Huge bore exhaust systems

Post Tue Apr 12, 2005 1:53 pm

This is the sort of question I would never normally ask, but in light of the fact that I'm hoping to put another 70bhp worth of gas down my exhaust system, I think it needs to be a bit bigger.

Can anyone recommend a decent big-bore system with minimal restriction?

Cheers!

Alex

Post Tue Apr 12, 2005 5:43 pm

Hi Alex,

Blue Flame ?

http://www.blueflameperformance.com/

Post Tue Apr 12, 2005 6:31 pm

With 250+hp 75/80mm tube should offer substantial gas flow with out any floor fouling problems..

Post Tue Apr 12, 2005 8:35 pm

Try either a custom exhaust or an after market sports exhaust from an E30 M3,my Scorpion M3 exhaust is aprox 2 x 50mm bore tubes so should be plenty big enough ?

Custom is best if you can find a decent place to make you one.

The M3 exhaust uses slightly differant hanging points and won't bolt up to your down pipes so fitting isn't straight forward.

Post Tue Apr 12, 2005 10:17 pm

Cheers for the replies guys!

Not sure I can stretch to a custom jobby (not that I have any idea how much they cost) Was really just hoping for something off the shelf that I can mod to suit my purposes.

Interesting that a single 75mm dia pipe has a greater area than the two 50mm dia pipes.

Not too fussed about the manifold fitting as the manifold and downpipes will be made to suit the turbos.

I just really can't be arsed to make a whole system!

Post Tue Apr 12, 2005 10:24 pm

Turbo-Brown wrote: Interesting that a single 75mm dia pipe has a greater area than the two 50mm dia pipes.

Being a 'maths geek' :lol:

I had to check this!

It is indeed true!

The 75mm tube would have a 12.5% larger area than the two 50mm ones.

You'd need two 53mm tubes to have roughly the same area as the 75mm single tube.

Post Tue Apr 12, 2005 10:26 pm

thats wierd

Post Tue Apr 12, 2005 10:31 pm

Sorry for the O/T but whilst i've got a maths guru's attention

can you check the area of the following for me please ?

1 x 65mm circle
6 x 45mm circle

Cheers

Andy

Post Tue Apr 12, 2005 10:34 pm

1 x 65mm = 13273.23 mm^2

6 x 45mm = 38170.35mm^2

Just incase ---- ^2 as in to the power of 2 ---- 2 squared

Post Tue Apr 12, 2005 10:42 pm

Cheers mate,it's for my TB's,i was curious

Post Tue Apr 12, 2005 10:46 pm

No probs mate.

I guessed along those lines, the 6 x gave it away!

Area of a circle is just:

A = Pi x R^2

A = area

Pi = ~ 3.14

R = Radius

^2 = squared

Post Tue Apr 12, 2005 10:59 pm

LOL,can you tell i skived to much school !

Post Tue Apr 12, 2005 11:00 pm

Andy335Touring wrote:LOL,can you tell i skived to much school !

Post Wed Apr 13, 2005 1:34 am

here's one for you dave, !!!without using a calculator!!!!

whats the squere route of 32????

Post Wed Apr 13, 2005 10:46 am

craigieeb wrote:here's one for you dave, !!!without using a calculator!!!!

whats the squere route of 32????

4 x 2^.5 aprrox 4 x 1.4 = 5.6

Post Wed Apr 13, 2005 11:12 am

davetouring wrote:
Turbo-Brown wrote: Interesting that a single 75mm dia pipe has a greater area than the two 50mm dia pipes.

Being a 'maths geek' I had to check this!

It is indeed true!

The 75mm tube would have a 12.5% larger area than the two 50mm ones.

You'd need two 53mm tubes to have roughly the same area as the 75mm single tube.

Thats why the Is Exhaust is single pipe, 55mm which has more flow than two 42 mm pipes found on the 325i
Its also to do with the fact that two pipes create more friction than one pipe.

Andrew

Post Wed Apr 13, 2005 12:11 pm

E39 530's have a drain pipe zorst as do 540's too must be for this reason

Post Wed Apr 13, 2005 1:13 pm

I need a custom exhaust for the S50 conversion.

From a rough measurement of the manifolds, the pipes seem to be about 57mm each.
I was going to get some pipes that are as close to 57mm as possible and make it up from that.

Im assuming that 2x57mm pipes will be big enough and/or that its fairly close to the orginal E36 size.
Does anybody actually know the bore size of the E36 3.0 M3 exhaust?

Post Wed Apr 13, 2005 1:17 pm

im using an e30 m3 supersprint backbox for the m5 engined car....

just the one silencer...

Post Wed Apr 13, 2005 2:33 pm

Karan wrote:im using an e30 m3 supersprint backbox for the m5 engined car....

just the one silencer...

No centre box then??

Ive got a custom/modified E30 325i back box here. I was going cut and weld the larger pipes into it and use that. It just deciding what size pipes to go for.

Post Wed Apr 13, 2005 4:34 pm

no.... prob no centre box..... will see if it is too loud.....if it is.... ill get one put in..

Karan

Post Wed Apr 13, 2005 8:45 pm

Turbo-Brown wrote:Was really just hoping for something off the shelf that I can mod to suit my purposes.

A good motor factors should be able to get you 30, 45 & 90 degree bends and go to a steel stockholder for the exhaust tubing which is in 20ft lengths this will make you a rather cheap system...

Post Wed Apr 13, 2005 8:58 pm

or if you go to a place called the pipe line center (if you have one near you), they'll sell you what ever you want, thats where i went for my 3" pipe bends for my exhaust, and a shed load of 1.5" bends for the 6 branch manifold : )