Continuing with our “dirt racing education” series, we turn to dirt late models. If you are a casual fan and want to know more about dirt late models, you will have to dig a little deeper when doing some research. This is because a quick Google search for “late models” will yield you thousands of results and include a style of late models that run on pavement. For the purpose of this article, we will only be focusing on dirt late models.
In this article, you will find:
- Define Dirt Late Model
- Types of Dirt Late Models
- Late Model Specs
- Chassis Builders
- Engine Specs
- Popular Dirt Late Model Series
- Major Dirt Late Model Races
Helpful Links
- Dirt Late Model Racing – Technical Overview
- Dirt 101 – World of Outlaws Late Models
- Engine Builder – 438 small block
- Dirt Late Model Engines
- FloRacing VIDEO – Breaking Down Dirt Late Models
Hey Google, Define Dirt Late Model
A Dirt Late Model is a full-bodied style dirt car designed to run on dirt ovals. The frame and body are custom built to provide aerodynamic downforce at top speeds.
Types of Dirt Late Models
The most common form of a dirt late model you will find is a “super” late model. These are the top cars in dirt late model racing and the ones featured on some of the top national touring series. In more regional style dirt late model racing, you will find “limited” dirt late models and “crate” dirt late models. In some cases, these two can be the same. At first glance, you would not be able to tell the difference between the three, as the main difference exists underneath the hood.
Dirt Late Model Specs
I could write 10,000 words breaking down the specifications of the bodies and everything else that goes into a dirt late model. Instead, check out the dirt late model rules for Lucas Oil Speedway for a full breakdown to get an idea of some common rules and specifications.
Some common specs you will find include:
- Weight – 2,350 with driver
- Spoiler Height – 8 inches max
- Droop (left rear height limit) – 50 1/2 inches
Chassis Builders
In dirt late model racing, you won’t find the likes of Ford, Chevy or Toyota building frames for these teams and drivers. These cars are custom built and the manufactures are very competitive when it comes to marketshare. Some of the most popular dirt late model chassis builders today include:
Engine Types
For those just getting started out in dirt late model racing or for those racing locally on a budget, crate late model racing is probably where you will find them.
Crate
Some common types of crate late model engines include the GM 602 and 604 engines. These engines must be factory and not altered. They usually produce around 400 HP and stay under 6,000 RPM.
A GM Crate 604:
- Engine Type: Chevy Small-Block V-8.
- P/N: 19419604D1.
- Power: 400 hp @ 5,500 rpm / 400 lb.-ft. @ 4,500 rpm.
- Displacement (cu in): 350 cu. in.
- Bore x Stroke (in): 4.00″ x 3.48″
- Block: Cast iron with 4-bolt main caps.
- Crankshaft: Forged 4340 steel.
- Connecting Rods: Powdered metal.
“Limited” 358
When a driver is ready to make the jump from crate racing, a “limited” 358 dirt late model is usually the next step. A 358 dirt late model engine can produce around 600-650 HP and run at 8,000 RPM. Here is a breakdown of some 358 late model rules for a specific track.
A.) Engines limited to 358 Cubic Inches.
B.) Block must be a standard production block or approved aftermarket block that was less than 358 cubic inches originally. No aluminum blocks
C.) Crank minimum weight of 46 lbs.
D.) RODS- Any rod up to 6 inches. NO TITANIUM RODS.
E.) Flat top pistons only.
F.) Any steel head, or DART steel head, valves must be in factory location. Heads must have a 60 cc minimum combustion chamber. Aluminum heads with 2 barrel 650 carburator. No relocating rocker arm studs. Rocker shaft systems are allowed.
G.) Production valve or production replacement, steel or stainless steel only. Any spring, any retainer permitted. Roller rockers permitted. Stock valve guide angle. No relocating valve guides. No titanium except for valve springs, retainers and locks. No valve stem diameter smaller than a 5/16” (.310”) Shaft Rocker legal.
H.) Flat tappet cams only no rollers.
I.) Block must be cast iron.
J.) Must have a working clutch and starter. Multi-disc clutch permitted.
K.) Gear drive units permitted.
L.) No needle bearing cam, crank or rod bearings permitted
“Super” Late Models 400-430 cubic inches
Drivers and teams competing in the national touring series use these engines. They are the pinnacle of dirt late model racing and can produce over 800 HP.
We usually try and stay around the 13.5:1 to 14:1 range. Usable rpms to 8,500 and those kinds of combinations will last 1,000-1,200 laps before they need freshening up.
The block for the 438 is a Brodix with 4.500˝ bore spacing. The crank is a billet Crower crankshaft. Connecting rods are Dyer Top rods. Pistons will be either Diamond or CP. The cylinder heads start life as Brodix and then they get CNC’d from there, and the intake manifold is a two-piece manifold and will be CNC’d to match. The engine has a billet 850 carburetor, titanium valves and titanium retainers and Crower stainless steel rocker arms – all particular to the 4.500˝ bore spacing.
Greg Jones – EngineBuilderMag.com
Popular Dirt Late Model Series
Dirt late model racing is arguably the most popular form of dirt racing in the United States. There are two major national touring “super” dirt late model series that include some of the best dirt drivers in the world.
Major Dirt Late Model Races
Some of the biggest events in all forms of dirt racing involve dirt late models.
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