16v Cat Q's

toddao · Post by **toddao** » Sun Jan 04, 2009 1:02 pm

Does anyone know what the differences are between the 16v Catalyser and Non-Cat models. I am interested in fitting a Cat ( for considerable tax saving reasons) but realise this simply won't be bolting the thing on - there must be engine management issues etc.
Possibly there are pieces from a 16v Cat donor available - is it possible to bolt the necessary electronics on there or is the engine somehow different? This possible donor also has A/C but I'm not sure I've got the stomach for that.

Cheers

toddao · Post by **toddao** » Sun Jan 04, 2009 2:28 pm

This seems to answer the question. It's possible but too much f'ing about really!

http://www.bx16valve.co.uk/15.html

DavidRutherford · Post by **DavidRutherford** » Sun Jan 04, 2009 2:34 pm

The engine management issues that you need to consider is that the engine must run at lambda=1 with a quite small tolerance. Much outside of Lambda=1 means you will poison the cat.

To do this, you generally need an engine management system with a lambda sensor, which then adjusts the mixture accordingly to keep the engine running at lambda=1

Have you got access to the 16v with the catalyst on it? Easiest thing to do would be to pull the entire wiring loom, ecu, exhaust downpipe etc. and convert it to the later cat spec.

toddao · Post by **toddao** » Sun Jan 04, 2009 4:45 pm

Access will be fleeting as it's heading off to the boneyard. I was hoping that I could swap everything as you describe above David, however ( from the above link):

These differences are acheived using lower height pistons and the common cam pulley arrangement is a #3 inlet cam pulley with a #2 exhaust cam pulley

I don't think I'll have the time or the inclination to swap the different pistons and cams too

DavidRutherford · Post by **DavidRutherford** » Sun Jan 04, 2009 7:35 pm

That wouldn't be essential just to get a catalyst on the engine working properly. Any engine can have a cat fitted to it, providing the mixture is maintained within the limits.

Some of the very late Mini's (austin minis that is) had a catalyst on a carburettored engine, so clearly (almost) anything is possible.

Kitch · Post by **Kitch** » Sun Jan 04, 2009 8:20 pm

The catalyised cars had a few differences (DFW for cat, D6C without)

One of the cams was different (could be both, but think it was just the inlet)

Different pistons (lower comp)

Different ECU

AFAIK that was about it, but there may be smaller harder to notice differences.

Kitch · Post by **Kitch** » Sun Jan 04, 2009 8:20 pm

Ah....you already knew that!

Mike E (uk) · Post by **Mike E (uk)** » Mon Jan 05, 2009 9:54 pm

The carburettor cars (metros etc) with cats were renowned for cat failure.

The mixture control was not accurate enough-and some had manual chokes too IIRC.

Some MOT testers turned a blind eye to the emissions test on these cars.

I doubt if it would be worthwhile converting a BX to cat version, it would be easier to buy a cat version of the car to start with.

Or register your car in another country- much better idea.

Mike

toddao · Post by **toddao** » Mon Jan 05, 2009 11:24 pm

Mike E wrote

it would be easier to buy a cat version of the car to start with

That could be the solution! For the money that I would save having a Cat I've been offered a walking wounded Catted 16v. Just gotta convince the wife that it's sound economics!