Hi All,

I have medium bore LCB fitted to my 1330 with an RC40 box but no centre box so its a bit loud for my liking, I'm considering fitting the Maniflow twin box system to reduce exhaust noise and was wondering if its worthwhile fitting a 2" system, firstly will it bolt straight on? If not I should be able to change the collector to one which will fit a 2" system right? Secondly will 2" improve flow therefore performance or will it reduce performance?

As mentioned its a 1330 Mark 2 S engine with Mk1 Head which has been ported running a 45 Weber, 1.5 roller rockers etc.

Cheers

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Jenk.

The only authoritative data I've seen that examines exhaust system performance is that published by David Vizard....

Coincidentally (perhaps?) he also designed the RC40.

You could insert a resonator to make it a twin box RC40 (which meets ACT noise regs where the single box system doesn't) with no loss in performance.

Or you could spend a lot more money for a questionable outcome.....

Cheers, Ian

I would do as above. Fit a resonator in the centre section and it will take out some of harsher noise.

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1963 Morris 850 Smoke Grey
1963 Morris 850 Shadow Blue
1965 Morris Mini Smooth Van
1966 Morris Mini Van
1969 Morris Mini Deluxe Resto
5/72 Clubman Gt

Thanks 1071 & Scoop... before anyone else suggests fitting a resonator I am aware of that and have considered it... I'm looking for answers to the questions I've asked please

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Jenk.

Are these not the answers to the question you asked???

"The only authoritative data I've seen that examines exhaust system performance is that published by David Vizard...."

"You could insert a resonator to make it a twin box RC40 (which meets ACT noise regs where the single box system doesn't) with no loss in performance..." i.e. You could try a Manifold ..it might be quieter .... and it might not lose much in performance Or you could go with the suggestion ..... which works well ..and is quieter....

You could try a 2" inch system ...which might work with your engine ..or might not.... or you could read DV and decide how his views might impact your specs....... As I said..I don't know of anyone else who has done the level of testing that David has ... and who is willing to document the results of his research.

The bottom line is that no one can give you a direct answer without testing your setup .... The real answer is:

"It depends....."

Cheers, Ian

I was always under the impression that 1.75in was about as big as you should go on a road Mini and that anything over that will lose out on performance and especially torque. I've got a Maniflow 2 LCB on my Mini Van with a twin box RC40 and plenty of sound proofing inside and it's reasonably civilised (for a Mini anyway).

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Slide
1965 Mini Van (1360)
1970 Mk2 Cooper S (1310)
1978 Rover SD1 V8 (4.6)
1996 Land Rover Discovery V8 (4.0)