^ also depends on valve lift, duration, and timing though, which doesn't get mentioned there i.e. without a turbo, back pressure is necessary if the valve timing is fixed and matched to the exhaust system i.e. no point installing racing camshafts on a 2.0 Ford Cortina unless you change the exhaust (and carb) as well ...and vice versa
So it's not about back pressure but gas velocity and the flow.
Fair enough, but by removing the cat you're changing the gas removal velocity.
I now consider myself wrong to a certain degree, and will wait for a dyno chart of before and after fitting till I make up my mind for definate.
Thanks to all who have contributed to this discussion. This is what's so great about this forum and it's members. All this info and no 'flaming' of someone that has opposing view. Good work guys! B)
But I know that N/A engines require a certain amount of back pressure to get the engine working at optimum, but FI engines just want to get rid of the gasses asap.
I'd actually agree with that statement, with a slight tweak .... "an N/A engine in a shopping-car requires back pressue due to the way it's designed, but an N/A engine for a racing car does not want back pressure"
Very few articles actually explain the difference that a decat will make to say an engine between 1.4 and 2.0 litres that is normally aspirated. It all seems to be focused on higher power cars that have had the timing etc tweaked.
In all honesty no one is going to get Mega power from a non type R accord
Best thing to do is avoid going over board
I'm now gonna concentrate on handling ordering a Coilover kit and strut braces etc......
Started with some 2.5" stainless pipe I got for free ages ago
Then removed the o2 bung from my old downpipe
Welded that on and polished up the pipe, also bought 1 flange of ebay and machined the two bolt one out to 2.5" (was a old fiesta flange) also ebay spacer
Not sure if its much faster but its louder B)
and raspy!
Would you be interested in making another one I'd be willing to pay you a fair price.?
As the ones online I'm sure won't take a spacer and are more hassle than there worth
I could make one but id need the correct flanges, o2 spacer and o2 bung. It wasnt to bad doing mine as I changed all the flanges and new they would match. If the decats online have a hole for a o2 sensor then the spacer will definetly fit as they all have the smae thread, m18 x 1.5. Only other thing I could suggest would be getting intouch with an exhaust place to make you one? Cas coukd easily do it or there are plenty other places. If your in fife then try chizfab! They now do custom exhaust and im sure it would be more than £50-60. Let me know how you get on.
The sensor is screwed into the cat which requires a 22mm spanner to remove it, mine were very tight! The wiring from the sensor has a plug on the end of it the secondary o2 sensor is there just to monitor the cat so if it did set of a eml it would still run. Thats why you need the spacer to "fool" the sensor.
This has explained everything! Thanks a lot mate! Sorry if the questions were a bit dumb lol
But it's better to have everything properly explained than do something wrong
our 2nd sensor failed and it had an effect on the running of the engine (down on power, jerking on occasions on m/ways), so it does more than monitor the cat.
If you have the facilities to cut and weld a pipe, why didnt you simply cut the internals from the cat and weld it back together?
Thus MOT testerman thinks car still has cat fitted so no issue for test.....
If you have the facilities to cut and weld a pipe, why didnt you simply cut the internals from the cat and weld it back together?
Thus MOT testerman thinks car still has cat fitted so no issue for test.....
Car could still fail a mot on emission though, and I would then have to buy a new cat. This way cost me £19 and il need to remove 5 bolts come mot time.
Also my secondary o2 sensor has just thrown up a fault code. Cars still running fine but il be getting new one asap, should hav changed the both at the same time lol
