Floyd

iTrader: (9)

I know what an up pipe is of course, but what is the Venturi bit?

Does the MY00's up pipe have any pre-cats in it or is it just a poorly machined pipe?

F

Floyd

iTrader: (9)

I take it that know one else knows then?

F

Pete Croney

My guess is that it chokes the feed into the turbo, increasing gas speed.

It would give better spool up, at the expense of power.

Adam M

Dont think the design is that dissimmilar from normal up pipes. It is just a gas flowed version. I believe a venturi just means it narrows but retains lamina flow, so pete may well be right. Probably just marketing hype, and unless the uppipe is the weakest link in the system, I wouldnt bother changing it.

Floyd

iTrader: (9)

Thx Pete/Adam,

The other point I was interested in was the pre cat. I thought there was a unit in the MY01's but I didn't think there was one in the MY00's. Is this correct?

F

pat

As an interesting aside, venturi have been used in exhaust ports to speed the exhaust gas up to get it to go supersonic. When this happens it emits an unbelieveably loud noise, but any further increase in gas flow does not incur any additional pumping losses... ie that's all the back pressure you'll ever see ragardless of the amount of gas. Very weird phenomemon and not exactly practical for road cars, but an interesting touch for drag racer engines... if you are gonna try to get six thousand BHP out of a relatively small internal combustion engine you need all the help you can get!

[Edited to say the MY00 does NOT have a pre-cat in the up pipe, that was introduced with the MY01 late Boxer Master Phase II engine. The bulge is a harmonica joint which allows the exhaust headers to expand and contract with varying temperatures]


[Edited by pat - 10/18/2001 12:48:08 PM]