does a decat effect performance on an ek9?


L

loveland

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Oct 15, 2008
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i have an ek9 with a full 5zigen miracle fireball system with no silencers and a decat pipe. very loud.

one of my friends mentioned that an ek9 needs a catalyst as having one without effects performance. is this true?

his argument was that the catalyst creates some back pressure which means more torque. without a cat means the car is more flat.

i always thought by having a decat pipe means exhaust gases escape more quickly meaning more performance. i know that in motorcycles especially dirt bikes, back pressure is very important.

thanks oLi
 
to put it as simply as possible, your mate is talking alot of poo poo :)

Decat = more power over a CAT in every scenerio
 
yes your mate knows nothing

i regularly put my cat in and out when the exhaust does my head in and i always get shocked by the response you get when you put on a decat,
 
I agree about a little bottom end torque been lost as I found this but midrange and topend a good improvement
 
Top end defo, think how much more ignition how much more fuel and how much more combustion which = more exhaust gases. :D

Gases out = better for car, more free flowing!

MORE POWER!!!
 
a de-cat has the potential to create more power but in most cases you will find that it doesnt.
this is only because the ecu is setup to run with a cat so if you remove it in most cases it creates a slight power loss.
you need to remap a car in order to get gains with a de-cat in most cases.
 
Dont listen to your m8 a decat is a good thing on any car that revs very high. As at high rpm the gasses are plentyfull and need to get out quick e.g high exhaust velocity good. So your cat which would at as a restriction will lower gas velocity.

Plus the reason dirt bikes needs backpressure is becuase its 2 stroke and a 2 stroke engine needs the gasses to bounce back then out. My m8 is a biker and was explaining it to me one day but i didnt get it all ( to much drink ) all i know is 2 strokes need backpressure.
 
It's always better without cat, but it depends on which car you do it with how big the results are.
 
yeh i noticed lower torque gains with a catalyst as my bro has got an ek9 with feels manafold and feels fast cat, but to be honest cannot feel much difference.

i know on a EP3 type r there is a sensor in the catalyst and if u decat it you need a simulator so ur ecu thinks u got a catalyst in.

does an ek9 have a sensor in its catalyst as i have not got the original catalyst as it was taken out in japan.

thanks
 
No EK9's dont have any sensor in its cat. The EP3 civic's have two 02 sensors one before cat and one after. EK9's only have the one which is located on the exhaust manifold downpipe
 
rice said:
a de-cat has the potential to create more power but in most cases you will find that it doesnt.
this is only because the ecu is setup to run with a cat so if you remove it in most cases it creates a slight power loss.
you need to remap a car in order to get gains with a de-cat in most cases.
Click to expand...

Wise words!...youll find you somtimes get a power gain from the leaner conditions when its not tuned but over time you'll adversely affect your engine. Flowing more air needs more fuel TUNED via the ECU to get the engine running perfect and reliably (i.e. so your engine doesnt start using lots of oil in the long run!).
 
Eh I always thought ek9 has an o2 sensor on the mani and then a temp sensor of some sort on the cat? Never had a look down there myself tbh though...
 
EK9turbo said:
Wise words!...youll find you somtimes get a power gain from the leaner conditions when its not tuned but over time you'll adversely affect your engine. Flowing more air needs more fuel TUNED via the ECU to get the engine running perfect and reliably (i.e. so your engine doesnt start using lots of oil in the long run!).
Click to expand...

hmm ok well my car has not been burning oil yet. it has been very good. coming up to its first oil filter change and have not needed to top up. it has an AC Tecnik full induction kit on it (Long arm). oil drip tank an oher stuff. took out the passenger footwell plate and found the ECU. its has been moved or tampered with as it was fitted upside down. dont know weather it is stock or not. its big though lol.
well find out code and stuff on car tomorrow as i am working on it thanks
 
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