Wiring the Porsche LS3, perhaps the most daunting of tasks was not to be taken lightly.
Wiring the engine with the GM performance universal wiring harness was very painless and simple, with each connector properly labeled.
However getting the GM electronics to talk to the Porsche electronics was a task in itself. To bring life to the factory Porsche LS3 gauges and other chassis powered units and devices, we had to strip down the factory Porsche engine harness and adapt the original sensors to the LS. This process ensured that vital information could be communicated to the car itself as well as the important task of starting the Porsche LS3 with the starter signal and alternator power. Although there are still warning messages as expected, we were able to get full function of the factory gauges, tachometer, water temp. and oil pressure.
There are many items to consider in a Porsche LS3 swap, and the next item to consider is the cooling system. With the fuel system sorted out utilizing a nice set of Holley fuel rails and custom lines, we could begin adapting the Porsche LS3 cooling system. Although the routing of the Porsche LS3 cooling system can seem a bit “complex” it is fairly simple and utilizes most of the stock hard pipes.
We opted for the Renegade Hybrids electric coolant pump and front adapter plate to optimize space constraints. The rear-most hard pipes were replaced with flexible hose supplied with the kit to adapt to the stock remaining Porsche system.
From the diagrams below you can see the differences between a conventional return-type system and a returnless system. The return type utilities a pressure regulator after the fuel rail and the returnless system uses a pressure regulator before the fuel rail.
The LS engine does however operate at a different pressure and as result, demands more fuel. Because of this, we will need to run a different fuel pressure regulator and an upgraded fuel pump. The Porsche uses an integrated fuel pump and pressure regulator unit in-tank, this difference will result in some customization to get everything mated together.
Another issue we encountered, was that the clearance between the intake manifold and the top of the engine bay is extremely tight. To eliminate this, we will be looking into a Holley performance AN flanged fuel rail to eliminate the stock fuel rail crossover tube.