Chevrolet Z11: A Full-Size Car That Forgot to Be Sensible
Pay More Money, Get More Engine and Considerably Less Impala
By 1962, Chevrolet had a problem that could be measured in cubic inches.
The 409 had been the engine everybody talked about, and Chevrolet had done rather well with it. But Detroit’s horsepower war was moving fast. Pontiac had 421 cubic inches, Chrysler was throwing Max Wedges at the dragstrip, and Ford was not exactly sitting in the corner knitting.
The 409 was still good.
Good was becoming insufficient.
Vince Piggins Wanted More
Vince Piggins ran Chevrolet’s performance operation during an era when the corporation preferred descriptions more respectable than “race department.” The title may have been polite. The assignment was not.
His people were there to make Chevrolets win.
By August 1962, Piggins was laying out Chevrolet’s 1963 competition program, including a particularly direct answer for drag racing. Keep the basic W-engine architecture, stretch the 409 to 427 cubic inches, put it in a lighter Impala and build enough cars that Chevrolet could call the package production equipment without everybody laughing too loudly.
The Beach Boys could keep singing about the 409.
Piggins had already moved on.
The Engine Was Only the Beginning
The new 427 remained part of Chevrolet’s W-engine family, not the later big-block most people picture when somebody says “427 Chevrolet.” The 409’s 4.3125-inch bore stayed, the stroke grew to 3.65 inches, compression climbed to 13.5:1 and a pair of Carter four-barrels sat on a special high-rise aluminum intake.
Cold air came in through the cowl, and Chevrolet rated the package at 430 horsepower and 575 pound-feet of torque. That was the number Chevrolet printed, and race departments have always demonstrated remarkable restraint when putting horsepower numbers where racing officials might read them.
The engine was ready. Now Chevrolet had to deal with the automobile surrounding it.
An Impala Contains a Lot of Impala
The 1963 Impala was a proper full-size Chevrolet: long, wide, comfortable and built to handle family duty, grocery duty and whatever else somebody expected from the largest Chevrolet in the showroom. Unfortunately, every pound of that respectability had to leave the starting line with the 427.
That was fine if somebody was driving Aunt Mildred to church. It was less useful when the fellow in the other lane had also discovered horsepower.
Chevrolet’s answer was RPO Z11. “RPO” stood for Regular Production Option, which may be the most optimistic use of the word “regular” anywhere on the car.
The Weight-Reduction Committee Got Busy
The hood, front fenders, grille filler panel, bumpers and assorted brackets gave up their steel for aluminum. Chevrolet even supplied an aluminum fan shroud, because once engineers start weighing things on a race car, nothing nearby should feel secure.
Then they went inside. Radios and sound deadener contributed nothing to a quarter-mile pass, most cars went without heaters, and even the front anti-sway bar disappeared. Anything that made an Impala nicer to own without making it quicker had suddenly developed a very uncertain future.
By the time Chevrolet finished, the Z11 was roughly 300 pounds lighter than a comparable 409-powered production car.
It was an impressive sales proposition: pay extra and Chevrolet would make sure you received less Chevrolet.
What Stayed Was There for a Reason
Chevrolet was not simply throwing parts into a dumpster. The equipment that remained made the car’s purpose fairly obvious: a Borg-Warner T-10 four-speed, Positraction rear axle, deep gearing, special suspension pieces, metallic brake linings, vented drums and a tachometer all surrounded that dual-quad 427.
Technically, the finished package was an Impala Sport Coupe. It simply had about as much interest in ordinary Impala duties as a bulldozer had in parallel parking.
Then Chevrolet Had to Call It Production
This was where factory drag racing became entertaining. Build one lightweight 427 Impala and everybody could reasonably call it a race car. Build a batch, assign the package a production option number and suddenly the argument shifts to how many cars Chevrolet has to manufacture before everybody agrees it is “production.”
Piggins’s original program called for 50 lightweight cars. The cars were to be built at Flint, with engines coming from Tonawanda, and there was no giant badge on the fender announcing that this particular Impala had been assembled specifically to ruin somebody’s Sunday at the dragstrip.
It was simply RPO Z11.
Just another factory option — provided your idea of an option included a 13.5:1-compression 427 and a front end containing enough aluminum to make the local body shop nervous.
Hayden Proffitt Changed Teams at the Right Time
Hayden Proffitt already understood the factory horsepower wars. He had been winning with Pontiac, and by 1963 he was driving Chevrolet machinery just as the new Z11 Impalas arrived at the Winternationals.
That created another problem, this time for NHRA. The cars looked like Impalas, Chevrolet had built them and somebody in an office had thoughtfully assigned them an option number. Nobody looking under the hood or at all the missing weight had much trouble figuring out why they existed.
You did not order a Z11 because the aluminum bumper made it easier to park.
It was a factory drag racer wearing an Impala’s name.
NHRA Had to Find Somewhere to Put Them
Traditional Super Stock rules had been written around combinations produced in meaningful numbers. Detroit was now learning that if racing required production machinery, the factories could manufacture specialized machinery specifically to satisfy the requirement.
At the 1963 Winternationals, the limited-production Chevrolets created enough classification trouble that they landed in a special Limited Production category rather than strolling into ordinary Super Stock and pretending nothing unusual had happened.
Fair enough. A full-size Chevrolet with aluminum fenders, little interest in comfort and a special 427 deserved at least its own argument.
The Big Chevrolet Was Fast
Once the Z11 reached the track, all the foolishness began making perfect sense. Hayden Proffitt, Dave Strickler, “Dyno” Don Nicholson and others turned the big Chevrolets into serious threats during 1963.
The trick was not simply stuffing a larger engine into an Impala. Chevrolet had worked on the entire package: more engine, less weight, cold air, serious gearing and equipment selected because it helped the car get through the lights rather than because somebody might enjoy it on the way to the grocery store.
The radio was gone. If the driver needed entertainment, two Carter four-barrels opening in front of him ought to have been sufficient.
Then Chevrolet Remembered It Wasn’t Racing
The timing could hardly have been better. Chevrolet developed one of its wildest factory drag packages, got the cars onto the track and demonstrated that they were fast.
Then General Motors reaffirmed its retreat from organized racing.
Official factory involvement dried up, leaving the Z11 as a one-year burst of what Chevrolet’s performance people had been building while the people upstairs were still deciding how much racing they were willing to admit was happening.
Only a small batch of Z11s was built. It was enough to make the point.
The Factory Had Learned the Trick
The Z11 demonstrated how badly Detroit had begun stretching the word “stock.” Chevrolet did not need somebody sneaking an oversized engine past inspection; it manufactured the engine. Racers did not need to replace steel panels with aluminum after delivery; Chevrolet thoughtfully did that before handing over the keys.
Even stripping unnecessary equipment could be handled at the factory. Why make the racer remove the radio and heater when Chevrolet could save everybody the trouble and neglect to install them in the first place?
Then the whole collection was wrapped in an Impala body and given an RPO number.
Technically, the customer was buying a production Chevrolet. It just cost more, had 427 cubic inches under the hood and arrived with roughly 300 pounds of perfectly good Chevrolet already missing.
That was the Z11: enough Impala to satisfy the paperwork, enough 427 to satisfy the driver, and one more lesson for Detroit.
If the rules demanded a stock car, there was no reason the factory couldn’t build a stock car specifically for racing.