Turbo Selection

Pushing the F21’s

Frankenturbo Mixed Flow F21 turbochargers
FrankenTurbo F21 / Mixed Flow

I think I’ve just about reached the point of having diminishing returns with respect to upping the boost (26 psi out to redline) on the FrankenTurbo F21’s.  Back pressure on the exhaust side is getting up there and FATS times aren’t coming down as much as they were when going from 22 to 24 psi.

I’m working with Daz on the tune, and he’s looking to clean a few things up before I head off to the dyno to get numbers for these turbo’s.

Chart of Intake Manifold versus Exhaust Manifold Pressure
26 psi Intake Manifold versus Exhaust Manifold Pressure
This chart above illustrates what happens to exhaust back pressure when there is a leak on the intake side. A few pulls later a hose clamp slipped off and I had an audible boost leak. The chart below was made after eliminating the air leak.

Note: I had to switch pressure sensors to create the chart above since the 4 bar sensor on the exhaust manifold was being maxed out at 26 psi of intake manifold pressure.  There is possibly some accuracy discrepancy between the two sensors.  I would allow for up to 2 psi of error when comparing the exhaust manifold pressure from the chart immediately below with the two further down the page.

27 psi Intake Manifold Pressure vs Exhaust Pressure
27 psi Intake Manifold Pressure vs Exhaust Pressure

 

This is a comparison made holding approximately 24 psi.

Intake Manifold vs Exhaust Manifold Pressures
24 psi Intake Manifold vs Exhaust Manifold Pressures

 

This is the F21MF version of the boost profile used with the BW K04’s.

Intake Manifold vs Exhaust Manifold Pressures
22 psi Intake Manifold vs Exhaust Manifold Pressures