Racing crate engines on dirt is a unique animal. Matt Long (No. 25) shares with us the sec
They look the same, they share the same chassis, the racing is just as exciting, and they even (sort of) sound the same. But there is a world of difference between Super Dirt Late Models and the Crate Late Model class.
Customarily powered by GM's 604 crate motor, the Crate Late Model class was originally designed as an entry-level racing class that would allow racers to use older chassis that had been cycled out by the Super Late Model racers. In many ways, the Crate Lates are still that, but the class has also grown into much more than that over the few years since its inception. Now there are touring series just for the class, and very accomplished racers that could have success in Super Late Models who choose to stay in the Crate class because they like the overall package. But racing a Crate Late Model isn't simply racing a Super Late Model that's a little bit slower.
The difference in power is significant, and that can affect the way the suspension must be set up for the best lap times. For example, Super Late Model drivers can use the throttle to get the car to rotate through the turns, but with 350 to 400 horsepower, Crate drivers simply don't have that luxury. On a half-mile dirt track, corner entry speeds can be 20 to 30 mph slower, so you really have to do more with the chassis to get the car to do the same thing.
Adjustable shocks can be a godsend for small race teams. Instead of swapping out shocks, t
Another critical difference is in the Super Late Model class. The engines are more than strong enough to easily overpower the tires, so good throttle control is vitally important. In the Crate classes, not only are the engines not strong enough to overpower the tires, but every driver also has approximately the same amount of power. In an attempt to get an advantage, some teams will cheat up the motor-but you're on your own there. Teams that take a more sporting approach instead make the driveline as efficient as possible in order to get all the power available from the crankshaft to the rear wheels.
To get a better idea of what it takes to win in Crate Late Model dirt racing we checked in with racer Matt Long who races the FastTrack touring series and won eight times in 45 races last year. Long is a great example of the success of the Crate Late Model class. This is just his fifth year racing-all in the Crate class-and he has enjoyed success without a large budget or even a lot of volunteer help. Mostly, he says, his race team is a two-man operation, him and crew chief Jim Cook Jr., but they are still able to keep the car properly maintained and competitive.
"In this class," he says, "winning really is all about the chassis. It doesn't matter how good you are as a driver if you can't get the car set up right. Everybody has the same amount of power so you have to do something different to separate yourself from the pack."
One of the great things about dirt racing is that the track is always changing. Dirt track racers can never assume a setup that works well during the heats is going to be the best option when the feature starts. Normally, a dirt track will start out wet and tacky with lots of traction but dry off and get slicker as the night winds on and the laps on the track pile up. Because of that, Long says you should find a baseline setup that works for you in most situations, then tune for the specific conditions of the night you are racing while also keeping in mind a plan for how you will adjust the car as the night goes on.
Driver Matt Long measures the length of the rear suspension bars. By moving the right rear
"A Late Model chassis has a ton of adjustments you can use, but if you try to use all of them it's really easy to adjust yourself right out of the ballpark," Long says. "You have to find the adjustments that work best for you. The things that work best for us and we most often turn to are the shocks, the springs-particularly the right front-and the rear bars."
Using adjustable shocks makes tuning changes quick and easy. Long and Cook will normally go with an adjustment to the front shocks as the track changes throughout the night. As the track dries out and slicks up, adding a little rebound to the front shocks will help hold the front end down after Long uses the brakes before entering the turn. More rebound shifts the weight over the front wheels and helps the car turn until you get back on the gas.
You can also soften up the compression on the right rear shock as the track gets slick to help you get more traction as the car rolls over on the right side. Likewise, increasing the compression on the left rear at the same time will further help you stick the right rear just a bit more.
Crew chief Jim Cook Jr. maintains a rigorous maintenance schedule on the car to make sure
You can also achieve similar results with the springs. For example, if they feel the need for a more drastic change, Long and Cook can go with a lighter spring on the right front along with the shock adjustment to further help the car turn.
Adding a stacked spring system to the right front wheel can also help add bite to the car without causing it to push. A car that pushes will scrub off speed, which is deadly in the Crate class where the entire game is about maintaining as much speed through the turns as possible. By using a stacked spring setup-for example a 250 pound spring with a 600-the softer spring will allow the right front wheel to bite on turn entry but the 600 pound spring will hold that corner up until the throttle gets picked up through the middle of the turn and off.
The rear bars on a Dirt Late Model chassis can be quite intimidating for new racers because what the changes actually do aren't always obvious. But Long recommends a few specific changes that are easy to remember and understand how they work and work well in most situations.
Speaking of the brakes, Long says investing in a good set of lightweight brakes can be ver
At the racetrack, Long only moves the ends of the rear suspension bars that connect to the chassis. The ends that connect to the rearend through the birdcage aren't touched. The lower left rear bar is the one Long most often turns to for adjustments. Moving it down will usually take out some of the roll steer and helps tighten up the car. In general, both lower bars will help increase bite when moved up, but they will also increase roll steer. The upper bar on the left rear can also be raised to increase traction to the rearend, but this too will increase rear steer on the loose side.
In addition, and if you have time, you can also change the wheelbase difference side to side by changing the length of the suspension links at one wheel to affect changes to the rear alignment. Normally, Long and Cook set the rearend up so that the right rear wheel is 1/4-inch behind the left rear. If the track gets slick, moving the right rear wheel forward will help tighten the car up. But if the track is extra tacky, moving it even farther back will help keep the car loose.
Overall, Long says that the fastest setup for a Crate Late Model is a bit touchy. A tight car will kill speed, so you want to never scrub the front tires, but to keep the car driveable it needs to be right up on the edge of being tight.
The best place to start is with a baseline setup that works well for both your driving style and your car at most places. Normally, your chassis builder can give you a baseline setup for your area of the country and the type of track you normally race. Then, you can slowly adapt that setup to your specific needs.
Having all of your transmission and rearend gears (pictured) REM-polished can be a bit exp
But make only small changes at a time, and if you find yourself way off in left field in terms of your setup, that probably means you've missed something that may be broken or bent on your chassis and you're trying to correct it with an extreme setup. If you find yourself in that situation, go over your chassis with a fine-toothed comb the next time you get back to your shop.
Keep an Efficient Driveline
Besides finding the perfect setup for your car, the second key to winning in the Crate Late Model class is making your driveline as efficient as possible. After all, it only makes sense that if everyone has the same, limited amount of power, you want to make sure that all power possible is transferred to the rear wheels.
One of the biggest energy-saving investments you can make is in the transmission and rearend. Both Long and Cook advocate using REM-polished gears in both places. "REM" is simply a machine process for polishing and smoothing metals, that yields a lower coefficient of friction between parts. Translation? More power is put through to the wheels. They also use only low-drag bearings and even go so far as to apply antiseize lubricant to both ends of the axles every week.
"You just have to make sure that nothing is binding up in the drivetrain," Cook says. "You are so limited in power, that every little bit you burn up as friction in the transmission or rearend can really cost you."
The valvesprings used in GM's crate engines are inexpensive stock units, so it's not surpr
Cook also recommends being very careful with your lubricants-some might say it's almost to the point of being obsessive-but it's hard to argue with an eight-win season in one of the top touring series for this class. Cook replaces the transmission oil with new B&M fluid after every 150 to 200 laps. He also refuses to simply dump the gear oil back into the quick change rearend after making gear changes.
Because gear changes happen so often, the gear oil is still good so many teams will collect the oil and pour it right back into the quick change after making a gear swap. But this is also a time when contaminants and grit can get into the oil-after all, you're usually working on the ground underneath a dirty race car chassis-so Long and Cook collect all the oil in a large bucket and strain it through a fine-mesh paint strainer back at the shop before it ever goes back into the rearend. It means you have to carry more gear oil with you to the track, but that's a price they are more than willing to pay.
Finally, Long and Cook offered a few tips for racing with a crate engine. They race with GM's 604 aluminum-headed motor, but these tips are also good for the GM iron-headed 602 motor. When it comes to the engine, Cook and Long both subscribe to the same rigorous schedule with the lubricants. To make sure the motor oil is fresh and as good as possible, it's replaced on the same schedule as the transmission-every 150 to 200 laps.
Cooling is critical with these engines. Long has found that this small notch cut in the no
One of the reasons for this is because this engine doesn't have the best internal parts, and racing it puts a lot of stress on the entire system. The meat of the usable powerband on the 604 is normally between 6,100 and 6,400 rpm when carbureted correctly. You want to be right around this range when exiting the turn and somewhere around 6,800 rpm at the end of the straight.
But continually racing at this rpm level is very tough on the lightweight valvesprings. The hydraulic lifters help protect them a bit, but they will give up pressure and when that happens it further hurts power production. So, they are automatically replaced just like the motor oil-after every 150 to 200 laps.
"That probably sounds a bit extreme," Long says, "but the good news is that the valves are really cheap. They are nothing special and you can get them at the parts counter at just about any Chevrolet dealership, so replacing a set of springs isn't all that expensive."
The last tip when it comes to racing a crate motor is to take additional steps to make sure it stays cool. As mentioned earlier, the lower power production means this engine is always "lugging" around the track and builds heat very quickly.
A four bar system on Dirt Late Models can be confusing or intimidating to new racers becau
Another factor that some teams don't think about is the lower rpm levels these engines run at also equates to less radiator fan speed. Now you have the combination of the engine pulling as hard as possible while the radiator fan isn't pulling as much air through the radiator as you might find with other engines. While theoretically a racer could install a smaller-diameter fan pulley or a fan with more efficient blades, Long says most racers he knows use the same KRC dress kit and almost all have the same diameter pulley.
Because of this, Long says you really have to stay up on your cooling system. Keep an eye on the radiator to make sure it stays clean so that it works as efficiently as possible. Also, use a double-pass radiator which increases the cooling potential over a cheaper single-pass radiator. And believe it or not, Long says his team will normally use two new radiators over the course of a season. And this doesn't include radiators thrown out from wreck damage. "Racing on dirt is hard on radiators," Long explains, "and every time a fin gets bent you lose just a little bit more ability to cool the engine. So sometime around mid-season you usually reach a point where you are just better off to replace the thing."
So, if you're racing crates on dirt-or are considering making the switch-don't make the mistake of thinking there is no way you can give yourself an advantage over the competition. In the long run, the smart racer will always come out on top, and with these tips for making the most of your crate-powered Dirt Late Model, you can too.