Gibtec may be a new name in competition piston-making, but its leaders aren’t new to the craft. Nick Plantus, one of the three founding partners of Diamond Racing in 1968 and his colleague, Rob Giebas from a younger generation, served roughly 20 years with the same operation, usually involved in development programs for NHRA Pro Stock programs.
But when asked where he sees the biggest challenges in race engine tuning, Giebas responds with one word: Nitrous! Why so? “Well, the top tuners will tell you nitrous engines have never been completely mastered—there’s still an element of mystery about them. Nitrous oxide induction requires a totally different approach, and it’s a volatile science; if the tune-up is off a little, parts need replacing.
“Unlike the turbo or blower guys, who might get 50 or 60 runs from their pistons, when those nitrous guys are really pushing hard they’re replacing rings every three or four runs—it resembles the Top Fuel class in many ways. If they ease off a little on the tune-up they’ll become uncompetitive. And when the racing gets close, they’ll routinely dismantle the engine after every pass. Leak-down tests, ring end-gap checks, raised ring lands, pinched rings these are constant topics in their world.”
What provokes a raised ring land or a pinched ring?
Race fuel burns relatively slowly, and if the motor detonates it doesn’t burn the charge properly. As the piston travels down the cylinder, fuel under the ringland and around the ring ignites, causing the ringland to jolt upwards as it fires and the gas expands. Or it might pinch the ring if the mixture is too lean. When you’re forcing a nitrous engine onto the ragged edge of ultimate performance, an elevation change of just 200ft can make a fatal difference.”
“It’s not just them—most professional engineers who are involved in piston design are constantly making changes. If they didn’t have access to billets they’d probably need several entirely new forgings, which are expensive and take weeks to get.”
What’s the advantage of pistons with buttons?
“They are popular for two reasons. When the piston pin bore breaks into the oil control ring groove, the button prevents the expander in the oil control ring from distorting around the half moon opening, a deficiency more prevalent in power adder engines. But the biggest advantage is convenience: changing pistons with buttons slashes the time and the frustration of fiddling about with the round wire locks or the double spirals.”
If there’s one thing that sets a premium piston apart from a mediocre one, what is it?
“Ultra flat ring grooves—they’re the key to power.”
Gibtec Pistons and Moore Good Ink