[Vwdiesel] 2.25 inch exhaust

[James Hansen]

You can also take the stock ball and socket downpipe connection from the 
stock exhaust, cut the  stock pipe out of the lower connection, weld a 
2.5" pipe into it with a bend to conform to the stock direction.  This 
gives you 2.5" from the manifold exit.  The 1.6 litre naturally 
aspirated manifold looks like a manifold set up to scavenge whose exit 
point is roughly 2.5".  This gives you 2.5" exit to exit.  On a 1.6 
litre motor, it is a tad excessive, but 2.5" pipe costs not much more 
than 2.25", so no  big deal really. Glasspacks are okay, if you like 
noise. That's what they are made for.  Dynomax and their competitors 
make a fine product that flows better than a glasspack, and have 
accceptable noise levels.  I reread that, I feel old...

At a point, the increase in volume of the pipe (and pressure drop of the 
exhaust gases exiting the manifold) causes loss of exhaust gas velocity 
to the point you lose scavenging benefits.
That would probably be a good question to ask the guru, but it's fashion 
to run 5" pipes on 3/4 ton diesel trucks, so who knows if it's fashion 
advice or technical advice you get these days.

ymmv
-James

Terry Briggs wrote:
> Well I got some good news. Having talked with a diesel guru the other 
> day, he told me that the cutoff for any type of increase in pipe 
> diameter would be around 2.5" for a 1.6 na diesel. The one thing that 
> he said would help the greatest, along with a size increase would be 
> some sort of performance header like the hotrods use. I don't think 
> they make such a thing for a VW diesel, and I don't have the cash to 
> have one fabricated from stainless {if your gonna do it, do it right}  
> So I have it setup to go to a shop around here and have the exhaust 
> ripped out from about half way down the head pipe back. 2.25" pipe, 
> with one of those california turbo mufflers. They are short with very 
> little restriction and only cost $20, it's either that or try just a 
> glass pack and tail pipe. Will be interesting to see what happens with 
> the fuel mileage.
> 
> Terry Briggs
> Third Wheel Engineering
> 2576 King Circle
> Corning, NY  14830
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