Scorpion LeMans Q'.

[Letsplayskatch]

Hello all,
Does anyone know if this will fit a E30 318is?

http://www.potn.co.uk/p1433111.htm

I have the Tech2 rear bumper already, so the tail-pipe exit is fine. Would I require a reducer pipe for it to hook upto my standard centre-section?
Im after the Scorpion LeMans backbox system but understand they only make them for E30 6cyl and E36 318is models.
Cheers!

[Theo]

It wont fit, your iS system has a single pipe, whereas the 325i has a twin pipe system. You could mess around with a Y piece and a welder if you were really desperate to have that sort of tailpipe.

[Letsplayskatch]

Yeah thats what I thought - is there a y-piece avaliable from somewhere that you or anybody know of? I have a friend with an E36 318is who has an M3 exhaust fitted. Although, he said it was on it when it was bought, so doesnt know where to get the y-piece from.

[robbo86]

Scorpion do not do an exhaust to fit an e30 IS

[Letsplayskatch]

Yes I know that. My question is about whether or not the exhaust I've listed will fit with a reducer pipe (y-piece), so I can gauge whether or not to bother with it if it's too much hassle.

While I'm here... does anyone know the external diameter of the inlet to the backbox of the exhaust listed above? I.E the diameter of the two pipes going into the backbox itself.
Also, any idea of the distance between the two inlet pipes themselves? Basically I need to know 'D' in the image below, as well as the distance between the hole centres on the inlet to the Scorpion backbox listed above.



I know the diameter of my centre section, but need to know the diameter for the y-piece I need to get.

[Letsplayskatch]

So nobody has ever used a pair of vernier calipers then...

[DHFiS]

What are you trying to achieve by fitting this exhaust?

[Letsplayskatch]

Is that a rhetorical question?

[stonesie]

In the back of my mind i have a feeling that the 325 pipe work is 48mm and the 320 is 45.. if it's twin-pipe, some 320's had a single pipe from the center box back.

[Letsplayskatch]

Hmmm indeed. So if 325s and 320s had twin and single pipework, then why do scorpion offer the one I posed above for fitment on both vehicles

some 320's had a single pipe from the center box back.

So would this explain why the backbox on offer here has a single-pipe centre section? (eBay) : Here

[minicooper172]

Why fit a twin pipe to a four-pot? You haven't got the exhaust gas volume to warrant it, and it means cutting bumpers or finding new ones.

[tomson]

Early chrome bumper 320i's had the single pipe system, later cars had twin like a 325i.
There is meant to be a difference in thickness between 320i & 325i systems but in my experiance I've swapped parts between cars with no issue. I can only think that if you have a genuine BMW exhaust there is a difference in thickness but as these cars are 20yrs old not many have a genuine exhaust, more likely a kwikfit special, hence I've swapped bits between systems successfully.....

[Letsplayskatch]

Why fit a twin pipe to a four-pot? You haven't got the exhaust gas volume to warrant it, and it means cutting bumpers or finding new ones.

What on earth are you on about? Someone missed a physics lesson...
Gasseous expulsion is required to be as thorough as possible - in any 4-Stroke engine. The less back-pressure = the better. Only engines with the 2-Stroke cycle require back-pressure (i.e. slightly more restricted pipework) in order to keep the air and fuel in the cylinder chamber before it's been compressed; thus stopping it from escaping with the exhaust fumes...

And BMW saw it 'wise' (albeit, probably for aesthetic reasons) to fit the E46 M3 with a quad exhaust; so if it's good enough for them then it's good enough for me.

[minicooper172]

There's a bit of a difference between a 1.8L 4-pot and a 3.2L straight 6, isn't there...

If you want the gas to exit fast then take your manifold off.

Up to you, I don't really see the point, since you'll have to get a twin exhaust all the way to the manifold. And you'll need a 4-2 manifold for it to really change anything, since if it goes to one pipe the gases will be much faster in that part, then slow down where it breaks out into to.

Or buy a 325i?

[Letsplayskatch]

There's a bit of a difference between a 1.8L 4-pot and a 3.2L straight 6, isn't there...

Absolutely, but only in terms of displacement. Gas laws still apply to either engine, regardless of thier displacements. Theyre still both 4-Stroke engines, working off the same principles..

Unfortunately it's not as simple as running without a manifold. If that provided any form of performance advantage, then everyone would be running about with cars sounding like tanks. Just look at F1 - short but complicated exhaust manifolds.

[stonesie]

Some backpressure is required to aid scavenging of the exhaust gasses from the cylinder, the amount required is affected by a number of factors including valve timing and overlap.

On turbocharged cars the exhaust system can be as free flowing as possible because the turbo itself provides the backpressure.


As an example, the prototype Spitfire had no manifolds, they were soon added

[minicooper172]

Absolutely, but only in terms of displacement. Gas laws still apply to either engine, regardless of thier displacements. Theyre still both 4-Stroke engines, working off the same principles..

Unfortunately it's not as simple as running without a manifold. If that provided any form of performance advantage, then everyone would be running about with cars sounding like tanks. Just look at F1 - short but complicated exhaust manifolds.

I was joking about taking the manifold off...

You can't have no back pressure whatsoever, you're saying that you don't need any back pressure with a four-stroke engine... Why not take the manifold off, then?!

The difference is increased displacement therefore increased gas flow, therefore bigger cross-sectional area of exhaust pipes.