K04 Pre-turbo pressure readings

[FlyboyS4]

More baseline pressure performance for the K04 turbochargers.

[james 408]

what's the significance? that the exhaust pressure isn't 100% being converted into intake pressure doesn't surprise me...

[FlyboyS4]

what's the significance? that the exhaust pressure isn't 100% being converted into intake pressure doesn't surprise me...

There's a few things I'm interested in, main thing is to have some data I can use to compare to other turbo's with.

[Monty23]

The significance is understanding how restrictive the exhaust housing is for the amount of flow your trying to force through the turbine. The data is certainly more useful if you can actually adjust the turbine housing a/r.

[jibberjive]

Thumbs up for the data.

[Doug@FrankenTurbo]

The significance is twofold.

First, the stock exhaust valvetrain will reach its limits at about 60psi of pre-turbine back-pressures. If you exceed the limits, the valve springs will not be able to hold the valves closed against that pressure behind them. This leads to a condition called "valve float" which wrecks the combustion cycle and immediately kills power.

Second, higher back-pressures impact the ignition timing advance. The pressurized exhaust gases will contaminate the intake cycle, raising the air/fuel mixture temperatures and leading to premature detonation.

These two considerations make pre-turbine back-pressures a critical metric for hybrid turbo design. And that's why we monitor them closely in all our testing.

[julex]

Thanks for measurements.

[Nichtknicken]

Flyboy, mind sharing your hardware setup for logging the exhaust pressure? I am running oddball K03 hybrids and it might be useful for me to keep an eye on drive pressure when I turn boost up. I have been considering buying a Zeitronix Wideband controller with aux inputs and pulling exhaust pressure from the sai port on the passenger side head.

[FlyboyS4]

Flyboy, mind sharing your hardware setup for logging the exhaust pressure? I am running oddball K03 hybrids and it might be useful for me to keep an eye on drive pressure when I turn boost up. I have been considering buying a Zeitronix Wideband controller with aux inputs and pulling exhaust pressure from the sai port on the passenger side head.

It looks about like this. I've since replaced the long rubber hose with a pressure snubber and a much shorter length of tubing, but the basic concept is the same.

[Nichtknicken]

Thank you. I somehow missed that looking around your site. Much appreciation for putting up your pressure logs, should make a nice point of reference for me in the future.