high flow cat?
Thread Starter
Racer
Joined: Nov 2004
Posts: 265
Likes: 0
From: Angleton Tx
high flow cat?
I was told my 1990 had a high flow cat. How can this be proven and
are there really some converters that truly give your car more performance? I know they claim to make better flowing converters, although this is regulated by the EPA. Seems they would all be about the same for a particular vehicle. Has anyone changed out the
converter to another brand or maybe even a truck converter and
gotten better results?
are there really some converters that truly give your car more performance? I know they claim to make better flowing converters, although this is regulated by the EPA. Seems they would all be about the same for a particular vehicle. Has anyone changed out the
converter to another brand or maybe even a truck converter and
gotten better results?
Race Director
Joined: May 2006
Posts: 10,691
Likes: 71
From: Phoenix Arizona
All C-4's have "high flow" convertors. Some of the newer ones are better,(marginally). The restriction is actually more in the manifold. Alot of people gut or get rid of the pre cats, or remove the rear ones. I myself believe STRONGLY in keeping cats on a car. For the street, if you plug your ears, you would never notice a difference JMO
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
I would categorize the L98 exhaust restrictions in the following order...
1) Stock mufflers
2) pipe-size (2 1/4)
3) pre-cats
4) main cat
There are cats that have a lower density which improves air flow (over stock). Installing headers without changing the items above would accomplish nothing. Therefore, I believe the exhaust manifold to be the lowest restriction point in the exhaust (though it is the first).
Going from stock (shorties) to long-tube headers has reported gains of 10-15 HP. Changing the items above can exceed that. And, the final cost should be less.
I think the best setup is to convert to duals with pre-cats and an x-pipe, then adjust for sound level. With the exception of configuration rules in certain states, this would pass emissions. If you include headers, you might need more muffler to be happy with the end-result -- and that could offset the extra money spent on manifolds.
1) Stock mufflers
2) pipe-size (2 1/4)
3) pre-cats
4) main cat
There are cats that have a lower density which improves air flow (over stock). Installing headers without changing the items above would accomplish nothing. Therefore, I believe the exhaust manifold to be the lowest restriction point in the exhaust (though it is the first).
Going from stock (shorties) to long-tube headers has reported gains of 10-15 HP. Changing the items above can exceed that. And, the final cost should be less.
I think the best setup is to convert to duals with pre-cats and an x-pipe, then adjust for sound level. With the exception of configuration rules in certain states, this would pass emissions. If you include headers, you might need more muffler to be happy with the end-result -- and that could offset the extra money spent on manifolds.
5th Gear
Joined: Oct 2012
Posts: 5
Likes: 0
I was told my 1990 had a high flow cat. How can this be proven and
are there really some converters that truly give your car more performance? I know they claim to make better flowing converters, although this is regulated by the EPA. Seems they would all be about the same for a particular vehicle. Has anyone changed out the
converter to another brand or maybe even a truck converter and
gotten better results?
are there really some converters that truly give your car more performance? I know they claim to make better flowing converters, although this is regulated by the EPA. Seems they would all be about the same for a particular vehicle. Has anyone changed out the
converter to another brand or maybe even a truck converter and
gotten better results?
and while cruising the sound is not noticeable at all. Just replaced my stock cats with a Magnaflow high flow system, my only regret was not purchasing the O2 sensors
to be installed at the same time. The resonance is definitely noticeable way better sound and acceleration has definitely improved!
Race Director
Joined: Feb 2002
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From: Compound in the Grove, Ga.
2026 Corvette of the Year Finalist - Unmodified
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St. Jude Donor '16
All cats have identifying numbers and or letters, some have tags this will tell you everything about the cat make-up. Any company that recycles cats can decipher the codes. Most aftermarket cats have a wire type internal build most factory cats have a honey comb type substrate.
Last edited by FASTAZU; Jun 25, 2019 at 01:21 PM.
Melting Slicks
Joined: Nov 2007
Posts: 2,830
Likes: 147
From: Gainesville FL
All cats have identifying numbers and or letters, some have tags this will tell you everything about the cat make-up. Any company that recycles cats can decipher the codes. Most aftermarket cats have a wire type internal build most factory cats have a honey comb type substrate.
Race Director
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From: Compound in the Grove, Ga.
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Joined: Feb 2002
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