Author Topic: Free Flow or small bore LCB exhaust manifold for 998 build  (Read 798 times)

Offline The_R1_Kid

Free Flow or small bore LCB exhaust manifold for 998 build
« on: November 02, 2017, 09:49:38 PM »
Hi All, This is a great forum. I'm fully restoring a 77 Mini 1000 this winter.

Mini spares accidentally sent me a Free flow exhaust manifold instead of the small bore LCB. They quickly sent the correct LCB, so I now have both to choose from.
Reading about the free flow it seems to be marginally better in the mid range and that is what I tuning for on the 998.

998cc
Twin HS2 with short velocity stack
12G295 head rebuilt with light port work
10.5:1 compression
Kent 266 cam
Shooting for a good street engine with great mid range torque.

Does anyone have experience with either or both exhaust manifolds?

Offline MPlayle

Re: Free Flow or small bore LCB exhaust manifold for 998 build
« Reply #1 on: November 02, 2017, 09:55:29 PM »
No personal experience with either on a small bore engine (998 or 850).  I have had experience with the LCB on a 1275 over the stock cast manifolds.

Another thing to consider in your choice is what type of output from the differential is on your car.  Is is pot-joint, yoke style or hardy-spicer?  The LCB style often has clearance issues with yoke style and hardy-spicer outputs and drive shafts.  The Free-Flow style has fewer issues by reputation.


Offline jedduh01

Re: Free Flow or small bore LCB exhaust manifold for 998 build
« Reply #2 on: November 03, 2017, 10:44:07 AM »
Nice Win!

I personally prefer the Cooper free flow = Less Joints to keep together + tweak over time ( very possible to knock the exhaust on low clearances. more joints to leak with the LCB )

Now for performance= your head being 1275 on a 998 it WANTS to breathe better= the LCB could help do that. might only be better at HIGH RACE RPM... if you use the car there.

I Personally noticed NO Actual performance benefit between the same engine and LCB to Cooper Freeflow = The Cooper Free flow was kept to Clear Yolk Axles + noise reduction.  That was the most win. (quieter cabin)

 I say = Since you have both= Try em out!   Work with it = get a good tune then swap.  Expect to have to re tune.    But the benefit could be found in different ways = from cabin noise vs performance might take you in different directions.


Goodluck!

Offline The_R1_Kid

Re: Free Flow or small bore LCB exhaust manifold for 998 build
« Reply #3 on: November 03, 2017, 11:10:00 AM »
Thanks for the replys looks like I'll install the free flow initally thats a good idea to swap them out as it really isnt that much work.

Oh the head is a small valve 12g295 from a cooper s? 1.2" intake and 1.0" exhaust valves not from a 1275 as far as i know.

Offline jedduh01

Re: Free Flow or small bore LCB exhaust manifold for 998 build
« Reply #4 on: November 03, 2017, 12:14:32 PM »
My Mistake = i was thinking a different Casting number  = different head .  12G940 - 1275

by all means = you have them both.  only invested in one... try them out = sell the one you dont like.  Yes it will require some different exhaust work to reach  but few clamps and changes are easily overcome.

https://www.7ent.com/products/pipe-adapter-freeflow-header-to-maniflow-system-l71.html

Is the typical 'extender' that can be used to make up for the legenth difference in Cooper Freeflow + LCB