector



Member Since: 17 Sep 2009
Location: West Yorkshire
Posts: 6772

England 2004 Defender 110 Td5 CSW Bonatti Grey
Will the 1999 front pipe fit a 2004 td5 110 and does anyone know the part number as all the "decat" ones are around £80
Cheers
Ray
Post #168606 15th Sep 2012 8:45pm
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T1G UP



Member Since: 08 Dec 2009
Location: Bath
Posts: 3101

England 2011 Defender 110 Puma 2.4 XS CSW Orkney Grey
mk1collector wrote:
Will the 1999 front pipe fit a 2004 td5 110 and does anyone know the part number as all the "decat" ones are around £80
Cheers
Ray
YES, and no! but they are around £30 at a motor factors
Post #168613 15th Sep 2012 8:56pm
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