12 replies to this topic

[HarryMini93]

Was just wondering what exhaust setup will be best for my 998cc engine, i'm thinking some like this:
- Cooper freeflow manifold
- Maniflow side exit exhaust 2" twin box

Let me know what you guys think or even what exhaust system you run on your 998.

Thanks
Harry

[Spud_133]

Cooper free flow and rc40 twin box. Anyone who says that a twin box is too small and restricts power is wrong on the vast majority of minis as I have the above, just with a lcb on my 1293 and it still chucks out 93bhp

[lawrie124]

Cooper free flow and rc40 twin box. Anyone who says that a twin box is too small and restricts power is wrong on the vast majority of minis as I have the above, just with a lcb on my 1293 and it still chucks out 93bhp

 

agreed

[Andy!]

rc40. Failing that, any 1.75 inch diameter exhaust. It's been proven to be the optimal size for the 998cc engine

[HarryMini93]

Cooper free flow and rc40 twin box. Anyone who says that a twin box is too small and restricts power is wrong on the vast majority of minis as I have the above, just with a lcb on my 1293 and it still chucks out 93bhp

Thanks for the reply, what diameter would you reckon? I was thinking 2" as they sound really nice.

[petechap]

1.75", the bigger it is the more power you will loose 

[Spud_133]

1.75" on mine. But I can't hear what it sounds like through the twin carb roar.

[blacktulip]

stage 1 kit from minispares, job done, the RC40 can handle outputs up to 120bhp according to Vizard.

[BVY]

2" is too big. You will definitely lose power!

[Burnard]

rc40. Failing that, any 1.75 inch diameter exhaust. It's been proven to be the optimal size for the 998cc engine

 

Wrong.

2" is too big. You will definitely lose power!

Wrong.

 

 

 

Over the past few months me and a colleague have been looking into exhaust gas flow and the vast majority of what gets said on here about mini exhausts is wrong.

The truth is that it depends. The best size for MOST 998's, is closer to 1.65inch. 1.75 is sold because its the best compromise between the 998 and 1275 engines. In truth, it is too small for 1275, and too big for 998.

The biggest gains will be seen from the manifold its self, everything that follows is largely irrelevant, but that really depends on where you want the power.

Im not going to expain myself because quite frankly it would take too long and is not worth my time seen as you wont be spending the money.

What you do want is a cooper freeflow manifold from maniflow, along with a 1.75 inch center section (box or no box makes no difference to the power) then to a single tail pipe back box.

If your engine is anything close to standard and you can be bothered, spend the money and get a 1.65inch manifold back system made, and have the freeflow manifold made up to match that. but this will cost quite allot more than off the shelf stuff.

[Dan]

  Burnard are you describing the inner diameter or the outer diameter?  And I would like to know about your testing because your statement about the centre box and system layout directly contradicts all the real world testing of physical components that has been done over the decades.  All the real world testing has found that the Freeflow manifold and side exit, twin box RC40 style setup is the best for the small bore engine.

[Wright&Wright]

 

rc40. Failing that, any 1.75 inch diameter exhaust. It's been proven to be the optimal size for the 998cc engine

 

Wrong.

2" is too big. You will definitely lose power!

Wrong.

 

 

 

Over the past few months me and a colleague have been looking into exhaust gas flow and the vast majority of what gets said on here about mini exhausts is wrong.

The truth is that it depends. The best size for MOST 998's, is closer to 1.65inch. 1.75 is sold because its the best compromise between the 998 and 1275 engines. In truth, it is too small for 1275, and too big for 998.

The biggest gains will be seen from the manifold its self, everything that follows is largely irrelevant, but that really depends on where you want the power.

Im not going to expain myself because quite frankly it would take too long and is not worth my time seen as you wont be spending the money.

What you do want is a cooper freeflow manifold from maniflow, along with a 1.75 inch center section (box or no box makes no difference to the power) then to a single tail pipe back box.

If your engine is anything close to standard and you can be bothered, spend the money and get a 1.65inch manifold back system made, and have the freeflow manifold made up to match that. but this will cost quite allot more than off the shelf stuff.

 

 

Burnard if it's not too much trouble I'd really like to see any data you and your colleague have collected as I'm very interested to see your results.

 

As for the exhaust size HarryMini, i've got a cooper freeflow manifold and a single box centre exit 1.75" system from maniflow too.

 

It pulls so much better than the 2" system I had on before and IMO sounds even better. Makes a beautiful rasping sound.

 

At the end of the day it comes down to personal preference, the deep bellowing Lancaster bomber type sound that echoed through the car got too much for me in the end, especially if you're interested in doing lots of runs in the show season.

[Andy!]

 

rc40. Failing that, any 1.75 inch diameter exhaust. It's been proven to be the optimal size for the 998cc engine

 

Wrong.

2" is too big. You will definitely lose power!

Wrong.

 

 

 

Over the past few months me and a colleague have been looking into exhaust gas flow and the vast majority of what gets said on here about mini exhausts is wrong.

The truth is that it depends. The best size for MOST 998's, is closer to 1.65inch. 1.75 is sold because its the best compromise between the 998 and 1275 engines. In truth, it is too small for 1275, and too big for 998.

The biggest gains will be seen from the manifold its self, everything that follows is largely irrelevant, but that really depends on where you want the power.

Im not going to expain myself because quite frankly it would take too long and is not worth my time seen as you wont be spending the money.

What you do want is a cooper freeflow manifold from maniflow, along with a 1.75 inch center section (box or no box makes no difference to the power) then to a single tail pipe back box.

If your engine is anything close to standard and you can be bothered, spend the money and get a 1.65inch manifold back system made, and have the freeflow manifold made up to match that. but this will cost quite allot more than off the shelf stuff.

 

Well, by "any 1.75 inch diameter exhaust." i did mean out of the exhausts that were available to buy cheap enough for a standard (or close to standard) 998cc engine.