midrange

I'm learning! If you follow my posts, you will see I worked for a Porsche race team. I wasn't the most knowledgable guy there, but i was there to learn.. Anyways, not getting into that BUT our engine rebuilder, a german engineer (older retired guy and did work for a hobby with us) is the one who explained the backpressure to me. I wish I have the exact terminology that he explained it but I don't and this is going back years now.

This mechanic, Rudy Bartling is his name [still works on Audi Porsche in Tronna (Toronto) today as advisor, engine rebuilder] was a very very knowledable man. This guy built engines like kids putting a 2 piece puzzle together. Never once did he have to seek how to build a German engine. He knew.. This being said, I took his word very seriously.

My brother bought a turbo car and got into the conversation of exhaust systems. This was the day he explained "backpressure" to us, saying N/A needs back pressure, turbos absolutely don't..

Long story short, since yesterday and reading your posts, and doing research, technology has escaladed A LOT since of course Rudy's time of learning when he was younger in germany. I have found and learned that yes, infact what you are saying is undoubtably correct to a major degree... I have also learned though, my flip flop explanation is also correct... You can lose torque by making an exhaust more free flow.

So accordance to everything mentioned on this thread, you need vacuum not back pressure to promote scavaging. Correct?

mickhelpaul

ya i am to searching for these if u get the best result inform me.

d3br34k5

I really don't have anything to add, but I've enjoyed reading what's here.

That said (reconsidered, I've got something too add), I'm not too sure anything will pass emissions in Ontario without a cat. It's ridiculous.

I'm 200% positive that running your S4 (OP) without cats would be more environmentally friendly than my dding my 4.0L Jeep TJ for 250kms/day.

DriveClean is a scam.

sakimano

I realized driveclean was basically a driver tax when my friend's girlfriend had to take her 2 year old Honda Civic in for a test (years ago).

At least they made it 5 years or older before you get tested now. It's still goofy.

sakimano

I was at Canadian Tire the other day and asked how they do emissions testing on AWD cars


they don't put you on the dyno...they just hook up the sniffers to the tailpipe, scan your obd, and rev it a few times.

mikeh

I had to get emissions testing done for my licence renewal and went to CT. You are right, they stuck a wand up the tail pipe, reved it to 2000 rpm and held it there for a bit, checked the obd and the gas cap.

The manager at Burlington Mall CT is an Audi enthusiast and owns a TT. He came over (because I stayed with my car) and we chatted a bit.