Sealed crate motors are the...
Sealed crate motors are the current "next big thing" in stock car racing. They save you money but limit your tuning options.
Like it or not, the crate engine revolution is upon us. More divisions at more tracks are going with pre-fab power. That, however, doesn't mean there is nothing you can do to make sure you're getting maximum power from your engine. Your options are more limited, but the proper care and feeding of a crate engine can provide you with a power advantage on the track.
This story is aimed at giving you several ideas to chose from and try on your own crate motor. However, the rules are so varied that no list can apply to everyone. Some racers may be allowed to pop off the valve covers to adjust the lash, while others may not. And, of course, we're not so naive as to believe that all of you reading this are boy scouts, unwilling to bend the rules slightly if necessary. (Heck, a few of us are short on merit badges.) Knowing that, we've also provided a few suggestions that might push the gray areas of the rule book. All the original parts are kept; they are just modified a little. The key, if you are poking around in the gray areas of the rule book, is to work on parts of the engine that aren't normally checked. In other words, forget about your head porting tools. But we've got a good one to try if you're running a stock water pump.
Note: Just because we mention a few ideas that might not be legal where you race, that doesn't mean Circle Track condones cheating. Of course, we don't condemn it, either. We're not your momma-you can make your own decisions.
You religiously kept up a rigorous schedule of maintenance with your previous engines, right? Well, just because there's less you can do now, that doesn't mean you should ignore the things you can do. The variables you can control are now even more important. These include things like keeping fresh plugs, plug wires, and a clean air filter in the car. Crate motors don't run forever, and they can develop problems. In fact, because they are built on an assembly line and not one at a time in an engine builder's shop, crate motors are often not built to the same standard as older race engines. If your series has a certified rebuilder, contact that operation to set up a schedule for maintenance that you aren't allowed to perform.
OK, now that we've gotten the obvious stuff out of the way, let's get on to the good stuff.
Advancing your timing two...
Advancing your timing two degrees is usually safe without causing detonation and can produce power.
Engine timing is rarely set ideally from the factory. The manufacturers time the engines for smooth-running reliability; what we want is the most power available before the onset of detonation. According to several engine builders, you can safely get away with advancing the timing two degrees. You can potentially make more gains by taking it a little farther, but if you want to see what more timing will do, it's best to try it on an engine dyno in which you can keep a better diagnostic eye on everything.
Most series will allow simple carburetor adjustments, which is good because you probably will need to make a few. For oval track racing, crate motor setups usually run too rich at the top end. The quick fix is to pop in a set of jets a few steps smaller, but this isn't always the best idea because the engine is now lean at idle and at the lower rpm. The real culprit is a power valve that is too large and dumping in too much fuel when the revs are up. If you have this problem, try swapping it for a smaller power valve.
Modern cylinder heads have efficient combustion chambers, so indexing plugs isn't the trick that it was a decade ago. Careful plug selection can net you a small gain, depending on what the factory sent you. Here's the scenario: The flame kernel begins at the electrode and extends outward evenly until it hits an obstruction, which hinders combustion efficiency. The first obstruction is likely to be the top of the combustion chamber and the short side of the cylinder wall.
A plug with an extended nose...
A plug with an extended nose pushes the electrode farther into the combustion chamber. The more centrally located in the chamber the flame begins, the more efficient combustion will be. Just be careful to not create piston/plug clearance problems.
By choosing a longer plug that extends deeper into the cylinder, you move the electrode closer to the center of the combustion chamber. Now the flame front is more balanced as it extends (if only by fractions of an inch), and it can extend farther in all directions before meeting an obstruction. This causes the air/fuel charge to be burned more efficiently, which means more power.
Be aware that we are only talking about slivers of horsepower, but if you add up several improvements, you can get something significant.
If you have a choice, make sure to run racing-quality accessories on your engine. Most are already chosen for you as part of the crate engine package (fuel pump, water pump, etc.), but one usually open for improvement is the alternator. Simply getting rid of the alternator and depending on the battery is the best option, but that's usually only possible for four-cylinder classes. For V-8s and longer races, choose the smallest alternator with the least amount of output you can get away with. This will reduce the parasitic losses involved with turning the alternator. For more information on how limited amperage is enough when it comes to alternators, call a few manufacturers. Almost all of them have done testing with every conceivable combination.
We also wondered about drivebelt configurations that rob the least power. For more information, we turned to Rob Benson, who runs the dyno testing program at Hendrick Motorsports. Benson, who has tested both V-belt and serpentine belt systems, says he has found little difference between the two. His advice to racers is simply to keep using what you've got and save your money.
Crate motors are typically restricted by how much air they will flow through the heads. That doesn't mean, however, that other restrictions aren't also detrimental. For instance, stacking a restrictive stock air filter on top of the engine only compounds the problem. A stock paper filter is good at removing even the smallest contaminant particles from the air, but the cost is airflow. As a racer, you want an engine that makes the most power, not one that's going to last 100,000 miles, so go with the lightest, least restrictive air filter possible to keep the flow free and easy. Oil-impregnated fabric filters-such as those made by K&N-are made for racing and are usually the best bet.
On solid lifter cams, tightening...
On solid lifter cams, tightening the lash will make the cam act larger. Valve duration, overlap, and maximum lift are all increased.
The greatest restriction on the water flow through the engine is usually the water neck outlet on the engine. Most crate motors use a cast water neck, but if yours uses an AN fitting (or you can change out the cast piece), the standard size is 16. Upgrade to a size 20 AN fitting to reduce the restriction.
If you are allowed under the valve covers, adjusting the lash on solid-lifter-equipped engines is a good way to make a cam act bigger in nearly every important dimension. Closing the valve lash on a solid lifter cam causes the valves to open sooner and close later. This has the effect of extending the duration as well as the overlap period and increasing maximum lift by a few thousandths of an inch. The overall effect may be negligible-or even detrimental-at idle and low rpm, but at racing speeds, the engine's improved ability to ingest the air/fuel mixture should result in increased power.
On an engine with iron cylinder heads, you can usually get by with as little as 0.004 inch valve lash when the engine is hot. Aluminum cylinder heads are tougher because of the material's increased rates of expansion. A simple way of setting minimum valve lash with aluminum cylinder heads is to work with the engine cold. Close the lash until you can turn the pushrods with your bare hands. These guidelines should help you set the minimum lash possible without hurting your engine, but at these levels you need to show extra care to properly warm up the engine before stressing it.
Just like adjusting the valve lash, the following tip is dependent on your access to the front cover. If possible, you can advance or retard the cam- shaft to help tailor the engine's power curve to your track and driver. Advancing the cam one or two degrees typically increases bottom-end, or low-rpm, power while retarding the cam does the opposite. Again, we're only talking about small amounts, but when everything else is equal, every little bit helps.
Narrowed main bearings present...
Narrowed main bearings present less surface area and, consequently, less parasitic friction. This is definitely a job for an experienced engine builder, as a botched job can cause a host of problems.
When talking to engine builders, we were given several ideas that were good with the exception of one small problem: legality. Although we don't want to promote blatant cheating in racing, it's common knowledge that the best place to find a perfectly legal race car is in the back of the pack. With that in mind, we offer the following tips that push what we'll euphemistically call the "gray areas." We chose these because we thought they would either be particularly hard to spot, or in areas not normally checked. Still, adopt these strategies at your own risk. Remember, the tech man reads us, too.
You may need to ask an engine builder for help with the following. Excessive surface area on the main bearings can cause unnecessary drag. If your crate motor utilizes OEM bearings, they can probably stand to be narrowed by as much as 0.1 inch. Make sure you don't expose the oil holes or you will lose all oil control. Similarly, narrower, low-tension piston rings can really save on parasitic losses, but this involves getting past all of the "tamper-proof" seals that your engine probably came with.
While you have the bearings out, you might also consider a performance-enhancing coating designed to attract oil and aid lubricity. Just be careful, as some of these add a colored patina to the bearing that is easy to spot.
Racing water pumps like this...
Racing water pumps like this unit from Moroso take into account that coolant flow at idle isn't a consideration. An OEM pump, however, pushes much more coolant through the motor than necessary at race speeds.
Pushing fluids through the engine soaks up power. Minimizing oil pressure to cut parasitic losses is old school in traditional racing engines, but that ability is typically limited in crate engines. If you can get the oil pan off, however, this adjustment is pretty easy. By simply putting a lighter spring in the oil pump, you can reduce the workload on the pump. It's unlikely that someone is going to tear you down to check your oil pump spring.
The same goes for the coolant flowing between the block and the radiator. This tip isn't useful if you are allowed to use a racing water pump, but if you are using an OEM unit, you are likely pushing too much water through the block a lot faster than necessary. OEM pumps are designed to provide adequate cooling for street cars, which spend 90 percent of their time between idle and 3,000 rpm. Oval track stock cars are high-rpm monsters, and cooling during extended rpm periods at low rpm is not a concern. If you can get your water pump apart, cutting every second vane off the impeller will reduce water flow to more manageable levels-you'll just need to make sure your ducting and overall cooling system works effectively. Also, it's probably best to cut the vanes off on a milling machine. A hack job will unbalance the impeller and lead to power-robbing cavitation.
Many crate engines currently being designed for racing are rpm limited. The limit is often below peak power levels. If you are hitting the rev limiter but the valvetrain still seems to be holding up, you can potentially free up some power by using lighter springs. Instead of changing the springs, which can be easy to spot by a tech man, lower the seat pressure by going with thinner spring shims or cutting a few thousandths of an inch out of the spring seats.
Don't do too much or you may make the springs too weak to do their jobs. This is another area where a qualified engine builder can be helpful, both in determining the minimum spring pressure you can get by with and in making the cuts on the cylinder heads.