Photography Credit: David S. Wallens
There’s a sound that, even if you’ve never heard it before, is instantly recognizable as bad. Worse than a too early alarm after a rough evening, a screaming baby on a plane, or your drunk uncle droning on about how the “real” government put chemicals in his soup to turn him into a zombie, this automotive equivalent of the shart will send chills down the spine of even the most seasoned gearhead.
That sound is your connecting rod remodeling your engine by adding a new window.
And that, dear reader, was not how our C5 Corvette project ended, but rather how it entered the long, tedious final chapter of its tenure with us. So in the interest of shedding some of the emotional burden, here’s the story of our Corvette’s final hour, its rebirth and what we learned when our engine exploded.
When our projects start to wind down, we usually make the decision to move on and sell it to a new caretaker. In our case, we had a verbal arrangement with a buyer, a good friend and a valued member of the amateur motorsports community.
“Do you want a deposit?” our buyer asked.
“No, we trust you,” was our reply. “Besides, if you send us money now, something awful will happen.”
Turns out we didn’t need the deposit to fulfill that prophecy.
During our final track session with the C5 Corvette–which wasn’t even a full-on test day but rather a photo session so we could fill our archives with content on a popular project car–some gentle acceleration pulls ended in a horrendous thump, followed by the sickening “clackclackclackclackclack” of iron hitting aluminum. And the smell, and smoke, of oil. So. Much. Oil.
Here’s where we’ll provide the first lesson of the story: When you blow an engine on track, you have some hard decisions to make. Within seconds, it was clear that the failure was catastrophic, and in most situations the proper reaction would be to exit the track immediately and park near a corner worker. That prevents the track from becoming overly oiled and gets you and your car the help it needs as quickly as possible.
The catch in our situation was the fact that the track was lightly staffed. We’d have to go a ways to reach the next corner worker station.
With lots of smoke but no visible flames, we made the decision to at least coast until a fire extinguisher was in sight. Then we’d bail to grab said safety device.
Upon coming to a stop and opening the hood, we quickly assessed the situation. There was no fire, quite a mess behind us, and one apparent conclusion: This particular 525-horsepower LS3 was done forever and off to engine heaven.
Upon contacting the buyer, we confirmed that they were still a customer for a repaired car. Then we set about extricating the dead V8. Side note here: There’s no mess quite like blown engine mess, especially when there’s 10 quarts of dry sump lubrication hosing out of the side of the block like a lawn sprinkler.
After removing the engine, we did a little forensic examination and called the builder, BluePrint Engines. Well, actually, we had our mechanic, Jesse Spiker of Spiker Motorsports, call the builder. At this point, we didn’t want to complicate the situation by approaching it as a media outlet. We just wanted to see what support was available for our blown engine.
After some cursory disassembly, we came to a likely conclusion that a faulty rod had been the cause of the disaster. The rod had snapped near the crank journal, fairly cleanly, and the portion of the rod still connected to the crank punched out through the oil pan on a subsequent rotation.
Lowering the now perforated oil pan revealed chunks of engine on the windage tray. The snapped end of the rod had contacted the inside of the block on subsequent rotations, doing its best impression of every tool from Harbor Freight: It eventually became a hammer. Photography Credits: J.G. Pasterjak
That portion of the rod still connected to the crank continued to spin smoothly and freely on the journal, however, showing no obvious signs of bearing failure. Likewise, the top part of the rod still articulated smoothly in the piston. There were no obvious signs of anything putting too much pressure on the rod due to a jammed bearing or a piston digging into the bore. We could only find a cleanly snapped rod.
Jesse communicated this to BluePrint, along with the fact that the engine was installed in a track car and had been converted to a dry sump. BluePrint requested some pictures and documentation and asked plenty of questions about how the engine was used, how it was installed and how we drove it on track, after which the company–ready to be impressed?–honored the warranty.
We’re not going to say that every track engine that ever blows up should be replaced by the builder, but the advice we’ll give here is that documentation is your friend. We were able to send pictures, videos and data logs showing that we pushed the engine hard but always operated within proper temperature and pressure parameters. We think this went a long way toward the builder standing behind its product.
A happy ending, though: Our engine builder warrantied the engine. We dropped the powertrain and suspension subframes and bolted the new one in place (and did a bit or pressure washing while it was out. Oil is icky.) Photography Credits: Jesse Spiker
But the complication here was that even though we were in line for a new engine, that line was long, with peak covid-era supply chain slowdowns–especially for metal goods–still plaguing the engine market. Months stretched out into more than a year of downtime.
And after installing that new engine, we still had to tune it, meaning more downtime. Even if the new engine is exactly the same as the old one, don’t assume your old tune is optimized. The old tune could be a fine starting point, but it’s worth taking the time to make sure the new engine likes it as well. (Cue more relief that we didn’t take a deposit.)
After all those delays, though, the handoff finally occurred.
Our former project C5 Corvette now lives with its new owner at a big farm in Pennsylvania, where it can run and play with its new friends. Photography Credit: J.G. Pasterjak
Wrapping this all into some sort of teachable moment is difficult because we can’t point to a grievous action here. The first team meeting post-explosion had a definite “Well, that’s racing” vibe to it, and maybe that’s one of the key lessons: If your hobby involves pushing things to their limit, at some point you’re going to break something.
It’s an unfortunate reality of our world, whether you’re talking about a 50-year-old Datsun four-banger, a 525-horsepower crate engine or a brand-new GR86 fresh off the showroom floor. As good as engines have gotten these days, they still occasionally break.
Maybe the other lesson here is that you can never have too much documentation or too many gauges. During track sessions, we would monitor oil pressure, oil temperature, coolant temperature and air/fuel ratio, always ready to end a session or at least back off the throttle for a lap if anything seemed amiss.
And our Holley Dominator ECU’s ability to record this data made reviewing it comforting as well. Sometimes your eye might miss a momentary drop in oil pressure or an impending spike in temperature, but by reviewing the data, we could spot trends in those numbers that we could incorporate into our driving patterns in future sessions.
And ultimately, being able to show our work may not have saved our engine, but it potentially helped our case when it came to having its replacement covered by the manufacturer, who was convinced we were treating it right.
The timing of the failure is ironic, but the duration of the time this obviously defective rod survived surprises me. Were those stock rods? GM began improving the quality of their rods as far back as the vortec 350 truck engines of the late 90s, and the LS bottom ends are well known to be very robust. However, for an endurance race car, I would expect an aftermarket rod would be used.
I really liked this car.
Interesting. There was a spate of LS1 and LS6 engine blowups on track where the PISTON turned into granola and the free swinging rod and wristpin beat the cylinder wall apart, sometimes clear through to atmosphere.
It is hard to do a postmortem when all of the metal bits are Grape-Nuts and they are thoroughly distributed to the other cylinders and the ground. I am of the mind that those failures probably started with dropping a valve.
My favorite carnage photo was intact piston rings resting on the passenger side control arm of a CTS-V.
If this is the end of the project, what was the final cost of the build?
I am fascinated by the photo of the entire driveline dropped out of the bottom.
WOW We saw a lot of oil Pan Failures in NASCAB
As mentioned earlier it is hard to determine where things went wrong with all the bit and bobs of metal scattered around.
Good luck
Did not end that quickly though, flew home, Chrysler would only fix it at there leasure 4 weeks +-, ,the case was not broken, they "repaired" it, no compensation, no transportation etc, memory warrenty then was maybe 1000 miles.
Never darkened there show room floor since.
The world has changed in many was for the worst, but in the case of Co s standing behind the product mostly better!
You never know.
The laws of physics say that a part will break as soon as the stress on any point is greater than the strength at that point. And yet, things break in half sometimes just because you looked at them hard, instead of when they're being beaten to death.
I snapped an axle half-shaft on a Civic once. Doing about 5 mph navigating out of the parking lot at work.
CrashDummy said:If this is the end of the project, what was the final cost of the build?
It's a tricky tickertape because the natur eof projects is ccasionally doing stuff multiple times until you get it right, and none of those times are free.
You could probably duplicate the car pretty easily for under $40,000, though.
Floating Doc (Forum Supporter) said:The timing of the failure is ironic, but the duration of the time this obviously defective rod survived surprises me. Were those stock rods? GM began improving the quality of their rods as far back as the vortec 350 truck engines of the late 90s, and the LS bottom ends are well known to be very robust. However, for an endurance race car, I would expect an aftermarket rod would be used.
I really liked this car.
Yeah that motor had been through a lot by the time it broke. I'm not sure whether the failure means the rod was stronger than I gave it credit for despite a defect or if it just had a short life expectancy at high load. I tend to think the former, since I rarely hear about failures like this in these motors.
And, yeah, I really liked it, too. It'll probably be a while before I build something this fast and easy to drive again.
I missed this - why did you use a 525 hp LS3 that was built by a third party and not a GMPP crate? Were those rods "upgraded" or OE parts?
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