Because of the higher performance...
Because of the higher performance expectations, some machining processes not normally seen on street engines become vital for a racing powerplant. Here, engine builder Chris Lafferty cuts new valve pockets in a piston to achieve the proper piston-to-valve clearance. In a street application, a set of pistons with extra-large pockets would easily have been ordered up, but an engine builder simply cannot afford to give away compression like that for racing.
If you have ever been racing down the straightaway at your local track and been blown away, you've probably had time to reflect on the things that you could have done better to go faster. Many times though, racers simply blame the problem on money-specifically, the opponents' overabundance of it.
Granted, racing isn't cheap, but if you plan to go racing and expect to be competitive, there are some things you can't nickel-and-dime to death. The engine and the work performed while building it are areas where that is often done. If you are price shopping rather than quality shopping when it comes to your engine, you should probably just sell your race car and buy tickets to the next big race. That will fill your needs and save a lot of money, too.
It's no secret that people are in business to make a living. When you are beating up your engine guy for a better deal, remember that you may just be cheating yourself. His light bill doesn't get paid by doing stuff for free, so the quality of work you get back may suffer. Most engine builders charge in the $40-$70 an hour range for labor, but an engine builder with a sterling reputation can get a premium on that amount. Maybe you are paying for results, or maybe you are just paying to get his name on your valve covers. You decide.
Let's talk a bit about the machining and clearance-checking processes involved in building a good race engine, and which steps can be beneficial to you, even though the up-front costs may be steeper:
Proper pin bore clearances...
Proper pin bore clearances are easy to miss, but they reduce friction and cut down the chance that a wrist pin can gall inside the piston.
We'll begin with the basics, deburring your new block. This may seem like money thrown down the drain, but if you've ever had an engine mysteriously blow up, only to find on later inspection that a piece of casting flash in an oil passage impeded flow to the rotating vitals like it was the Hoover Dam, you will understand that deburring is not just for cosmetics. Much of the time involved in this process is simply time spent at the parts washer, making sure every piece of trash is out of the oil galleries. In this business, the details make the difference between a good engine builder and a great engine builder. If you're saying, "I've built 100 race engines and never done that," remember, it only takes one.
Typical Job Time: 3-10 hours
Time spent to deburr and condition your rods (even new ones) will keep debris out of an engine. The point of this exercise is to remove all sharp edges that could possibly scuff materials off the bearing, as well as keep those materials from imbedding themselves into the bearing and gouging into the crank. Also, honing the rods to make sure they are the proper size will insure the bearing will be held properly and last.
One not-so-obvious benefit is that the rod bolts must be installed during this process and torqued to race specifications. This means the bolts are stretched when torqued and should be checked for fatigue and proper torque with a stretch gauge. Doing this now reduces the chance that a fatigued bolt will make it into the engine and let you down on the track.
Typical Job Time: 3 hours