Why is the Gear Vendors Overdrive so popular on Drag Week? Racers know it will live behind 4,000 hp, can be installed in a weekend, and doesn’t share fluid with your transmission so it won’t get contaminated when your automatic detonates.
To truly understand the function of the overdrive, we are first going to hit you with some basic drag racing concepts. On an ideal quarter-mile pass, you leave the line at torque peak, and shift through the gears at horsepower peak until you cross the finish line. The gear ratios in the transmission, rearend, and overall tire diameter determine the engine rpm as you pass through the speed trap. A higher overall numerical gear ratio raises rpm, and a lower numerical gear ratio lowers it. Simple, right?
As tires get wider, they also get taller, and as horsepower increases, peak power happens later in the powerband. All of this requires a higher numerical gear ratio in the rearend to get the engine speed up before the end of the quarter-mile and get the car off the line in the first 60 feet. If you can get through the traps without blowing up the engine, generally more tire and more gear is better.
The downside? A numerically higher gear ratio also raises the cruising rpm. For example, using the equation rpm = mph x gear ratio x 336 x 1.00/tire diameter, a Drag Week car traveling at 80 mph on the freeway with an aggressive gear ratio like 4.88:1 on a 33-inch tire spins the engine at nearly 4,000 rpm. If you’ve spent any time in a quick Drag Week car, you know that is a lot of noise, engine wear, and fuel consumption for a 300-mile trip to the next track.
This story is from the March 2022 edition of Hot Rod.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 8,500+ magazines and newspapers.
Already a subscriber ? Sign In
This story is from the March 2022 edition of Hot Rod.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 8,500+ magazines and newspapers.
Already a subscriber? Sign In
Making Connections
Project T-top Coupe: We install a Terminator X Max for big power.
LET IT BREATHE!
Project X’s new ZZ632 big-block needed to breathe, and this do-ityourself stainless exhaust kit was just the ticket to make it happen.
TUNING OPTIMIZED
VARIABLES WITHIN FUEL-INJECTOR CONSTRUCTION CAN LEAD TO POOR ENGINE OPERATION. HERE'S HOW TO TUNE YOUR FUEL INJECTORS.
Re-Flange It!
We check out the fab skills needed to run a flat hood on a 1970 Mustang with a very unique and too-tall engine.
THE TRIBUTE FOR THE WIN
Ron Capps wins the NHRA U.S. Nationals driving a Don Prudhomme-Hot Wheels tribute Funny Car.
So Close
Following a nearly flawless performance, a pít lane penalty kept the C8.R off the top of the podium in the IMSA Sportscar Weekend.
A RADICAL SHIFT
When you're a teenager and the police know you by name, it's not usually because of your volunteer work or class-topping GPA. Not at all. That was especially true for Jeff Kainz when he was behind the wheel of his 1975 Camaro. In the '80s, while cruising his hometown in North Dakota, his buddies with police scanners often heard the police tell one another: \"Kainz is out on Main Street.\"
WILD MASH-UP
Built to long-haul the 2023 HOT ROD Power Tour, this 1984 Monte Carlo’s facade hides a performance secret!
6 TIMER!
Tom Bailey captures his 6th HOT ROD Drag Week Unlimited/Overall title with his Sick Seconds 1.0 Camaro.
JIM MCFARLAND'S INFLUENCE WENT WAY BEYOND HOT ROD MAGAZINE.
Jim McFarland, the multitalented, multifaceted Texan who enjoyed several careers in the automotive performance industry, passed away in October 2023 at the age of 88.