9 replies to this topic

[colinu]

Will be fitting my recently built 1380cc engine soon. I currently have a large bore Maniflow system (2" LCB, pipe, and rear box). Is that best for a 1380cc or should I use a 1 3/4" system instead?
Note this isn't a wild/race build - more of a fast road with manners using a big valve stage4 head and ACD-RS+ cam (no aim to rev this over 6500rpm).

[Gulfclubby]

I'd say if you don't want to rev it too high and have a correspondingly mild cam to go with the engine, the smaller exhaust diameter will give you a little more oomph.

[bmcecosse]

Big engine = big exhaust. It will be fine.

[Guess-Works.com]

or in the middle, 1.7/8"

[Cooperman]

If you have a 2" system already I would say use it.
By choice a 1.75" might be slightly better, but as it's 1380 I doubt you would actually notice any difference.

[E.L.M.O]

Personally for my 1380 I am going 1 3/4" and a 2" pipe.

[colinu]

OK, I'll stick with my Maniflow 2"... and save myself a small fortune (full systems ain't cheap here in the USA).
Or here's another thought...
What if I keep the 2" LCB and back box, and connect them with a 1 3/4" pipe? Maybe a good/cheaper compromise???

[Gulfclubby]

In any case, the difference is going to be marginal at best. I wouldn't spend too much time worrying about this and simply fit the existing setup.

[E.L.M.O]

In any case, the difference is going to be marginal at best. I wouldn't spend too much time worrying about this and simply fit the existing setup.

Yeah I agree with that to be honest, its only something worth deciding if you have neither and need to buy a setup. Go with what you got!

[racingbob]

my system on my 1380 was 2" but was race engine 110bhp at wheels

2" should be fine tho i had other engine 1330 rev to 7000 max and was fine with the same exhaust