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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558  
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are you pushing it a bit harder after changing pipe back , testing so to speak , might be worth leaving it a while before worrying about fuel use to settle back in to normall driving style
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27th Sep 2014 9:14pm |
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| Caterham Member Since: 06 Nov 2008 Location: Birmingham Posts: 6318 
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I know nowt but would be surprised if it wasn’t using more.....
Hence people buy free flow exhausts to get the engine running more efficiently. |
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27th Sep 2014 9:20pm |
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| Lambley Member Since: 20 Apr 2013 Location: Mid Devon Posts: 1435  
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Maybe your right, I have probably been testing it a bit, I'll give it a couple of tanks of fuel and work out what the difference is
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28th Sep 2014 9:52am |
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| bga86 Member Since: 17 Jan 2014 Location: Here and there Posts: 205 
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Simple answer lambley is yes it will use more fuel. With the cat in place the exhaust flow is restricted (all be it slightly) so the engine cannot breath as easily. Did this experiment with my last td5. Tested over 3 tank fills with the cat on and 3 with it off I would get between 30 and 35 miles more from a full tank with it removed
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28th Sep 2014 12:42pm |
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| K9F Member Since: 12 Nov 2009 Location: Bournemouth Posts: 9610 
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Turbo will not spool up as quick so you will naturally give it 'more gas' to compensate. Engine running temperatures will also be up a few degrees making the burn less efficient. 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!! |
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28th Sep 2014 12:51pm |
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| Lambley Member Since: 20 Apr 2013 Location: Mid Devon Posts: 1435
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Thanks bga86, that confirms it then. I'm Going to see Gary at Alive on Thursday to make sure everything is running perfectly so I'm not sure wether to change it back again now.
What do you recon is more restrictive- a centre silencer or cat? |
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28th Sep 2014 12:52pm |
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| K9F Member Since: 12 Nov 2009 Location: Bournemouth Posts: 9610
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My standard offset centrebox was changed for a straight through. Rearbox was removed. A cat is more restrictive in nature due to the internal 'Cell Per Square Inch' CPSI structure. Think it's 400 on a standard diesel cat.
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!! |
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28th Sep 2014 1:01pm |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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I agree with the " more gas to compensate bit but with needing a cyl firing temperature of roughly 550 degrees c I cant see a few degrees running temperature really making much differance |
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28th Sep 2014 1:17pm |
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| Lambley Member Since: 20 Apr 2013 Location: Mid Devon Posts: 1435
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Cheers all.
So, to keep the noise down but power up - I'd be better off with a std centre silencer and rear section but decat front pipe? I've currently got a cherry bomb in the middle |
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28th Sep 2014 1:23pm |
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| bga86 Member Since: 17 Jan 2014 Location: Here and there Posts: 205
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Correct
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28th Sep 2014 2:06pm |
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| pannawonica Member Since: 21 Nov 2010 Location: Clackline Western Australia Posts: 568 
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I have just removed the centre box and cat, not a lot more noise hard to pick really. As I did the mods over a period of time I have to say I was surprised at the gains from removing the centre box. A big plus too reducing the amount of heat coming up the floor.
 I suppose the heat issue is not such a problem for most over there, however when its over 50c well worth it! More to the point is I'm getting about 50k's extra from the tank. |
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30th Sep 2014 9:34am |
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| Naks Member Since: 27 Jan 2009 Location: Stellenbosch, ZA Posts: 2660  
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Hmm, must also remove the centre box as summer is kicking in over here.
It's going to be a hot one this year, expecting 45C+ --
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 Discovery 4 Workshop Manual: https://bit.ly/2zXrtKO Range Rover/Sport L320/L322/L494 Workshop Manual: https://bit.ly/2zc58JQ |
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30th Sep 2014 9:56am |
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| Lambley Member Since: 20 Apr 2013 Location: Mid Devon Posts: 1435
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Thanks again for the replies, I've decided to go back to the original set up I had, decat front, cherry bomb centre and std rear. I can't see the sense in keeping the cat on the front at the cost of 3/4 mpg, seems to go against the 'saving the planet' argument somehow.
As for heat in the system - what about using wrap? I used to do it on my race bikes, it stops the heat coming through the exhaust and keeps it internally, it's probably a load of tosh but on a race bike it was meant to add about 2 bhp. I was going to do it and see if it helps reduce the noise any, if it was wrapped from the from somewhere near the top of the downpipe to the cherry bomb then surely it'd help reduce that 'tinny' rasp and turbo whistle? Just a thought. |
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30th Sep 2014 10:06am |
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| pannawonica Member Since: 21 Nov 2010 Location: Clackline Western Australia Posts: 568
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[quote="Naks"]Hmm, must also remove the centre box as summer is kicking in over here.
It's going to be a hot one this year, expecting 45C+ [/quote]
makes a big difference to the heat coming up from the floor. |
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1st Oct 2014 2:39am |
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