One of the first low cost performance modifications most people make is the addition of a throttle body coolant bypass. The LS1 (and other GM engines) routes engine coolant through the throttle body to keep the throttle plate from sticking in extremely cold weather. This has the rather obvious result of heating up the throttle body and possibly the incoming air. Since hotter air is less dense, the engine produces less power. I'm not sure how much this modification will help, but since I live in Southern California, and since it costs less than thirty dollars, I figured what the heck.
Installation is very straightforward. First remove the intake tract ducting forward of the throttle body. Beneath the throttle body you will see two hoses attached with spring clamps. It should be noted that the engine must be dead cold before you begin this process. You first need to remove both hoses from the throttle body. This can be a pain due to the type of clamps used and their position below the throttle body inlet. Two pairs of needle nose pliers did the trick. Be prepared for a fair amount of coolant to come out. Once both hoses are off, it's a very simple matter to install the bypass (just a coupler really) and clamps. Make sure the clamps are tight and secure, this is your cooling system we're talking about. It's important to make sure the hose is secured in a position where it will not contact the fan belt or pulleys. We secured it to the upper radiator hose with a wire tie. Don't make the tie too tight or you'll constrict one or both hoses. Put the intake tract back on and you're ready to go. Be sure to start the engine and look for leaks when you're all done.
Since this modification was done in concert with a few others, it's impossible to tell exactly how much gain
was realized. All in all, I think it's worth doing for the small investment of time and money.
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