The Limited Drag Radial (LDR) class is one of the most competitive in all of drag racing, and if you want to challenge for a win at any event you need a car that’s sorted out. With our all-new Project BlownZ28 that we introduced a few months ago here, we wanted to have a chassis that would serve ax a solid foundation built around the principals of what makes a radial-tire race car work. Since we are expecting big power from the 572ci Pro Line Racing ProCharger-blown engine, getting it to the ground is a top priority.
To make BlownZ28 a top-tier ride, we went to Skinny Kid Race Cars in Michigan to have a competitive car created that would also turn some heads in the staging lanes. In this first of a three-part build series, we’ll highlight the early stages of the build with renowned car-builder Keith Engling — affectionately known as Skinny Kid — beginning with the chassis and body and on to some of the key components.
The Chassis, Brakes, Suspension, And More
The LDR class that BlownZ28 will be competing in only allows racers to run on either a 275/60/15 or a 295/65/15 Mickey Thompson drag radial tire, based on which power-adder is being used. Having a limited choice of tires requires racers to have a knack for tuning a chassis so they can maximize both horsepower and traction. To make all of this come together seamlessly, the underpinnings of the car must be built so its true potential can be extracted, and that’s where Engling and his crew come in. Building fast race cars is what Keith has been focused on for decades and he knows what it takes to build a winning car through his years of experience on the jig table and at the track.
“The big innovation phase with these style of cars happened about 20 years ago. We were doing a lot of stuff back then that really hadn’t been done before when it comes to small-tire racing. The chassis themselves have been the same for a while, we are just moving engines around because we’ve figured out that’s how you go faster on radial tires,” Keith says.
We’ve put a lot of time into understanding and perfecting what it takes to create a race car that is dependable. – Keith Engling
Achieving consistent performances in heads-up racing requires a car that’s predictable, and that predictability comes from acquiring data after you’ve made a lot of laps down the track. The chassis of BlownZ28 is a standard 25.3, 4-link design that Keith has created and has continually refined based on what he’s learned at the track. When a project begins at his shop, Keith looks at the needed SFI certification for the chassis, what kind of tire the car will be using, and the intended style of racing, before he starts laying out any tubing so he can apply his wealth of knowledge to the build.
Knowing that BlownZ28 would be running in LDR, Keith went to his chassis playbook and selected a standard 4-link rear suspension and strut-style front suspension that fit within the rules of the class. Keith also had to take into account the use of radial tires on the car during his pre-project planning.
“The type and size of tire do make a difference in how we approach a build, along with the engine package that will be used, so that we know where to place everything in the chassis. For the rear of the car we used the typical brackets you would see in a big-tire car that’s making a lot of power…there’s nothing really different there. Now, how we set up this car is going to be very different from the big-tire car since it will be on radials. Radial-tire cars obviously don’t use wheelie bars, so that needs to be taken into account with how the car is built and setup,” Keith explains.
To create the right suspension Keith uses his design to get the front struts in the exact location he wants. The custom 4-link rear suspension is attached to a Skinny Kid-built full floater rear-end that uses a Strange Engineering 9.5 billet center section to house the 40-spline Strange axles. To round out the rear suspension, Skinny Kid built a wishbone, anti-roll bar, and shock mounts that hold the Menscer Motorsports shocks in place.
Advancing the design of a chassis that’s specific for radial tire racing has been a contributing factor to the barrage of record-setting passes. This comes from chassis builders like Engling continually trying new things so data can be acquired, analyzed, and then used to improve a car’s design. One of the biggest things chassis builders have learned is that where you place the engine in the chassis is key when radial tires are used.
“With how things have continued to progress in the radial world we’ve tried to lower the crank centerline in the chassis while moving the engine as far forward as we can. We’re also placing the engines lower in the car, since that will help control it wanting to wheelstand. With a car like Ken Quartuccio’s Corvette, we had over 200-pounds of weight in the front — if the engine could have been moved further forward that wouldn’t have been necessary at all. The goal is to keep the car off the traction control or wheelie control because all that does is slow the car down. If we can make the car go down the track without using the traction and wheelie control it will be a lot quicker, since the ECU won’t be pulling power to avoid it going up on the bumper,” Keith says.
The radial car separates in the back instead of squatting like a slick tire car, so the tub actually goes higher because of how the chassis is set up, tub clearance is never an issue on a radial tire car. – Keith Engling
Using the correct braking system is vital when you have a car capable of running low 4-second passes at 200 mph in the 1/8-mile. To provide the highest level of braking possible, a full stable of Strange Engineering parts was added to BlownZ28. The front brakes consist of a Strange Pro Series II spindle-mount kit designed for struts. These brakes work specifically with a one-piece billet or forged wheel. A single-piston billet aluminum caliper uses a set of carbon-fiber brake pads to squeeze the carbon-fiber rotor and bring the car to a stop after each pass.
In the rear, a 40-spline floater kit that includes the Pro Carbon brake kit was added to strengthen BlownZ28’s ability to stop. The 40-spline floater kit was needed because of the Skinny Kid-built full floater rear end and it provides a robust mounting point for the brakes. Strange Engineering uses a set of 11-inch carbon-fiber rotors with its Pro Carbon brake kit to provide plenty of stopping power. A billet aluminum four-piston caliper is attached to the aluminum mounting plates to hold the carbon brake pads in place.
Reducing unsprung weight is one way to gain a performance advantage and is a requirement for a build of BlownZ28’s caliber. You can accomplish this by using a high-quality wheel package that’s both light and strong. To make this happen, BlownZ28 will ride on a set of spindle-mount RC Components 15x 3.5-inch Hammer-S front wheels. For rear wheels, a set of 15×13 Hammer-S units with the double-bead-lock option will be used. These wheels will be outfitted with a set of Mickey Thompson 275 Pro drag radial tires. You can learn more about this wheel package in a previous article right here.
Getting the chassis built is only part one part of the process — getting the body mounted properly is just as important as the tubes beneath it. How the body sits on the chassis is significant, so great care must be taken in making sure everything is done correctly. With a car that is going to be running on drag radials, body location is much different than race cars that use slicks.
“We put the bodies as low as we can and with the radial cars. These bodies can be mounted even lower because we don’t have to deal with wheel tubs for big tires that cause clearance issues. The radial tire doesn’t grow as much as a slick and it’s a shorter tire, so we don’t need the wheel tubs to be very high in the car. That allows the body to have even fewer modifications done to it; because if you look at my Pro Mod, for example, it has that large wing on the back because the tubs for the big tires need space,” Keith explains.
After the body was positioned and secured to the chassis it was time to add some windows to BlownZ28. A full set of Optic Armor windows were added to the Camaro to seal it up. The Optic Armor windows are made from an optical grade polycarbonate material that’s nearly shatterproof. Besides adding an extra layer of safety to the car, the Optic Armor windows also provide a substantial amount of weight savings over standard glass. And, they’re impressively clear.
There’s a lot of custom work that goes into a build like BlownZ28 to ensure everything fits correctly. Keith explained what went into making the windows and other body panels fit correctly during the installation process.
“With the body on a car like this, we go through and re-flange all of the windows for the lexan. This is done so when they’re fastened to the car and the doors are shut everything is flush with the body. We cut off all of the drip rails and gutters that run along the body so they have a 1/8-inch lip as part of the re-flanging process. When we add the windshield it will be totally flush with the roof. The same thing with the deckled and other panels — they all sit flush with the body because all of the factory support material has been removed.”
As you can see, Skinny Kid Race Cars has really been working hard on making BlownZ28 a killer Limited Drag Radial machine. In the next installment of our series, we will show you what went into finishing the car up, including the fuel system, plumbing, safety equipment, and other items. To follow all of the progress on the different parts of BlownZ28 make sure to check out the project page right here.