Wheelie Control
It stands to reason that if you can measure the angle of a vehicle — very accurately at that — that one could also program responses to those measurements. That concept brought about one of the most sought-after features of the VPS: wheelie control. In utilizing this technology, the tuner can program if-do variables to retard ignition spark, cut the ignition, shift the transmission, or throw the parachutes to prevent a catastrophe in the event of a higher-than-planned wheelstand. This can be set up in tables via your compatible ECU or the Profiler/handheld screen.
We were one of the first teams to get ahold of the VPS and we’ve found it to be a much smoother way to manage the pitch of the truck. It sets it down much softer and is more manageable and accurate. – Bruce McConnell
“You set up a start point on the wheelie control — a starting angle — and a rate at which it is going to make the correction. Then you set up another point at which it will start dropping cylinders as needed. Two to 2-1/2 degrees of pitch is very popular among radial-tire racers for a starting point,” Davis explains. “So at that point, your example configuration might start retarding 2- to 5-degrees — depending on nitrous or turbo — per degree of rise. By the time it gets to 5-degrees of pitch, it’s got 15- or 20- degrees out of it depending on the combination, and if it’s something they’re willing to do they can start dropping cylinders with our Smart Drop. And that’s what sits them down nicely. All of this also has a start time, so it won’t start doing any of this until the car gets a predetermined length out from the starting line, since some cars will snatch the front end up on the hit. It’s when these cars come up at half track that it’s a problem … you don’t want it to kill a bunch of timing right off the line if you don’t need to.”
Bruce McConnell’s ’48 Dodge.
West coast racer Bruce McConnell campaigns a popular 4.8-second, 1946 Dodge pickup sporting a 410-inch, single turbo combination that’s prone to awe-inspiring wheelstands. McConnell, who races for the joy of it, linked up with Davis early in the development of the VPS in hopes of taming his bright orange truck to keep it out of potentially damaging touch-downs. Equipped with a Profiler and a Holley EFI, McConnell has found the VPS both highly useful and relatively simple to set up.“When we first started this whole thing five or six years ago, we were looking for a way to stage the truck better. We were pointed to Shannon’s Bump Box, and were so impressed that I bought a traction control system. I later got a Profiler and worked through that and then we started using a ride height sensor to help with wheelstands. The problem with a ride height sensor is that when it drops out of range it drops back to zero and so we couldn’t control it,” McConnell shares. “We were one of the first teams to get ahold of the VPS and we’ve found it to be a much smoother way to manage the pitch of the truck. It sets it down much softer and is more manageable and accurate. The nice thing about the Profiler is we can define all of the situations and events, so when it’s at a given angle, this is what we need to do.”
In this real-world data from a radial-tire car, you can see the correlation between pitch, G, and time retard as the car hikes the front end early in the run.
Properly configured, McConnell’s driver, Doug Driggers, is able to keep his foot in the throttle and trust the system to keep the truck from reaching dangerous pitch angles.
“Doug and I laugh all the time about this, because when it does go down the track and carries the front end 10- or 12-inches off the ground out at half track, Doug is always saying to himself, ‘c’mon Shannon I’m waiting on you, I’m waiting on you.’ The instinct of a driver is to lift when he feels it, so he had to get over that mentality and allow the Davis stuff to do the job. Now you don’t lift, because you’re pretty certain the system will handle it. Doug says he can hear and feel the engine pull down in the cab,” McConnell adds.
Hey Yaw, Let’s Roll
Davis envisioned the VPS going beyond simple wheelie control in regards to safety by utilizing the programmability of the yaw and roll axis of the device. In doing so, one can set parameters to, for example, kill the ignition and throw the parachutes if the vehicle’s yaw angle become too extreme — in other words, if the car is out of shape and sideways — to help the driver regain control. The VPS’s sensors can even detect and calculate deviations from zero in forward heading, allowing one to program the same actions if the car is drifting out of the groove into the marbles or on a collision course with the wall.