 | Home > Technical > Removing a cat on a 2011 Defender 110 2.4 Puma |
 
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| K9F Member Since: 12 Nov 2009 Location: Bournemouth Posts: 9610   
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What even with one of his maps? Good excuse to get a hybrid one then.
 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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25th Sep 2014 7:47pm |
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| diesel_jim Member Since: 13 Oct 2008 Location: hiding Posts: 6180 
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I think that without sufficient backpressure the turbo can spin too fast (think of the back pressure as a buffer to stop the exhaust gas from leaving too quickly)
With the turbo going too fast it can cavitate... whatever that means.... sounds expensive though...  |
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26th Sep 2014 8:03am |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558 
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cavitate means it spins so fast that it doesn't actally move anything , water pumps can cavitate (they spin in they own pocket of bubbles ) if spun to fast and its common to fit a bigger drive pulley to slow the pump down on a race engine that revs higher than standard and it eat the impellor away
some ford engines used to suffer with porus blocks if you didn't run antifreeze , said to be caused by the small bubbles collapsing , bit like a ultrasonic cleaner (the bubbles were said to eat the block away inside ) I think its mainly to do with fluids not sure if a turbo can cavitate thought you may like to know !!! |
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26th Sep 2014 8:30am |
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| diesel_jim Member Since: 13 Oct 2008 Location: hiding Posts: 6180
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Every day's a school day! |
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26th Sep 2014 8:53am |
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| SupraAyf Member Since: 08 Sep 2014 Location: Durham Posts: 142 
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Does anyone know the standard boost pressure of a healthy turbo running with a cat fitted against the potential boost spike readings of a turbo with the cat removed.
Also, what boost pressure reading activates an over-boost DTC? - Andrew - |
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26th Sep 2014 10:40pm |
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| landy andy Member Since: 15 Feb 2009 Location: Ware, Herts Posts: 5906 
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Any fan / impeller / propellor can canvitate.
Andy |
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26th Sep 2014 11:13pm |
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| AntonioSC Member Since: 10 Sep 2014 Location: Florianopolis, SC Posts: 6  
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Many thanks, guys. The "surgery" photos were great.
Best |
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27th Sep 2014 12:19am |
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| dgardel Member Since: 30 Nov 2008 Location: Veneto (Heart & Head) Posts: 3586 
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W/o the correct backpressure, when you release the thottle, the turbo continue to spin for inertia.
But engin not more demand for air so the "air column" push the impeller in the exhaust direction very hardly and the axial bearing (not the rotating bearing called radial) could fail....  Click image to enlarge Discovery 5 td6 HSE Stornoway Gray Outback Engineering Limited Edition
IID Pro MV License |
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27th Sep 2014 5:57am |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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trouble is any back pressure is going to be so changeable due to revs and load on the engine , exhaust has to cope with gas flow from tick over (none) to full throttle (lot more)
i know what you mean by load on thrust bearing , but not sure this could be a issue (you see alot of turbos with just a stub exhaust where noise isnt a issue and they cant have any back pressure as you lift of throttle there cant be much if any increase in pressure (to put any more load on impellor) as there is no butterfly in the inlet any excess pressure will go into engine and intercooler , hoses etc right size of exhaust on a n/a engine is inportant as you want exhaust gas scavenging effect something not really needed on turbo engine |
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27th Sep 2014 9:27am |
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