Tech Talk #37 – The Hidden Costs of Horsepower

DavidTechArticlesBy David Reher, Reher-Morrison Racing Engines

I believe that an informed customer is a better customer. Whether I’m buying a laptop for my daughter to take to college or a new CNC machining center for our shop, I like to know as much as possible about the product before I sign on the dotted line. So in this spirit of full disclosure, I’m going to tell you something you need to know about racing engines: The more powerful the engine, the more maintenance it requires.

That statement may seem self-evident, but some racers simply don’t make the connection between horsepower and upkeep. As interest in Top Sportsman, Top Dragster and other fast sportsman eliminators skyrockets, more racers are opting for big-inch, high-horsepower engines. Unfortunately, they don’t always ratchet up their maintenance schedules at the same time.

When Buddy Morrison and I started building big-block Chevrolet V8s 20 years ago for bracket racing and heads-up sportsman eliminators, a 468-cubic-inch Rat that made 675 horsepower was a “killer” engine. Now our shop can scarcely keep up with the demand for 622ci big-blocks that produce nearly 1,300 horsepower. Think about it: We’ve increased displacement by 30 percent while nearly doubling the output. A top-of-the-line 622 sportsman big-block now produces more power than a state-of-the-art 500ci Pro Stock engine. Add a dose of nitrous oxide to one of these big-inch sportsman powerplants and you’ve got a serious contender for any all-out doorslammer or dragster category.

While power levels have escalated dramatically, the basic package hasn’t changed since the ’60s. We are still using the same bearing sizes, the same crankshaft design, and the same lifter bores that debuted on the original big-block Chevy in 1965. What has changed, however, is the stress that we inflict on these components.

Everything I’ve learned about engines can be summarized in one sentence: You increase an engine’s power by increasing its cylinder pressure. Period. You can raise cylinder pressure by adding cubic inches, improving airflow, injecting nitrous oxide, or pressurizing the induction system. Regardless of the method, the inevitable result of higher cylinder pressure is more stress on internal components.

When cylinder pressure and rpm climb, you have to beef up a wide range of parts to withstand the higher loads. The thickness of the wrist pin walls has to be increased and the head gaskets have to be supplemented with wire O-rings. As camshaft profiles become more aggressive to fill bigger cylinders in less time, the lifters, rocker arms, and valve springs must be upgraded. And it’s not just the engine that feels the effects of more power. The stress on transmissions, torque converters, rearends and axles also multiplies.

A few years ago, our 509ci Super Series big-block was considered a big engine, and we still build a fair number of them. Assembled with aftermarket steel cranks and connecting rods, these engines have exceptional life expectancy. Some of my customers have raced for six or seven seasons on the original block, crank, and rod assembly. We’ve periodically replaced pistons, lifters, rockers, and valve springs, but the basic package is nearly bulletproof. At the other end of the scale, a 622ci big-block with aluminum rods, a lightweight reciprocating assembly, and a camshaft with .900-inch lift requires much more frequent maintenance – I’d say it’s due for an inspection after 100 runs.

If a racer who is accustomed to making 400 runs between rebuilds decides to step up to a much more powerful combination, then he or she also needs to adopt a much more intensive maintenance schedule. Similarly, people who are new to our sport must recognize that racing engines are not street engines. They require frequent care and feeding to remain healthy.

Owning a fast race car is similar to owning a private airplane, and I’ve had experience with both kinds of machinery. Several years ago we got a great deal on a twin-engine plane – but while we paid far below its market value, it still cost a bundle of money to maintain. That’s because there are no shortcuts on aircraft maintenance. Our plane’s paint was a little faded and its interior wasn’t pristine, but the parts that mattered to me – the engines, propellers, landing gear and air frame – were in first-class condition. Other pilots have different priorities: they’ve got trick paint, the latest gee-whiz avionics, and lavish cockpits – but their engines are down on compression, their magnetos need rebuilding, and the landing gear is in rough shape.

I care more about how something works than how it looks, so it makes sense to me to spend money on proper maintenance rather than on impressing people. I often see parallels at the drag strip – the racer with polished valve covers and bad valve springs, or the dragster with chromed parts everywhere and leaking shock absorbers. I’m not down on people who want their cars to look good; I just hope that they pay as much attention to the parts you can’t see. The fact is that no one ever won an award for the best-appearing bearings or the best-engineered lifters, but those are just a few of the parts that are absolutely crucial to engine performance and reliability.

I don’t expect every racer to spend countless hours working on an engine – after all, that’s what keeps Reher-Morrison and other professional engine builders in business. People have busy lives, and many sportsmen competitors have business and family obligations that compete for time with their racing. I don’t think a serious sportsman racer needs to pull the valve covers after every run like we do in Pro Stock – but I think it’s only reasonable to check the valve springs for tension and lash at least once every race weekend. Take a look at what gets trapped inside the oil filter and run a compression test regularly. A little time spent on preventive maintenance can save big money in the long run.