How to Build a Supercharged Engine for the Street
A supercharged engine is one of the most impressive things on the street and is definitely the most fun that you can have. It can also - believe it or not -- get impressive gas mileage, as long as you don't floor it everywhere you go. It will last as long as a conventional engine with very little service. Building an engine requires experience, so these instructions assume you have the necessary experience or have someone that does.
Other People Are Reading
Instructions
-
-
1
Purchase a 4-bolt main block and a steel crankshaft. Have the machine shop double-keyway the crank and the crank damper. The crankshaft damper must be of the solid type, such as a fluidamper, because the standard damper will come apart right away.
-
2
Put the bottom end together. The connecting rods should be somewhat stronger than standard -- use something like Miloden. The pistons should be dished for a supercharger with no more than 8.9:1 compression ratio. They should also be the floating-pin type.
-
-
3
Put the top end together. The heads make a big difference in the power, so a decent set of heads should be used. The emphasis should be on the exhaust side --the exhaust valves should be slightly larger than standard. Install a good set of high-performance valve springs and stronger push rods. They don't have to be expensive, just a little stronger than stock.
-
4
Install a camshaft that is designed for a supercharger. It can have a relatively high lift without the normal idle problems associated with high lift. The supercharger tames the cams to a more manageable idle.
-
5
Install the supercharger. Remember not to overtighten the aluminum bolts, since they are made to break away in the event of an internal explosion caused by a broken valve. Install the fuel management. Two 465 Holley carburetors are a good combination for the street.
-
6
Install the supercharger belt. Within a minute of start up, the belt heats up and increases tension considerably. Leave it very loose at start up to the point where it has 2 inches of deflection. It will be bowstring-tight quickly after it heats up.
-
7
Purchase a good electric fuel pump with plenty of volume; the pressure is not as important as the flow. You want no less than 8 pounds of pressure under load so that it never runs lean.
-
1
Tips & Warnings
A supercharged engine can easily double the horsepower and almost double the torque. However, the engine will rev up much faster than a conventional engine. You will need a short-snout water pump to clear the belt. The long-snout will hit the blower belt. You will need to use a smaller distributor, such as a points distributor. The HEI distributors will not fit between the supercharger and the firewall.
A supercharged engine will rev as fast as you depress the gas pedal with no lag. This produces considerable shock and stress to the drivetrain, which can and will cause catastrophic failure if not dealt with up front. The engine mounts, especially on the left or torque side will fail quickly, so replace with solid ones. The torque converter will fail almost immediately if it is not a decent one. A B&M converter will not last more than a few passes, so use a TRW or better with a stall rating of no more than 2500 RPM. Make sure you have a decent transmission such as a turbo 400 or equivalent. Make sure you have a driveshaft loop and that the driveshaft has solid universals that are much stronger. The rear or third member should not have excessive play in the ring and pinion - that could cause shock, so be sure there are only five to six thousandths of play. The engine can easily twist or bend the body of the car. The rear window can pop out. Install frame connectors if possible, or at least install a six-point roll cage to the frame to strengthen it and make it stiffer.
