Engine of the Week: Twin Supercharged 426 Hemi Engine
https://www.enginebuildermag.com/2021/1 ... mi-engine/
What a beast of a HEMI. If Arrington needs a test truck, I'll volunteer my RAM.We caught up with Mike Copeland of Arrington Performance during the 2021 PRI show where he told us all about his new twin supercharged 426 Hemi build capable of 1,500 hp! Check it out.
Just a few weeks removed from the 2021 PRI show, and we’re already thinking back on it with fond memories. We saw a ton of cool engines and caught up with a bunch of folks who are both old friends of Engine Builder as well as new.
One of those newer friends is Mike Copeland, owner of Arrington Performance in Brighton, MI. We first met Mike at the 2021 Hot Rod Power Tour during the first stop at Summit Motorsports Park in Norwalk, OH. Mike spoke with us about his 1984 Dodge Rampage nicknamed Outrage, which featured a mid-engine 392 Hemi.
This time around, when we saw Mike during the PRI show, he wanted to tell us about a brand new 426 twin supercharged Hemi build he finished in time for both SEMA and PRI.
“I love PRI,” Copeland says. “It is so good to be home again, right? This is where we all get to hang out – all racers. The place is full of gear heads and it doesn’t get any better. We brought out one of our latest engines. This is a Gen III 426 Hemi.”
The engine uses a forged crank and rods and Wiseco pistons – all specifically designed for a 1,500-horsepower target. It uses the production block, but all the clearances have been gone through.
“Like any high-end engine builder, we used engine surface plates and four-square cornered the pistons to get them all at the exact same height,” Copeland says. “We go through and set the cam journal and then measure that to the crank, then we set the crank journal and everything is set off of that. Any variances in the block gets machined out. Dodge does a pretty good job, but their numbers may be a little different than ours.
“The cylinders are all bored and honed using block plates. We eliminate the variable valve timing with most of these. We also eliminate MDS. We don’t run any of that in the engine.
For a street engine, variable cam timing is actually an advantage. You can rotate the camshaft and then we have to limit them when we use aftermarket cams for more lift and duration. Running that lets you change the cam location and get more torque at lower rpms. As you get into higher rpm, we rotate the camshaft and get the performance back at the top. We have to eliminate that with big camshafts, and obviously with a 1,500-horse target, this is a pretty serious beast. We eliminate that because of the cam size. It’s still a hydraulic roller made exclusive for Arrington.”
To help the all-forged bottom end and larger camshaft, Copeland told us that the valvetrain features Thitek GIIIH Bear cylinder heads.
“It’s the biggest Thitek head they make,” he says. “It flows the most air and has larger valves. We use Hellcat lifters and we also run a Holley intake on it with a Sniper 105mm throttle body. We’ve modified the ports in it as well. Hemi intakes are a little bit limited, so you have to get what you can get.
“The Holley throttle body is actually an LS and we welded a piece to the front of their intake to support it. Anytime you get a blow-through type application, big throttle bodies really help. This is where you get the biggest bank for the buck. That’s why I went with the 105mm. I’m using a Holley Dominator to control it.”
With top-notch internals, quality heads and intake, Copeland took a step up by choosing to add billet, twin TorqueStorm superchargers.
“Hemis move a lot of air, so if you want to make a lot of power with them, you’ve got to run two superchargers,” he says. “You can make 9-10 lbs. on a smaller Hemi, maybe 12 lbs. with a single, but here, our target is 20 lbs.”
TorqueStorm delivers a good product for the price, and at 20-lbs. of boost, Copeland says 1,400-1,500 horsepower should be easily attainable.
“One of advantages too is that these superchargers are lower rotational mass and lower rotational friction,” he says. “People don’t think about weight of the supercharger components. You have to accelerate it and then you have to slow it down. A lot of times when we’re running on engine dynos, when you lift off of it, you can actually hear the supercharger weight squeal the belt as you lift off of the throttle. That’s a real good indicator that you’ve got a lot of components moving and they weigh a pretty good amount. We don’t get that with these.”
With a 1,500-horsepower goal, this twin supercharged 426 Hemi engine is getting dropped into Copeland’s own 1969 Dodge Dart street car. Knowing what we know about Mike, we’re sure he’s going to have some fun with this combo!
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