Watch This Supposed-Stock Z06 Belt Out Some Serious Horsepower

We’ve all heard the “must’ve been built on a Friday!” statement when something is not quite optimal. In the automotive realm, the idea is that those who assembled the vehicle may have had their minds preoccupied with other things during their participation in the build. The folks who build Corvettes in GM’s Bowling Green Assembly take a lot of pride in our rides. Thinking this applies to products rolling out of that plant today would be a bit of a stretch, but could the opposite be true?

Race Proven Motorsports (RPM) recently released this video of a 20,000-mile, 2013 Z06 Corvette that is supposedly in a bone-stock configuration. The car is exceptionally clean and doesn’t show any signs of tampering. The car’s likely new owner wanted a little more performance. Since the warranty is long gone (at least so far as the calendar is concerned), the guys at RPM were commissioned with turning up the wick on the C6.

The entire car looks VERY clean and unaltered. The LS7 only has 20,000 miles on the clock.

Of course, standard operating procedure dictates that a little dyno time is in order, to adequately compute the extent of the benefits from adding aftermarket goodies. In this video, RPM goes through a few projects working their way through the shop at various points of completion. For the C6 Z-car in question, that starts with the car on the dyno for its initial baseline run.

It all starts out innocent enough, strap car to dyno, hit loud pedal, and watch the screen for numbery goodness. The guys take a second to guess where this bone-stock LS7 lands within the bell-curve of power output. Seeing a few cars through their shop, the guys make a rough guess of around 450 to 469 horsepower.

Rated at 505 horsepower, the typical run of 427 cubic-inch LS7s will fall somewhere between 430 to 460 horsepower to the rear wheels with the occasional flier posting 470. The difference from the engine’s rated horsepower is attributed to parasitic loss as the power runs through the drivetrain, generally accepted as a 10-15% loss from crankshaft numbers.

The eyebrows begin to lift when the screen posts a personal best of 492 horsepower and 443 lb/ft of torque – to the wheels! If the opening statement were indeed true, that would mean this Z06 must have been built during the lunch break on a Wednesday, placing the build during the absolute peak of production between recovery from one weekend and anticipation of the other.

The car soon finds itself on the dyno. The numbers even surprised the guys at RPM.

Of course, we all know in our modern age of auto production, outside influences no longer bear such a profound effect on the end product. Even so, there is no doubting the stars definitely aligned during the build process of this particular Z06. Perhaps they had the dyno set to adjust for an all-wheel-drive vehicle. It can happen!

There are a few things that stand out, such as promoting such spectacular numbers from a reportedly-stock vehicle and making a video about it but not delving into the ECU. The guys at RPM do this stuff every day, so it would be easy to see if anyone had changed anything within the tune. We’re not sure that you’d see that amount of power, even with a tune, but some increase would definitely post it closer to what this car lists.

The car churned out 492 horsepower and 443 lb/ft of torque. Very good for a stock C6 Z06! The guys even went in and posted the change if they were to use SAE numbers instead. 479 and 431 were the resulting numbers corrected to SAE.

So, if the settings were correct and the Z-car is indeed stock, the guys at RPM have perhaps exposed the single C6 that was built at lunch, on a Wednesday. We’ve all heard about cars that supposedly came together during the perfect performance storm, finding themselves on the higher end of the bell-curve. Many times, the reports come directly attributed to the seat-of-the-pants dyno, but in this instance, we’ve got an honest-to-God dyno chart to back it up.

Where do we go from here?

Let’s say this car is all it claims to be. We’re actually happy for its owner, as they’ve got themselves a real runner! But they obviously want more and that’s what the guys at RPM are going to give it. Question is, will they be mucking with the super-tuned engine build that afforded all that performance, or are there other factors within the driveline that will continue to carry the car’s horsepower numbers?

It didn’t take long and parts were hitting the floor!

RPM plans to give the car a heads and cam upgrade while also replacing the clutch. They’ve started with the disassembly but have not posted a video showing the completed work or the final dyno numbers. That gives us the perfect time to pontificate about all aspects of this car’s performance. Do you think 496 rwhp is even possible in a stock C6Z? As the guys at RPM have said, they really don’t have any reason to raise the bar on the baseline run.

All LS7s were hand-built at GM's Performance Build Center in Wixom, Michigan and featured a plate noting who built the engine. This particular engine also got a hand-signature!

Also, does anyone care to guess what the run numbers might be once the rollers stop spinning for the second time? Do you think the blessing this car received from the factory will continue to carry it ahead of the pack, or will it fall more in line with your typical head/cam package? Take a second and let us know in the comments section. Then we’ll find out together when the next video comes out.

About the author

Andy Bolig

Andy has been intrigued by mechanical things all of his life and enjoys tinkering with cars of all makes and ages. Finding value in style points, he can appreciate cars of all power and performance levels. Andy is an avid railfan and gets his “high” by flying radio-controlled model airplanes when time permits. He keeps his feet firmly grounded by working on his two street rods and his supercharged C4 Corvette. Whether planes, trains, motorcycles, or automobiles, Andy has immersed himself in a world driven by internal combustion.
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