This is an Arias 454 Hemi V8 that has been dyno tested and shown to produce 739 bhp at 6,500 rpm. The seller notes that it can produce up to 1,100 bhp with a pulley change, and given the racing heritage of these engines, there’s no reason to doubt him.
When you start talking about a “Hemi” 454 Chevrolet big block V8 many old school muscle car guys will laugh at you, thinking you’re conflated the 426 Chrysler Hemi V8 and the Chevy 454. Although it might sound like an accident, it isn’t. These are very real engines developed by Nick Arias Jr and used extensively in drag racing, boat racing, and tractor pulling competition with much success.
This is an Arias 454 Hemi V8 that has been dyno tested and shown to produce 739 bhp at 6,500 rpm.
The Hemi Chevrolet Big Block V8 By Nick Arias Jr
Nick Arias Jr was a hugely influential figure in specialist American V8 engine design – his Hemi-head conversions for Chevrolet big block engines remain some of his most fascinating and under-appreciated creations, and they never fail to attract a huge amount of interest when people encounter them for the first time.
Arias’s name is often associated with forged pistons through his companies Venolia and later Arias Pistons, but for a unique subset of drag racers and engine builders, it was his Hemi cylinder heads for the Chevy 454 and other big blocks that left a major mark on the industry.
Arias began developing these heads in the early 1970s – aiming to combine the airflow efficiency and combustion characteristics of Chrysler’s 426 Hemi with the more accessible, affordable, and abundant Chevrolet big block lower end.
The idea was relatively simple – to deliver Hemi-like power and breathing capabilities without requiring racers to switch engine platforms or reconfigure their driveline setups. To do it, Arias designed a series of custom heads that bolted directly onto a big block Chevy block, typically the 454 or 502, with true hemispherical combustion chambers, large intake and exhaust valves, high-flow ports, and a canted valve angle configuration.
The Arias Hemi heads weren’t just lookalikes or cheap copies – they offered major improvements in volumetric efficiency and allowed higher compression ratios while resisting detonation. The heads accepted custom intake manifolds and typically required shaft-mounted rocker systems, but the overall package fit within a conventional Chevy big block engine bay and bolted right onto the same engine mounts.
Racers could keep their bellhousings and transmissions in place – which made the conversion far more practical than a full 426 Hemi swap.
One of the most well-known implementations of the Arias Hemi head conversion was on a 572 cubic inch Chevy V8 built for drag racing. As covered in MotorTrend’s 2008 article here, the engine used Arias’s 10º hemispherical combustion chambers and produced serious horsepower on race fuel, paired with a Dominator-style intake manifold and high-lift cam. Builders reported that even naturally aspirated setups could push past 1,000+ bhp when combined with forged internals and careful tuning.
The engine has seen minimal use since it was built, it was installed in a Ford T-Bucket hot rod for testing purposes, at which time it was dynoed. It’s now being sold with everything needed to install it and get it running, as well as a TH350 three-speed automatic transmission.
Despite their proven performance potential, Arias Hemi heads never saw large-scale adoption or production. The conversion cost, complexity, and custom component requirements kept them in niche territory and almost all were used in race set ups.
Still, they offered a fascinating blend of old-school ingenuity and top-tier engineering, and the surviving examples are now much sought after.
The Hemi Chevrolet Big Block V8 Shown Here
The engine you see here is reportedly one of the five pre-production motors built in this series, with a total of 52 units built in total. The pre-production variants have a number of unique variations when compared to the later units.
It’s built around a tall-deck, four-bolt main 454 Chevy big block, fitted with aluminum Arias Hemi heads, a fuel injection system, a high-torque starter, and of course, that supercharger bolted to the top.
The engine you see here is reportedly one of the five pre-production motors built in this series, with a total of 52 units built in total. The pre-production variants have a number of unique variations when compared to the later units.
The engine has seen minimal use since it was built, it was installed in a Ford T-Bucket hot rod for testing purposes, at which time it was dynoed. It’s now being sold with everything needed to install it and get it running, as well as a TH350 three-speed automatic transmission.
It’s now being offered for sale out of Arlington, Washington on Bring a Trailer and you can visit the listing here if you’d like to read more about it or place a bid.
Images courtesy of Bring a Trailer
Articles that Ben Branch has written have been covered on CNN, Popular Mechanics, Smithsonian Magazine, Road & Track Magazine, the official Pinterest blog, the official eBay Motors blog, BuzzFeed, Autoweek Magazine, Wired Magazine, Autoblog, Gear Patrol, Jalopnik, The Verge, and many more.
Silodrome was founded by Ben back in 2010, in the years since the site has grown to become a world leader in the alternative and vintage motoring sector, with well over a million monthly readers from around the world and many hundreds of thousands of followers on social media.
