What is hi-flowing?

[myne]

I've often heard this term bandied about, and it obviously does something for turb performance, but I've never really cared what it was. Then today, I saw a pic of a turbo that had a series of vanes on the housing itself, but they faced the opposite direction to the turbine vanes.
I'm guessing it's to help spool it up a bit quicker by directing the flow at lower rpm.

Is that what hi-flow is?

[-==L=a=N=c=E==-]

In a nutshell, highflowing is when you have the turbo rebuilt with a larger then standard compressor. And sometimes modified turbine.

So at the same boost levels you were running before, you are pumping more air in. Geting a Higher Flow.

[myne]

Oh is that all. Cheers.
What the hell did I see then?

[-==L=a=N=c=E==-]

Possibly a VATN turbo?

[mic*]

So at the same boost levels you were running before, you are pumping more air in. Geting a Higher Flow.

I would have said generate more boost at the same rpm's... At the expense of slower turbine spool due to increased inertia of the larger compressor.

VATN = Variable Angle Turbine N???

The angle of the turbine vanes is variable to suit both quick pick up, and high rpm's.

EDIT: VATN = Variable Area Turbine Nozzle = different thing

[AE86slut]

today, I saw a pic of a turbo that had a series of vanes on the housing itself, but they faced the opposite direction to the turbine vanes.
I'm guessing it's to help spool it up a bit quicker by directing the flow at lower rpm.

It wasn't in Zoom magazine was it? In issue 94 there was a pic on page 37 of a VNT (Variable Nozzle Turbine) turbo which has vanes on the core side of the turbine housing that direct flow onto the impeller blades in varying degrees. The result is almost zero lag. Unfortunately it's only suitable for diesel engines at the moment though, as petrol engines produce too much heat for it to handle.

[mic*]

Porsche will be celebrating the turbo's 100-year anniversary a little late when it introduces the next 911 Turbo sometime next year with Variable Turbine Geometry. This technology allows the angle of the compressor's turbine blades to continually adjust. While some diesel engines have enjoyed this technology since the Nineties, the higher exhaust gas temperatures created by gasoline engines necessitated the creation of new heat-resistant materials to handle the hotness. Porsche and Borg Warner Turbo Systems were able to overcome the heat issue and have developed a VTG turbo system that will be incorporated into the next 911 Turbo. The VTG turbo will allow Porsche's flat-six to mimic a twin-turbo setup with a much broader torque curve and more flexible powerband than a standard single turbo could provide on its own. Power ratings for the new VTG turbo engine haven't been released and probably won't be until the new 911 Turbo surfaces sometime next year...

This is variable angle stuff... for petrol.

[myne]

That'd probably be it.
I glanced at it from a distance while someone else was reading it and it didnt really register till I'd walked away.
Pity it wont work on petrol engines though.

[AE86slut]

Nice work mic*... I'd be very interested to have a peek at that design!

[oldcorollas]

high flow (sorry... HiFlo ) refers to a number of different things, but ppl lump it all together under the same term...

first is bigger compressor to get more air in....

second is bigger turbine to allow more gas out...

third is (i believe?) machining the turbine housing so there is more space between the turbine and the housing, allowing more gas to escape... increasing lag as it is not as effective in spooling up, but giving more flow up top so the need for a big wastegate is reduced... seems like a silly idea really

basically, high flowing a turbo is what turbo shops do when the owner is too stingy to buy a correct sized turbo

[mic*]

Well said. Sizing is a science. Gimmicks ie "Hi-Flo" are for sales.

[chris davey]

That'd probably be it.
I glanced at it from a distance while someone else was reading it and it didnt really register till I'd walked away.
Pity it wont work on petrol engines though.

Mic just posted that it is going on 911's. New 911 better not be diesel!!!

[myne]

Yeah, I must have taken too long with my reply. When I started it, his wasnt up yet.
Working + forums = slow replies

[mic*]

Introducing the new model, Porsche will be presenting the world's first turbocharged gasoline engine with variable turbine geometry (VTG). This technology featured in turbocharged diesels since the '90s ensures a significant improvement of engine flexibility and acceleration particularly at low engine speeds. So far, however, much higher exhaust gas temperature of up to 1000° C in comparison with the turbocharged diesel has always proved to be an insurmountable barrier. But now Porsche has solved this problem in close cooperation with Borg Warner Turbo Systems by using high temperature-resistant materials from space technology wherever required.



The core features of the VTG system are the variable turbine blades guiding the flow of exhaust gas from the engine in exactly the direction required on to the turbine wheel of the exhaust gas turbocharger. The principle of variable turbine geometry thus combines the benefits of a small and large exhaust gas turbocharger all in one – a combination ensuring both very good response and high torque at low engine speeds as well as superior output and high performance at high speeds. And the supreme level of torque is now maintained consistently throughout a much wider speed range.

Definitely PULP...

[chris davey]

Oldcorollas: on point 2 re larger turbine, it also reduces exhaust gas back pressure which is a very good thing for a turbo engine. Lets it breath better in the top end. Increasing the Radius (R) of the turbine which idecrease A/R (ie. 5/8=.625, 5/9=.55)and therefore make the boost threshold lower than before.

I was thinking of doing the opposite. Keeping the same turbine but using a smaller housing.