23 replies to this topic

[greggy50]

It's the twin exit which causes the problem. If you want a twin exit on a 998 the diameter of each final exit pipe should be about 1.2".

For optimum efficiency it is vital that the final exit is the same cross-sectional area as the rest of the pipe from the end of the ex. manifold in order to keep the molecular velocity of the exhaust gas the same at the exit as at the end of the ex. manifold. If the final exit is larger, the velocity is reduced and the pressure increased. Think of a hose pipe and think what would happen if the very end was made a larger diameter. The water would not exit efficiently or cleanly. It is basic physics.

 

I am surprised at Maniflow selling that final exit box. It is vital that the final exit cross sectional area is the same as the main pipe. The science is called 'Bernoulli's Theorem' - check it out if you wish.

 

Okay cooperman will take your word for it as respect the fact you have a lot more expertise on the subject that myself :)

 

So I presume I need

 

1 x Maniflow Centre Exit Exhaust (proper silencer)

http://www.minisport...single-box.html

 

1 x Maniflow Manifold

http://www.minisport...b-manifold.html

Edited by greggy50, 06 March 2014 - 12:14 AM.

[KernowCooper]

No you want a freeflow manifold on the 998 engine its better than the lcb on the small bore engine here http://www.maniflow....56&product=1507

[greggy50]

No you want a freeflow manifold on the 998 engine its better than the lcb on the small bore engine here http://www.maniflow....56&product=1507

 

Okay thanks

 

Would I be right in assuming that the centre exit exhaust would fit directly into the manifold itself?

 

And then I just need to locate the correct fitting kit with brackets/gaskets etc...

 

Thanks (sorry I seem such a idiot!)

[KernowCooper]

Manifold/Centre Pipe/Silencer 3 parts mate

[greggy50]

Manifold/Centre Pipe/Silencer 3 parts mate

 

Yes it comes with the centre pipe already :)

 

So think will go for this

 

Free Flow Manifold £72 inc VAT

http://www.minisport...b-manifold.html

 

Maniflow Centre Exit £80 inc VAT

http://www.minisport...single-box.html

 

So just over £150 which doesn't seem too painful...

 

Thanks everyone!

[Anthony30]

http://www.maniflow....56&product=1085

.

[greggy50]

Just seen the adaptor part... However literally just become a TMF+ member and with my 7.5% discount it appears minispares are by far the cheapest option now 

 

Think this is what I need to order :)

 

Exhaust Manifold

http://www.minispare...c/C-STR816.aspx  

L71 Adaptor

http://www.minispare...|Back to search

Exhaust

http://www.minispare...C-ARA332SB.aspx

Total = £160 inc delivery

-       7.5% Discount = £148 = Bargain :)

Edited by greggy50, 06 March 2014 - 01:08 AM.

[KernowCooper]

looks good

[Cooperman]

That is an absolutely ideal system for a 998 and will be good for a modified engine as well. On a 998 it won't be too noisy and will work efficiently, maximising the power output. It's a top quality product as well and I think you'll notice the power increase too.