Dirt Late Model Engines - Engine Builder Magazine

Dirt Late Model Engines

The small blocks are preferred over the big blocks in dirt racing because of their lighter weight for better handling through the turns. In this type of racing, the way your car drives through the corners is way more important than horsepower down the straights.

Dirt Late Model racing was originally a grassroots division that sported old Ford coupes with Flathead Ford V8 engines and home-built race cars that were VERY unsafe. These racers risked life and limb for a trophy. 

The division has now become professional in every way possible. Multi-million-dollar purpose-built dirt racing facilities that hold thousands of spectators are now the norm. Major sanctioning bodies that promote over 100 races per year paying millions of dollars in prize money AND a trophy. The race cars are $100,000 purpose-built factory race cars with engines that can hook-up 900 horsepower on dirt. Dirt Late Model racing has come a long way in 70 years or so.

There are two major sanctioning bodies in Dirt Late Model racing – the Lucas Oil Dirt Late Model Series and the World of Outlaws Late Model Series. Both of these sanctioning bodies promote 50-60 races per year each with prize money varying from $10,000 to $100,000 to win every race. Both series pay their season champion $125,000 – $150,000. Both sanction bodies have races on TV, and some of them are live. As you can see, Dirt Late Model racing is BIG business.

The business side of Dirt Late Model racing is one thing, but the main reason for this article is to discuss the engines involved in Dirt Late Model racing. Nearly all, about 99% of the engines used in this type of racing, are either small block Chevrolet or small block Fords. 

The small blocks are preferred over the big blocks because of their lighter weight for better handling through the turns. In this type of racing, the way your car drives through the corners is way more important than horsepower down the straights. 

One thing to remember about these engines and this style of racing is that it is truly a ‘run what you brung’ and ‘hope you brung enough’ division. The rules are very minimal. Two valve per cylinder pushrod V8 with one carburetor on gas. That’s it!

The small block Chevrolet that is used in Dirt Late Model racing has evolved from the original 1955 265 cubic inch V8 small block. The blocks these days are made from aluminum with steel main caps and the bore centers have been widened from the original 4.400˝ to 4.500˝.  This allows you to run a much larger bore. 

The crankshafts and connecting rods are both billet steel and are paired with a forged or billet aluminum piston with low tension rings for less drag on the cylinder walls. Roller cam bearings are used in conjunction with 55-60mm camshaft journals for less camshaft deflection. Camshaft belt drives are used for less valvetrain harmonics. Large diameter roller lifters are used for better valvetrain stability. 

On the oiling side of things, aluminum dry sump oil pans are utilized with up to four pick-ups inside the pan for better oil scavenging. The aluminum cylinder heads used will vary from engine builder to engine builder, but anything goes, so each builder has their own design that hopefully will give them an advantage over the competition. 

When it comes to cylinder head selection, you’ll typically find 10- and 11-degree valve angle heads along with SB2-type cylinder heads as well. Titanium valves will be used exclusively with the latest trend in valve springs, which is a very small diameter spring with low seat pressure. The rocker shaft system will utilize steel rockers bolted to a very rigid steel stand along with large diameter, thick wall pushrods. This keeps the valvetrain stable for 9,000+ rpm. 

Up top, the intake manifold choice also varies between the different engine builders as everyone has their own secrets. You will see anything from a cast, hand-ported manifold to an exotic, CNC-ported, billet manifold. 

In addition, most engine builders will look for added performance through the use of different types of coatings on different parts of the engine. Bearings, pistons, piston pins and valves are popular areas where applied coatings can help the engine parts live longer.

The small block Ford that is used in Dirt Late Model racing has evolved from the 1968 351 cubic inch V8 Windsor engine. The Ford is built in exactly the same way as the Chevrolet engine. The most popular cylinder head for the Ford engine is the D3 Yates head. This cylinder head was originally developed for Outlaw type engines and then was used by Ford in NASCAR until the introduction of the current FR9 program.

The two engine packages (Ford and Chevy) make about the same peak torque and horsepower numbers, but the big difference is in how they drive on the race track. Generally, the Ford has more power above peak horsepower and the Chevrolet has more power below peak torque. Each driver is an individual who wants his engine package to perform in a certain way, so inherently some drivers prefer Chevys and some prefer Fords.

The stresses involved in a Dirt Late Model engine are incredible. I personally think these engines are more stressed than any other type of oval track racing engines. Dirt Late Model engines are making 700+ lb.-ft. of torque and over 900 horsepower! They have a very high compression ratio and the rpm varies from 2,500 to 9,000+! 

Pistons are one of the more highly stressed components due to exposure of speeds of almost 6,000 fpm! These engines also have to run 600+ miles before a rebuild, typically. Valve springs are changed at the 300-mile mark as these components are also prone to premature failure. One big issue is keeping them cool. Since the noses of the race cars are scraping the ground, no air gets under the nose. In fact, you can’t have any grill opening on the cars because you will pack your radiator full of dirt!

In short, building a competitive Dirt Late Model engine is one of the most challenging endeavors a performance engine builder can do. If you find success, it can be a very rewarding market, and one in which racers will keep coming back for more. EB

You May Also Like

Complete Engine Packages

In today’s world of supply chain disruptions, it is a big benefit to be able to source an entire engine system and not have to wait for that last back-ordered component to arrive.

Motorsports and car enthusiasts of all types indulge their interests to have fun. Nothing kills fun faster than stuff breaking or not working properly. A common cause of failure is mismatched parts or systems. Improper choices can create weak links or simply not work at all due to incompatibility. At Borowski Race Engines, we have found it very beneficial to help customers avoid these pitfalls on their builds by offering “complete” systems tailored to their needs.  

Top Fuel and Funny Car Engines

They’re the pinnacle of drag racing, and the engine builders, crew chiefs and teams who make these cars function at peak performance all season long are looking at every single area of the engine and the car to make it down the track as fast as possible.

Building Big Block Marine Engines

Find out what it takes to build a formidable marine engine.

Marine Engines
Developing a Honda 2.3L Engine for Road Racing

One of the most important aspects of engine building has nothing to do with the engine at all. You have to understand the customer and what they are trying to achieve.

Honda Engine
The Undying Mystique of Nissan’s RB26 Engine

With all the winning and global interest, the RB platform saw an incredible amount of growth in aftermarket support and OE performance applications. Nissan produced one of the biggest icons ever to hit the racing scene!

Other Posts

World Products’ Sportsman II 23-Degree SBC Cylinder Head

This true high-performance cast-iron cylinder head has been continuously improved since its introduction over 20 years ago.

World SBC Sportsman II head
Dealing with Deposits to Boost Engine Life

Traditionally the role of engine oil has been to slow down engine deposit development, but in concocting its latest engine-protecting blend, the Valvoline team stumbled upon something… surprising.

ProCharged 540 cid Big Block Chevy Engine

Prior to Sick Week 2024, we saw photos of Big 3 Racing co-owner Chuck Stefanski’s wagon, a 1981 Chevy Malibu rebodied as with LeMans parts, getting finishing touches, including an awesome ProCharged 540 cid big block Chevy engine. Check it out!

Big 3 Racing wagon big block Chevy engine
Big 3 Racing’s ProCharged 540 cid Big Block Chevy Engine

There’s just something about a badass wagon that hits different, and Chuck Stefanski of Big 3 Racing definitely has a badass wagon. The drag-and-drive build was completed in time for Sick Week 2024 where we caught up with Chuck to get the details of the car’s wicked ProCharged 540 cid big block Chevy engine for

Big Block Chevy engine