Arias-headed 365ci LS engine

This 480hp, Arias-headed LS was built by Kustom Bitz in Croydon, Victoria

Photographers: Chris Thorogood

UPDATE, 2 May 2023:

Some years ago, Brian Murphy charged Ron Smith from Kustom Bitz with the task of building this Arias-headed LS donk for his ’32 roadster. The engine is now in the car and it’s ready for registration this week.

Here’s the original feature on Brian’s engine from the December 2015 issue of Street Machine.

December, 2015: Everyone loves a hot rod with a bit of classic engineering up front, like a flathead V8 or even a four-banger, but they require some mechanical sympathy and a bit of maintenance to run their best.

“I’m doing this ’32 roadster for a customer and he was quite keen on running a flathead,” Ron from Kustom Bitz says. “I love flatheads, but when he told me he wanted to drive it up and down the east coast doing all the hot rod runs, I knew I had to set him straight. The trouble is, flatheads are great if you want to trailer your car to the event and then cruise around there, but if you’re going to be doing big miles you’ll be forever working on it.”

Obviously that was a bit disappointing for the bloke, because he definitely wanted to do some miles with the top down and the wind in his hair. So he went away for a couple of months and came back with a new plan. “He pulls out his tablet and shows me this engine he’s bought, and I say: ‘What have you done? It looks like an Ardun-headed flathead!’” Ron recalls.

What the customer had actually done was buy a 480hp Arias-headed LS engine – all the coolness of a hemi-headed donk, but with the reliability of a modern powerplant.

The bottom end is your basic six-litre LQ9 cast-iron block with a 4.005in bore and 3.622in stroke, filled with forged Arias pistons attached to standard rods with ARP bolts and a factory crank. All the magic is in the top end, with a pair of Nick Arias Jr LS-AH ported heads and a matching cast-alloy intake topped by a four-barrel Holley.

“They’re a true hemi head,” Ron says. “They’ve got canted valves on each side, and they’ve even modified the front to run a dizzy.”

The set-up is good for 480hp at 6500rpm, which is plenty to push a ’32 roadster around, but for those looking for a bit more poke, Arias does a 403ci version that punches out 700hp! Bloody hell, where do we sign up?