Outer Limits 4x4 Board

not sure if its off the 3.0l or 4.2l but my GQ has one on it. I do know its water cooled and is set at 11 lb boost. What type(make) of turbo's were in this model patrol and how much boost will they produce without hurting the turbo.

DR Frankenstine wrote:not sure if its off the 3.0l or 4.2l but my GQ has one on it. I do know its water cooled and is set at 11 lb boost. What type(make) of turbo's were in this model patrol and how much boost will they produce without hurting the turbo.

you could run 25psi if you wanted, if the fuel was kept up to it... turbos will handle lots... its the rest that you have to worry about.

Unlikely you will hurt the turbo unless you are running a ceramic turbine wheel (as some Nissans did).

The question would be if the turbo is capable of sustaining high boost at a particular rev range, before it runs out of puff. You would need to check the A/R ratio, compressor wheel size, turbine wheel and housing size in order to generate a map (if you couldn't find one) and calculate potential boost per load / revs from there. The turbine on the GU was quite small to say a Garrett GT28BB 350HP for example (which WILL produce 20-25psi all day every day before they hit their surge limit)

I only want to run 15lb and im sure that will be fine with an intercooler. Ill get the intercooler hooked up and set the boost then ill adjust the fuel to suit.

Intercooling will only reduce your intake temps slightly, the Mean Effective Pressure in the cylinder still increases as boost goes up, regardless of temps. Intercooler save your valves (by reducing EGT's) and allows more fuel to be burnt by virtue of the cooler, denser air entering the cylinder - which pushes EGT's back up.

Apart from MEPS (Mean Effective Piston Speed), MEP (Mean Effective Pressure ) and inertial change of the piston is the gauge of how much load you are putting on the engine, thereby determining it's lifespan.