Knocking out HoneyComb

[RBVS]

RBVS,

 

Race cars also don't use a hollow cyclinder (knocked out cat) in the middle of their exhaust, they use a straight through pipe as they know the hollow cyclinder increases back pressure.

 

What boost setup have you got to be able to run a minimum of 14psi?

 

Obviously a 14psi wastegate? or a stocker RB20 type wastegate with a gated bleeder?

 

There is no doubt there is power to be had if the cat is replaced with a straight through pipe.

 

Providing the cat you are using supports the kind of exhaust flow levels you are after then a cat is not going to restrict power hardly over a cat converter that has had its guts knocked out. Thats providing the cat is in good working order to begin with. A typical symptom of a stuffed cat is the lack of boost.

I know they wouldnt use a a knocked out cat they would'nt have a cat at all., LOL. I have autronic sm2 which has boost control. I tuned the solenoid to stay closed so it was basicly a pipe from the plenum to actulator. With the cat hollow the exh would flow very well and the wast gate could no flow enough. (needed to be made bigger to run less boost.) The point is that when i put the un guttered cat in it restircts the exhaust enough to make minuim boost 12psi. with just a gutted cat as only change it will run 14psi in the top end. (the ungutted cat is in new condition)

roy,

i new someone was going to be a smart ass and tell me that some race cars use cats, but if they didnt have to do you think they would?

[Roy]

roy,

i new someone was going to be a smart ass and tell me that some race cars use cats, but if they didnt have to do you think they would?

Settle petal, not beign a smart ass....just trying to highlight that thanks to their use in motorsport, there are cats available that dont hurt performance.... hopefully one day the technology will filter down to us.... to tar all cats as power robbing is a little generic and not true.

[knore]

I think that we can all agree to this:

Changing to a straight thru pipe 3", regardless of the flow or size of the cat will increase power.

But is also illegal.

[sweetr33]

does anyone know the process u go through if inspected for a cat and its not there? Or did someone say 10k and someone else repeats what they read and so on?

[Duncan]

A concern is that in NSW they have started setting up roadside defect stations which include EPA testing.

For those betting on putting a cat back in before you get tested watch out...these ones are on the spot.

For road use, I'd personally suggest a full NOS install instead of knocking the cat out....the fine is far less and 100hp is a hell of a lot better than 5rwkw.

I don't think anyone has a problem with no cat for track use

[RBVS]

Settle petal, not beign a smart ass....just trying to highlight that thanks to their use in motorsport, there are cats available that dont hurt performance.... hopefully one day the technology will filter down  to us.... to tar all cats as power robbing is a little generic and not true.

agreed, good point. I not saying all cats are crap as general, but looking at a stock cat i disagree that "if you dont have a pipe through the cat then it does 'nt make a differnce to flow". the stock cat is small and basicly with the mesh knocked out is a oval ''4 pipe. As thats what some people are sudjesting.