Honda Insight Dragcar

The gasoline-electric hybrid Honda Insight is one of the cleanest burning, most fuel-efficient production vehicles on the planet. The fact that more than 66 mpg can be squeezed out of it on the highway doesn't hurt. Why else would anyone want to putt around in something that musters little more power than a lawn tractor? And since it might even emit less of those pesky hydrocarbons than the lawn tractor, earth lovers can rest easy.

We're interested in the Insight for altogether different reasons. We asked 2003 IDRC All-Motor champ, 'Bisi Ezerioha, why he's building one, and the answer has nothing to do with fuel economy or saving the ozone layer.

WhoIf you're familiar with sport compact drag racing, then it's likely you've heard Ezerioha's name mentioned. As of this writing, Ezerioha is one of only three racers to break the nine-second naturally aspirated front-wheel-drive barrier and consistently places among the top eight in races sanctioned by virtually every promoter in existence.

Having campaigned a 1988 Honda CRX HF for nearly a decade, Ezerioha's claim to fame is his 2003 IDRC Championship title. Scooting down the track at more than 135 mph, the CRX won with an e.t. of 10.02 and claimed the notoriety of being the world's quickest and fastest naturally aspirated front-wheel-drive unibody car.

Fast forward to 2005. Ezerioha is looking to retire the CRX in hopes of stepping up his game with something entirely new.

WhyThe goal for Project Insight is straightforward: 'Bisi and his team are building a naturally aspirated class drag car, legal for competition in all of the major sanctioning bodies. It's currently scheduled to be finished in time for 2005 preseason testing. And we're following along.

This series of stories will be a fundamental guide on what it takes to build a chassis and engine for the All-Motor Class. Though Ezerioha is not one to make predictions, we're expecting the Insight to surpass the CRX in every way.

HowWhen selecting a vehicle destined for the dragstrip, there are two givens. First, the chassis must have minimal aerodynamic drag. And second, it needs to be light. The Insight is both. With a gasoline-electric hybrid vehicle producing less than 70 hp, it's a must for Honda engineers to develop alternate ways for this micro-machine to muster some get-up-and-go.

The solution is to allow it to slip through the air and to be as light as a feather. With superior aerodynamics and light weight, the Insight will require less energy to accomplish the same amount of work. In other words, it can keep up with cars making significantly more power, thanks to its efficient shape and weight. Aware of the requirements, Ezerioha put his analytical skills to work in his quest for the ultimate straight-line chassis.

Understanding that the Insight boasts the lowest coefficient of drag of any current production vehicle, comparison tests were made between the Insight and the CRX.

The coefficient of drag, otherwise known as Cd, refers to the specific effect a given shape will have on the airflow that's placed upon itself. A lower Cd means less drag, which means quicker acceleration. Thanks to this design characteristic, it's possible for the Insight to operate at the same speed as the CRX with 32 percent less power under the hood. Even more aero advantages are realized upon inspection of the underside of the chassis.

In order to minimize air leakage to the underbody, the lower sides and rear of the body form a strake that functions as an air dam. As the floor pan rises toward the rear, it creates a gradual increase in underbody area that smoothly feeds air into the low-pressure section at the rear. Additionally, the rear roofline is tapered downward, creating the optimal teardrop shape necessary for minimal aerodynamic drag.

The Insight's lightweight characteristics are accomplished by utilizing an aluminum and magnesium alloy construction that weighs 1/3 less than the steel equivalent. The chassis is reinforced by utilizing stamped aluminum panels that are welded throughout the vehicle to ensure its rigidity. In comparison to the CRX, the Insight has more bending strength and more torsional rigidity, yet is 40 percent lighter.

The ChassisThe roll cage and chassis guidelines follow the NHRA General and All-Motor Class regulations. Besides making it NHRA legal, the foremost priority in the construction of the Insight chassis is also making it as safe and as rigid as possible, all the while keeping the weight to a bare minimum.

To ensure an ideal strength-to-weight ratio, 4130 chrome-moly tubing was used in lieu of mild steel. By using chrome-moly, 'Bisi's team was able to take advantage of a material with a wall thickness that's only .083 inches, as opposed to the .118-inch requirement of mild steel. Same amount of tubing, less weight.

After the hybrid was purchased from a wrecking yard, it was stripped and hauled to Steen Chassis in Signal Hill, Calif., where a 10-point roll cage was fitted, along with a steering column, a solid rear axle, wheelie bars, front wheel tubs and engine/drivetrain mounts.

Working with an aluminum chassis is tricky. Aluminum is light; generally, that's a good thing, but in this case, there's a downside. Since most dissimilar metals cannot be welded together, an alternative method of attaching the chrome-moly roll cage to the aluminum chassis was in order.

Traditionally, the mounting points of the roll cage must mate to the chassis using 6-inch square by .125-inch thick steel plates affixed to each post. That's 10 plates total. These plates are welded to the bottom of each post and then either welded or bolted to the chassis.

When bolting them to the chassis, a plate is also required on the underside. Since they can't be welded to the chassis because of dissimilar metals, the only choice is to either bolt in the cage or come up with another solution. Merely bolting the cage won't be as safe or as rigid as everyone would like.

Owner and head fabricator Gary Steen and son Jason, of Steen Chassis, came up with a solid plan for mating the cage to the chassis. Rather than bolting it in, a chrome-moly subframe that ties everything together was built inside the vehicle. The aluminum chassis bolts to this subframe, but first the roll cage and suspension mounting components are welded directly to it.

Adding a subframe added some extra pounds, but it also allowed weight loss in other places. Smaller diameter tubing is employed in the rear and all 20 mounting plates are no longer required.

Aside from building an entire tube frame chassis and sticking the body panels onto it, this is the best solution for a car that will most likely be shooting down the strip in excess of 140 mph. Think of it as assembling an Insight shell around a cage rather than assembling a cage inside of an Insight.

Main Hoop And SubframeFirst on the agenda was to construct the subframe, starting with the rearmost portion. The first tube serves as the rear of the subframe and as the bottom of the main hoop assembly. The minimum requirements for the subframe tubing are 1.625x.083 inches when using chrome-moly alloy.

The main hoop went in next and was constructed of the same material as the subframe. The main hoop is the upside down, U-shaped portion of the cage that attached to the floor, directly behind the driver's seat. It also serves as the central mounting point for the rest of the cage.

Vertically, measurements were taken so the roofline section of the hoop is a minimum of 3 inches above the driver's helmet. Measurements need to be taken of the width so the hoop's uprights were within 1 inch of the chassis. Next, the main hoop was bent, cut to length and notched. A hydraulic tubing bender was needed for this process as well as some sort of tubing notcher.

The hoop was positioned into the car, a maximum of 6 inches behind the rear of the driver's helmet location, set onto the rear subframe tube and tack welded in place. Positioning the main hoop on the subframe eliminates the need for any plates.

To comply with NHRA rules, the builders had to know exactly where the seat would be placed prior to welding the main hoop. Steen constructed a seat bracket that's welded directly to the subframe prior to installing the main hoop. Alternative methods for positioning the main hoop are allowed, but additional tubing is required, which means more weight.

Per NHRA regulations, a cross bar must also be placed within the main hoop, spanning perpendicular to and connecting both uprights. Smaller, 1.250x.058-inch chrome-moly tubing was used here. This bar was installed at the maximum of 4 inches below the driver's shoulders and was used to attach the seat and safety harness brackets.

With the main hoop complete, it was a good time to remove it from the chassis and complete the welding. According to the NHRA rulebook, the heliarc TIG-welding process is required when working with chrome-moly. The MIG-welding process is only permitted when working with mild steel. NHRA rules also state that grinding the welds is prohibited, and that all welds must be free of slag and porosity.

Once the main hoop was permanently placed back into the chassis, the subframe was completed. Three additional sections of tubing were laid on the floor, forming a box shape when attached to the rear subframe tube.

In Front Of The Main HoopSteen tackled the halo bar next, followed by the A-pillars and the dash bar. The halo tube is the section of the cage directly above the driver's head, in front of the main hoop and encompassing the perimeter of the roofline.

Next, the A-pillar tubes were sized, bent, notched and tacked in as well. These bars connect the front of the halo tube to the front section of the subframe, one on each side. Both the halo tube and the A-pillars must be the same diameter and thickness as the main hoop.

Alternatively, the A-pillar tubes can span from the subframe all the way up to the main hoop, following the roofline. In that case, a transverse bar is required, just below the roofline, near the top of the windshield.

A transverse dash bar is not mandatory unless the firewall is altered. But, in this case, its addition tied the front of the cage together and allowed a place to mount the steering column. Smaller diameter tubing of 1.25 inches was required here. The steering column was constructed of 1.25-inch tubing and was attached to the dash bar with two 1-inch diameter tubes. A quick-release steering adaptor was also welded into place.

The new column attached to the original steering joint, near the firewall, inside the vehicle. In order to position the steering wheel further toward the rear of the car, Steen used a lengthier column.

The diagonal side bars, which run alongside the doors spanning between the A-pillar tube and the main hoop, were fitted next. The driver's side bar must pass the driver at a point midway between his or her shoulder and elbow. If only one bar is being used on each side, the standard 1.625-inch tubing is mandatory.

Behind The Main HoopBehind the main hoop, 1.375-inch tubing was used. Depending on the diameter of tubing, the number of tubes required by NHRA differs. When using this smaller diameter tubing, there is a minimum requirement of four bars spanning from the main hoop and connecting to the rear of the chassis. This structure will later house wheelie bar mounts and a parachute.

Under The HoodThe rules are lenient under the hood so tubing diameters and mounting points vary between classes. The frame kickers, also known as the down bars, were built from 1.25-inch tubing. These tubes span from the front dash bar, through the firewall, into the upper strut mounts and terminate into the front crossmember. First, a front crossmember would be fabricated and bolted into place.

After taking critical engine and transmission measurements to ensure clearance, 1.25-inch diameter tubing was cut and placed across the front of the chassis. There's nothing to weld in the engine compartment, so Steen fabricated a bolt-on crossmember.

With the roll cage complete, we'll take a closer look at the Insight's suspension, engine and transmission next time.