exhaust sizes

BiX Veteran Volks Folk

2,499 posts · joined Sep 2002 · 27 May 2003, 3:38 pm

#51115

Just looking into upgrading my exhaust system and i have a few questions. I don't want to much noise, but a little is ok.

1- Primaary pipe size? what is the best? i currently have stock ported heads, but am saving up for 044's.

2- what effect will happen if i go for say to large primary pipes for now on the stock heads(but will b ok for the 044's eg 1.5 inch), will I loose low down power torque?

3- what size for the collector back pipe should i run, and where?

I have seen a system that runs foward then back with a muffler using 2 inch pipe?

any experience opions would be great.

[Edited on 27-5-2003 by BiX]

Robo Compulsive Aussie Vee Dubber

4,491 posts · joined Feb 2003 · 27 May 2003, 5:24 pm

#51148

Im running 1"5/8, SS, on my 2ltr Kombi extractors.
Rob....

Boxer Power
Member of DMLRK.....Die Mittler Lebuns Resto Komeradschaft

OvalGlen Custom Title Time!

1,361 posts · joined Aug 2002 · 27 May 2003, 9:13 pm

#51305

What size engine?
How hot a cam?
What carburetion?
- I have 1 5/8 primaries on my 1916 with almost standard cam and it has a very poor low end - probably because the primaries are too Big.
It would go much better with 1 1/2.
- The Lowest back pressure after the collector the better - but to keep it quiet for street and comfort then a large diameter long run with large muffler is my choice.
I went for 2 1/2 with two straight through Glass Pack mufflers, ( thats through one then through the next with one outlet - not split with two outlets.)
I tried the Split - two mufflers - two outlets once but found that it was too noisey, maybe it was just the way I set it up.

Regards,Glenn>

OvalGlen Custom Title Time!

1,361 posts · joined Aug 2002 · 27 May 2003, 9:16 pm

#51307

pic, from behind

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Regards,Glenn>

70AutoStik Insano Dub Head

730 posts · joined Aug 2002 · 27 May 2003, 11:28 pm

#51444

044s are matched to 1&1/2" pipes (you have to give up your heater boxes for this, which makes your car unroadworthy - no demister.) Many have run them happily with standard pipes, simply open the inlet side of the pipes if you're worried about flow (a quirk of fluid dynamics is that a step to a larger pipe is less detrimental to flow than the reverse.)

You will lose a little bottom end if you run the 1.5" pipes with stock-ported heads, but if you match-port the heads to the pipes you probably won't be upset by it.

The "back pipe" (secondary, or collector) should theoretically be about twice the CSA of the primaries for an extractor, but it is so short in most VW exhausts that they end up being a "header." Therefore, you should look at a pipe size with which you can produce a nice flow (no sudden steps) of as large as will suit your muffler. If you extend it's length (to 0.5-1+ times the length of the primaries) you can keep it to 1.414 times the diameter of the primaries to create an extractor system - but you want a nice smooth collector to make this work well.

(Sorry 'bout the edit - found I typed in some funny numbers.)

[Edited on 27-5-2003 by 70AutoStik]

Baja Wes V6 Baja Pioneer

3,119 posts · joined Aug 2002 · 28 May 2003, 8:50 pm

#51768

70AutoStik wrote:(you have to give up your heater boxes for this, which makes your car unroadworthy - no demister.)

That is not true. You do not need a demister for your car to be legal. You do however need a demister if you want to jam an oversized engine in your car.

Wes - www.offroadvw.net - 200HP Quad Cam V6 in a VW Baja - with climate control... 🙂
www.taylorcycles.com.au - My DH MTB racing brothers shop.