3 replies to this topic

[Aaron_Gardner]

basicaly ive got a 998, just put a cone filter and a carb needle in it and i want to upgrade my manifold and exhaust system next. im goin for a centre exit RC 40 system but dont no what manifold to get. are the freeflow maniflow ones the same as just a free flow LCB ?

Im confused lol

[lrostoke]

This is from a Keith Calver article on tuning

Exhaust Manifold.

Progressing back along our route to power, the exhaust manifold is next. The standard iron one isn't too bad for an entirely standard engine, but is less efficient than the standard iron inlet manifold. The fact they are cast as one causes power losses on it's own by creating a severe, power robbing 'hot spot' in the inlet tract. Since separating them is only possible by destroying one or the other, loose the exhaust manifold.

Generally I use and highly recommend the Maniflow 'Cooper Freeflow ' exhaust manifold on SBUs. Originally developed by Maniflow owner Dave Dorrington when he was at Downton Engineering for the 970 S, it definitely has sufficient flow to cope with just about anything a 998 will could throw at it, and is easier to fit/seal than an LCB. Its design also suits the SBUs torque/power curve better than the commonly used LCB. And that's another common pitfall - fitting an LCB to the SBU. Some vendors sell what has become commonly termed the 'standard bore' LCB to fit everything - for exactly the same reasons they sell the 2.0" exhaust systems - it's what the misinformed Mini owners ask for, and there is a very cheaply made 'budget' example available that costs less than a Cooper Freeflow. This 'standard bore' LCB is in fact a 'medium bore' LCB developed for the BBU so is simply too big for the road-going SBU. In back to back tests I've done with this budget LCB and the Cooper Freeflow, I've always found the Freeflow gives better results. Not to mention the fact they last a hell of a lot longer through quality manufacture too!

I also use an LCB on SBU for the road, but this is the pukka small-bore LCB developed by Maniflow specifically for the SBU. The primary and secondary pipes are smaller, as is the tail-piece (fish-tail, 'Y'-piece). It does produce slightly better torque/power curves than the Freeflow but is marginally more expensive and less easy to seal off properly.

From a physical point of view

The following picture shows difference in design of Freeflow and LCB (long center branch) Left is a freeflow, middle is LCB

Edited by lrostoke, 21 May 2009 - 10:31 AM.

[Aaron_Gardner]

Ahhh i see now, so which one isbetter in peoples opinion ? Its just that the LCB ones seem to be alot cheaper

[Retro_10s]

In short:

The LCB is best for engines that are 1275cc upwards.
The Freeflow is better for small bore motors from 850cc to 1098cc.

In my opinion LCB's are generally cheaper because unless you're buying a top quality item they are inferior in build quality - they often fit poorly to the head and the Y-piece can have problems sealing up.

If you want the noise and a cheap manifold that will still work fine on a 998 - get the Budget LCB.

If you want the noise and a slightly more expensive manifold that is more suited to your engine, will help performance more and fit without any problems - get the Freeflow. It's designed with your engine in mind - the LCB is not.

**note - you can now buy something called a 'small bore lcb' from minispares - i have no expeience of these - any one got one - care to add your experiences of it here?