Exhausting...

[Roverranger]

Here's an exhuast question...

I have a 92 RRC, my cats are getting punky on the 'y' pipe. I'm wondering if I can go to a custom exhaust shop and get a new 'y' made up without the cats, for better performance and cheaper too? Do the O2 sensors really do something? Could I just unhook them, or is this a pipe dream?

THANKS...

-Mike

[DallasRover]

I don't know about your area, but I have to have the Cats or I won't pass emission inspection. You need the O2 sensors or your truck will run like crap as they are tied into the fuel injection/emissions system I believe. I am sure some others will chime in but I believe you need them.

[Disco Mike]

Mike,
You can get new cats, on line, thru a muffler shop or order a complete new Y Pipe depending on how much youwant to spend. I don't think you will benefit from the new HiFlow cats and would suggest you check out
http://www.completeexhaust.com/produ...roducts_id=184
Their prices are great.
You could go to Atlantic British and look at their exhaust systems.
Mike J.

[choffa@comcast.net]

Removing the cats is illegal. If NH has annual inspection the truck should fail. The O2 sensors are an integral part of the engine management system, both are needed to control the fuel injection system for each bank of cylinders.

You can replace the cats with universal convertors, about $50.00 each from Summitt Racing. They will require welding to the existing Y-pipe and some custom pipe bending/welding. Straight forward replacement for any muffler shop.

CJH

[OkieRover]

Originally Posted by choffa@comcast.net

Removing the cats is illegal. If NH has annual inspection the truck should fail. The O2 sensors are an integral part of the engine management system, both are needed to control the fuel injection system for each bank of cylinders.

You can replace the cats with universal convertors, about $50.00 each from Summitt Racing. They will require welding to the existing Y-pipe and some custom pipe bending/welding. Straight forward replacement for any muffler shop.

CJH

Okie says x2. Ditto whatever.

[Roverranger]

Hey thanks guys, I figured the O2 sensors were probably needed, I would love to buy on of those stainless systems, but $ouch$$

I think I could get by without the cats here in NH, they are required for inspection, though I've had quite a few older vehicles that I've slid through without issue, and it's old enought whereas it doesn't go through actual emmisions testing. (which we actually just started here this year)

I'll look into just replacing the cats, probably with the universal ones, as I believe the pipes are ok. Though I did find a place in the UK that has pretty good prices for the entire 'y' pipe assembly.

Thanks for the info!!!

-Mike

[loadsalandys]

Just for the record, you can dispense with the cats and the lambda O2 sensors by changing the tune resistor in the efi loom. The ECU's for these engines were designed for both cat and non cat use,and depending upon the type of tune resistor fitted, the ecu is set to work either with or without the sensors.

Whether or not removing cats from a vehicle already fitted is illegal depends upon your local laws, but here, the deciding factor is whether the actual emissions pass, not whether there is a cat fitted.

Removing the need for cats can be useful when an engine and loom is retro fitted to a vehicle which was not originally fitted with cats. Lots of people here take them off in any case, as the emissions can still pass, and if running on lpg which many do here too seeing as petrol is £4.00 a gallon, (about 7USD?) the vehicle is then emissions test exempt, so that's great too.

If you would like more info about tune resistors, like what is it and where is it, I would recommend a look at www.v8engines.com which gives you a wealth of info about all V8 issues.

Cheers, Rob.

[Muddy Oval]

Removing the cats is illegal ANYWHERE in the USA. It doesn't matter if there's local emissions testing or not, it's not legal.
Shop around, but don't buy some no-name junk or you'll be replacing it all again all too soon.

[loadsalandys]

So there then, you are stuck with the blighters.

But here's a case in point. IF you wanted to fit a 3.9 efi to your '72 2 door, would you HAVE to fit the cats too, by law, or does the age of the vehicle dictate that you don't need them on that vehicle seeing as it never had them?

[siam]

Okay I thought the O2 sensors were in front of before the catalist .. So if you were running with no cats it wont matter to the metter reading right? Hmmmm it'll still fail though.. hehehe

[loadsalandys]

Originally Posted by siam

Okay I thought the O2 sensors were in front of before the catalist .. So if you were running with no cats it wont matter to the metter reading right? Hmmmm it'll still fail though.. hehehe

Quite right, in theory yes.

Although it's more usual here to replace the whole set of front pipes with plain ones which don't have the sensors, so it saves the buggery of welding sensors into plain pipes to reset the tune of the ecu. If you just cut the cats out and weld up with pipe, that's fine, and you could use the sensors normally. Certainly for competition, I would have thought you'd not want cats in. For road use, apparently in the US, it's not allowed to remove them if fitted. Don't know about competition rules if that's relevant. Probably not, I'm just waffling in what-if's.

[Muddy Oval]

Last time I checked, if I put a later EFI 3.9 in my 72 which doesn't have cats- I would have to include the emissions equipment of the 3.9 model year of the engine. The vehicle has to comply with the model year of the engine or the chassis/body and if they differ, the more restrictive (newer) sets the standard. Silly isn't it?

[loadsalandys]

Originally Posted by Muddy Oval

Last time I checked, if I put a later EFI 3.9 in my 72 which doesn't have cats- I would have to include the emissions equipment of the 3.9 model year of the engine. The vehicle has to comply with the model year of the engine or the chassis/body and if they differ, the more restrictive (newer) sets the standard. Silly isn't it?

Yes, silly. For once, we seem to have less restrictive practice here! As far as vehicles with chassis go, i.e. Land Rovers and Range Rovers in our case, the whole vehicle identification is taken from the chassis. So you could take a 1972 RR chassis, put a '95 model body and mechanicals on it, and it would carry its 1972 registration number and i.d. number, still be road tax exempt and emissions exempt, the same as any other pre '73 vehicle here. Hence the straightforward swap with the '94 model 4.2 efi which is in my lightweight. No cats and no emission control. Lovely, just like the good old days!