Tech Info on the stock LSJ Intercooler Pump

Posted by Alex Darmos on

The stock coolant pump for the liquid to air intercooler system is made by Bosch. ZZPerformance set out to collect some quick technical information on how this pump behaves in a real world environment. Here is what we came up with:

All things considered, this pump outperforms anything we have ever used or tested. ZZPerformance has tested pumps from Rule, Flojet, Centri-puppy, Jabsco, Shurflo, Central machinery, Meziere, GM, JC whitney, Johnson, Attwood and others. We have been using various Bosch pumps for some time as they are OEM on quite a few cars and are very reliable.

Free flowing the LSJ Bosch pump topped 8GPM with 13.1 volts and pegged our 12GPM gauge at 16+ volts.

When we added the most restrictive part of the LSJ intercooler system to the setup (the intercooler), flow dropped to around 4.5 GPM.

Anything over 4 GPM is good for an intercooler system, however with the flow dropping to 1/2 of what the pump is capable of; we knew there was room for gains. We installed our dual pass end plate on the intake and retested. This increased flow to 6.25 GPM at 13.1 volts, which is very good.

This pump weighs 2.2 pounds, has 3/4″ fittings and draws about 2.7amps at 13.5 volts. Results varied depending on the voltage and load, at low voltage, it drew 1.8 amps and at high voltage, it drew 3.5 amps max. We do not believe there to be a better pump available when weight, current draw, flow and performance are all factored in.

*Update for new Bosch pump info 3-5-09

Shown below is the lower end of a 4 year old pump disassembled. It uses a magnetic drive. This adds reliability by allowing the motor of the unit to become completely separated from the drive. The entire setup is sealed with O-rings. A magnetic drive cannot short out by the impeller getting stuck; only adding to its reliability. The magnetic field strength will increase with raised voltage along with motor rpm. This, in theory, means the pump could output more than the % you raise the voltage by, which explains some of the results we achieved when raising voltage.