With the LS327 engine permanently mounted in our 1968 C10, I decided to start the fabrication process on the intercooler assembly. Since I knew I'd be sending out a handful of parts to Eddie Motorsports to have powdercoated once I finished, I wanted to get this portion wrapped up as soon as possible so that they could be out getting shot while I moved on to something else. It's this kind of thinking that sometimes gets me into trouble!
Originally, our plan was to route the inlet directly from the TorqStorm supercharger into the GM throttle body. This was obviously the simplest method as it only required a few bends and a short piece of straight tubing to get from the outlet on the supercharger to the throttle body at the front of the engine. With our projected estimate of 6-8 pounds of boost, this seemed like a logical idea. The more we discussed things, however, the more it became apparent that if we wanted to either add more boost to the mix or not run the risk of having to take timing out of the engine, we needed to find a way to cool the incoming charge.
The reason the incoming charge needs to be cooled is simple: superchargers create increased inlet temperatures. By compressing the incoming air to create more pressure or boost, heat is created. Adding a heated intake charge increases detonation problems, wear, and heat damage. All of which are the enemy of a high-performance engine. So, what we want to do is bring that increased inlet temp back down near where it would be for a naturally aspirated engine or perhaps even cooler.
To do so, we have three basic options:
An air-to-air intercooler, which cools the incoming charge by passing it through an aluminum intercooler that is mounted in the path of cool, fresh air. This is the simplest solution and is maintenance free.
An air-to-water intercooler, which cools the incoming charge by passing it through an aluminum intercooler that is cooled by water that is pumped via an electric pump from an external tank. This method involves a number of additional components, increased maintenance, and is the most complex.
Chemical cooling via water and/or methanol injection. This option introduces a water/methanol mixture into the inlet system to cool the incoming charge on the way to the combustion chamber. Like the air-to-water method, this system also requires a number of extra components including an external tank, pump, and a controller to determine when to inject the mixture.
Since our project is being built for street duty and not as a fulltime track rat, I opted to go with the simplest method, an air-to-air intercooler. Though not the easiest of the three to install, as it will require quite a bit of fabrication initially, once in place it will be completely self-sufficient.
When it came to picking out an intercooler to fit our project, we got with the guys at Vibrant Performance to discuss our needs. Based on our projected boost, horsepower and displacement, they recommended using their largest intercooler, which is good for nearly 900 horsepower. Featuring aluminum bar and plate construction for maximum cooling efficiency with minimal pressure drop, the 33x12-inch intercooler will just squeeze between the radiator core support and grille in the '68. To mate to the supercharger on one end and the throttle body on the other, Vibrant also provided a handful of 3-inch aluminum tubing bends as well as a few feet of straight tubing. TIG welded together, the inlet tract will be attached to the components using Vibrant four-ply reinforced silicone hump hose. These allow the engine to move while the intercooler remains solidly mounted without risk of cracking the aluminum inlet tract thanks to the hump hose's inherent ability to flex in the middle, or hump portion, more than a traditional silicone coupler.
Though simple in execution, the addition of a front-mounted intercooler isn't without its share of headaches, as there's just enough space for it to coexist in front of the A/C evaporator and the grille. The front valance will need to be reworked as will the lower grille opening and turn signals. This requires a bit of thought as the deletion of the front turn signals all of a sudden becomes not a problem of logistics, but of legality. Thankfully, there are a few solutions when it comes to moving them. The biggest hurdle I had to overcome was the fact that I had almost no previous experience TIG welding aluminum. Needless to say there was a steep learning curve when it came to welding the 1.5mm wall T6061 aluminum tubing. A few practice scraps and it was trial by fire; in the end I think it turned out pretty nice and my confidence when it comes to welding aluminum has definitely improved.
With the intercooler now providing adequate cooling to the incoming air to our LS327, I'm much more confident that the whole package is going to be able to perform above and beyond my expectations without falling victim to a short-sighted weak link.