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