Pre-Cat removal
Thread Starter
Race Director
Joined: Nov 2000
Posts: 17,103
Likes: 39
From: stop the fun suckers
Has anyone removed the Pre-cats on their LT1 eqipped vette?!??! Did you still pass emissions.. did you notice any power improvment?!? what did you replace them with
Burning Brakes
Joined: Jul 2001
Posts: 1,038
Likes: 3
From: Clinton IL
I have put a couple of LT-1 engines in other cars (36 Ford Coupe, trucks, etc). None of these applications needed a cat. So, I don't know your status of emission testing.
What I can tell you is the sound will be louder and you may pick up a few more RPM on the power band. The LT-1 with stock style mufflers or flow masters sounds wicked without cats. However, it is very loud at certain RPM levels.
I thought they did not have emission testing in Jax anymore?
What I can tell you is the sound will be louder and you may pick up a few more RPM on the power band. The LT-1 with stock style mufflers or flow masters sounds wicked without cats. However, it is very loud at certain RPM levels.
I thought they did not have emission testing in Jax anymore?
Racer
Joined: Apr 2001
Posts: 413
Likes: 0
From: glendale Arizona
Welcome to the great city of Phoenix, I just passed emissions in Phoenix on my 89 roadster L98 and have gutted pre cats in it and it passed pretty easy, recently they went from the im240 to a more severe test, but you will find that most of the people in the inspection stations know nothing about the corvette, they couldn't slide the mirrow under the car to see if there is a main cat (there is) and seem more concerned that the gas tank held pressure and the gas cap would hold pressure, I really don't think you have a lot to worry about.
traxx1
traxx1
Instructor
Joined: Jul 2001
Posts: 198
Likes: 0
From: Dead center of Seoul
Although I have an L98, and do not have to have an emission test...
I removed the entire exhaust system (only kept the stock exhaust manifold/headers). I put a full flowmaster system with 1 performance cat. Without any other modifications I noticed a performance boost...not as sluggish.
-Dave
I removed the entire exhaust system (only kept the stock exhaust manifold/headers). I put a full flowmaster system with 1 performance cat. Without any other modifications I noticed a performance boost...not as sluggish.
-Dave
Melting Slicks
Joined: Jun 2001
Posts: 2,525
Likes: 1
From: Sarasota, FL
What is the method for gutting cats/pre-cats? My cat is new (about 1 year old) from Midas (I didn't do it!, the last guy did), so I wanna keep it on there, plus the Front Range of Colorado has pretty strict emissions tests (cleared 'em by a mile last month). The pre-cats are stock and I am sure that by opening them up I could get a bit of power. Is there a noticable increase in noise, etc? Please let me know how to do this. thanks, Bob
Thread Starter
Race Director
Joined: Nov 2000
Posts: 17,103
Likes: 39
From: stop the fun suckers
All my cats are currently functioning.. It just seems a little redundant to have a main cat and two pre cats.. i suspect they work more like resonators then "cats" and control noise more than emissions!
Did you guys who removed it feel a noticeable gain?!?! is it worth the effort?
Did you guys who removed it feel a noticeable gain?!?! is it worth the effort?
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Drifting
Joined: Dec 2000
Posts: 1,733
Likes: 0
From: Sarasota FL
Re: (BluByU)
I did this on my car (L98) and it made it slightly louder. New cat construction is more efficient. MAD or Ecklers list a Dynomax Y-pipe w/o pre-cats and matching cat that has CARB certification. I did'nt use it because I wanted the larger 2 1/2" pipe. I can't really say that I can feel a big diference (poorly calibrated butt). It certainly can't hurt it!
Here in VA they do IM-240 but the visual inspection is not hard to beat. Most guys don't have a clue.
Here in VA they do IM-240 but the visual inspection is not hard to beat. Most guys don't have a clue.
Racer
Joined: Oct 2000
Posts: 476
Likes: 0
From: Socorro New Mexico
Re: (BluByU)
I had installed 1:6 rollers, computer chip, a pressure regulator (upped 5psi), and port matched the plenum and runners. Then my pre cats chuncked. I installed the MAD 2.5" stainless Y pipe. I definately noted a difference. I am convinced (by the seat of my pants) that they were a big help, but I also suspect that my pre-cat airflow was a little worse than usual. None the less I'm happy and it was cheaper than replacement.
