Building a solid engine combination to jump into the world of boosted Pro Mod or top level radial tire racing is a must if you want to win. Out of all the different options on the market, the 481X platform has proven to be one of the fastest and most reliable out there. Alan Johnson Performance Engineering (AJPE) might be known for their NHRA Top Fuel and Funny Car engine packages, but their 481X program is just as strong and their new Stage 4 481X head is set to change the game.

The 481X motor is a Chevrolet based mill that used a symmetrical port design for the heads. This motor is capable of incredible boosted power no matter if you strap a blower on top, or put a set of turbos in front of it. AJPE has been working on some improvements on their 481X cylinder heads and the Stage 4 is the final product.

The goal for the Stage 4 was to make this head stronger by adding some stiffness to the valvetrain according to AJPE’s  Rick Wilkinson. “The idea was to reduce valvetrain flex and movement in the package by tying it down to the head the best we could. We’ve increased the fastener size, we’ve increased the amount of fasteners to help reduce that flex.”

Besides having a stronger valvetrain, the Stage 4 heads have some other features previous models didn’t. “In this head we can put a 9/16 pushrod on the intake and exhaust where it was only on the exhaust side in previous versions. The whole girdle assembly is different and much stronger on this head. There’s also options for a 65mm cam tunnel, dog bone style lifters, or .937 keyway lifters,” Wilkinson explains.

If you’re looking to add even more power to your 481X give AJPE a call or visit their website to get your hands on the Stage 4 head.