No matter what engine you're...
No matter what engine you're running, there are things you can do to up the power ante. Although Clements Racing Engines won't reveal all the specs on its 800hp, 400ci, all-aluminum monster, many of the tricks used here can be used to get more horses from your mill.
We've all heard about the three inevitabilities in life: death, taxes, and a mother-in-law who thinks you don't deserve her daughter. For racers, there's at least one more: the nagging suspicion that you are down on power. Whether it's true or not, it's always fun to dream about how many more races you could win with just a few more ponies spinning the crankshaft. With that in mind, Circle Track humbly presents these 15 tips for getting more power from any engine. Try not to burn up the tires.
It's a simple rule: Compression equals power. Of course, everybody knows it, including race officials. That's why almost every class has limits on combustion-chamber volume and mandates flat-top pistons to effectively limit compression. So why is this a tip? Easy-make sure you are pushing your compression limit on every cylinder. If you aren't, you're leaving power on the assembly bench. Combustion chambers in stock cylinder heads can vary by a couple of cc's for several different reasons. They include core shift, valve seats cut to varying depths, or other casting problems. Because engine builders want to make sure their pieces are legal, the practice is to bring as many combustion chambers to the minimum cc limit and leave the rest large.
Make power by maximizing the compression in every cylinder. Instead of being afraid to make a chamber too small, use a few tricks to open them back up in order to bring every chamber to maximum compression. If there are differences in the volume of the combustion chambers, there are several options to even them out. You can deck the head on angle from side to side; then, once the chambers are too small, you can open them back up by dishing the valves as necessary. If you are still pushing rule limits on cc or compression, cut slightly larger valve pockets in the tops of the pistons. Finally, check your rules. Some classes that don't normally allow any grinding work on the heads will allow minor touchups to enlarge a problem cylinder.
Roller cam/lifter combinations...
Roller cam/lifter combinations require less energy to turn and can also take advantage of more aggressive cam-lobe profiles not possible on flat-tappet cams.
If your rulebook allows roller cams, you should definitely take advantage of it. Roller lifters allow cam designers to push the ramp speed limits that hold back engines controlled by flat-tappet cams. That alone translates into power with more aggressive cam profiles that open the valves quicker and keep them at the upper limits of the lift zone longer. If you aren't allowed to use roller cams, machine in the largest lifter bores possible. Larger-diameter flat-tappet lifters also allow more aggressive lobe ramps.
There is also the friction factor. The roller lifters greatly reduce parasitic losses associated with driving the valvetrain. While we are freeing up horsepower by reducing friction, don't forget roller rocker arms. These are common at mid-to-upper levels of racing. If you're racing in a Super Stock class, check to see what you're running. Good roller rockers can add as much as 10 hp at the upper rpm limits.
Synthetic means fake, but when it comes to motor oil, the gains that can be made are real. You need mineral-based oil in a new engine in order to get the rings to set. After that, don't let anything except premium-blend synthetic oil get into your engine. Synthetic oils lubricate better at lower viscosities, hold up better against heat, resist gumming up, and just plain work better. Back-to-back tests on an engine dyna-mometer with an engine that has already been broken in showed a 5hp gain in synthetic over mineral oil at the same weight.
The superior lubricating properties of synthetic motor oil will often allow you to move to a lower weight. But be careful here. Before changing weights of oil, be sure to check with your engine builder first.