Big Bore Exhaust Q's

Post by **forbesg** » Thu Oct 08, 2009 1:41 am

I've seen it posted a number of times & also seen many Brit. vendors talk about big bore exhausts for the minor. What size (OD) is considered big bore for a minor?
I'm guessing 2" (~50mm).
I'm considering building my own (due to cost), can get 1.6mm mild steel pipe for a very reasonable price.
Does anyone have any pictures of one at the rear, to give me an idea of what it would look like.

Post by **PSL184** » Thu Oct 08, 2009 8:13 am

We use 1.5" over here as a "big" bore

Post by **bmcecosse** » Thu Oct 08, 2009 9:45 am

I made one - just followed the route of the standard pipe - but in larger bore pipe! I happened to have a suitable Cooper S straight through silencer - it's fitted in the normal place under the passenger footwell.

Post by **Stig** » Thu Oct 08, 2009 9:58 am

I think mine's about 1.5" (40mm), but to be honest it's not the pipe that's the main restriction, it's the standard silencer.

When I fitted mine the new pipe was damaged in transit but I found that the old narrow bore pipe fitted inside (rather than outside) the output pipe of the new silencer. I ran it like that for a week or two (LCB - new silencer - old pipe) until I got a replacement for the pipe. I didn't notice much difference in performance when I changed the pipe to the bigger one - nothing like as much as the change to HIF38 carb, LCB and better silencer anyway.

That's the Grumpy's large bore system, it's not significantly louder either.

Post by **jonathon** » Thu Oct 08, 2009 11:57 am

1.5" is fine , 2" is too large . PM sent

Post by **forbesg** » Fri Oct 09, 2009 6:47 am

Awesome

Thanks Lads.

-Grant