Custom Induction for 354 HEMI Street Rod

1st Gen HEMI projects and products.

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Custom Induction for 354 HEMI Street Rod

Post by scottm » Wed Apr 23, 2014 10:32 pm


Custom-Built Induction For A 354 Street Rod Hemi ... -rod-hemi/
It’s either the top end of an engine or the valve covers that first attracts a gearhead’s eye. With this ’56-based 354ci Hemi, there’s no conflict as where the senses will focus. Here’s one of the most innovative and visually enticing homebuilt induction systems to come across our pages in some time. And it’s headed for a ’33 Dodge pickup street rod.

The owner of the project, Rick Simonich, has a background in automotive mechanics and currently has a business machining parts and pieces for a variety of industries. On this project, he certainly has leveraged his experience. He even built the dyno shown in the second video. While many custom pieces were fabricated for the project, and the focus for EngineLabs is on the induction system.

The first time around, he built a flat-slide throttle body in an attempt to be unique, but soon found that it would not work as intended.

“I thought I’d be the one to get the flat-slide to work, and I found out that too much vacuum pulls the plate down. In part throttle and idle conditions you’d have to have a return spring about the size of a valve spring, so I ended up having to build another throttle body and go conventional,” he explains.

Not only is the throttle body machined and built in-house, he’s also fabricated the tunnel-ram style intake manifold with a number of interesting features. It consists of billet plates that are mounted to the head, with fuel rails centrally-located with a common feed manifold at each end. The injectors are positioned underneath the runners and fire directly into the intake port At the top of the manifold is a sheetmetal box capped at each end with a billet plate, and it’s fed at the top by the triple-hole throttle body of Rick’s own design.

The throttle body was built with a progressive linkage to ensure smooth drivability, as without using a progressive linkage all three bores would crack open at the same time and dump too much air into the engine.

“The more the throttle plates are open, the less response you get out of them. Right off of idle, any crack makes a big difference since you’re changing the cross-sectional area a lot. I’ve seen people with eight Hilborn plates hooked together, and they are real jumpy driving through a parking lot. So what I did is to use the progressive linkage where the middle bore handles the drivability off-idle, and then the secondaries come in when you want more power,” says Simonich.

Each throttle bore measures 2.25-inches and are designed to flow enough based on his experiences with other engines of this size and type. The decision to go with three bores came about when he tried the flat-slide throttle body. His calculations are based on the real estate needed to make the flat-slide mechanism work.

“From initial testing, it seems like it will work out just fine as the ECM makes it all work well together,” he adds.

“We’re using an AEM Infinity ECU that controls the spark, and I also have LS coils on the engine. I want everything to look old school, not have any wires exposed, and hide everything, but I want all of the features that EFI has to offer. The Infinity system is pretty good – this is the first time I’ve used it,” says Simonich. “If you know what typical electronic fuel injection systems consist of, how they interact, and how to wire them up, then the Infinity is a nice unit. It has tons of features that I’ll never even tap into. As far as getting this thing to run and run smoothly, even though I didn’t realize I had a coil unplugged on the dyno (ed. note – see dyno video), the system compensated for that and I was able to make a full dyno pull before I realized that it sounded a little bit rough.”

It’s a unique design, and one that’s certainly impressive to see. Thanks for sharing it, Rick!
More Photos:

That's a really slick setup! 8)
Scott Moseman
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Re: Custom Induction for 354 HEMI Street Rod

Post by 301roadster » Sat Apr 26, 2014 2:47 am

how cool it that nice work :) :)

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Re: Custom Induction for 354 HEMI Street Rod

Post by DHEMI » Sat Apr 26, 2014 8:39 pm

Looks like the one my buddy built for his 392 back in 1967.He used a Hilborn 4 port and went 210 m.p.h. at Bonneville.

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