Celebrate 4/26 Hemi Day With Record-setting Monster Truck Engine

Hemi engines hold a number of speed and victory milestones in the world of motorsports, but for this observance of National Hemi Day EngineLabs is showcasing one of the more unusual record  holders–the world’s fastest monster truck!

The famous Hemi Dog will be barking loud this Sunday while celebrating National Hemi Day.

It’s April 26, or 4/26, which is the traditional Hemi Day for Mopar lovers of the iconic hemispherical-chambered cylinder head. Last year was quite the celebration as the Chrysler Hemi engine observed its 50th birthday. It was February 1964 that the Hemi officially debuted in the Daytona 500 in which Richard Petty led a 1-2-3 Mopar finish.

A direct ancestor of that classic Gen II 426ci Hemi engine is found in the Raminator monster truck, which is campaigned by brothers Tim and Mark Hall of Champaign, Illinois. The Raminator is recognized by the Guiness Book of World Records as the fastest monster truck with a speed of 99.10 mph. With Mark Hall in the driver’s seat, the truck set the mark on the front straightaway at the Circuit of the Americas track in Austin, Texas last December. The previous record was 96.8 mph set in 2012 by Randy Moore at zMAX Dragway.

Powering the 10,800-pound Raminator is a supercharged 565ci Hemi built at Hall Brothers Racing.

Hemi engines now come in many sizes and configurations, including this killer 572ci crate version from Mopar.

“The motor is essentially a Top Alcohol motor except the rules don’t allow big superchargers,” says Tim Hall. “We’re allowed only a 8-71 blower driven at 10 percent over, so we will use more compression.”

As with any engine builder, Hall won’t disclose some details, such as the compression ratio that he will only hint is “over 10:1.” The foundation is a Brad Anderson (BAE) billet block bored to 4.470-inch and fitted with a 4.500-inch stroke Bryant billet crankshaft, Bill Miller (BME) connecting rods and either Ross or JE pistons (he’s used both in building engines for the two-truck team). Lubrication is handled by a custom Dan Olson pan holding 19 quarts of CenPeCo 70W racing oil that are fed through a RCD pump.

Here’s an assembled 565ci Hemi long-block at Hall Brothers Racing.

Oil control during donuts

“Because the engine sits backwards in the truck, it’s a bit of challenge for the oil system,” says Hall, noting that the pan is designed to counter the effects of G-forces on the oil supply not only during acceleration but also when the truck is aggressively spinning donuts. “They’ll get going so fast that they sling oil up into the cylinders and away from the pickup.”

Two more views of the Hall Brothers Hemi.

“There are a few things we do different than the alcohol drag racers,” explains Hall. “For example, we have to run the power steering pump off the supercharger. Another thing we’re dealing that the drag racers aren’t is we have 30 inches of wheel travel.”

Why not use a dry-sump system?

Hall tried mocking up a dry sump system but the massive control arms on the 4-link suspension interfered with the pump position at full compression.

“Obviously the dry sump would give us more pan clearance, but that pump was in the way with the scavenge lines,” says Hall.

Some of our favorite Hemi images.

The BAE cylinder heads feature titanium valves, triple valve springs and Stage V rocker arms that are motivated by a Comp Cams roller camshaft. Topside are a Littlefield 8-71 supercharger and an Enderle “Big and Ugly” injector-scoop. Enderle also supplies the 13 gpm fuel pump while a MSD 44-amp Pro Mag supplies the spark. Finishing details include an RCD front cover, mag drive and starter, while Hall fabricated the 2.5-inch zoomie headers. Backing up the engine is a 2-speed MonsterGlide XST transmission from Coan Racing.

A couple of our favorite Hemi advertisements.

Nothing phony about the record run

The engine puts out an estimated 2,000 horsepower on methanol. It wasn’t changed in any way before the team made its record attempt at COTA.

“We didn’t want to bastardize the record,” says Hall. “Aerodynamically we know we’re dirty. So if you went in and cleaned up the aero, and pulled a driveshaft so you’re running only 2-wheel-drive, you could make the truck go faster. But in our mind that would skew the record. We wanted it to be a genuine monster truck.”

The Raminator made its record run at the Circuit of the Americas in Austin, Texas.

The Raminator made its record run at the Circuit of the Americas in Austin, Texas.

The Raminator team did change the gear ratio in the transfer case, which is a tuning tool they use at different tracks to adapt to the many different terrains and surfaces over which the competitions are held. As a preventative measure, Hall also put in a 8,500 rpm chip.

“We didn’t hit it, so it was turning around 8,200 rpm on the run,” says Hall.

The team had tested at 106 mph but couldn’t break the century mark when the record attempt was arranged at COTA; there was limited opportunity that day as the Nissan Delta Wing also rented the track for a test session.

“We wanted to make one more run but they didn’t want people and cameras around any longer,” says Hall. “One of the interesting things is to watch the tires on the run. They grew like the tires on a dragster.”

The Raminator’s record run was just one milestone in a rather good year for the Hemi. Perhaps the most noise was generated by the release of the 707-horsepower Hellcat Hemi in the 2015 Dodge Challenger SRT.

For a look back at other interesting EngineLabs stories on the Hemi engine, check out this list.

About the author

Mike Magda

Mike Magda is a veteran automotive writer with credits in publications such as Racecar Engineering, Hot Rod, Engine Technology International, Motor Trend, Automobile, Automotive Testing Technology and Professional Motorsport World.
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