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Blown Legal

Want a Supercharged Engine That Will Pass Smog? Here You Go!

Smog laws don't have to prevent you from making horsepower, as long as you use the correct parts, build the engine the right way, and tune it until it delivers a clean exhaust.

It is true however, that smog laws and legislation are making it more and more difficult for performance enthusiasts to build their toys beyond what the factory did. Things like restrictions of certain years and elevated testing at smog stations are definitely keeping people from modifying some of the later classics.

It is still possible to build a reliable, "smog-legal" engine that will make more than enough horsepower to get you into trouble, and pass the sniffer--and visual--test when the time comes to renew your registration. To give you some insight into how this is possible, we took this little small-block and created a shining example of what you can build when you do a little homework to discover what is available and make a smart decision on what combination of parts to use.

One thing you must take into account, though, is that not all smog laws are the same and you must be aware of the laws where you live. Some will have it a little easier than others, but for those in California we're still faced with the most stringent regulations in the country.

The short block we chose is a 383 that was built by Golen Engines. An Eagle cast-steel crank and a set of SIR connecting rods make up the stroker's bottom end, while a set of forged slugs from JE Pistons fill the holes. Actuating the valves is an Extreme Energy smog-legal bumpstick from Comp Cams. But the biggest addition, and the one most likely not to be considered "smog legal," is the Weiand 142 street blower.

Since the engine will be supercharged the pistons are of a "dish" design instead of the standard "flat top." These pistons equate to a mild 8.5:1 compression ratio, but this will help keep the engine from hammering itself to death with detonation when it's on boost. The cam also is a special grind for a supercharger, since blown engines require a different lobe spread than those that are naturally aspirated. This smog-legal blower cam has a split duration of 218/224 at .050 inches, which is fairly small, but that's exactly what this motor needs.

A set of World Products Sportsman II cylinder heads sits on top of the Golen short-block. These castings are smog-legal steel units with a large 200cc intake runner. This is an excellent street head for the budget-minded enthusiast and comes fully assembled for a fairly reasonable price.

The coolest part of this motor is the Weiand street blower, though. This aluminum lung is smog-legal in all 50 states and proudly displays its Executive Order, or E.O. number. Out of the box, the roots design cranks out roughly 4 pounds of boost, but that should be more than enough to get any street freak's attention. The blower comes complete with everything you'll need including an intake manifold, water neck, belts, pulleys, and gaskets.

To fire the supercharged mix we chose a Performance Distributor's DUI high-voltage HEI distributor along with a set of their Live Wires. The distributor was custom curved by DUI and will retain the use of the vacuum advance. The Live Wires are pre-assembled and come wrapped with a neat heat sleeve that will withstand very high temperatures.

Every part that was chosen for this engine is smog-legal and comes with a government issued E.O. number. It is good to point out that simply because it is an aftermarket smog-legal part, it will still require some tuning and adjusting to get it to pass the smog test procedure. Do not think that you can simply bolt parts on an engine and it will automatically pass a sniffer test.

So follow along as we show you the best of both worlds. And we'll prove that you really can have your cake and eat it, too.

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