Getting the fly-by-wire electronic 90mm throttle body that comes with the newer LS engines
•Accessory Drive Systems
Almost every vehicle GM builds with an LS engine has a different accessory drive. Most of the car-based systems interchange. Because of availability, the most popular systems used in engine swaps are the Corvette and the "F" car. Another popular system is the CTS-V. It tucks in closer to the engine and works well in limited space applications like a LS7 Solstice.
There are a number of aftermarket kits available to fit many applications. If you prefer factory components, GM Performance Parts offer a complete CTS-V (PN 19155066) and Corvette (PN 19155067) accessory drive kits. They come with every component required, including the bolts. Truck-based accessory drive systems do not work well with car intake manifolds since the throttle body interferes with the alternator bracket. Remember, the crank pulley must match the accessory drive system you are using. All production A/C compressors are located low on the passenger side. In many applications it will hit the frame in this location. There are a number of aftermarket companies that make brackets to relocate the A/C compressor to a location above the thermostat housing. This can eliminate the requirement to modify the frame.
All LS water pumps share a common bolt pattern, and will interchange between engines. This allows you to use an LS3 water pump in space-confined applications. It works with most accessory drive systems and is much shorter (over one inch) on the front compared to a LS1 pump.
Both radiator hoses come out on the right side of the engine. This makes it difficult to install the upper radiator hose in some applications. Using a dual pass crossflow radiator allows both hoses to hook up on the passenger side. An additional benefit to dual pass radiators is they keep the coolant in the radiator longer. This allows the fan to remove more heat, and it increases the ability of the radiator to cool more efficiently. All LS-based engines have a small hose connected to the front of the cylinder heads. In some applications, it is hooked to the lower left side of the throttle body, then to the radiator. Either way, this tube must be hooked to the radiator in the area of the upper radiator hose. It vents air from the top of the cylinder heads, and not hooking it up can cause engine damage.
Closed cooling systems with a pressurized overflow bottle cool better than a standard system with an open overflow bottle. The additional coolant in the bottle, plus the higher pressure, allows the system to cool more efficiently. This type of system is used in the Cadillac CTS-V, Pontiac Solstice, as well as other GM vehicles. They make good candidates to salvage used parts from. If you choose to install one of these systems, the lower line from the bottle should be tied into the return heater hose (the most forward 3/4-inch nipple on the water pump housing) on a LS engine. The vent hose from the cylinder head should be hooked to the small upper nipple on the bottle.
All production LS engines are built with a 195-degree thermostat. Never remove the thermostat from an LS-based engine since it's designed to direct flow through the engine, and removing it can cause engine damage. You can run a lower temp thermostat, but remember the engine controller uses engine temperature to determine fuel and timing curves.