Vehicle & Technical > Range Rover
V8 Downpipe, one or two cats?
Jonny Boaterboy:
O.k I have brought a 2m section of flexable exhaust pipe. £27.98 it's galvanised mild steel (not too sure how long it will last! decided to go with that RRB rather than paying £60 for new down pipes as I want to change the whole system for a stainless one in the future so did not want to spend too much on this repair) will there be any problems having flexable exhaust pipe instead of the ridged steel pipe i.e. no support excess noise, poor gas flow as it's got ridges inside??
I've cut the cat out and had a look inside and there were a few bits of lose ceramic in there but not much...... I thought that the whole of the inside of the cat would have had a ceramic matrix in there? if it should have, were has it all gone? not so worry about passing the emissions now as If it passed with the cat in the state, should have no problems without them!
Is it worth using stainless steel bolt to refit to the manifold or just stick with steel?
Range Rover Blues:
I've tried with stainless bolts, they still get rusty.
Can't comment on the flexu pipe as I've not tried it, I'd have suggested looking for decent secong hand downpipes if they don't have to last you too long, they don't suffer form excessive rust that far foreward.
Jonny Boaterboy:
Well I have done it! What a pain in the arse the whole Job was! getting to the manifold down pipe nut's and bolts was difficult and long winded, and then fitting the flexi pipe was just as hard as they were a tight fit, I had to put 4 slots in the exhaust and crush it down to get it to go on! Worth the hassle though, sound is alot nicer, slightly deeper but not too noisy I have added some photos to my gallery, cut one of the cats open.... have a look at the photos
Range Rover Blues:
Err, how do I get to your galery these days :-k
Rossko:
Just to clarify a few points raised along the way.
The Lucas injection system on 3.5/3.9/4.2 EFI will NOT adjust the ignition timing to suit modified exhausts ... it has a conventional distributor, after all.
If the injection system has oxygen sensors, yep as folks say do keep them even if removing cats. It gives better efficiency (i.e. power and economy) than "retro-converting" to sensor-less configuration.
The use of oxygen sensors does indeed allow the Lucas injection system to self-adjust to an extent to cope with significantly free-flowing exhausts, K&N filters, etc. BUT only at light loads, steady state conditions. They do NOT allow any self-adjustment when running full throttle. Everything works off a fixed map then. This system is not smart enough to use long-term fuel trim techniques. So if you are obsessed with max performance you would need a remap. In real life very few people would bother!
When messing with the exhaust, take the oxygen sensors out first and put back last. You might not think it, but they can be very fragile inside. Welding or hammering the exhaust with them fitted will more than likely destroy them internally.
cheers, Ross K
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