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MPW Performance-built 426ci Gen 3 Hemi - Mill of the Month

By Andrew Broadley, 01 Dec 2020 Features

MPW Performance-built 426ci Gen 3 Hemi - Mill of the Month

And now for something completely different: a balls-out, twin-turbo Gen 3 Hemi!

With all the LS-ing of the world that’s been going on of late, it’s easy to forget that the Mopar brigade have a modern, fuel-injected bent-eight of their own.

This article was first published in the November 2020 issue of Street Machine

First seen Stateside in 2003, the Gen 3 Hemi has since been available in a range of displacements, from 5.7L to 6.4L. Peak Gen 3 undoubtedly occurred with the blown 6.2L version fitted to the Dodge Demon, with 840hp (on race gas) as delivered. Here in Australia, we’ve had the slightly less raucous Hellcat version available in the gloriously staunch Jeep Grand Cherokee Trackhawk, along with the more common aspirated Gen 3 Hemis found in lower-spec Jeeps and Chrysler 300s.

Gem 3 Hemi mill front

It’s an engine that is not widely messed with in this country outside of basic bolt-on upgrades, but Mopar guy Daniel Buchanan is all about the road less travelled. There is nowhere near the aftermarket support for Gen 3 Hemis that there is for GM and Ford equivalents, which means Daniel has had to stick with the factory block and Hemi cylinder head castings, the latter having been hand ported and decked out with Inconel valves by Aussie cylinder head guru Nathan Higgins.

Cubic capacity is out to 426 inches thanks to a Callies Magnum crank, Diamond pistons and 6.125in Callies I-beam connecting rods, which are actually small-block Chev specification. The inlet manifold is a ported four-barrel carburettor-style item that has been modified to accept 16 fuel injectors, required to deliver methanol to the hungry Hemi. It’s topped with a Wilson elbow and throttlebody. The engine will be dry-sumped, but the specifics of the oiling system are yet to be finalised.

Watch next: MPW Performance workshop tour - video

Gen 3 Hemi mill

But the real shove comes courtesy of the twin GTX45 Garrett snails, mounted atop a pair of sexy-as-hell custom MPW turbo manifolds. Boost will be regulated using CO2 and two 60mm GenV Turbosmart wastegates. Methanol negates the need for an intercooler, so the compressed charge heads straight down the Hemi’s gullet.

It’s an impressive-looking package that’s destined for Daniel’s street-style Chrysler 300 drag car, which rolls on a full chassis by McDonald Brothers, will sport a full interior and looks gangster as hell. We can’t wait to see it at the track!

Gen 3 Hemi mill

POWER PLAY

“WHEN it comes time to tune it, we’ll limit things to around 1500hp at the hubs,” says MPW’s Adam Rogash. “We have enough turbocharger to make more, but that’s about the limit for the factory block and we need to stay conscious of that. It’s definitely been cool to play with something a bit out of the ordinary like this.”