Simple pre-cat query

[Dutchone]

I have read most of the recent threads on the 'whys and where fors' of removing the pre-cats and I don't want to go over it again,but I didn't notice any comments on:
For a serp 500, and ignoring the rather subjective view as to whether removal makes a difference to the sound.

My question is: does the engine benefit from the 'un-restricted' manifolds? My gut feel is NOT as I would hope that TVR designed the 500 manifolds to pass the required volumes of exhaust gas with pre-cats fitted, and that there is no reason for a standard engine to need more.

Or am I being overly naive and there is an improvement to be had in increased gas flow.

Any views especially from you track and race chaps would be worth reading.

Thanks, Paul

[mongoose]

Theres no real noticeable improvement in performance,but it does improve the sound a bit.The best reason to remove the pre-cats,is to get rid of some of that unwated underbonnet heat imho

[old64er]

I noticed an improvement to sound and performance on my 93 griff.

They were fairly full after 12 years of low mileage and one had become detached and started to hit the nearside lambda, which i replaced not too long after.

[Dutchone]

Thanks both,
Mongoose: good to hear from you again - I had forgotten about the reported reduction in engine bay temperature with the pre-cats removed.

Old64er: Similar situation to you with respect to car age and mileage so may be my pre-cats are past their best.
You have given me something to think about anyway and that is what I needed.

Cheers, Paul

[steve-v8s]

Also understand that they are worth removing if they are all clagged up or falling apart. It has been said that ideally you need some cones in the hole to keep the gas flow the same.

[old64er]

steve-v8s said:

Also understand that they are worth removing if they are all clagged up or falling apart. It has been said that ideally you need some cones in the hole to keep the gas flow the same.

I read this before removing mine.
I didn't have the non-reversal cones in and it still drives ok? and made good power and torque on the rollers.

[jonathant]

FWIW I didn't bother getting pre-cats in my replacement manifolds because the cost was a couple of hundred pounds cheaper. I have to say I didn't notice any performance or aural benefits.