Extra Horses

A racing engine may seem like rocket science to those who are not into engines, but it isn’t difficult to find some extra horsepower. A simple look at the basics of engines can often yield a few more ponies here and there. After all, that’s how the big boys do it. One or two new-found horsepower at a time and, before you know it, there’s a big difference under the driver’s foot.

We polled a number of professional engine builders to look for basic areas that elusive horsepower can be hiding. The results may surprise you in just how simple they are to find.

Tuning

Dale Francis has been an engine builder for over 20 years including a stint in Winston Cup. He now builds mostly higher-end engines used in the professional levels of oval track racing. He points out a few of the areas where the power is and just how much can be hiding in those areas.

“Tuning is a big issue,” says Francis. “A lot of guys leave a lot of horsepower unfound just from tuning. I’ve found as much as 75 to 100 hp in a 600-horse engine that people have left unused just because they didn’t tune it properly. Timing, operation, header, pipe and collector styles—there’s a lot of different avenues on that.”

Francis shoots a rapid-fire list of what areas yield what power.

“Headers, 30 to 40 hp. Camshafts, as much as 50 hp. Cylinder heads, restricted, cast-iron engines, 120 hp. If you’re talking a full-open engine, then you’re talking 300 hp between cylinder heads and manifold.

“Carburetion is really crucial. You take 10 different carburetors and they’re all going to react differently. Planning the fuel curve right, that’s just basic—just knowing your air/fuel curve is right in the engine. Intake manifolds, 50 to 75. We did a manifold test here a while back. We did 15 manifolds across the engine on a 302 road-race type engine. That was our baseline for an engine. With the best intake manifold it made 535. With the worst it made 428.”

“Timing is really crucial,” he says. “There are small horsepower gains in water pumps; probably 8 hp from the worst to the best water pump. Pulleys, you can see probably 15 hp running the proper pulley system. In a dry-sump pulley arrangement, probably dependent on what kind of pump you’re using, probably 15 to 20 hp. Oil pressure in a wet-sump type of engine, there’s 10 to 15 hp in oil pumps and oil pressure.

“Ninety percent of your guys that run local racetracks, they all try to find as much oil pressure as they can, and that’s not the key because: one, they’re loading the camshaft and they’re loading the distributor up; and two, they’re robbing horsepower from the engine because they are overstressing it and they don’t need to.”

Francis says a team can find up to 30 hp by keeping oil off the engine’s crankshaft. Two ways to do this are with a windage tray and modifying the crank with knife-edge and radius cuts on the trailing and leading edges of the counterweights. That keeps oil flowing away from and rolling off the crank faster.

“Not only does it help there, it helps oil temperature when you keep it off the crank so it’s not whipping it up and foaming it,” Francis says. “One of the biggest things is it keeps weight off the rotating mass and keeps the oil from getting all beat up and whipped around.”

Oil Pans

Jim Mikel of Performance Technology has some great credits under his belt. Last year, his engines powered the champions in ARCA Bondo Mar-Hyde racing, the NASCAR Featherlite Modified Series, and the runner up in the USAC Silver Crown. That’s three distinct series with three distinct engine types.

Mikel points out an area that’s often overlooked for power advantages: Oil pans.

“That’s a free deal, typically. Anytime you can do better on an oil pan it’s a gain everywhere,” he says. “It’s not like doing something with cylinder heads that are sometimes a top-end gain or torque gain. Typically, if it’s better, it’s better straight across the board. There’s no give-and-take to it. And normally as your oil pans get better, your oil temperatures drop. A lot of people that have oil temperature problems have water temperature problems because if you have high oil temperatures, the water temperatures will be higher also. As you make your pans better, your oil temperatures drop and your power numbers go up.”

“From a bad dry-sump pan to a good dry-sump pan, there could be 10 or 12 hp,” Mikel says. “So there’s easy hp there. Same deal on wet-sump pans. You can have bad wet-sump pans and you could have good wet-sump pans.”

Mikel’s main point, however, is to not have the oil add weight to or slow down the crank.

“It basically has to do with keeping oil off the crankshaft. The further you can keep the oil away from the crank, the better your trap doors are in the pan, the less oil you have to run in it. So it stays away from the crankshaft. A lot of times if you are dynoing a motor and it’s got a wet sump on it, you can take a quart of oil out of the thing and pick up three horsepower. That’s the typical deal—bigger is better in an oil pan.”

Once your pan is working at its peak efficiency, another area becomes ripe for improvement.

“The next thing is reducing friction,” Mikel says. “When you do this oil pan thing right, then you can go after the rings and friction loss. It has to do with reduced oil ring tensions, reduced ring thickness, and you’ve got bearing coatings. A roller bearing cam bearing will reduce a little bit of friction —nothing big. The biggest source of friction in a motor is the rings.”

“The weight of engine components—there again, this is a loaded question. If you lighten the crankshaft itself up, from a rotational standpoint, lighten your connecting rods, lighten your pistons, that car will move from point A to point B faster. It won’t show up as dyno power, but it will show up on the stopwatch.”

Mikel says, however, that this could cause a driver to spin his tires more at some short tracks that require tires that are hard to get hooked up. “I’ve had people already put in heavier flywheels and clutches and go faster. It smoothes up the power application of the racetrack.”

“Parasitic Losses”

Fritz Kayl has seen everything when it comes to engines. His KATECH business has built plenty of NASCAR engines including Winston Cup. His Busch motors were champs for three years straight. Today, most of his work is with the OEMs close to his Michigan shop, but he is still well known for his racing engines.

His work involves something called a “load cell.” It’s like a dyno as it’s a measuring device; but, instead of measuring the horsepower created, it measures the power needed to operate an engine or assembly. He explains that operating power, parasitic losses, and friction can take away close to 200 hp on a high-end NASCAR engine.

“Anything in parasitic losses you can decrease goes to the flywheel,” Kayl says. “The engine doesn’t know if it goes to the flywheel or it’s eaten up internally.”

That means ancillary assemblies such as water pumps, oil pumps and alternators take power to run that doesn’t make it to the flywheel. But those items have a give-and-take in how their functions affect the performance of the engine. Making a higher horsepower water pump may mean a less effective water pump.

The question becomes, “How can I get the water volume I need at the minimum cost of power?”

Kayl says, “They [water pump manufacturers] can hone in on impeller design and start improving the impeller design to require less power to flow the same amount of water. So there’s been a lot of work in the impeller design area.”

Carburetor

Tony Alteri works the T/A Engines shop in Connecticut where two-barrel race engines are somewhat of a house specialty. He points to one of the major sources of power.

“Your carburetor always is very important. If it’s not really responsive, if it’s not real good on restarts, then it’s not good off the corner,” Alteri says. “Make sure your carburetion is right. The fuel curve and throttle responses are very important. There’s ways to alter the fuel curve. You can change some of the accelerator ramps, power valves and squirters.”

Alteri illustrates the importance of using the proper exhaust components. “Exhaust is very important: type of header, meaning the primary tube size; type of collector, whether it’s a stock collector or a merge collector; size of the collector, both the length and OD,” Alteri says. “The smaller the OD of the collector is, the more bottom end the motor has. The bigger the OD of the collector is the more top end it’ll have. A longer pipe off the end of your header collector is more bottom end. A shorter pipe increases your midrange and top end.”

But be warned that going too big on exhaust pipes will have a price. As Alteri says, “The motor will fall right on its face coming off the corner. It loses all its back pressure and the exhaust doesn’t know how to get out of the motor.”

If you are a racer who doesn’t have access to dyno time, there is a way to check if your headers are too big.

Alteri says, “After a good eight to 10-lap hard run in practice, if the paint isn’t discolored all the way back to the end of the pipes, you have too much pipe on the car. Cut them off and shorten them. The motor is telling you, ‘Cut me off where the discoloration stops.’”

Exhaust performance doesn’t stop at the end of the headers either. Tailpipes, “H” pipes and “X” pipes, all make a big difference.

Alteri says, “One thing we play a lot with in our motors is exhaust. The ‘X’ pattern really scavenges the exhaust—which means it pulls the exhaust out of the motor harder. In turn, it makes more bottom-end power. The ‘H’ doesn’t do as well because of the way it’s connected. It’s better than two straight pipes.”

Ignition is another area Alteri says can contribute power—even within restricted equipment rules.

“Say your rules say you have to run an HEI ignition, and the coil must be in the cap and must have the module bolted in. You have to get a module that has what they call more saturation time. That holds the spark longer from the coil so it fires harder down the wire. And you also need to have a good low-resistance coil that will put out the volts.”