High Flow Catalytic Converter on downpipe?
High Flow Catalytic Converter on downpipe? I have a cammed LQ4 turbo with a 4" downpipe
The exhaust right now smells extremely bad, due to my cam (I tried messing with EOIT on the tune w/ no luck)
Has anyone used a high flow catalytic converter on their downpipe? How bad would this kill performance?
I would get a 4" high flow catalytic converter.
Any advice?
The exhaust right now smells extremely bad, due to my cam (I tried messing with EOIT on the tune w/ no luck)
Has anyone used a high flow catalytic converter on their downpipe? How bad would this kill performance?
I would get a 4" high flow catalytic converter.
Any advice?
I'm mainly looking to see if anyone on the forum has ever ran a high flow cat on their downpipe
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Get rid of the overlap will help... but you know that.
How far did you run EOIT? You may need to get aggressive with it. You added a bunch of cam duration and trying to skip all the overlap.
You might try open loop and run it richer or leaner... the wideband is probably not accurate with low airflow and overlap. To me lean on gas is much worse than a little rich as far as the eye/nose burn.
Like someone said above e85 smells much better.
If nothing else works I would do the cat with a loudvalve in front of it. Basically skip the cat when in power. Cat placement will be tricky. It needs to get to temp but not too hot.
How far did you run EOIT? You may need to get aggressive with it. You added a bunch of cam duration and trying to skip all the overlap.
You might try open loop and run it richer or leaner... the wideband is probably not accurate with low airflow and overlap. To me lean on gas is much worse than a little rich as far as the eye/nose burn.
Like someone said above e85 smells much better.
If nothing else works I would do the cat with a loudvalve in front of it. Basically skip the cat when in power. Cat placement will be tricky. It needs to get to temp but not too hot.
Last edited by Gabbiani; Dec 20, 2016 at 10:12 AM.
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Verdad Gallardo Sure, you can run a cat on it. Even the "hi-flow" units will probably rob some power. Not like it's gonna explode or anything. Denmah ran one for awhile on a turbo LS. Think it was worth like 60whp or something at his boost levels. (wasn't aftermarket "hi-flow". )
Denmah didn't run a hi-flow converter? he ran a stock converter??? I could see that robbing 60whp lol
Get rid of the overlap will help... but you know that.
How far did you run EOIT? You may need to get aggressive with it. You added a bunch of cam duration and trying to skip all the overlap.
You might try open loop and run it richer or leaner... the wideband is probably not accurate with low airflow and overlap. To me lean on gas is much worse than a little rich as far as the eye/nose burn.
Like someone said above e85 smells much better.
If nothing else works I would do the cat with a loudvalve in front of it. Basically skip the cat when in power. Cat placement will be tricky. It needs to get to temp but not too hot.
How far did you run EOIT? You may need to get aggressive with it. You added a bunch of cam duration and trying to skip all the overlap.
You might try open loop and run it richer or leaner... the wideband is probably not accurate with low airflow and overlap. To me lean on gas is much worse than a little rich as far as the eye/nose burn.
Like someone said above e85 smells much better.
If nothing else works I would do the cat with a loudvalve in front of it. Basically skip the cat when in power. Cat placement will be tricky. It needs to get to temp but not too hot.
That's a good point you brought up about running it richer/leaner. I have it in open loop right now, and running it at stoich via wideband (which smells very strong). I've tried going leaner (17.0 AFR) but the smell gets worse - as you pointed out. I'll rich it up and see what that does. Any advice on the EOIT?
Don't quote me on the power numbers was going from memory. It's on his most recent truck build, think it was a big 8" truck unit. 4" inlet and 3.5" outlet.
https://www.youtube.com/watch?v=C-rl...ature=youtu.be
https://www.youtube.com/watch?v=C-rl...ature=youtu.be
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
Exactly, might be more useful if you stated what cam you are running.
And if you have overlap, and possibly raw fuel passing through, it will kill any cat.
Either use a cam suitable for the application, or get rid of the cat
And if you have overlap, and possibly raw fuel passing through, it will kill any cat.
Either use a cam suitable for the application, or get rid of the cat
I ran high flow cats on it before with no issue at all with the same cam - but it was using two 3" high flow cats off of long tube headers (before turbo install)
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
Not too huge..so what exactly is the smell you're referring to ?
And whether any cat will affect performance, will depend on the size of the cat and whatever performance level you're even at.
But I've never seen a cat help performance, that's for sure.
And whether any cat will affect performance, will depend on the size of the cat and whatever performance level you're even at.
But I've never seen a cat help performance, that's for sure.
Thanks for the reply. With EOIT I went to about 6.2 on my Normal table, while keeping the boundary value at 6.5 (Gen3). Someone suggested I leave the Normal table at stock (5.55 at full temp) and increase boundary to 7.2 - I did that with no change in AFR (should show richer if fuel was sprayed after EVC).
That's a good point you brought up about running it richer/leaner. I have it in open loop right now, and running it at stoich via wideband (which smells very strong). I've tried going leaner (17.0 AFR) but the smell gets worse - as you pointed out. I'll rich it up and see what that does. Any advice on the EOIT?
That's a good point you brought up about running it richer/leaner. I have it in open loop right now, and running it at stoich via wideband (which smells very strong). I've tried going leaner (17.0 AFR) but the smell gets worse - as you pointed out. I'll rich it up and see what that does. Any advice on the EOIT?
So may not be pulling fuel through overlap just air.
I don't like pump gas without cats. Its disgusting with any cam.