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K9F

Member Since: 12 Nov 2009
Location: Bournemouth
Posts: 9610

2008 Defender 90 Puma 2.4 XS CSW Stornoway Grey

jst wrote:
will you get increased turbo lag though?

Theory is the turbo will spool up quicker....

If you go through life with your head in the sand....all people will see is an ar5e!!

Treat every day as if it is your last....one day you will be right!!

18th Oct 2012 8:21pm

jst

Member Since: 14 Jan 2008
Location: Taunton
Posts: 8145

2011 Defender 110 Puma 2.4 USW Stornoway Grey

do you not need resistance to reduce flow to help build pressure to get it spooling?

i can see the benefits of no restrictions at higher flow rates.

i have been toying with the idea of de-cat for a while, in fact have had one on the shelf ready to go for nearly 4 years...... Cheers

James
110 2012 XS Utility
130 2011 M57 bespoke Camper
90 2010 Hardtop
90 M57 1988 Hardtop

18th Oct 2012 8:26pm

ZeDefender

Member Since: 15 Sep 2011
Location: Munich
Posts: 4731

2011 Defender 110 Puma 2.4 SW Baltic Blue

jst wrote:
how long is a while?

That depends on how long hernia surgery takes to heal

Don't imagine I'll be crawling under the exhaust until the dressings come off

And yes - the conflicting turbo, power and emissions theories is why I'm doing it. There aren't many vehicles you can muck about with so easily and reversibly

Tell someone you love them today because life is short.
But shout it at them in German because life is also terrifying and confusing...

18th Oct 2012 9:04pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20561

How easy / difficult is it to remove the cat anyway? Never tried it myself.. KEEP CALM AND Drill ON
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18th Oct 2012 9:14pm

K9F

Member Since: 12 Nov 2009
Location: Bournemouth
Posts: 9610

custom90steve wrote:
How easy / difficult is it to remove the cat anyway? Never tried it myself..

K9F wrote:
landy andy wrote:
You will have to remove the gearbox cross member to get it out tho. Andy

Yes you do! Unless you wish to take drastic action and cut the old exhaust out....the decat pipe can then be manipulated into place without unbolting the gearbox cross member. (I didn't cut mine out but I know a man that did!).

On the Puma the decat being the size of an immersion heater I needed to slightly apply pressure with a jack on the gearbox to give me the extra couple of millimetres room to facilitate the 'cat' removal. Box o' spanners and a couple of hours it should be done whatever method/approach you take. Good luck!

If you go through life with your head in the sand....all people will see is an ar5e!!

Treat every day as if it is your last....one day you will be right!!

18th Oct 2012 9:34pm

jst

Member Since: 14 Jan 2008
Location: Taunton
Posts: 8145

ZeDefender wrote:
jst wrote:
how long is a while?

That depends on how long hernia surgery takes to heal

about 1 week then Cheers

James
110 2012 XS Utility
130 2011 M57 bespoke Camper
90 2010 Hardtop
90 M57 1988 Hardtop

19th Oct 2012 7:37am

DarrenJ

Member Since: 07 May 2012
Location: North Beds
Posts: 312

2011 Defender 90 Puma 2.4 XS CSW Stornoway Grey

Looking forward the facts and figures, great project

Darren

19th Oct 2012 7:49am

ZeDefender

Member Since: 15 Sep 2011
Location: Munich
Posts: 4731

jst wrote:
about 1 week then

Would be nice (but perhaps a little optimistic

)

Just checked with our local mechanic who has agreed to check the emissions before and after decat. Normally he would only measure smoke particles for a diesel, but he says CO2, CO and HC shouldn't be a problem. As long as I don't mention the word "decat" he is legally OK. Pity he can't fit it for me but he would be breaking the law. He also can't measure NOx (EGR blanking) at the exhaust but says it might be possible via diagnostics.
Anyone know about this (I haven't noticed on Scangauge II)?

Matt Tell someone you love them today because life is short.
But shout it at them in German because life is also terrifying and confusing...

19th Oct 2012 8:17am

tatra805

Member Since: 16 Aug 2011
Location: Dolany
Posts: 436

2008 Defender 110 Puma 2.4 CSW Bonatti Grey

i think no exhaust values are measured over the onboard system as the exhaust has no lambda sensors, not even 1 in front of the cat.

There are codes for the scangauge to read out these sensors on other cars but not on this ford engine as far as i know.

Really looking forward to your results, drill and hammer are prepared just waiting for your green light

19th Oct 2012 8:44am

megatoad

Member Since: 07 Jan 2012
Location: Hertfordshire
Posts: 358

2006 Defender 110 Td5 XS CSW Zambezi Silver

What is the legal position in the UK on decatting?

I must admit that the lag on my TD5 is terrible at times, when starting off uphill I have to wind the turbo up a bit before pulling off or it can stall (The wife stalled on Sutton Bank after a bloke pulled out of a layby round the first bend and took 4 attempts to get rolling

serves her right for taking the micky)

I however like to keep things legal so while a decat sounds good, is it legal? He who dies with the most toys wins

Defender 90 & 110, S1 80", Disco 1, S111 88
LRSOC & CVLRC

19th Oct 2012 8:55am

Glynparry25

Member Since: 16 Feb 2009
Location: Miserable Midlands
Posts: 3015

2009 Defender 110 Puma 2.4 XS DCPU Tonga Green

jst wrote:
do you not need resistance to reduce flow to help build pressure to get it spooling?

i can see the benefits of no restrictions at higher flow rates.

i have been toying with the idea of de-cat for a while, in fact have had one on the shelf ready to go for nearly 4 years......

James, it is the complete opposite.

Just think how the turbo works- you need to spin the exhaust turbine wheel as easily as possible. The way this works is by pressure differential.

If the exhaust gas is pushing on one side of the wheel at say 25psi at 1000rpm, 50psi at 2000rpm and 100psi at 3000rpm and back pressure from the exhaust is 50psi the turning force on the turbine wheel is -25psi at 1000rpm, 0psi at 2000rpm and 50psi at 3000rpm.......... so turbo will start to spin after 2000rpm.

If the exhaust is 'straight through' and has a back pressure of 5psi, the turning force on the turbine wheel is 20psi at 1000rpm, 45psi at 2000rpm and 95psi at 3000rpm...... turbo will be spinning are ready to go from below 1000rpm

^^These figures are completly random and there are other factors (such as exhaust pressure increasing at different RPMs, compressor wheel resistance etc) but just as an idea to show how a free flow exhaust helps the turbo.

I have straight through 2.5 "ID exhaust all the way from turbo through to back box which is small and high-flow muffler. I am at full boost by 1250RPM and is pulling like a freight train. I can't use full throttle in 1st gear as the rev counter would go from 1000-4000rpm in about 1 second.

Glyn

19th Oct 2012 9:03am

Caterham

Member Since: 06 Nov 2008
Location: Birmingham
Posts: 6312

2011 Defender 110 Puma 2.4 XS CSW Stornoway Grey

1000 - 4000 rpm in 1 second.........I presume you're not taking about the defender but some petrol hotrod

joking aside if reduced restriction improves spin up on the turbo then I can't wait for my warranty to expire and get rid of CAT.

with the improved low speed spin up of the turbo does the engine need to be re-mapped for any improvement to be realised?

cheers Glyn

19th Oct 2012 9:20am

Naks

Member Since: 27 Jan 2009
Location: Stellenbosch, ZA
Posts: 2646

2010 Defender 90 Puma 2.4 SW Alpine White

Caterham wrote:
with the improved low speed spin up of the turbo does the engine need to be re-mapped for any improvement to be realised?

Only if you want to dice with GTis

Seriously though, no. If you de-cat and remove the centre silencer box, you will be more than happy with the added zoom-zoom at lower revs --
2010 Defender Puma 90 + BAS remap + Alive IC + Slickshift + Ashcroft ATB rear
2015 Range Rover Sport V8 Supercharged

Defender Puma Workshop Manual: https://bit.ly/2zZ1en9
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Range Rover/Sport L320/L322/L494 Workshop Manual: https://bit.ly/2zc58JQ

19th Oct 2012 9:53am

The Boy

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

2009 Defender 110 Puma 2.4 XS CSW Rimini Red

I kept a center box in mine to try and keep a little back pressure but lost the rear. I find the most benefit is low down however others might disagree. Though I run a standard tune 95% of the time with the tune in it will spin the wheels in 2nd on a damp road if you push the loud peddle hard below 2000rpm.

19th Oct 2012 10:14am

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20561

Personally I think the most usable power range would be between 1000RPM and 2500 - 3000RPM above that is only really for a split second. Could also do with a boost in power in 5th and 6th gear always find these gears a little dead.. Although perhaps it's me not using enough revs. KEEP CALM AND Drill ON
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19th Oct 2012 10:29am

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