When you think of a 500 horsepower four-cylinder, unless we’re looking at a super secretive Pro Stock drag build, it has generally been safe to assume that the engine is either boosted and revving to the moon or bored and stroked with a healthy shot of nitrous — well, add another naturally aspirated build to that list.
Just west of Indianapolis, Indiana, lies Danville — home to 4 Piston Racing (4P). Growing up around Indy, Luke Wilson and Josh Klein have motor oil running through their veins and started 4P together over 20 years ago to fulfill their dream of building some of the best race engines in the industry. Living by the saying “Pick one thing you’re good at, and do it better than anyone else,” Wilson and Klein chose to dedicate their lives to perfecting cylinder head development and designs.
Wiseco Piston stopped by 4 Piston Racing and talked to Wilson about their recent 500 naturally aspirated horsepower Honda K24 build for a specific FWD drag class that limits engine displacement.
This build starts with your standard cast 2.4-liter K24 block, and then undergoes the 4P “K480” rebuild. The K480 build is specifically designed for the abuse of high-end drag racing and grudge racing — as 4P puts it on their website, this really is a “no compromises” four-cylinder build.
Starting with the bottom end, this K24 gets a custom Winberg crankshaft that increases piston stroke from 99 mm to 106 mm, and is encased in ACL Race Series bearings. The standard 87 mm cylinders are treated with ductile iron sleeves from L.A. Sleeve and given a slight overbore to 90 mm.
To keep the reciprocating weight as low as possible, which enables this engine to scream to 10,400 rpm, the forged Wiseco pistons weigh just 260 grams and are supported by a set of 340 gram aluminum GRP “Pro Stock” connecting rods — producing some serious cylinder pressure with a 16:1 compression ratio. A custom ported oil pump is also used to prevent pump cavitation at those high engine speeds.
Sitting in-between the deck of the block and the heads mating surface is a custom designed 4P head gasket for an optimal seal, sitting on top of that is a 4P in-house designed “Peacemaker” CNC cylinder head capable of flowing in excess of 430 CFM with 0.650-inches of lift.
A Skunk2 BMF billet camshaft times the engines breathing while a set of stiff PSI Pro Stock valve springs snap the 1.510-inch Ferrea titanium valves shut and prevents them from floating if you miss a gear. And a 70/71.5 mm Kinsler induction system pulls air in through a set of CNC ITBs before injecting the required Q16, Methanol or similar race gas.
Wilson says if you slap these parts on your K24, it will be capable of producing between 460 and 480 horsepower on a Dynojet right out of the box. With some additional fine tuning of the mechanics and dialing in the calibration, this monster can move enough air on its own to produce over 500 horsepower from just four cylinders!