Removing the Catalytic converter

[unclejemima]

Where I live, they don't do air quality test, so I could ditch the cat...but I also don't want to offend those of the environmental background ;) I would probably only removing the cat for a race I'm planning on entering.

Would it have any effect on the engine computer at all with it missing (dash lights and running issues, ext.)

It is a 20 + year old car now! I imagine the cat would be getting pretty bunged up.

I hope to get a fujitsubo exhaust what is supposed to give a few more hp as well.

With a free-er breathing exhaust, would it run leaner...cause potential detonation and reduce engine longevity, or is the EFI smart enough to compensate for any modifications?

I may do a dyno run before and after the cat to see exactly how much power I gain if any.

[maiku]

the stock cat is tiny and restrictive. if it does help, it would only be a little.
I doubt the computer would care. as long as you put the right fuel and the engine is in tip top shape, there shouldn't be an issue.
and any exhaust will be an upgrade compared to the stock one.

my cat was tiny and clogged. since an OEM one is rare and expensive, my mechanic just put one from a family sedan. it's about 2x the size and does the job nicely.

[steveinjapan]

There is an oxygen sensor in the cat though, so if it's disconnected you'll get a "check engine" error message, which you can ignore of course.

[Steve_M]

The CAT provides a certain amount of back pressure to allow the Oxygen sensor to be able to correctly measure the fuel mixture.

With out this back pressure the oxygen sensor will miss read and most likely cause you a lean mixture which will cause problems with excess cylinder heat and burning of valves.

I can see no benifit to removing the CAT, im certain any gains you may get will hardly noticable. You are probably better off losing a feel pounds of personal weight to see performace gains.

The CAT does have a temp sensor in it, which if removed will cause warning light on dash (Not engine light), but this light does not cause engine miss running/malfunction, it is just Japan regulations, due to overheating CAT will not be effecient.

[Steve_M]

for a race I'm planning on entering.



From my experiences, be prepared for engine rebuild after uses of a Beat on track, extended high revs and high speed cornering.

This is the main reason I no longer own a Beat.

[unclejemima]

From my experiences, be prepared for engine rebuild after uses of a Beat on track, extended high revs and high speed cornering.

This is the main reason I no longer own a Beat.

Thanks Steve.

Did you see this post? http://www.u-ukhbc.co.uk/vbb/showthread.php?p=19910#post19910 I'm betting you are suggesting that this is probably not a good idea.

Just curious what you think about the other Honda motors if you have any experience. The K, B, F and H series I was wondering (K series is new Civic, B series is Old Civic, F series if S2000, and the H series is Prelude)

Does the E07A have any fatal flaws, can it be better rigged for track use?

Would the one run at pikes peak be a bad idea?

Thanks!

[LawrenceHarding]

For the last few years I have been involved with Guernsey Autocross (check it out on YouTube) which is a low contact form of banger racing on a beach. For the past few years the champion has raced a late 80s Prelude. Most of the leading drivers also use Hondas, mainly late 80s/early 90s Civics and CRXs preferably VTEC. This is a low budget sport, mostly using cars which would otherwise be dumped with engines etc remaining standard. Minimum prep requires removal of lights, glass, external trim, mirrors and plastic rear bumpers. Most people gut the interior to save weight, some reposition the rad in the back (less vulnerable) and beef up the front of the car. Really keen Honda drivers fit Acty or Today front brakes which allow the use of 12" wheels with rotovator tyres. Racing is normally done using 2nd gear only and it is usual for cars to be hitting the rev limiter at the faster parts of the track. Despite this abuse some cars go on for years.

[LawrenceHarding]

I forgot to mention, with regard to "cats" that we keep the manifold and downpipe and ditch the rest of the exhaust.