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ABS Speed Sensor
Air Flow Meter / Sensor
Air Intake Pressure Sensor
Alternator Current and Voltage
Amplifier Earth
Camshaft Sensor
Carbon Canister Solenoid Valve
Crankshaft sensor
Coolant Temperature sensor
Diesel Glow Plugs
Digital ECM to Ignition Amplifier Signal
Distributor Pickup
Dual Trace
Electronic Fuel Pump
Exhaust Gas Recirculation
Idle Speed Control Valve
Knock Sensor
Lambda Sensor
MAP Sensor
Relative Compression
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Supercharger Diagnostics

Compressor Efficiency Test

This is a check to see if the compressor is putting excessive heat into the charge air. If there is a big difference between the calculated and actual air temperature then something is wrong or the wrong compressor is being used. If the wrong compressor is used it will be operating in the lower part of the compressor efficiency map.

Compressor efficiency should be measured in the power band that is most important. For a rally car this is at 60% rpm and upwards. For a road car the mid-range is more important.

Turbine Performance Test

Any good high performance exhaust should have less than 1psi back pressure. Even very quiet manufacturer exhausts should not have more than 2psi back pressure.

With pure performance in mind a higher output is desired. The turbine housing selected will not achieve peak boost until 500-1000rpm past the standard. A turbine housing with this A/R ratio cuts exhaust back pressure so that, at max power rpm, exhaust pressure at the turbine inlet will be about the same as max boost pressure.

Intercooler Efficiency Test

There are two intercooler tests. One to check flow and the other to check temperature drop. Pressure loss should not exceed 10%. Less pressure loss is better, so long as thermal efficiency doesn’t drop. The pressure test must be carried out at 20%, 50%, 70% and 100% power load and must be carried out three times or more.

The temperature test can also be carried out during these runs. The temp must be noted at four separate places along the charge air circuit.

Pressure Leaks and Ductwork

A pressure leak test can reveal a lot of problems prior to doing more sophisticated tests. Every join in the ductwork needs to be checked. All manifold and throttle body gaskets. Clearance between the throttle spindle and throttle body allowing air to escape. Every hose connected to the inlet system anywhere between the compressor outlet and cylinder head must be checked for cracks or leaks. The fuel injector seals should be checked.

Next the duct work from the turbo to the cooler and then to the inlet manifold must be checked. Are all the bends necessary. Are all joins internally smooth.

Water-to-Air Intercooler Checks

Ensure waterflow is sufficient. Check that the water entering the cooler is the same temp as the ambient air. Water circulation rates need to be within limits. The reservoir limit should be good. Correct any ducting problems.

Bleed all air in the water circuit. This acts as an insulating blanket and prevents heat transfer. Very careful bleeding will fix this. It must be rebleeded several times.