Because the car counts are...
Because the car counts are still high and the competition is great, many racers with the skills to move on to the V-8 classes prefer to remain in Mini-Stocks because they can be a lot of fun when done right.
Mini-Stock racing will always be among the most popular among stock car racers. The Mini-Stock classes are great for beginners because the smaller four-cylinder engines limit speeds by keeping power in check. Also, fewer cubic inches keep the cars more equal, even if one car is running an illegal engine. Rules designed to keep costs in check also make this class more appealing to many racers running without the advantage of a fat wallet.
But good car counts and great competition mean that Mini-Stock racers are always looking for any advantage they can get to stay ahead of the pack. And you'd better believe smart racers and engine builders have found ways to be faster.
With that in mind, we've compiled a list of top tips to help with your Mini-Stock program. So no matter if you are racing in the Young Guns class or the Mod Fours, whether you prefer the traditional Ford Mustangs and Pintos or you are among the growing ranks of racers campaigning Toyotas, there is something here for you.
We'll begin with ideas for helping you produce more power while still getting good durability from your engine, and then we'll move on to ways to improve the handling of your chassis.
In high-rpm race applications,...
In high-rpm race applications, drag from the piston rings can lead to a serious loss of horsepower. Smaller metric rings, such as this 1.2 mm, 1.5 mm, 3.0 mm combination in your Ford 2.3 motor, can free up a little power.
Mini-Stock engine builders say that one of the great challenges when working with Ford's 2.3 liter four-cylinder engine (far and away the most popular engine in the Mini-Stock ranks because it is durable and plentiful), is getting power from the limited displacement. One way to get around the displacement limitation is to spin the rpm's up to buzz saw levels. The overhead valvetrain geometry allows this, but when the rpms reach-and often exceed-8,000 rpm, friction losses come into play.
Then the focus turns to reducing horsepower losses caused by friction inside the engine. One great area for this is the piston rings. Stock 2.3 engines use standard ring packs, but this really isn't necessary in a racing engine. Engine builder Ken Troutman of KT Engine Development says he has found you can safely reduce both the ring size and tension considerably without damaging either the engine or power output. Normally, he says he switches to a metric ring pack designed for import motors that measures just 1.2 mm for the top ring, 1.5 for the second and 3.0 mm for the oil ring. These rings are not only thinner, but they usually also have less radial depth (thickness from the inside to the outside edges of the ring) which results in less ring tension.
Using lighter rings like this requires good cylinder honing procedures or else you will never get good ring seal-so spending a couple extra bucks to hone the cylinder with a torque plate in place is imperative. This package is catching on and while it previously required an expensive set of custom pistons, many suppliers, such as Race Engineering, are now keeping Ford 2.3 pistons with ring lands sized for metric rings as a shelf stock item.
Nitriding is a surface preparation...
Nitriding is a surface preparation that both hardens and adds lubricity, or slickness, to metal. A nitrided cam is easy to spot because it will be flat black.
The overhead valve system in Ford's 2.3 motors is both a blessing and a curse. The geometry of the design makes it capable of 8,000 rpm without losing significant valve control. But it can also be difficult to get an aggressive race cam with big lobes and aggressive ramps to live for any length of time. This is especially true if you are allowed to run solid lifters.
One solution used by many engine builders is to have their cams nitrided. Many manufacturers, such as Comp Cams, are offering nitriding as a service directly from the factory. Nitriding is different from surface hardening. The nitriding process uses ammonia gas and high temperatures to infuse the cam with a ferrous nitride on the surface. That's a bunch of geek-speak that means the surface of the cam gets a lot harder and slippery. Both of these factors are good because there is no such thing as a roller lifter when racing the Ford 2.3. A nitrided cam will be more expensive than a standard cam, but many engine builders say that the extra longevity you get from the cam will offset the price.
Stock four-cylinder Toyota...
Stock four-cylinder Toyota engines have a single-row timing chain. Give yourself a little peace of mind by upgrading your Toyota race motor with a double-row timing set for greater durability.
LC Engineering specializes in building high-performance Toyota four-cylinder engines. Toyotas are gaining popularity in Mini-Stock racing because they are a good design, and with all the Celicas and Camrys out there, blocks and heads are still plentiful. One problem with Toyota's four-cylinder design is it only comes with a single-row timing chain. LC Engineering's tech department recommends upgrading that to a double-row chain so that it will hold up under racing stresses. The timing chain itself isn't an expensive component, but a timing chain that breaks at speed will result in broken valves and expensive engine damage. To fix this problem, LC Engineering has designed and sells an upgrade kit for a double-row timing chain. The kit comes standard on all race engines sold by LC Engineering.
Small rod journals equal lower...
Small rod journals equal lower bearing speeds and reduced rotational weight in both the crankshaft and the rod. Because of the lower power levels produced, Mini-Stock engines can reliably use Honda-size rod journals to create power without significantly reducing durability.
The Nextel Cup guys have been using Honda-sized rod journals for years. By cutting the rod journal down to a 1.888-inch diameter, the bearing speed is significantly reduced. This cuts friction in the engine, freeing up horsepower. Smaller journals also cut weight in both the crankshaft and connecting rods, and a few ounces shaved off the rotating assembly at each cylinder adds up.
Honda journals haven't really caught on among the V-8 classes in Saturday night racing, however, because the significant reduction in journal diameter (a Chevrolet rod journal, for example, is 2.100 inches) harms engine longevity. Unlike the Cup Series, Saturday night race teams simply cannot afford to sacrifice an entire engine for the sake of a couple of extra horsepower.
But in Mini-Stock racing horsepower usually tops out at just under 200, a level that 1.888-inch rod journals are more than capable of handling. Stock crankshafts are almost always reused in the build, and they will have to be turned down anyway to clean up wear from miles of road use, so turning the journals down to Honda diameter doesn't incur big cost increases. Running a Honda journal does, however, require a little extra money when purchasing your rods because they are a specialty item.
Dan Esslinger says Esslinger...
Dan Esslinger says Esslinger Engineering's aluminum cylinder head for Ford 2300 engines is designed to be just a little better out of the box than a fully ported stock head. This means that while the head is more expensive than pulling a stock Ford head out of the junkyard, it does offer savings over trying to make a high-end race head out of the stock piece.
Just a few years ago there were no conversations about using aftermarket cylinder heads for Ford Mini-Stock racers. That's because there weren't any available. But Esslinger Engineering recently came out with an aluminum stock replacement head that offers a serious performance advantage over the stock design. Many Mini-Stock racing classes do not allow this head yet, but Esslinger says it has been catching on because, while Ford 2300 blocks are still plentiful, cylinder heads are becoming increasingly scarce because they are prone to cracking.
Keep an eye on this development. Esslinger's aluminum cylinder head isn't established in Mini-Stock racing yet, but it is probably only a matter of time.
This hose where the oil-fill...
This hose where the oil-fill cap normally is found connects to the exhaust header just below the merge collector. The exhaust pulses can help create vacuum inside the engine crankcase, freeing up power.
It is a trick that drag racers have been using for years, and in upper-level racing classes it often is specifically disallowed. But using the exhaust to pull vacuum in the engine is a trick that usually isn't mentioned in the Mini-Stock rule books. Just like a well-designed exhaust header utilizes exhaust pulses to help pull spent combustion gasses from the cylinders, you can use the headers to help draw a small amount of vacuum inside the crankcase. In the Ford 2300 engine the crankcase vent tends to catch a lot of oil, so many racers route a hose from the crankcase vent to the valve cover. But Johnson's Machine Shop, which specializes in four-cylinder Fords, routed a hose from the valve cover to the exhaust header just below the merge collector. The low-pressure pulses inside the header draw air from inside the engine, acting like a vacuum system.
Johnson's also added an anti-backfire valve off of an old Chrysler to keep anything from coming back into the valve cover. This trick works, but just be aware that at high rpms you can get an oil mist sucked into the manifold, making the car smoke. But, hey, that may make your competitors think you are running a race engine on its last legs and underestimate you.
These rockers have the wear...
These rockers have the wear pads covered with machinist's dye because they are about to be checked to make sure the cam's lobes ride over the middle of the pads. In high-performance situations standard rockers won't hold up to aggressive cam designs, so aftermarket rockers with hardened wear pads should be used.
This tip has more to do with longevity than power, but it is still important. Remember earlier how we mentioned nitriding your camshaft to protect it? Well, the aggressive cam designs used in Mini-Stock race engines are also hard on the rockers. Fortunately, the solution for this is simple. Many engine builders, including KT Engine Development, use and sell rockers with hardened wear pads. Standard pads will grind off slowly, which not only puts metal into the oiling system but can change the valve timing events.
Unibody cars, such as the...
Unibody cars, such as the Mustang (shown here) and Toyota Celica are notorious for their flexibility. Intelligently bracing the suspension will make sure your suspension settings stay accurate on the racetrack.
One of the problems with racing a stock-based chassis in any class is undetected flex can wreak havoc with your chassis settings. Stock chassis are designed for safety (crumple zones), ease of manufacture (cost) and minimum weight (gas mileage). None of those factors are necessarily helpful when it comes to resisting the g-forces a chassis will see as it powers through the turns on the racetrack.
Flex means those chassis settings such as caster, camber, toe and even frame heights that you worked so hard to set precisely can change on the racetrack without your control. Use the front and rear kickouts on your rollcage to help brace the suspension. At minimum, you should have hoops welded over the upper shock/strut mounts. Also consider additional bracing that extends to the ends of the front and rear sections of the chassis to limit twist.
Modifying the rear trailing...
Modifying the rear trailing arms to increase the pinion angle downward can increase forward bite.
Most rule books say you cannot move the suspension mounting points. This includes the spring perches and shock mounts, but there is rarely a provision saying the rear control arms cannot be modified. Car owner Blake Bentley shared this tip with us. He has the top trailing arms on his Mustang cut and welded back together with an inch removed from the overall length. When they are reinstalled in the car, it is enough to give the pinion a downward angle of four or five degrees. That change in rear suspension angle gives the car more bite on turn exit.
Although relocating the suspension...
Although relocating the suspension mounts is rarely allowed, the crafty racer with a good knowledge of how suspensions work can change the way the front clip attaches to the center section to get what he's looking for. Also, notice the aluminum sheet to make sure hot air from around the engine and headers cannot make its way into the intake.
This is one that many racers aren't thinking about. While talking to driver Nick "Hot Rod" Walker, his dad Billy mentioned how they gained some speed by changing the way the front clip mounts to the center section. Usually, rules prohibit any changes to where the suspension mounts are located, but because it is so often necessary in order to fix wreck damage, nothing is said about how the front clip is attached to the car's center section. Billy Walker says they have been able to move the front clip to give 1/4-inch of lead to the right-front wheel, which helps the car get through the turns predictably.
Running a bead-lock wheel...
Running a bead-lock wheel on the right-rear is a no-brainer when it's allowed.
When it comes time to mount tires, bead locks are definitely a pain. But the trouble is worth it. Often in Mini-Stock racing you are allowed to run a bead-lock wheel on the right-rear because that corner takes so much abuse. A bead lock not only will help ensure the tire stays on the bead and doesn't lose pressure, but it also helps with tuning. With a bead lock in place, you can run lower air pressure to help get traction on the right rear.
Not all Mustangs are created...
Not all Mustangs are created equal. By selecting a lower control arm based on the model year, you can achieve better camber numbers than otherwise.
Even with adjustable camber plate, the Mustang's MacPherson strut front suspension limits the amount of camber you can dial in to the wheels. You can increase the camber split between the right- and left-front wheels by running early and late model lower control arms. In 2000, Ford made the lower control arms slightly longer. If you are running an older model Mustang, you can increase your negative camber on the right front by installing a late model lower control arm. Conversely, if you are running a newer car, you can gain positive camber on the left front by running an older lower control arm.
It may look like a bead lock...
It may look like a bead lock at first glance, but it isn't. The ring does, however, greatly strengthen the rim to make it better able to handle a racing "mishap" without losing pressure in the tire.
If the racing action at your track is a little bit rough-and-tumble, you may want to consider reinforced wheels. They aren't bead locks because the ring does not exert pressure against the tire to hold it in place. Instead, it is welded to the inside lip of the rim to strengthen it.
Driver Larry "Round Boy" Teal, who also is part of the staff at Johnson's Racing Engines, says the design works.
"I got hit by another car right in the wheel in one race," he recalls. "I thought for sure it was going to knock the tire off, but it stayed on. The ride was so rough after that it nearly rattled my teeth out, but at least I was able to finish the race."
Another trick used by Nick and Billy Walker in their Mini-Stock racing program is to run less rear percentage than many other teams. Billy says they usually run 49 percent rear weight percentage and sometimes even less. Conventional wisdom says you want 50-52 percent rear percentage to maximize traction at the rear wheels, but Billy makes the point that these small engines are so dependant on keeping the rpm levels up to make power he'd rather spin the rear wheels a little on turn exit than risk bogging the engine down. Whether this tip is useful may depend a lot on the driver's comfort level with a light rearend, but it may be worth a try.