Preturbo 335i Strange Results

[Richard L]

Originally Posted by rudypoochris

So basically the shaft speed may be less, but the work is around the same? Then really the turbo is seeing less "damage" due to overspeed but roughly equal thrust loading wear?

Methanol comes on at a boost switch set too low atm (8psi). It is not progressive at the moment, but I may switch it to be progressive with boost. The check valve makes it not progressive since the tank is pre-boosted to whatever the last pull left it at.

Are other people seeing reduced shaft speed or reduced work with pre-turbo meth?

Although water is heavy but compared to the mass of air going through the turbo, it is much less. There will not be to much variation on the BCV's PWM.

You cannot guarantee the distribution of water drop when it travels toward the compressor wheel. Some will pool on the flange wall and migrate/trickle towards the utmost tip of the turbo. This will exert most load on the turbo. Long term, it will unbalance and pit the compressor wheel, followed by excessive shaft wear.

I am not sure why you are using methanol instead of water. Water has more cooling capacity.

Until you have balanced the air against the meth flow fed to the nozzle, you cannot
guarantee how well the mixture is atomised. I suggest running run water for one test, clip the jet on the windshield and see how well the spray is atomised. (driving test)

If you have a air compressor handy, you can do it without driving the car. You can also measure exactly how much water/methanol is injected for 1 minute.