De catting, power increases? drop in torque?

[mattgtd]

Just read a post from a Tamoura owner that was running de catted, apparently a well respected tuner advised him that although de catting can raise a few ponies up in the rev range, it often does at the expense of punching a hole in your torque figure - anybody else heard this before?
Also, has anybody actually had a chim rolling roaded before and after de catting it?

[Classichims]

The tittle says it all Matt.
That's it entirely.
Mine with De cat Y but pre cats in was low on torque but revved more freely at the top,
I've just put the cat Y back in and in everything but top revs it's much faster, I've just removed pre cats also and my engine seems much happier without them in place.

[ChilliWhizz]

I was running with no precats, main cat in, and sleeved box, then fitted Clive F Y, and returned box to standard. I RR'd before and after, but even before the 'after' RR the difference on the road was huge. I'd had a slight flat spot in the torque curve, but the 'after' RR showed this had disappeared! It increased mid range torque (hugely) and top end torque and power, about ten extra torques and similar bhp

Must be said though that beastie is quite highly modified, and I think removing the main cat took away a big restriction allowing the full potential of the mods to shine through Engine spec is on my profile if you want a butchers....

[sapper]

I sometime think about if its worth having a cat further down the system similar as it straightens out under the engine. I'm completely cat less, my fuelling is spot on so the cat would only be needed to get rid of the nastiest. I recon there would be space to fit one and the heat would no be so much of an issue down there.
Something like this
http://www.ebay.co.uk/itm/REDBACK-RACING-HIGH-FLOW...

Measurements would need to be investigated but it should work.
Any thoughts gents

Edited by sapper on Wednesday 4th June 21:30

[Classichims]

With the more modded engines with huge torque curves anyway it's probably minimal but a relatively standard engine like mine seems to work well with the main cat in and defo seems to have more torque with it???
I'm going to run mine with the cat in place then swap around again, it doesn't really make sense!
My engine is faster De cat but slower where I really use it 1500- 4500 revs!
The only time I feel the real bhp difference is when I'm over 4500 revs and then the de cat feels really rapid.
In real driving terms my car is more responsive and seems much faster with cat, does any of that make any sense?!!!!?

[locodude]

I can only tell you my specific circumstances but with a new MC1 cam in place of the standard TVR cam and one of clive's de-cat pipes she revs a lot freer than before. The cam certainly made a difference but the de-cat pipe seems to have made her breath a lot better. Standard 4.0ltr No pre-cats std silencer BTW. Oh and she spits flames as well so my mates say, especially noticable in the dark.

Edited by locodude on Wednesday 4th June 21:55

[Classichims]

I've been talking about an original Y de Catted
Maybe Clive has thought of this and his offers some back pressure at lower revs but still removes the gases at high revs more efficiently so works far better.
When I first put the de cat Y in it seemed far quicker and it is, but the engine didn't work in most every day situations very well.