6 replies to this topic

[AGRO_RB]

I'm looking at replacing the standard exhaust manifold and downpipe on my Clubman with some.extractors, I'm just not sure what to go for. The common 3-1 type seems to be cheap as chips and is apparently well suited to small bore engines like my 998. I've also looked at a few LCB designs, is it true that these are only suited 1275 and up? Would there be any detrimental effects using them on a small engine? The free flowing design of the LCB type is what's drawing me to them over the 3-1 type which would have a restriction at the end of the collector. For now my 998 remains exactly as it left the BMC NZ factory although I do plan on tickling things a little if I can't source a decent 11-stud 1275 or a complete 1100.

Also, what size piping should be used for the exhaust? Wanting to convert to center exit with a central single "hotdog" style silencer and either an RC40 back box or twin straight pipes.

[HarrysMini]

I've heard that the 3-1 (Cooper Freeflow) manifold produces more low end torque while the LCB would produce more high end power.

 

Most people tend to use an LCB on a 1275 and a Cooper Freeflow on a 998, but I will probably put a Freeflow on my 1275 as for a road car, low end torque is more valuable.

 

I wouldn't use an LCB on a 998 unless it has been tuned as it is likely to actually lose you power, rather than gain power.

Edited by HarrysMini, 01 December 2013 - 01:41 AM.

[AGRO_RB]

Interesting, I would have thought the longer runner design of the LCB would have helped develop torque over the short runner-to-collector length of the cooper manifold...

Exhausts are confusing

[Dan]

  The Freeflow manifold is a type of LCB (with not quite so long a middle branch), it is not a 3-1.  Tubular 3-1 manifolds are only really any use on very highly tuned race A series engines and are hard to seal anyway.  Small bore engines work best with the Freeflow and the larger engines with the traditional LCB.  It's all down to gas speeds and volumes, engine speed, and the timing of pulses in the exhaust system.  The relative distances between the branches determines when the pulses are introduced to each other.

[timmy850]

You'll need to change the inlet manifold too.. There are a few articles on minispares about different manifolds.. Here is one
http://www.minispare...4b-6d72bfbb88bf

You might be better getting the full kit? This one has a centre exit exhaust
http://www.minispare...px|Back to shop

[jaydee]

As above, the cooper freeflow is an LCB. Now you need to decide whether you want a cooper freeflow or the longer type (Y piece) LCB. One is a one-piece contruction, very reliable and suits better the small bore engines that lacks of low down torque.

The Y piece on the longer LCBs can be a pig if the exhaust is not of the best quality. These will give a better top end though.

[Vipernoir]

On a 998 I tend to use a Magic Pipe and an RC40.

 

Seems to work a treat, and is sooo much easier to live with.