Turbo Exhaust Theory
Turbo Mini Forums

Found this. Thought I would share it here.



Some interesting points.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Thanks.
The straight conical diffuser trick was new to me.

Tom

If i have more toys than you when i die, I WIN

Interesting,

seems to confirm what I thought and/or read elsewhere,

interestingly on my VNT the turbine extucer is 45mm, this tapers out to about 49mm at the downpipe flange, cunningly I have matched the down pipe flange to this and continued the taper in the flange to match the 2" down pipe o there is a nice 8ish degree taper from 45-52mm.

not very clear in this pic but the taper is there...

Interesting read, and that satisfies my decision to run a 2.25" downpipe and system which is pretty much the ID of the turbine outlet on the GT17. we know the bigger exhaust gives better results from Roberts experience with his side pipe at the dyno shoot out. The effortI also put in to my manifold looks like it might be worth something too.

Only real way to find out is get the thing running lol.

:)

i Designed and made my LARGE! single exhaust on the Benross machine made severall years ago

they do work.....lol

It's as simple as bigger is better, especially close to the turbocharger itself.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

ive opted for a 2" downpipe which imidiatly goes three inch from there backward.

It made me thing that the 1.75" exhaust on the van will start to be a restriction if/when we push for more power. I reckon a home brew 2" is on the cards

side pipe ala challenge cars?

You got it!

If something is worth doing, it's worth doing half of.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Upstream of the turbo, it's a different matter altogether:

"For turbo cars, you throw all that out the window. You want the exhaust velocity to be high upstream of the turbine (i.e. in the header). You'll notice that primaries of turbo headers are smaller diameter than those of an n/a car of two-thirds the horsepower. The idea is to get the exhaust velocity up quickly, to get the turbo spooling as early as possible. Here, getting the boost up early is a much more effective way to torque than playing with tuned primary lengths and scavenging. The scavenging effects are small compared to what you'd get if you just got boost sooner instead. You have a turbo; you want boost. Just don't go so small on the header's primary diameter that you choke off the high end."

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I have run my own design of 2.5" onto a 4 1/4" oval for many years now always thought the playmini downpipe was one of the choke points and that proves my thinking correct.

Own the day