The type of carburetor you...
The type of carburetor you run will determine what to do from there as far as where to find extra horsepower.
Somebody found that extra...
Somebody found that extra power in Ryan Newmans Penske-powered ARCA engine. He has already visited Victory Lane this season.
Gather all of the information...
Gather all of the information regarding series rules and restrictions before you call the camshaft manufacturer. Wallace suggests going to a company such as Comp Cams or Crane for your camshaft.
Using new parts, especially...
Using new parts, especially valvesprings, is a good way to ensure you do not lose any horsepower.
When the valvesprings start...
When the valvesprings start to lose between six and seven percent in tension, you need to change them. By using this On Head Valvespring Pressure Tester by Comp Cams, you can check the spring pressure on an assembled engine.
Finding horsepower depends mainly on what type of racing you are doing, what the rules are and what components the series allows you to run. Then, you spend your time maxing out those rules. First, you want to start with the carburetor and work your way down. Some racing series will only allow you to run a two-barrel or other small carburetor. What type of carburetor you run will determine what you do from there down to find that extra bit of horsepower. If you have to use a smaller carburetor, the next component you want to look at to gain some horsepower will be the camshaft. The camshaft should be tailored to whatever carburetor you run. Your best bet would be to go with a camshaft from a company like Comp Cams or Crane. Let them recommend what type of camshaft you should run. What you want to do is gather all the information you can on the rules, as far as what restrictions there are on cubic-inch carburetors, whether or not you have to run cast-iron heads and whether you have to run a flat-tappet cam. Once you get that information, give it to your cam manufacturer and it should recommend the best possible camshaft for your particular application and series.
The next biggest thing as far as finding some extra horsepower is the cylinder heads. First, you need to find out whether or not your racing series allows you to run an aluminum aftermarket head or if you have to run a cast-iron head. If it is a cast-iron head, you need to find out if it can be an aftermarket head or if it has to be factory-supplied. If you are knowledgeable about cylinder heads, you can do some work on them yourself. If not, I recommend going to a reputable machine shop to have this type of work done. Another thing you can do is look around to see who is running good and take your cylinder heads to the same place they are getting theirs worked on.
As far as what can be done to the cylinder heads to gain horsepower, there again, it depends on the rules. Unless you are into some high-end racing, there are very few series across the country that will allow you to do a lot of cylinder head work. Basically, a valve job and a clean-up of the intake and exhaust pockets are about all you can do to them. However, there is a lot of power that can be gained or lost if you decide to work on your heads yourself and you dont know what to do, so it is still better to farm that out to whoever is doing the local stuff and is fairly competitive.
If you have to run a flat-top piston, no pop-ups, such as in some of the ARCA racing divisions, cut the deck on the block to get the minimum clearance. You want to cut it down to minimum clearance between the piston and the head to try to gain all the compression you can.
In the ARCA Sportsman division they have a cubic-inch-to-weight rule. If you are running on a short, really tight racetrack where it is hard to hook up, you are probably better off running the smaller engine (less than 360ci) and taking the 200-pound weight break. If it is a larger track and you are able to hook up, it is probably best to find the biggest engine you can for whatever make and model you are running rather than avail yourself of the weight break.
It is hard to put a number on how much horsepower can be gained by doing headwork. If you start with aftermarket cast-iron heads, like Dart, you are basically getting a right-out-of-the-box product that doesnt need a lot of work. If your particular sanctioning body requires you to use factory original cylinder heads, there is quite a bit of power to be gained. You can gain probably 20 to 30hp by going in and really working the head over. However, if you are allowed to run aftermarket heads like Dart, I believe you will be better off.
With the bottom end of the engine, there again, you have to go with whatever the rules allow. What compression are you allowed to run? Once you find that out, go to the maximum amount. Finding a good local machine shop is probably the best thing you can do if you plan on building your own engine. However, finding a good machine shop that does good work can be pretty hard. Im not talking about a standard rebuild shop, but a guy who does some racing stuff and can guide you along as you are building your engine. You may pay a little more at a shop like this, but you will definitely be ahead in the long run. Building an engine with all-new pieces will cost more going in, but if you are going to run over an entire season it is better to start with as many new pieces as you can. You might get by with used components, such as the block and maybe a crankshaft, but for most of the internal pieces of the enginevalvesprings, cam lifters, connecting rodsit is wise to go with new stuff and keep track of the mileage. It costs more going in, but over a season of racing, it will cost less.
Basic Maintenance Basic maintenance can help you with your horsepower gain as well. If you properly maintain your engine, you will not lose any horsepower. Start with mostly new parts at the beginning of the year. You especially want to have new valvesprings. Before you actually run the engine for the first time, use a spring checker that works with the engine assembled. All you have to do is pull the valve covers, check the springs on the engine and write down that tension. Periodically, after each race, you need to check the valvesprings. When the valvesprings start to lose between six and seven percent in tension, you need to change them. After some time running a particular rpm you should get the feel as to when the springs go. Change them out regularly. It may seem a little more costly at first, but, one broken spring and valve and you will have a torn up engine, which will result in a repair job that will pay for all your valvesprings for a whole year.
Oil Coolers Running an oil cooler is another good bet. Keep a monitor on the oil temperature while youre running. If you have an oil cooler plugged in, it is really easy to plug in a filter on the scavenge side that you can take apart easily and check for any excessive metal or wear. If you see something you know has an internal problem, you can check it before you totally ruin the engine.
The oil weight may also affect horsepower gains. Normally, on an engine such as an ARCA Super Stock or Sportsman type, you can get away with running a light oil. Penske Engines runs a light oil in our Winston Cup cars. We use Mobil synthetic. Oil has made such tremendous gains lately. The only thing you need to worry about with these flat-tappet cams, like most of these engines are required to run is , the oil needs to have more zinc than is normally found in a production oil. Zinc helps with wear on flat-tappet cams. All the oil manufacturers have been required to take the zinc out because it damages catalytic converters on street cars. More production cars are going to roller-type camshafts instead of flat-tappets, therefore not having zinc in the oil does not harm the engine as it would in a race car. You can use an additive to get the zinc back. A multiple viscosity oil is OK, like a 20W-40 or 10W-30.
Remember, the viscosity needs to be matched with whatever bearing clearances you are running. A thin oil will not work with an excessive bearing clearance, like 3,000 or more. If you build the engine with bearing clearances down around the 2,000 range, you can run the light oil and there should be a little power with that.
Larry Wallace is the chief engine builder at Penske Engines.