Lifting a Fiberglass Funny Car Body
The list of subjects covered will be vast and detailed to the degree necessary for the above average fan and simple enough for the average fan to come away with a better appreciation of the intricacies of the modern "Nitro" car.
Today's lesson focuses on the Funny Car body, its aerodynamics and special safety features.
This Special Series Gives You The Insides and Outs of Nitro Racing from the Technical Side …
Mike Kloeber is certainly one of the most talented tuners to ever crew chief a nitro car.
He began working in the nitro ranks during his teenage years, spinning the wrenches for champions such as Gary Beck, Jeb Allen and the Candies-Hughes team, just to name a few.
Kloeber earned his first crew chief job in 1986 when the legendary Don "Snake" Prudhomme hired him away from Tom "Mongoose" McEwen.
He took a break from racing in 1990 to pursue an education in aeronautical engineering and was content to pursue a job in another field until he assisted Len Seroka in returning to Top Fuel.
The sport might have been on the sidelines for Kloeber, but a few trips to the track provided all the proof that he needed to confirm the passion still burned in his heart for drag racing.
Kloeber joined on with Jim Epler and tuned his Funny Car to the sport's first 300-mph Funny Car run.
Of all the accolades he gained along the way, few could compare with the six IHRA Top Fuel world championships he earned alongside of Clay Millican, a driver with whom he tuned from his first ride in 1999 up until 2007.
He's since enjoyed stints with Bob Tasca III and Kenny Bernstein Racing.
Kloeber accepts his latest drag racing role, an opportunity which provides the challenge of educating the above average drag racing fan with the intricacy involved in maintaining and tuning a Top Fuel dragster.
UNIVERSITY SYLLABUS
The purpose of this series is to bring a fuller understanding of the major components of Top Fuel Dragsters and Funny Cars with an insider's perspective. We will touch on many items in detail and how the components and various systems are interrelated along with a few side notes and an occasional story along the way.
The list of subjects covered will be vast and detailed to the degree necessary for the above average fan and simple enough for the average fan to come away with a better appreciation of the intricacies of the modern "Nitro" car.
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GETTING STARTED –FUNNY CAR BODIES
The current body on a Funny Car is a highly evolved and specialized product. Generations of style changes and the progression of aerodynamics from the original manufacturers have resulted in today's modern Funny Car. Most of the cosmetic changes to the grill, hood, windshield, roof and rear deck area are a function of aerodynamic demands. The whole body is designed to act as one big aerodynamic device.
THE BIRTH OF A BODY
Back in the day the body manufacturers would rent a production car and take a splash from the rental and graft it to an existing body or pieced together to make a complete new body. Many new bodies have used previous and sometimes different brand parts as a starting point. They would do something along the lines of using the sides of a Dodge Daytona to make a new Oldsmobile body etc. An incredible amount of bondo body filler was used to get the final shape. Back then everything was done by hand. There was lots of dust, trimming, shaving, shaping and elbow grease.
Today's bodies are very high tech. Original mold shapes are cut on large CNC controlled routers. The complete model information is programmed to the router and the design shape is much more accurate today compared to 20 years ago. In the old days when you would mount a body you could cut and fit a tube for one side and go to use the same length tube on the opposite side and it might be 2 inches too long or too short. The bodies are very symmetrical today.
Despite a dramatic increase in surface area from 20 years ago the bodies have remained at nearly the same weight out of the mold, about 100 lbs. I remember picking up a Plymouth Arrow body from G&K fiberglass for a new car Pat Foster was building for the Super Shops FC that he drove and was later driven by Ed McCulloch. It weighed 97 lbs bare. The integrity of the modern body is astounding. The old pure fiberglass body's had to be set on barrels or they would flop over to one side and break or crack because the sides and rocker panels didn't have enough strength to support the weight of the body. Now you can stand on the hood when you get them bare.
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Fiberglass: A glass fiber reinforced plastic similar to carbon-fiber, but with much lower strength and stiffness, but also much lower cost.
Carbon Fiber:
A high strength, high stiffness material that when combined with a resin matrix creates a composite with exceptional mechanical properties.Prepreg:
A material impregnated with resin at a production facility, rolled on spools, and frozen to prevent the resin from curing prematurely.Aramid Fiber:
A synthetic fiber with exceptional strength and toughness commonly used in applications where high resistance to impacts is required. Typically we know this as Kevlar™Epoxy: A polymer resin that hardens when combined with a catalyst. Epoxy is one of the most common materials used to form the matrix in carbon-fiber fabrication.
Autoclave:
A pressurized vessel used to process parts and materials which require exposure to elevated temperatures to cure while under pressure.Composite Sandwich Core:
In a composite sandwich structure, the core is a lower density material placed close to the neutral axis in order to increase the stiffness to weight ratio.Polyacrylonitrile (PAN):
A raw material commonly used to make carbon fiber.Modulus of Elasticity:
A measure of the stiffness of a material, defined as the axial stress divided by the axial strain. The higher the modulus, the stiffer the material (i.e. the greater the stress necessary to cause deformation). Also known as Young's Modulus.Ultimate Tensile Strength:
The maximum stress a material can withstand in tension, above which failure will occur.Yield Strength:
The stress above which a material with remain permanently deformed even when the applied load is removed. MATERIALS THE BODY IS MADE FROM
In the 1970's the bodies were primarily made from fiberglass which is a polyester material. In the mid to late 1980's the bodies were reinforced with Carbon fiber to stiffen the sides that often buckled at high speed. Up to this point all the bodies were wet lay-up with some coring. By the latter part of the 1980's Harry West (Hairy Glass) was using better coring material epoxy resins, more carbon fiber and a vacuum bag system. Harry West was the guy who brought the Funny Car bodies out of the dark ages. Harry was even using Kevlar in critical areas before many people even knew that Kevlar was. The first body that was vacuum bagged was a Ford Thunderbird Mark Oswald drove for Candies & Hughes.
Today's Funny Car bodies employ the same technology as a state of the art military aircraft. Utilizing a high temperature prepreg carbon fiber and Kevlar composite, cored with Nomex honeycomb material. The body is cured in an autoclave allowing exact process control to achieve the greatest strength to weight ratio. The prepreg carbon used today has a high temperature resin that helps to make the body more difficult to combust when exposed to an engine fire or explosion. To give an example of how strong today's carbon fiber is, the highest modulus carbon fiber has a tensile modulus of 72 to 145 million psi and a lower end carbon would have 25 million psi. Steel has about 29 million psi. This also translates into increased stiffness. On the high end carbon fiber is more than 3 times stiffer and 10 times stronger than steel.
Carbon fibers were first developed in the 1950s as reinforcement for high-temperature molded plastic components on missiles. The first fibers were manufactured by heating strands of rayon until they carbonized. This process contained only about 20% carbon and had low strength and stiffness properties. In the early 1960s, the process was improved by using Polyacrylonitrile (PAN) as a raw material. This produced a carbon fiber that contained about 55% carbon and had much better properties. The PAN process has become the primary method for producing carbon fibers.
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Metalcrafters in California produces the Mustang and the Dodge Charger; Roush Advanced Composites in Michigan has been making the GM bodies and Harry West (Hairy Glass) in Florida produced most of the body's over a 10 year period prior to the autoclaved bodies.
AERO AND ITS ROLE IN PERFORMANCE
Starting at the nose, the first aerodynamic device is the body latch. The body latch's function other than what it's named for is to let air into the hole inside the beveled venturi shape. The latch is intended to allow the vent in the fuel tank to be vented outside of the body. This is more of a safety feature than an attempt to pressurize the tank. When the engine is hurt really bad and a fire ensues the little bit of fuel or fumes coming out of the forward facing vent can draw the fire into the tank and then you have real problems. I tried to use this kind of vent on the Rug Doctor Funny Car and I was told it was illegal and it had to go. I shouldn't have asked tech and just run it. Thankfully Austin Coil wanted to do the same thing years later and the vented body latch became common. We will never know how many tank explosions have been prevented. Austin Coil has made many contributions to Funny Car racing and has my complete respect for his unequaled accomplishments.
The basics of the Funny Car body start with the broad grill and front fascia. This is a wide vs. narrow arrangement facilitates the necessary front down force to make the car balanced enough to steer. There is a constant battle to keep a Funny Car in the groove. As you have seen from in-car camera footage a Funny Car requires a considerable amount of steering input. To successfully drive a Funny Car the driver needs to have a nearly psychic ability to know where the car is trying to go before it starts in that direction. If the driver is the least little bit late in steering response the car gets out of the groove and typically starts spinning the tires which compounds the difficulty in getting the car back in the groove. Changing the Gurney lips on the front fenders and nose weight are the only tools you have to adjust the front down force. One of the latest changes to the current Funny Car is in the body mounting technique that allows the nose to drop to the track at high speeds. By dropping the nose the car decreases the amount of air that can get under the car. When you decrease underbody flow the under side becomes less important and the flow of air tends to move around the car where it can be better directed.
The entire aim is to have as much air flow toward the rear deck and spoiler as possible. To get more air to the rear of the body the roofs have become smaller and narrower and the top of the roof has become taller in order to make the spoiler taller as well. Limits are placed in the maximum roof height and the spoiler as well. The area under the window sill has been maximized in width to keep air on the top of the body where it can be used to make down force and increase the volume of air to the rear deck.
With the optimization of roof shapes and windshield angles the rear spoiler is only run in the maximum downforce position in the worst of track and atmospheric conditions. Up to the later part of the 90's you ran the spoiler maxed out. As the roof shape and placement evolved the Funny Car teams were able to start to take some spoiler out to lower the drag and utilize the horsepower to make the car run faster at the top end.
The inner guide vanes or inner fences are a prominent part of the design that will be different and specific to each brand of body. The differences are small but optimizing the fence location is part of the total downforce.
FUNNY CAR DOWNFORCE
How much downforce does a Funny Car make? In a high downforce rear spoiler position the total downforce would be just over 11,000 lbs excluding the exhaust forces. I estimate the exhaust force to be just less than 2000 lbs. The HP drag or the amount of HP required to overcome the drag is in excess of 3000 HP. An interesting fact is the Funny Car and Top Fuel cars are relatively close in the total down force numbers.
BODY COMPARISON
To the bottom are the four different bodies used today. If they weren't so identifiable by the paint schemes could you tell which one was a Chevy, Dodge, Ford or Toyota? That's why they call them Funny Cars. If we put a real wing on the back and did a little work to the underside they might give a dragster a run for their money even with a weight disadvantage.
As you can see there not much difference between the bodies of today's Funny Car racing.
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INGENIUS ADDITIONS
Fire hole window treatment
The lip around the entire body is to keep air from getting under the body. Header cut outs are there with approach ramps to add downforce wherever possible. Window fire holes have a leading edge treatment and the trailing edge that is turned in to discourage air from going into the cockpit while maintaining access to the driver with a fire hose. Fender lips (a form of Gurney flap) add down force to the nose and make the car more drivable without adding ballast or taking rear spoiler out. Trailing edge fender rolls are a treatment that discourages air from entering the underbody from behind both the front and rear tires. Typically a lip or Gurney flap will be at the front of the injector opening to discourage air from entering the underbody area. By now you should have recognized a trend in preventing air from getting under the body. A lip in the front of the injector can add as much as 100 lb. of downforce with almost no drag penalty. Any one of these small additions by themselves doesn't add up to much but when you combine all of them you get a total worth paying attention to.
Front fender Gurney flap
Rolled in rear wheel opening
THE FUTURE FUNNY CAR BODY
Likely the most important addition has been the roof escape hatch. The roof hatch has saved many a drivers butt. It also serves as a great place to have a pop-up sign when the cars back up from the burnout. My all time favorite one was on KC. Spurlock's car, it said something to the effect of KC and Ron's "Too much fun club." They put that there for a good reason.
With a little luck we won't ever see the homogenization of the Funny Car body. They are all similar enough now. In the interest of cost cutting and rules making the likelihood of a single Funny Car body may come some day. I prefer the days of creativity when Pulde ran the Buick Regal body with a stock looking nose with a square back window and Bernstein was running the Ford Tempo and Don Prudhomme was running the Pontiac Trans Am. All three cars were competitive with entirely different appearance while still maintaining brand awareness. This current trend unfortunately is reflected in the production vehicles we see on the street. Today you can barely tell a Chevy Malibu from a Toyota Camry.
Source: http://www.competitionplus.com/featured-stories/9831-mike-kloebers-nitro-university-course-3-the-funny-car-body
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