Jump to content


Photo
- - - - -

Exhaust Size Mistake


  • Please log in to reply
9 replies to this topic

#1 ThermalEvent

ThermalEvent

    Mini Mad

  • Noobies
  • PipPipPipPip
  • 123 posts
  • Location: West Suffolk
  • Local Club: n/a

Posted 14 February 2022 - 07:37 PM

I'll have to come clean, I'm after some advice after realising I have ordered the wrong exhaust system from Maniflow.

I measured the 'Y piece' externally on my current exhaust at 1 7/8 and believed this was the size of the exhaust but after comparing what was delivered its not the case.

I have in currently got a 1 3/4 so for obvious reasons the new exhaust does not fit the manifold.

The engine is a 1330cc about 84hp and I'm wondering whether running the 1 3/4 pipe to the 1 7/8 back box with adapter will affect the HP?

My options are either sell the maniflow single centre exit silencer and pipe and cut my losses or adapt the backbox to fit.

Has anyone done this before or got any advice on running a larger rear silencer?

#2 D 'n A

D 'n A

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 99 posts

Posted 14 February 2022 - 09:22 PM

Can't you return it to Maniflow? I'm sure you are not the first one to make this 'mistake'

I just switched from a 2inch back pipe with DTM muffler to a 1 3/4 twin centre exit from maniflow and the engine runs way better in high RPMs.

I am no expert bu any means, but you will lose out on performance a little that would be a shame after spending all that cash to get to 84hp.

I would contact Maniflow if I was you and order the correct diameter.

#3 ThermalEvent

ThermalEvent

    Mini Mad

  • Noobies
  • PipPipPipPip
  • 123 posts
  • Location: West Suffolk
  • Local Club: n/a

Posted 14 February 2022 - 10:05 PM

Can't you return it to Maniflow? I'm sure you are not the first one to make this 'mistake'

I just switched from a 2inch back pipe with DTM muffler to a 1 3/4 twin centre exit from maniflow and the engine runs way better in high RPMs.

I am no expert bu any means, but you will lose out on performance a little that would be a shame after spending all that cash to get to 84hp.

I would contact Maniflow if I was you and order the correct diameter.


I'll have to have a chat with them tomorrow, I ordered it in stainless and took this as a 'custom' order when reading their return policy. I suppose if you don't ask you don't get!

#4 nicklouse

nicklouse

    Moved Into The Garage

  • TMF+ Member
  • PipPipPipPipPipPipPipPipPipPipPip
  • 18,998 posts
  • Location: Not Yorkshire
  • Local Club: Anonyme Miniholiker

Posted 14 February 2022 - 10:12 PM

The 1 3/4 and 1 7/8 slot together don’t they.



#5 ThermalEvent

ThermalEvent

    Mini Mad

  • Noobies
  • PipPipPipPip
  • 123 posts
  • Location: West Suffolk
  • Local Club: n/a

Posted 14 February 2022 - 10:18 PM

The 1 3/4 and 1 7/8 slot together don’t they.


They do at the Y piece but from what I've read it's going to lose some power? I thought (but could be wrong) the best option is to use the 1 3/4 pipe with adapter to backbox rather than 1 7/8 all the way?

#6 nicklouse

nicklouse

    Moved Into The Garage

  • TMF+ Member
  • PipPipPipPipPipPipPipPipPipPipPip
  • 18,998 posts
  • Location: Not Yorkshire
  • Local Club: Anonyme Miniholiker

Posted 14 February 2022 - 10:20 PM

 

The 1 3/4 and 1 7/8 slot together don’t they.


They do at the Y piece but from what I've read it's going to lose some power? I thought (but could be wrong) the best option is to use the 1 3/4 pipe with adapter to backbox rather than 1 7/8 all the way?

 

It will be fine. It is even mentioned on their web page.



#7 ThermalEvent

ThermalEvent

    Mini Mad

  • Noobies
  • PipPipPipPip
  • 123 posts
  • Location: West Suffolk
  • Local Club: n/a

Posted 15 February 2022 - 06:41 AM


The 1 3/4 and 1 7/8 slot together don’t they.

They do at the Y piece but from what I've read it's going to lose some power? I thought (but could be wrong) the best option is to use the 1 3/4 pipe with adapter to backbox rather than 1 7/8 all the way?
It will be fine. It is even mentioned on their web page.

Just checked and sure enough they do:

Maniflow developed LCB with larger centre-pipe, giving more equal and better pulsing, (see new developments) use 1 3/4" or 1 7/8" or RCM exhaust systems, dependng on BHP. ( see fitting kits and gaskets )

I did have the Mini on the dyno with the 1 3/4 exhaust so if I get time I'll do another run and see if there is any difference in HP.

#8 Tones61

Tones61

    Speeding Along Now

  • Members
  • PipPipPipPipPip
  • 440 posts
  • Location: Plymouth

Posted 15 February 2022 - 11:34 AM

Did this on my mpi stainless rc40 to maniflow lcb,
Just fit the system inside the lcb,
You won't notice any difference, :-)

#9 D 'n A

D 'n A

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 99 posts

Posted 15 February 2022 - 02:53 PM

 

 

 

The 1 3/4 and 1 7/8 slot together don’t they.

They do at the Y piece but from what I've read it's going to lose some power? I thought (but could be wrong) the best option is to use the 1 3/4 pipe with adapter to backbox rather than 1 7/8 all the way?
It will be fine. It is even mentioned on their web page.

Just checked and sure enough they do:

Maniflow developed LCB with larger centre-pipe, giving more equal and better pulsing, (see new developments) use 1 3/4" or 1 7/8" or RCM exhaust systems, dependng on BHP. ( see fitting kits and gaskets )

I did have the Mini on the dyno with the 1 3/4 exhaust so if I get time I'll do another run and see if there is any difference in HP.

 

 

The before and after will be very interesting! Little bit of myth busting :) 



#10 Cooperman

Cooperman

    Uncle Cooperman, Voted Mr TMF 2011

  • TMF+ Member
  • PipPipPipPipPipPipPipPipPipPipPip
  • 23,513 posts
  • Location: Cambs.
  • Local Club: MCR, HAMOC, Chelmsford M.C.

Posted 15 February 2022 - 03:19 PM

You won't notice any difference.
You only experience loss of power if you use a well oversize pipe or have twin final outlet pipes.
A modified road 1275 will work with 1.75" or 1.875" pipes.




1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users