It is a saw as old as the internal combustion engine itself-getting more power without spending a lot of money. Most of these tips involve common sense-or something that gobbles most of your credit-card limit. Who needs it? We need real solutions without breaking the bank-and our engines. It still boils down to the physics of drawing an air/fuel mix into the chambers, how tight we squeeze it, and how well we scavenge hot gasses when the action's over.
When we sat down at MCE Engines in Los Angeles and chatted about real, honest-to-goodness power solutions, it became an all-out tech session to explore what really makes more power. We learned real power gains don't always come from any one thing but rather lots of little things that add up to significant increases. Here's what we came up with.
This is an old, old tip, but it means an increase of 1 percent for every 10-degree reduction in temperature. If the underhood temperature is 160 degrees and you can feed your engine cooler ambient air that's 90 degrees F from outside, that's a 7-percent increase in power. Don't laugh-it's real physics and it really works.
Run Synthetic Engine Oil
Sure, it costs more, but it reduces internal engine friction by a significant margin over mineral-based engine oil. When we reduce an engine's internal friction using synthetic oil, we not only free up power lost to friction, we also reduce engine wear. The benefit is three-fold and makes great sense. It improves gas mileage, reduces friction, and frees up power. If the cost of synthetic engine oil turns you off, consider the cost of wasted energy and increased wear and tear using mineral-based oils.
Lower The Viscosity
If you're running 10W40 engine oil, drop your viscosity to 10W30, 5W30, or 5W20. This move all by itself frees up power-again, lots of stand-alone improvements that add up to big power gains. If you're not fond of full synthetics, opt for the best conventional high-performance engine oil or a synthetic blend.
Pulleys that underdrive an accessory are popular, but there's more to it than that. Underdrive pulleys, such as those from March Performance, reduce accessory speed at high revs, which protects them from failure. Underdriving also reduces accessory drag just like low gear decreases drag when you're pedaling a bicycle. This is a low-buck power tip that contributes to the power picture. Just make sure you don't underdrive more than 10 percent-any more than that reduces water-pump speed and can cause overheating when an engine is used in stop-and-go driving.
Install A Windage Tray
Windage trays keep oil away from the crankshaft at high revs. As the crank spins faster, it tends to draw oil out of the sump into the spinning crankshaft. Windage trays, such as those from MPG Head Service, prevent oil windage, which reduces internal drag. Knife-edging crankshaft counterweights also reduce crankshaft aero-drag. Oil and air drag rob power. Less drag-more power.
Install A Flex Fan or Thermostatic Clutch Fan
For years, we have debated the merits of different kinds of radiator cooling fans. Ideally, you will have a fan that does it all-cools effectively while borrowing as little engine power as possible. A traditional Flex-a-lite 17-inch aluminum six-blade flex fan moves a whole bunch of air across the radiator under normal operating conditions. At high revs, flexible blades flatten out, which reduces drag and keeps airflow consistent. Remember, above 35 mph road speed, your engine doesn't even need a cooling fan, as ram air through the radiator is sufficient.
Thermostatic clutch fans, such as those from Flex-a-lite, work even better than flex fans because they engage the water-pump drive only when needed. A clutch-fan freewheels on the shaft when it isn't needed. This frees up power. As the radiator warms, the fan clutch engages with some slippage, pulling cool air through the radiator. Any way you slice or dice the time-proven clutch fan, it does a wonderful job, answering the call only as needed. Use a plastic-blade clutch fan and grab even more power. Clutch fans are also quieter.
Install A Crankshaft Wiper At The Pan Rail
Crankshaft wipers, like windage trays, keep oil where it belongs. Use a crank wiper to free up power, too.
Use Low-Tension Piston Rings
Low-tension piston rings from manufacturers such as Federal-Mogul/Speed-Pro reduce friction and free up power. The downside is shorter service life, accompanied by increased blow-by. Excessive blow-by can hurt power, which is the other side of the coin. Getting power is all about compromise. You can't have it all.
Roller Timing Set
Roller timing sets are little more than a true dual-chain drive, which reduces friction. Roller timing sets reduce internal friction just like roller rockers and roller tappets do. Instead of tight, hard-over friction like you would experience pushing a wagon across rough concrete without wheels, roller technology puts wheels under the Radio Flyer, making the wagon easier to push.
Full Roller Rockers
The savvy engine builder thinks of every possible place power can be lost during an engine build. Whenever you examine internal friction issues, there are countless areas where power will be robbed. Bearing clearances, piston-ring tension, timing-set tension, and so on can make a big difference in power. Factory stamped-steel or iron rocker arms experience friction at the fulcrum, pushrod pocket, and valve-stem tip. This may not seem like much until you multiply these friction points 16 times over. It adds up to a lot of power loss (around 15 percent) due to friction. Full roller rocker arms, meaning roller tip and roller fulcrum, reduce friction dramatically. Think about it this way-less friction means more power. Full roller rocker arms can net up to a 15-percent increase in power.
If you are planning for power, consider the investment in roller-cam and cam thrust-plate bearings. Conventional cam bearings and thrust plates are friction sources. When you put your cam on roller bearings, you reduce friction by a huge margin. This is a nice, hidden power gain.
When you're building an engine, ask yourself how you can reduce friction everywhere inside. Low-friction piston coatings are a good place to start. Also think about temperature-resistant piston top coatings that allow you to push the engine a little harder at wide-open throttle. Speed-Pro pistons from Federal-Mogul sport coated skirts for reduced friction. Other piston manufacturers are doing this as well to win the war on power.
We hear a lot of you are concerned about the cost of roller-cam conversions, but there's no single greater way to free up power and make fresh power while you're at it than a roller-cam conversion kit. Roller tappets reduce internal friction-which frees up power. You may run a more aggressive cam profile when you're running a roller cam. Here again, that makes power, too.
High Energy Ignition
It has been proven time and again that spark intensity determines how effectively we light the mixture. A hot spark makes power. A weak spark doesn't penetrate the mixture like a big, fat, intense spark. Simply put, your ignition system means everything to power. Old point-triggered ignition systems are barely adequate for stock engines. We want to make real power through capacitive discharge and a programmed spark. A hot spark excites the mixture and gets your engine hop-ping. MSD, Crane, Mallory, and others can help with easy-to-install ignition systems, such as billet distributors and ignition boxes designed to shake the fuel/air mix right down to its toes. You will feel the difference at your backside.
If MSD or other high-end ignitions are beyond your reach financially, consider the Ignitor or Ignitor II from PerTronix, along with a 50,000-volt Flamethrower ignition coil. The engine doesn't know where that hot spark comes from-it only knows a powerful spark penetrates the mixture, inciting fury (and power) in the chambers.
Performance Distributors is yet another source for high-energy D.U.I. (David Unified Ignition) solutions you can drop right into your engine in an afternoon. What's more, you will feel the difference.
Run A Carb Spacer To Increase Plenum Volume and Insulate The Carb
Temperature has everything to do with power because heat and cold (plus relative humidity) directly affect pressure. Hot fuel does not make power. Cold fuel does. That's why we want to insulate the carburetor from engine heat in order to make power. Don't just use a gasket between carburetor and manifold; use a heat-insulating phenolic spacer from Summit Racing Equipment or Wilson to keep heat away from carburetor fuel bowls. This also increases power by getting those fuel bowls well above the hot manifold. Cooler fuel is dense and ignites with more fury, which means more power.
Carburetor spacers are also designed to improve low- and midrange torque by increasing air velocity between carburetor and manifold. This happens whenever we increase the length of our intake runners. A four-hole carb spacer, for example, gives you four runners-a continuation of the intake manifold runners. Try a 1-inch spacer first and expect to see a modest increase in torque. Then try a 2-inch spacer if it will fit-then compare torque values. These spacers are available in a variety of thicknesses and configurations.
Rocker-Arm Stud Girdles
Power comes in many ways, including making the valvetrain more stable. A rocker-arm stud girdle keeps rocker arms stable at high revs by stopping rocker-stud movement, which means more consistent power. Stud movement happens at high rpm, which upsets valve timing. Inconsistent valve timing steals power.
Deep-Sump Oil Pan
We suggest this for much the same reason we suggest a windage tray or high-volume oil pump. A deep-sump pan from Canton, Moroso, Milodon, and others keeps oil away from the spinning crank. It also keeps the oil supply plentiful when we pin the butterflies.
Mismatched ports will steal you blind when it comes to power. During an engine build or head swap, check out port match. Intake-manifold and cylinder-head port sizing must be identical. We're talking perfect port alignment or you will flush power right down the toilet. Cylinder-head ports that are smaller than intake-manifold ports disturb airflow and cause turbulence. Seamless airflow from manifold to cylinder head improves power. When you take delivery of your manifold, check port match and be prepared to do a little grinding. Get those ports seamless, and be certain the alignment is seamless as well. Ports don't have to be polished, just smooth. Polished ports, especially with carburetion, can sometimes rob power. A slightly rough surface helps keep fuel droplets in suspension with carbureted engines.
Exhaust scavenging is as important as smooth intake flow. Why? Because how hot gasses leave determines how smoothly the next air/fuel charge enters and lights, especially when it comes to valve overlap. Get the exhaust flow cleaned up by port matching exhaust ports and headers. Header tubes should always be larger than exhaust ports for smooth exhaust flow. Clean up exhaust ports and header-flange transitions to smooth up exhaust flow. High points and ragged edges (welds) create hot spots and turbulence.
Increase Valve Size
Larger valves make power two ways-by improving and increasing airflow into and out of the chamber. Valves that are too large can rob power, so make sure they aren't shrouded. Also, take an accounting of what happens to the valve based on camshaft lift and duration. How much shrouding occurs at different lift points?
Attention To Detail During Build
We keep harping about internal friction, but it happens so many ways. Blueprint your valvesprings and retainers in order to reduce friction and build in longevity. Gently file all sharp edges and coat valvesprings with a low-friction coating-the same kind used on pistons. Closely examine retainers, rocker-arm tips, studs, valve stems, tappets, pushrods, timing gears, and so on for ragged edges and imperfections that can create friction. The little things add up to substantial power gains.
Think about every possible friction point inside your engine and ask yourself how it can be reduced. Even a pushrod gently rubbing the cylinder head is a friction point. An oil-pump shaft brushing the block creates friction. Valve stem-to-guide clearances that are too tight mean friction. Piston-to-cylinder wall clearances that are a bit snug consume power and make heat. Side clearances and crankshaft endplay create friction. Distributor drive gear to block clearance is another source. The trick is to get just the right amount of clearance with every aspect of your engine build.
Multi-Angle Valve Job
A multi-angle valve job improves airflow, which improves power. When we increase the number of valve face and seat angles, we reduce air turbulence and resistance to flow as it enters the chambers. The more rounded the valve faces and seats, the smoother the airflow.
Use Ceramic-Coated Headers
Ceramic-coated headers, such as these Hookers being installed from Holley Performance Parts, lower underhood temperatures, which lowers induction temperature, which helps power. Ceramic-coated headers also keep extreme temperatures inside the header tubes, which depending on valve overlap, will make a difference in power as well.
When you're shopping for a stroker kit, consider the selection of lightweight components-pistons, rods, crank, and flywheel. The less rotating and reciprocating mass you have in there, the less power wasted getting it all to move. What's in your engine?
Use Zero-Gap Piston Rings
MCE Engines is an advocate for zero-gap piston rings because less power is lost via blow-by. The objective is to make the most of hot gasses and thermal expansion. Zero-gap rings keep heat energy focused and where it belongs. Childs & Albert is an excellent source for zero-gap rings. So is Perfect Circle.
Install A Low-restriction Air Filter
Look no further than K&N and Summit Racing Equipment for low-restriction air filters. This is a fundamental way to reduce restriction and improve airflow. Don't forget to clean your K&N filter periodically-and do it per K&N's instruc-tions. The K&N Xstream lid shown here is a great way to get additional filter surface area (and airflow) without raising the filter height and having hood-clearance issues.
Increase Rocker-Arm Ratio
Would you like to improve valve lift and make more power without a cam swap? See Crane, Comp, Jesel, Scorpion, and so on about a revised rocker-arm ratio. If you have a 1.6:1 rocker arm, check into a 1.7:1. First, make sure you have enough piston-to-valve clearance. The quickest way to lose power is engine failure because you didn't check these all-important clearances.
Limit Engine-Oil Pressure
None of us thinks about this one, but it's important. Set your oil-pump relief valve to a limit of 60 psi maximum with the engine hot. Excessive oil pressure consumes power via the pump shaft and load. It also creates excessive oil bypass, which can rob power and elevate oil temperature. When you build, blueprint your oil pump and remove all doubt about lubrication and power.
Remove All Of The Junk From Your Trunk
Remember the horsepower-to-weight ratio-10:1. One horsepower for every 10 pounds of vehicle weight is the maximum. If you want to haul, watch vehicle weight and plan power around it. Don't expect a rocketship if you have a 289ci small-block in that big Galaxie.