TD42 Comp Truck Boost

Q. Hi, my mate and I are in the process of building a comp truck and want to run a diesel for its engine braking qualities – plus it’s the engine that’s already in the truck (4.2 N/A GQ) so we save money by not swapping out engines. We want to turbo the motor, though, to give it a bit more oomph when it’s needed, like in the bog hole events. We’re not far from you guys (down the road a bit at Goulburn), and the idea was to fit the turbo ourselves then trailer it up to you for a proper tune. What sort of PSI do you reckon the TD42s can safely handle, and what power output can we expect?

A. Nice to hear.... a ‘Diesel Comp Truck’ instead of a V8 Petrol. Anyway the controlling factor of tuning is ‘how long’ the engine will be under ‘full load’. Given this is a ‘Comp Truck’, you could run around 15 to 20 PSI boost and upon running it on a 4WD dyno keep the fuel loadings moderately heavy. Basically you can have a 5 litre 250hp engine last for 500,000km or a 5 litre 1500hp engine last just long enough for a ¼ mile drag run. The more power - the shorter you want the engine under load.