Centrifugal superchargers are among the best power-adders available to heads-up drag racers, and they’ve evolved with the times to meet racer’s needs and pushed the boundaries of technology. ProCharger’s new F-4X supercharger is another step in the evolution of the centrifugal supercharger and it has already proven itself at the highest levels of drag racing.
The F-4X looks like a lot like ProCharger’s highly-proven F-3X supercharger at first glance, however, there are many differences between the two.
ProCharger started with a clean slate when it began developing the F-4X; its decision to start fresh opened up enormous doors for the engineers to create a supercharger that would not only make more horsepower, but be very durable too.
The F-4X is compatible with any current crankdrive for the F-3X supercharger. This saves racers money who are looking to upgrade superchargers.
Ken Jones from ProCharger provides the big-ticket differences between the F-3X and F-4X superchargers.
“The F-4X uses a brand new gear case and started as a clean-sheet design. The bolt pattern is the same on the case, so it will bolt up to existing crankdrives. The case itself is thicker than the F-3X gearcase. The F-4X also has a different internal step-up gear ratio, which means racers can run a different gear ratio inside the crank drive.”
Let’s take a look at the gear ratio difference first.
Inside a centrifugal supercharger, there are gears that spin the impeller so that air can be moved; the ratio of these gears determines how fast the supercharger will spin, and the goal is to reach the maximum speed for the supercharger. The max ultimate speed is measured in rpm, and is where the blower will make peak horsepower.
We’ve made this supercharger so it will work with all of our current components that way racers won’t have to make wholesale changes to get this blower to fit. – Walt Sipp, ProCharger
ProCharger’s Walt Sipp adds some details on the F-4X’s gear ratio.
“The max ultimate speed for the F-4X is 72,000 rom. The F-3X has an internal step-up ratio of 5.63, and for the F-4X it’s 4.77. You can think of that blower gear ratio like you would a rear end gear ratio…that’s what you’d be looking at with how it reacts to changes. That’s why we have to change the ratio in the gear drive to compensate. NHRA Pro Modified, for example, specifies a certain ratio for the gear drives. For the 5.63 ratio, the NHRA now requires a 1.20 ratio in the crankdrive, so at around 10,650 engine RPM, that puts the blower RPM at 72,000. To get to that same ultimate blower speed for the F4 we have to use a 1.42 ratio in the gear drive to go with the 4.77 internal step-up ratio inside the blower. So we had to change the crankdrive ratio to get the same ultimate blower speed we need.”
The gearcase of the F-4X was enlarged to make room for new gears and to increase durability.
Racers who participate in events outside of the NHRA can run any crankdrive gear ratio they choose; that means they can match it to their combination and dial up the horsepower.
ProCharger’s F-3X gear case is a workhorse that’s seen many upgrades and tweaks during its years of service. The F-4X uses a brand new gear case with all new parts. ProCharger went this route so it could focus on making the F-4X as durable as possible, since it’s being pressed into service in classes like Pro Modified, Radial vs The World, and Pro 275.
“The new gear case uses helical cut gears, and that allowed us to shift some of the loads inside the case. You’re supporting a ton of torque inside this case and it accelerates rapidly. Helical gears also make the blower much quieter, and it produces a different sound while it’s running. It wasn’t a strength issue when it comes to the gear change, it was about shifting the loads. It’s also a physically wider gear set, the result is a .3-inch deeper case, but the bolt pattern remains the same,” Jones explains.
Racers have to make minimal changes for the F-4X since it's so close in size to the F-3X supercharger.
ProCharger wanted to create an upgrade path for racers who currently have the F-3X and want the additional horsepower the F-4X supercharger offers. The engineers at ProCharger tackled this task by making the F-4X compatible with all current gear drives for the F-3X. A racer may have to make some modifications to their vehicle to get the F-4X to fit, but they’re minimal.
“We’ve made this supercharger so it will work with all of our current components so racers won’t have to make wholesale changes to get this blower to fit. Now, this blower already has a bigger housing so if someone wants to upgrade from the 140 to the 142 they won’t have to cut the car up. The inlet tube will only need minor changes for the F-4X to fit in any car where an F-3X was used. We did this with the racer in mind so they wouldn’t have to make a lot of changes,” Sipp explains.
The team at ProCharger worked very hard to bring the F-4X to market in less than a year during a pandemic — this is a fact that Jones is very proud of. ProCharger didn’t skimp on the testing or development of the F-4X, as the company didn’t want racers to experience quality issues that could have been avoided through proper testing.
“We did a fair amount of in-house testing for the F4’s gearbox. After the in-house testing, we moved to some hub dyno testing with key customers to see what the blower would do. Last came the track testing, and that went on for a while. After the World Doorslammer Nationals race, we felt there was enough data to validate a release date for the blower, and that was proven by the results at Gainesville. The F-4X-140 will enter early production for customers on April 26 as of right now,” Jones says.
The concept of an upgrade path for racers that will allow them to turn up their combinations is something that ProCharger had in mind with the design of the F-4X supercharger. ProCharger’s F-3X is designed to max out around 3,500 horsepower; the F-4X takes the torch from that point and moves it to the 4,000 horsepower range.
“The idea was that if you’ve pushed the F-3X as far as it can go then moving to the F4X is the next logical step in terms of horsepower capabilities. It’s nice to overlap them so customers can see there’s a gearbox for the future as bigger models come out. This blower is designed to grow with customers so they don’t have to change to a new combo as unlimited heads-up classes progress,” Sipp states.
The F-4X has performed well in competition winning several big races already in 2021.
ProCharger has been working with about 10 teams during the development of the F-4X supercharger. Thus far in competition, the F-4X has proven it is more than capable, with wins in Radial vs The World at the U.S. Street Nationals and Lights Out 12, as well as a Pro Modified win at the World Doorslammer Nationals.
“For Radial vs The World and Pro Modified racers, this blower we had people asking for in 142 trim last year. We didn’t think the F-3X could handle it, but the F-4X can. This blower allows for more power and provides the durability at this level that these racers needed. The F-3X-140 has done well but the F-4X-140 gives you room to grow,” Jones explains.
ProCharger’s commitment to pushing the limits of what a centrifugal supercharger can do really shine with the development of the F-4X-140 supercharger. The F-4X is designed to be a jumping-off point for further development and growth of ProCharger’s high-horsepower supercharger line. AndiIt will be interesting to see just how much horsepower racers will be able to extract from this robust and versatile supercharger.
