quote Originally posted by Joseph Upson: Where did you get your information on the coolant flow? It looks like the coolant would flow in the opposite direction since the thermostat housing appears to be located centrally at the back of the pump. I was confused for a moment with the 3900 coolant flow since the thermostat is located in the same area as shown in your picture however, the filler neck and crossover mounted at the end of the heads up high suggested that despite the thermostat location it is the inlet point for coolant.

I was looking thru the service manual for the LS4 and found some pictures in the section titled "Radiator Hose Replacement - Outlet LS4". Here is a picture from that section showing the outlet hose and where it connects to the engine...



EDIT: My initial statement about coolant inlets and outlets turned out to be incorrect/backwards. The coolant inlet to the engine is in-fact the t-stat housing. The smaller coolant port just below this housing is the heater core return to the engine which routes returning coolant across the t-stat. There is a bypass hole that connects the inlet/outlet portions of the system that gets closed off once the t-stat opens. Before that (with t-stat closed) coolant is allowed to circulate between the two sections of the system so the t-stat will always see a constant flow of coolant.

I apologize for this mistake and will update the coolant flow pics as soon as possible.

-ryan

[This message has been edited by Darth Fiero (edited 11-21-2007).]

[This message has been edited by Joseph Upson (edited 09-13-2007).]

This is why I fell in love with the LS4. For the last 2 years I've been eyeing the 3.8 Series II/III S/C until I started to learn more and more about this engine. With all of the porting Ryan's done and with the planned tuning, I'm hoping to deliver at least 340hp. And I'm guessing the all aluminum engine block is lighter than the 2.8L that's coming out!

[From ]www.modernracer.com]
The heart of the Grand Prix GXP is the new 5300 V-8 – the first time in almost 20 years that a V-8 engine has been offered in a Grand Prix. It also is the first application ever for the small-block V-8 in a front-wheel-drive configuration.



Engineered specifically for front-drive layouts, the 5300 V-8 produces a peak of 303 horsepower and 323 lb.-ft. of torque – with 90 percent of torque available from 1500 rpm to 5200 rpm. It also incorporates Displacement on Demand (DOD) technology, which debuted in 2005 GM extended midsize SUVs equipped with the Vortec 5.3L V-8 (LH6) engine.
With the 5300 V-8, DOD technology enables fuel economy gains of up to 12 percent in certain driving conditions by reducing the number of cylinders engaged in the combustion process. A sophisticated engine controller determines when to deactivate cylinders, allowing the engine to maintain vehicle speed in lighter load conditions such as highway cruising. When the cylinders are deactivated, the engine effectively operates as a V-4, with alternate cylinders on each cylinder bank disabled. The engine returns to V-8 mode the instant the controller determines the vehicle speed or load requires additional power. The process is seamless and virtually imperceptible.
The all-aluminum 5300 V-8 is based on the Gen IV small-block architecture, but is modified to accommodate the “east-west” mounting position of the Grand Prix’s front-wheel-drive chassis. To fit the “sideways” positioning in the Grand Prix, several changes were made to reduce the engine’s overall length, including the use of a shorter crankshaft and a single-belt accessory drive system.

[This message has been edited by blkcofy (edited 09-14-2007).]