There’s a lot of information out there about building engines—and not all of it holds up in the real world. At Owens Racing Engines, we’ve seen firsthand how certain myths and assumptions can lead to expensive mistakes, especially for people trying to save time or money.
Here are five of the most common engine-building myths we encounter, along with examples of what actually happens when theory meets reality.
❌ Myth #1: “Used Parts Are Junk—Always Buy New”
✅ What Actually Happens:
Used doesn’t mean useless. Many factory parts are extremely durable and can be reused—if they’re properly inspected, measured, and verified. At our shop, every component is checked for cracks, wear, and tolerance. If it passes, we use it. If it doesn’t, we replace it.
Example:
A customer brought in a Chevy 302 matching-numbers block that had already been bored .040 over. It was missing main caps and needed sleeves. Instead of scrapping it, we fit new caps, line bored the block, sleeved it, and sourced custom .045 over pistons to avoid going to .060. That block stayed in service—with its history intact.
That said, there are parts where new is almost always the smarter choice—such as valves, springs, rocker arms, and fasteners. It’s about balancing cost with reliability and knowing where to draw the line.
❌ Myth #2: “More Horsepower Means a Faster Car”
✅ What Actually Happens:
It’s easy to get caught up in horsepower numbers, but real-world performance is more complicated. Torque, gearing, and how and when power is delivered all matter just as much—if not more—than peak horsepower figures.
We’ve seen lower-horsepower cars outrun higher-horsepower builds in short distances simply because the torque was available earlier, and the gearing was matched to the powerband. A well-balanced 480-hp motor with instant response can outperform a 650-hp setup that struggles to get traction or suffers from lag.
❌ Myth #3: “More Boost (or Spray) Means More Power—Period”
✅ What Actually Happens:
Power adders like turbos and nitrous work—but they also multiply the stress on your engine. If the block, rotating assembly, or fasteners aren’t strong enough, that added power can lead to catastrophic failure.
Example:
A customer brought in a 347 stroker Ford that had been sprayed with nitrous on a stock OEM block. He said the car “shuddered like it blew a head gasket.” On teardown, the block had split completely in two, through the valley and all the way back to the rear main.
Boost and nitrous need to be matched with proper internals, machine work, and a plan. Without that foundation, the added power often does more harm than good.
❌ Myth #4: “Close Enough is Good Enough”
✅ What Actually Happens:
Clearances and surface finishes matter. Even small deviations in tolerances can affect oil control, ring seal, compression, and engine longevity.
Example:
A block arrived from another shop labeled as “ready to assemble.” When we checked it, we found the cylinders were .003” out of round. Ring sealing would have been poor, and the engine likely would have had performance and durability issues from the start. We corrected the bores with a proper torque-plate hone and ensured everything met spec.
Precision isn’t optional in engine building. It’s essential.
❌ Myth #5: “You Don’t Need a Machine Shop—YouTube Can Teach You Everything”
✅ What Actually Happens:
There’s a lot of great information online, and many people can handle parts of a build on their own. But issues usually arise when critical measurements, clearances, or installation steps are skipped or misunderstood.
Example:
We disassembled a motor that had been assembled at home following video tutorials. The piston rings were upside down and installed in the wrong grooves. That one error caused poor oil control and led to premature wear. The problem could have been avoided with proper tools, spec sheets, and some experience reading them.
The takeaway isn’t that DIY is bad—it’s that accurate measuring and verification are non-negotiable, especially with high-performance engines. Tools like micrometers, ring compressors, and torque wrenches need to be used correctly. Guesswork doesn’t belong in engine assembly.
🔧 Conclusion: What These Myths Teach Us About Engine Building
Behind every engine failure tied to one of these myths is a preventable mistake—usually caused by assumptions, rushed decisions, or incomplete knowledge. Whether you’re new to engine building or have been wrenching for years, these takeaways are worth keeping front and center:
✅ Used parts aren’t bad—unchecked parts are.
- Factory cores can be valuable if inspected properly.
- But some items—like valves, springs, and fasteners—are almost always better new.
✅ Horsepower is only part of the equation.
- Torque, gearing, and how the power comes on are just as critical.
- A lower-horsepower build can outperform a higher one with the right setup.
✅ Boost and spray magnify everything.
- If the foundation isn’t strong, added pressure reveals every weakness.
- Engine integrity comes before added power.
✅ Precision isn’t optional.
- Small errors in clearances or bore shape can lead to big problems.
- Close doesn’t count in machining—measured accuracy does.
✅ YouTube can’t replace measurement tools.
- DIY is possible and encouraged—but only with the right knowledge and tools.
- Guesswork leads to rework.
