been looking threw some sports CAT's for a mate of mine who says that it will increase BHP of his car.
his catalytic converter typically has 400 or 600 cells per square inch (cpsi), and he claims the original cat is restrictive in its flow, typically
allowing an open area of around 55-65%.
the Milltek sports CAT he wants to get quotes
quote:
A Milltek Sport Hi-flow Sports Cat which will be fully integrated into a large bore downpipe, has only 100-200 cpsi depending on application. These cats have an open area of between 75-85%, thus reducing back pressure substantially and increasing flow rates, all very desirable for extracting more performance, especially on turbocharged engines
isn't "sports cat" a contradition in terms?
seriously though a less restrictive one would flow better but would probably not do its job as well, 6 of 1 half a dozen of another
quote:
Originally posted by omega0684
ok, so it may increase flow and reduce backpressure but as it has less 'cells per square inch' does that mean its less efficient and therefore doesn't take as many pollutants out of the exhaust fumes as a standard CAT resulting in increased emissions?
I had Milltek sports cats (actually the complete system including downpipes) on my RS4 and it always sailed through the MoT. These where 100cell sports cats which certainly flowed much better than the standard RS4 cats.
Remember, for the type approval tests and to conform to the legislation!) cats need to convert aroudn 95-99% of CO, HC and NOX when they are warm
(typically after the engine has run for ~60 seconds)
For the MOT you just need a conversion efficiency of around 50%, meaning that it is OK for the catalyst to "let past" 10-50 times as much
CO, HC and NOx (probably not even measured come MOT time, i'm not fully up tot speed on the UK legislation) as during the type approval tests.
So:
MOT: sport cat OK
Type approval test: Sport cat certainly NOT ok.
quote:
Originally posted by sebastiaan
Remember, for the type approval tests and to conform to the legislation!) cats need to convert aroudn 95-99% of CO, HC and NOX when they are warm (typically after the engine has run for ~60 seconds)
For the MOT you just need a conversion efficiency of around 50%, meaning that it is OK for the catalyst to "let past" 10-50 times as much CO, HC and NOx (probably not even measured come MOT time, i'm not fully up tot speed on the UK legislation) as during the type approval tests.
So:
MOT: sport cat OK
Type approval test: Sport cat certainly NOT ok.
for about 300£ + u might get 3-4bhp...
Get considerable more than that on a Turbo car....
Any non type approved replacement cats fitted to a standard tintop 2001 onwards are now an MOT failure.
If you buy a replacement cat it must be type approved for the vehicle it is fitted too.
quote:
Originally posted by britishtrident
Any non type approved replacement cats fitted to a standard tintop 2001 onwards are now an MOT failure.
If you buy a replacement cat it must be type approved for the vehicle it is fitted too.
so what car is it for?
quote:
Originally posted by stevebubs
MOT is also a "visible only" test, so if the sports cats are hidden behind a shield, it would be hard to tell if they were original or not...I'd also question whether some corner street MOT places would recognise OEM vs aftermarket...