Im bored so was cruising ebay looking at stuff when I found this :

LINKY

Now, my question is...why have they linked Cyl 1-4 and 2-3 rather than just taking all of them straight down into a single collector?..

Random question, but im intreagued..

So that you have to buy more pieces when it needs replacing?

/cynic mode off.....

You need to read up on manifold design!!!

You use cross pulsing from the "opposing" cylinder in cycle terms to create a depression to extract from the other cylinder. This effect is magnified with a smaller cross section of pipe linked.

Its actually extremely complex in detail but simple in principle when you know the "ball-park rules" of what works and what does not.

There is a very good book on the subject called "4 stroke engine tuning" but I can't remember who wrote it, but it goes into all you need to know on exhaust manifold design.

That book is by A G Bell, very well written so anyone can understand it

same principle, but much longer lengths used here on my own DIY Vauxhall XE effort:



exhaust 2

Have a look at the R V8 factory manifolds - on left side 1/5 and 3/7 linked, on offside 2/4 and 6/8.

ATB

Simon