Post #1
Now, this might be a silly question, so my flame suit is on already...Would a decat give better MPG than a standard catalytic converter (or even a sport cat)?
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danposs86's GTi-6
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displaying posts 1 to 23 of 23
| Author | Subject: Decat and MPG |
 danposs86
Regular  Location: Sedbergh Registered: 18 Jun 2011 Posts: 287 Status: Offline |
Would a decat give better MPG than a standard catalytic converter (or even a sport cat)? |
 Posted 26th Mar 2012 at 14:27
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smegal
Seasoned Pro  Location: Leeds Registered: 26 Dec 2005 Posts: 5,940 Status: Offline |
Post #2
Probably worse as the low down torque is lower. ________________________________________ Ex SC-6Now in a Megane R26 |
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Posted 26th Mar 2012 at 14:29
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stan_306gti6
Forum Admin Location: Kent Registered: 18 Jan 2004 Posts: 21,769 Status: Offline |
Post #3
Its also much freer revving at the top and I'm sure that would give an incentive to use the revs more thus using more fuel...I don't think you would see an increase in MPG to be honest.  ________________________________________ "Supercharged - 454.1bhp/317.5lb/ft"Peugeot 306 GTi-6 2000 (X), Moonstone  |
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Posted 26th Mar 2012 at 14:47
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dragoon
Seasoned Pro  Location: Ghent - Belgium Registered: 30 Dec 2008 Posts: 1,071 Status: Offline |
Post #4
terribly worse mpg on a (semi-)standard engine.zero torque, but revs like mad and those bloody addictive backfires  ________________________________________ Team WheelwhoreTeam Limited Edition Astor 306 Francorchamps RIP Virtual Blue 208 GTi quote: I this place. So many illiterate deluded fool's acting 'ard . . . and so many literate intelligent people to rip them apart and knock them back down again . . . ahh  |
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Posted 26th Mar 2012 at 19:05
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monty-69
Senior User  Location: Colne Registered: 02 Jul 2006 Posts: 792 Status: Offline |
Post #5
I have found no noticeable loss in torque or mpg with a decat fitted.  |
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Posted 26th Mar 2012 at 22:07
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mattgti6phase2
Seasoned Pro  Location: inside my 6 abusing the tarmac!! Registered: 16 Jul 2010 Posts: 2,371 Status: Offline |
Post #6
My car made more than standard torque with a decat. Also torque was good from 2k up to peak. ________________________________________ Team Nile 6 Team: 40.2 MPG 5 x a 306 owner! currently abusing type r's in a town near you ™  I truely live for the 306 ® Build date: 29th October 1997 Wednesday's car midweek madness  |
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Posted 26th Mar 2012 at 22:10
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dragoon
Seasoned Pro Location: Ghent - Belgium Registered: 30 Dec 2008 Posts: 1,071 Status: Offline |
Post #7
I presume you guys still have the standard mid-section and perhaps even the backbox? because a decat, straight mid section and an almost straight through rearsilencer = zero torque________________________________________ Team WheelwhoreTeam Limited Edition Astor 306 Francorchamps RIP Virtual Blue 208 GTi quote: I this place. So many illiterate deluded fool's acting 'ard . . . and so many literate intelligent people to rip them apart and knock them back down again . . . ahh |
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Posted 26th Mar 2012 at 23:44
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monty-69
Senior User Location: Colne Registered: 02 Jul 2006 Posts: 792 Status: Offline |
Post #8
Standard centre and tryed both standard and scorpion back box. All the 6s i have driven with poor low down torque all had induction kits fitted Doesnt the airbox have a reduced diameter pipe fiited inside it to speed up airflow? |
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Posted 27th Mar 2012 at 00:10
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mattgti6phase2
Seasoned Pro Location: inside my 6 abusing the tarmac!! Registered: 16 Jul 2010 Posts: 2,371 Status: Offline |
Post #9
dragoon wrote: I presume you guys still have the standard mid-section and perhaps even the backbox? because a decat, straight mid section and an almost straight through rearsilencer = zero torque Full stainless from the mani back. Straight through mid silencer and straight through rear silencer. I find mine pretty grunty in any gear and the RR showed that. Although I believe the secret to a good exhaust system is having it built properly. My bore is smaller than standard to compensate the loss of back pressure provided but the cat. IIRC my results were 150 torques and 125 ish of those torques come from 2.5k rpm and build all the way until it peaks. ________________________________________ Team Nile 6Team: 40.2 MPG 5 x a 306 owner! currently abusing type r's in a town near you ™ I truely live for the 306 ® Build date: 29th October 1997 Wednesday's car midweek madness |
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Posted 27th Mar 2012 at 00:18
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stan_306gti6
Forum Admin Location: Kent Registered: 18 Jan 2004 Posts: 21,769 Status: Offline |
Post #10
I have a Devil Decat, straight through centre section and 4" Magnex backbox with no baffles now.I agree that this system probably loses torque but obviously because my car is supercharged this doesn't affect it. If you were running this setup NA I would think that you would use more fuel trying to get the car accelerating due to the lack of torque.  ________________________________________ "Supercharged - 454.1bhp/317.5lb/ft"Peugeot 306 GTi-6 2000 (X), Moonstone |
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Posted 27th Mar 2012 at 15:54
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coskev
Seasoned Pro  Location: Oswestry Registered: 01 Nov 2009 Posts: 3,132 Status: Offline |
Post #11
dragoon wrote: I presume you guys still have the standard mid-section and perhaps even the backbox? because a decat, straight mid section and an almost straight through rearsilencer = zero torque Disagree soz Mine had higher torque on a rolling road day than cars with cats and standard exhausts,mine had a Magnex de-cat and full system. Also my fuel consumption is higher with cat fitted for sure ________________________________________ Red GTB1756 powered Fabia VRS daily driver,LBSC Gti6 eater........Mac1 ZR R1 kit car build in progress. |
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Posted 27th Mar 2012 at 20:30
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dragoon
Seasoned Pro Location: Ghent - Belgium Registered: 30 Dec 2008 Posts: 1,071 Status: Offline |
Post #12
I experience something totally different then(full devil system with a probably tad too big bore) ________________________________________ Team WheelwhoreTeam Limited Edition Astor 306 Francorchamps RIP Virtual Blue 208 GTi quote: I this place. So many illiterate deluded fool's acting 'ard . . . and so many literate intelligent people to rip them apart and knock them back down again . . . ahh |
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Posted 27th Mar 2012 at 23:09
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mattgti6phase2
Seasoned Pro Location: inside my 6 abusing the tarmac!! Registered: 16 Jul 2010 Posts: 2,371 Status: Offline |
Post #13
dragoon wrote: I experience something totally different then (full devil system with a probably tad too big bore) Bore size is important when you have no cat. Mine has been reduced to conpensate having no cat and it has lovely back pressure. As Stan said bigger bores don't matter when your running forced induction ________________________________________ Team Nile 6Team: 40.2 MPG 5 x a 306 owner! currently abusing type r's in a town near you ™ I truely live for the 306 ® Build date: 29th October 1997 Wednesday's car midweek madness |
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Posted 28th Mar 2012 at 00:51
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jord294
Seasoned Pro  Location: somewhere in north wales Registered: 09 Nov 2009 Posts: 3,119 Status: Offline |
Post #14
Well, the economy in my Rallye has improved since fitting sports cat and exhaust system off miles.I put exactly 45 litres of esso super unleaded in (10 gallons), and the car has just returned 37 mpg Now you're all thinking, I must drive like a faggot! Pure and simply, when on a steady run, it's down to when I change gear. With the sound of the exhaust note and revs, I'm changing through the gears at approx 2k rpm. Any more than that and it sounds over revving. ________________________________________ FRESHLY RE-FURBISHED GTI BEAMSFITTING AND LOWERING AVAILABLE. ALL AXLES BUILT USING GENUINE PEUGEOT PARTS IF I'M NOT HERE, IT ONLY MEANS ONE THING.... I'M SOMEWHERE ELSE! |
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Posted 4th Oct 2012 at 08:39
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coskev
Seasoned Pro Location: Oswestry Registered: 01 Nov 2009 Posts: 3,132 Status: Offline |
Post #15
jord294 wrote: Now you're all thinking, I must drive like a faggot! Pure and simply, when on a steady run, it's down to when I change gear. With the sound of the exhaust note and revs, I'm changing through the gears at approx 2k rpm. Any more than that and it sounds over revving. That confirms you drive like a faggot!!!! Changing gear at 2k rpm in a car thats peak power is at circa 6krpm=faggot  ________________________________________ Red GTB1756 powered Fabia VRS daily driver,LBSC Gti6 eater........Mac1 ZR R1 kit car build in progress. |
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Posted 5th Oct 2012 at 09:59
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welshpug!
Capt Pedantic  Location: Bigend, Wales. Registered: 27 Mar 2007 Posts: 25,870 Status: Offline |
Post #16
mattgti6phase2 wrote: As Stan said bigger bores don't matter when your running forced induction oh yes they do  ________________________________________ need a part number? get on here - http://public.servicebox.peugeot.comBring on the Trumpets. |
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Posted 5th Oct 2012 at 10:03
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swiftyboi006
Seasoned Pro  Location: Maidenhead Registered: 12 Apr 2010 Posts: 2,110 Status: Offline |
Post #17
coskev wrote: this is exactly what i was about to post jord294 wrote: Now you're all thinking, I must drive like a faggot! Pure and simply, when on a steady run, it's down to when I change gear. With the sound of the exhaust note and revs, I'm changing through the gears at approx 2k rpm. Any more than that and it sounds over revving. That confirms you drive like a faggot!!!! Changing gear at 2k rpm in a car thats peak power is at circa 6krpm=faggot  ________________________________________ cherry p1.....SOLD (regreting this)blaze p2.....why did i buy this SOLD Black p3 |
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Posted 5th Oct 2012 at 19:19
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jord294
Seasoned Pro Location: somewhere in north wales Registered: 09 Nov 2009 Posts: 3,119 Status: Offline |
Post #18
Funny feckers!It's just proving how good these cars can be on fuel. I still had quite a bit of spirited driving within that tank full which p**sed off a couple of modern hot hatch owners  ________________________________________ FRESHLY RE-FURBISHED GTI BEAMSFITTING AND LOWERING AVAILABLE. ALL AXLES BUILT USING GENUINE PEUGEOT PARTS IF I'M NOT HERE, IT ONLY MEANS ONE THING.... I'M SOMEWHERE ELSE! |
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Posted 5th Oct 2012 at 20:46
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mattgti6phase2
Seasoned Pro Location: inside my 6 abusing the tarmac!! Registered: 16 Jul 2010 Posts: 2,371 Status: Offline |
Post #19
welshpug! wrote: mattgti6phase2 wrote: As Stan said bigger bores don't matter when your running forced induction oh yes they do Oh no they dont Bigger bore on a turboed motor is better obviously within reason, on SC you don't really need to increase the bore but can without any issue.There is far less need to retain back pressure on a turbo motor. Of course you already know this ________________________________________ Team Nile 6Team: 40.2 MPG 5 x a 306 owner! currently abusing type r's in a town near you ™ I truely live for the 306 ® Build date: 29th October 1997 Wednesday's car midweek madness |
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Posted 7th Oct 2012 at 02:15
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gnrlee
Forum Admin Location: Leeds Registered: 20 Aug 2005 Posts: 8,891 Status: Offline |
Post #20
I f**king love my de-cat balls to the cost! I live for the 6!!! ok p**sed up and the bed is calling! ________________________________________ Proud Member of the ASTOR Owners Club |
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Posted 7th Oct 2012 at 04:38
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thugpuggin
Seasoned Pro  Location: Bristol Registered: 10 Apr 2004 Posts: 26,784 Status: Offline |
Post #21
gnrlee wrote: I f**king love my de-cat balls to the cost! I live for the 6!!! ok p**sed up and the bed is calling! Quoted before you sober up and re read this post. ________________________________________ Black X Reg PIII.VGTi 6 A4212 pt 1 A4212 pt 2 Searching the streets of Bristol for 1.36p/day.Joint Kent Leader |
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Posted 8th Oct 2012 at 23:16
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oecken
Seasoned Pro  Location: Mt Cook, New Zealand Registered: 17 Feb 2009 Posts: 4,751 Status: Offline |
Post #22
coskev wrote: dragoon wrote: I presume you guys still have the standard mid-section and perhaps even the backbox? because a decat, straight mid section and an almost straight through rearsilencer = zero torque Disagree soz Mine had higher torque on a rolling road day than cars with cats and standard exhausts,mine had a Magnex de-cat and full system. Also my fuel consumption is higher with cat fitted for sure +1 Full magnex with decat, screw the fuel consumption i loved it pop, bang, flame ________________________________________  Ex-Black 6  - Speed has never killed anyone, suddenly becoming stationary... That's what gets you. |
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Posted 8th Oct 2012 at 23:37
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stan_306gti6
Forum Admin Location: Kent Registered: 18 Jan 2004 Posts: 21,769 Status: Offline |
Post #23
Even before mine was first charged, I loved the noise of the exhaust setup. It was so crisp on a nice chilly morning breaking the silence. ________________________________________ "Supercharged - 454.1bhp/317.5lb/ft"Peugeot 306 GTi-6 2000 (X), Moonstone |
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Posted 9th Oct 2012 at 07:23
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