Twin-Turbo 4.8” Bore Space Billet Hemi Engine - Engine Builder Magazine

Twin-Turbo 4.8” Bore Space Billet Hemi Engine

There's a lot of impressive engines that come out of Noonan Race Engineering in Spartanburg, SC. But, the 4.8" bore space billet Hemi engine was the one that started it all for the high-performance engine and machine shop. Check out the details of this water block 4.8" bore space billet Hemi.

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If you’re familiar with Noonan Race Engineering and the shop’s billet components and engines, then you’ll also know the Spartanburg, SC-based engine and machine shop is known for its Hemi platform. While it’s not all the shop focuses on these days with the addition of an LS, Porsche, Lamborghini, and Honda offering, the Hemi combo was what started it all.

The first complete engine from the four walls of Noonan Race Engineering was the 4.8” bore space billet Hemi. While the Engine Builder team was in Spartanburg earlier this year, we got a chance to get a full engine walkthrough from Noonan’s Barry Pettit. And, this particular 4.8 Hemi engine is a little bit unique to the rest of the 4.8s out there because it is a water block.

“This customer’s 4.8 Hemi is unique because it is an H2O block, so we actually have a water passageway through this thing,” Barry Pettit points out. “This is a pretty unique platform because you can street drive this thing and still have 4,000 horsepower. It’s a pretty unique piece and we’re extremely satisfied with it. We have a lot of these things out there now.”

Another notable customer with this engine is Dominator from Street Outlaws fame. The water block itself is a standard deck height, which is a 10.725”. With the 4.800” bore spacing, Noonan is able to get a 4.467” bore size in this engine – or what some people like to call the super bore.

“This combination is going to be a 4.150” stroke as it’s going to be a twin-turbo application, so it’s not a humongous stroke like what you’ll see in some 4.8 Hemis,” Pettit says. “It’s going to want to turn some rpm to get the boost to it.”

As far as components go, Noonan machines the block, the cylinder heads and the intake manifold in-house. From there, the 4.8 Hemi combo features a billet crankshaft from Bryant, R&R connecting rods, Diamond pistons, a Manton bar rocker assembly – essentially all the components you’ll see in a Pro Mod setup, but a guy can utilize it on the street.

“We have footage of one guy who had his car here and literally drove out the gate, went up to the red light and took a cruise,” Pettit told us. “Then, he went to the drag strip that night and ran a 4.10 in the eighth after driving it on the street that same day.”

The 4.8 Hemi is the older, but smaller brother of Noonan’s newer 4.9” bore space Hemi. The two engines, while similar, have some big differences.

“The block is going to be a fair amount different due to the water passages and everything from that side of it,” he says. “You’re going to have a normal cam height in the 4.8, but you’re not able to have the same camshaft diameter that you do in the 4.9. The 4.9 is going to have a 70mm cam. The biggest you’re going to have in this is a 60mm or 65mm, which is still great. It’s just part of the things that make a 4.9 a touch better.

“The other side of it is the serviceability of a 4.8 is a little bit different than the 4.9. It’s not as bad on a turbo or ProCharger application like this because you’re able to pull the manifold and everything off pretty quick, but on the 4.9, you’re able to get into the bottom end much faster.

“As far as the machine work goes, the 4.8 block is going to have a traditional main cap design. There’s some differences on a 4.9 where it’s actually a splayed main cap. It’s a little bit better supported. There’s some features here that are ‘traditional’ with a 4.8 Hemi. The 4.9 is going to have a little bit more of a difference in engineering with our own spin on things.”

Due to this 4.8” billet Hemi having a water block, the engine is streetable to a degree, as mentioned. However, it may or may not be the best option for something like a drag-and-drive event where you are required to drive hundreds of miles.

“We have some customers out there doing it,” Pettit says. “However, I never hear anything back about them, which is really a good thing because normally you hear about problems, but it also means I don’t know if the guys who do drag-and-drive stuff with it are having great luck or not.

“In our own experience, the guys actually built a car that’s kind of famous now called the Shitbox of Doom. They used an engine like this with a blower on it, left the shop here, drove it to Charlotte, ran a 5.97 and drove back home. That’s an hour-plus drive each way and everything was completely fine. From our own experience, we know it’ll do that.”

To help the 4.8 Hemi on both the street and the track, the engine also features a Barnes side oil pump that runs off the cam sync, and the Hemi has an RCD crank hub and gear ring. Plus, this build will be twin turbocharged.

“We still need to do a final consultation with the customer and figure out injector size and compression ratio and that sort of stuff, but knowing these guys, they’ll be very well into the 4,000-horsepower range by the time this thing is going,” Pettit says. “It should be able to do that quite well.”

Engine of the Week is sponsored by PennGrade1Elring – Das Original and NPW Companies. If you have an engine you’d like to highlight in this series, please email Engine Builder Editor Greg Jones at [email protected].

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