I just removed the CAT out of my 3.5RL [Archive] - The Acura Legend & Acura RL Forum

: I just removed the CAT out of my 3.5RL


Bowl
02-08-05, 04:49 AM
I removed the CAT and replaced it with a direct steel pipe, 2.5" in diameter. I had the shop recreated the bolts on both sides of the steel pipe to resemble those of the CAT's, so I can put the CAT back at anytime.

Result;
The car performs hugely different, almost like driving another car. It has lost a considerable amount of torque, which leads to noticeably more frequent gear shifts in low RPM (somewhat annoying). It has, however, some power gain in high RPM (about 4k and over)... but not much, though. There's no more heat felt around the shift lever, since there's no CAT. BUT!!!!!!!!! the rear-end muffler suffers from much, much more heat, which can be felt in the trunk. I can hardly put my hand on the trunk lining, it was like burning.

Conclusion;
I'll put the CAT back on first thing tomorrow, it's not worth taking it off. It's just better that way. With automatic transmission, torque plays the key role in everyday driving, not HP.

3g Legend
02-08-05, 07:18 AM
thanks for the data collection!

seems as though there is an ideal exhaust design out there to be made that provides the correct amount of back pressure to make torque but also free up some horsepower as well.

That stock cat does seem a bit long though. I wonder why.

Bowl
02-11-05, 04:56 AM
Should I try something else? Perhaps a smaller CAT?

3g Legend
02-11-05, 12:10 PM
Should I try something else? Perhaps a smaller CAT?


question, did you get a check engine light? If the ecu isnt liking the 02 readings past the cat then it will change the fuel and timing maps to try to compensate...so maybe there is a little hp loss there as well.

if no check engine light, maybe try smaller diameter tubing in that section. i would do that first before adding the cat.

is the exhaust note louder?

sleeprlegendcp
02-11-05, 12:14 PM
I would also look into an aftermarket cat like the one DV8 uses. That should keep your back pressure and still free up hp, and keep you legal. This all seems a little futile without comming up with some sourt of muffler and cat back exhaust system.
Later!
Lee

Bowl
02-11-05, 03:56 PM
question, did you get a check engine light? If the ecu isnt liking the 02 readings past the cat then it will change the fuel and timing maps to try to compensate...so maybe there is a little hp loss there as well.

if no check engine light, maybe try smaller diameter tubing in that section. i would do that first before adding the cat.

is the exhaust note louder?
I didn't get a check engine light. So I'll try putting on a smaller tube then. Thanks for your advice :) Oh and yes, it was a bit louder.

Aftermarket CAT? That sounds interesting but I have no idea where to find one... since my RL seems to be one of the very few in Thailand. I might have to import it and that would be very expensive.. Can I put on other model's aftermarket CAT instead? Thanks anyway :confused:

sleeprlegendcp
02-11-05, 05:41 PM
I didn't get a check engine light. So I'll try putting on a smaller tube then. Thanks for your advice :) Oh and yes, it was a bit louder.

Aftermarket CAT? That sounds interesting but I have no idea where to find one... since my RL seems to be one of the very few in Thailand. I might have to import it and that would be very expensive.. Can I put on other model's aftermarket CAT instead? Thanks anyway :confused:

I am sure you can find one in Thailand. The most important part is that you have the pipe sizes the same on your cat and the rest of your exhaust system. With the way you have it now the shop could just cut that test pipe you put in there and weld the aftermarket cat in there. Then you still have your bolts on both ends. While looking around for a cat also look for a muffler. Maybe a Remus universal will work.
Later!
Lee

Thai.95LCoupe
02-11-05, 05:59 PM
The Legend Spec. remus will work on the RL.

sleeprlegendcp
02-11-05, 06:06 PM
The Legend Spec. remus will work on the RL.

There you go! Granted this will cost much more than just removing the cat, but once you hear and feel it you will not question the cost. Good Luck on whatever you do!
Later!
Lee

BTW = Ask that shop about making you a Cold Air Intake for your car. Do this before dumping a lot of money in the exhaust.

Bowl
02-12-05, 05:28 AM
Thanks for all those tips ;) I've been thinking about the cold air intake as well, but I haven't been so serious on that. I wasn't sure if it's gonna make much difference, though.

sleeprlegendcp
02-12-05, 06:18 AM
Thanks for all those tips ;) I've been thinking about the cold air intake as well, but I haven't been so serious on that. I wasn't sure if it's gonna make much difference, though.

Anything that improves upon the OEM intake and exhaust system will help, plus the sound of an intake is really cool. It is up to you. If you do it I would get an AEM bypass valve just to be safe.
Later!
Lee

Bowl
02-14-05, 03:29 AM
What does a bypass valve do anyway?

Volk Racing
02-19-05, 07:01 AM
you can feel heat around the shifter from the exhaust pipes???

Is that normal?

Bowl
02-19-05, 08:38 AM
you can feel heat around the shifter from the exhaust pipes???

Is that normal?

Yes, it gets warm around the metal portion of the shift lever when I floor the throttle (for a little while). The thing is, I can't feel the heat when the CAT was removed, it was just metal cold. It's possible because the CAT is right under the shifter and under extreme revs, it gets red hot. Maybe you won't feel this in the US because the weather there is much colder than it is in Thailand.

JamesG
03-04-05, 04:08 PM
I was about to build a cai for my 97 jdm legend, what is the bypass valve?

Ken
03-04-05, 04:49 PM
I was about to build a cai for my 97 jdm legend, what is the bypass valve?

it is a filter thing that you put on to prevent water from gettting into your engine.

Ken1997tl
03-04-05, 07:42 PM
Or it could be for the Traction Control System

dretype2
03-20-05, 01:41 PM
hi can you tell me wher the transmition computer is located on my 95 4dr gs thanks

draztic1011
04-27-05, 02:44 AM
be careful about the cold air intake because any water that cold air intake sucks up any water up ur engine...... your car is going to be screwed

NWCYCLE
08-13-05, 05:24 PM
You Can Find A Part Call Ehaust Cones , They Fit Right Into The Header Pipe Off Each Cyclinder It Replicates The Exaust Wavelenth Of A Cat, Also Its A Real Pain To Do So, You Can Cure The Exhaust Heat Buil Up By Placing Either Exhaust Rap ( Looks Like The An Ace Stretchie Bandage) Or Building A Heat Sheid And Tac Weld It On Top It Will Provide A Dead Air Spot And Allow Heat To Ratiate Out The Side
All In All , Its Best To Leave It Alone
Have Fun

3g Legend
10-27-05, 06:28 PM
I was about to build a cai for my 97 jdm legend, what is the bypass valve?

James, the bypass valve from AEM is just a precaution in wet conditions. It keeps the motor from sucking a gulp of water and hydro-locking your motor.

Its not necessary if you dont have your air fulter all the way near the ground.