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The revolutionary Pro Stock ThunderBird Program


Pro Stock T-Bird

This series will show many firsts again. The T Bird Pro Stock that I designed in 1982-3 was responsible for my un-retirement of sorts. Having been through 2 years of chemotherapy, I was somewhat pleased with my job at General Dynamics. I was working in propulsion and the number of shapes that we were playing were the same, or less efficient than those I'd developed for heads and manifold runners over the years. Keep in mind that ENDYN was still cranking away and my sole reason for taking a breather was because my doctors felt that ENDYN's "environment" and long hours could have contributed to my cancer.

One day, an acquaintance asked me if I'd ever consider building another Pro Stock car again. After a brief moment of thought, I felt that I deserved to do something for "me" again, and the project was born. This is also where I decided to do what I wanted again, doctors or not.

After all the years racing and watching customers, I had some different ideas regarding "how" I'd reenter the sport's most difficult class. The "normal" amount of between-round thrashing wasn't for me, but sitting in a comfortable chair drinking tea while waiting for the next round was an appealing thought.

In order to achieve that end, running a conventional Pro Stocker was decidedly not going to cut it. A complete rethink of the ingredients was necessary and ultimately, every component produced (including the low revving engine) was quite unlike anything ever created for the class, before or since. To use Mark Donahue's words, we needed an "unfair advantage." The following is a brief attempt to touch on a few of our "interpretations" of how a Pro Stock car should be built.

Having been long associated with Ford, the new 83 T Bird looked like a pretty good starting place to me. Ford sent me lines drawings for the new car and the project began in full. I built a wind tunnel that had a rolling floor and began testing a quarter scale model that I made from the lines. The drag coefficient was not bad, but the amount of lift that the car exhibited at speed was terrible. By spoiling the lift, the drag went to pot, but worse, the car also was a lifting body whenever it was not traveling in a perfectly straight line. This may seem strange to drag racing fans, but Pro Stock cars travel a lot of the track at small slip angles and if the car really got loose, it could present it's entire side body to the airflow, with disastrous results.

The first project at hand was to make it harder for the air to pass over the sides of the car. From the roof back, some 1/8th inch welding rod swept into the "side to trunk" intersect cause so much turbulence that there was no longer negative pressure present and the car staid stuck. The best part was that nobody could see the change and we shared it with some select NASCAR teams with no fear of detection by inspectors.

In order to lower the car's drag, there were some rather dramatic engineering exercises necessary that had never been applied to a full bodied drag car before. I made the decision that we'd try to take advantage of the air rather than fight it. The goal was to create efficient ground effects by encouraging air to travel under the car, instead of up and over the body.

The first thing to go was the chin spoiler that was on all T Birds. This was relatively easy to do. The design and construction of tunnels under each side of the car with skirts preventing air from bleeding to the driveshaft tunnel consumed a lot of model testing and real world ingenuity, especially since aero devices under the car were prohibited by the rules.

More testing revealed where we should locate the venturi sections for optimum aero-loaded weight distribution. To complete the venturi shapes, the air was channeled between the rear tires and into the "air chute" at the rear of the car. Aside from simply rerouting the air, we were able to prevent the rear slicks from running over air at the rear as well. Eventually we even filled the "voids" in the front of the 9" third member with lightweight epoxy and micro-balloons to ease the flow around the rear end.

The rules didn't permit cutting the rear bumper area on the car, unless it was done for wheelie bar clearance. Since we needed the area for the air chute exit, I designed the wheelie bars to be long enough to require the surgery.

Building the real "thing" consumed about 4 months of continuous work, but keep in mind that the finished piece was the result of months of tunnel time and we also built several full-scale "models" to insure that the package was workable.Since we'd defined the optimum aero-envelope, the engine and chassis also had to fit inside the shape, or we'd have achieved nothing, and this was also a primary reason for the full-scale mock-ups.

When tested in the real world, our aero expectations were more than met and there were no spoilers. At 60 mph the car had increased from 2350 lbs to 3100 lbs, at 100 mph the weight was 3350, at 160 mph the weight was 3850, and at 195 mph we peaked at 4800 lbs, while maintaining a constant aero induced 38/62 weight distribution. This placed the cg directly under the driver's ass and we actually put the bottom of the seat lower than the floor in the car, making it a "legal" part of the venturi tunnel.

To make the car as efficient as possible, I took some liberties with the rules, especially the ones regarding sectioning the body. Some of the illegal body alterations included removal of 1.5" in body width, beginning with none in the rear, and tapering to the inch and a half at the nose. This required sectioning a long pie shaped piece from the top surfaces of the car. The doors were sectioned to yield a straight line intersect between the rockers (outside skirts) and the spoilerless nose piece.

The wheel wells were "moved" on all corners and reshaped considerably. The front of the forward wheel wells was designed to help "influence" the air to attach to the sides of the car behind the wheel well and simultaneously bleed some air into the well's trailing edges to provide more air for work in the tunnels under the car.

At the rear similar treatment was performed with some outside air used to help blow the boundaries (act as fences) for the air exiting the rear chute section. There were only a few body templates to meet in those days and my old saying "If you change something, change everything else and the templates will fit" worked to perfection. In order to help with some of the visual effects, we used 10 or 12 shades of white to make "small areas" look larger and "large areas" look smaller. Out optical illusions worked to perfection, as nobody ever mentioned any funny looking areas of the car.


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The Envelope - The cf. fenders, doors, and deck lid with the Ford roof and rear quarters. Sectioned everywhere and totally illegal, but it could pass the templates.


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The Air Chute - some pics showing some of the elaborate tin work to create the rear exit for the tunneled air.


Once the aero envelope was finalized, the next part involved was to design the chassis. The engineering goals were quite different from other cars of the day, and I've not seen anything yet that is as functionally efficient. The goals were to builds a chassis that could fit within the confines of the body's envelope, and to provide maximum driver safety. Other design criteria were: rigidity to prevent to prevent the chassis from becoming another "suspension member", prevention of tire shake harmonics, and creation of a package that would possess a relatively low polar moment, which would help the driver recover should the rear get out of shape. After considerable study, the last chassis that I'd designed for the BOSS back in the early seventies looked to be the answer. The asymmetric pyramid chassis was born again. Aside from the compact size, the most obvious feature is that the roll cage only encloses the driver. Keep in mind that the "add-on funny car cage" didn't exist and shrinking the cage provided much greater driver protection, as well as a stronger, lighter chassis. You couldn't take a passenger for a ride, so why protect the empty seat that the rules required? (It attached outside the chassis on the right.) The number of attach points made the engine a stressed member supporting the front end. The trans mounting was designed to make sliding the assembly rearward for clutch access a breeze, and the struts that supported the body work on the "passenger side" were designed to deform and bend in a manner that would prevent them from spearing the driver in an accident. It's safe to say that there was a reason for every inch of the project. My fabricators grew to hate me more than usual because I made them build samples from a couple drawings along with a lot of verbal instructions. They built eight "scale" chassis before they finally demonstrated that they really understood the concept. To my way of thinking, it's essential that whoever's is building anything, must be able to close their eyes and "see" the finished product and have full understanding "why" they're doing this and that.


tiny-unappreciated_education_1.jpg (3510 bytes) Unappreciated Education - the last (final) scale chassis by my fabricators.
tiny-unappreciated_education_2.jpg (3668 bytes) Unappreciated Education - another view.

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Laying Pipes - few shots of early chassis in preparation.


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The Little Monster - The name given the car once on all four. This is not your average Pro Stock chassis.


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The Bad Guy - 498 cid killer super swirl BOSS engine. It got good mileage, and only weighted 420 lbs.


Once complete, I took the car to the NHRA World Finals in fall of 1984. It survived tremendous scrutiny and passed the tech rather easily, with one official from Ford saying that it was the first drag racing car that looked as if someone had actually spent time thinking about prior to building. We loaded and headed home, confidant of our futures.

The reason for no decals was simply that I'd asked no free parts and I'd been given no parts, and I had decided that the aftermarket could pay me before I put the "stickers" on, rather than the other way around. If they didn't pay, I'd let them all advertise that their parts were on the "runner-up" for a while, they'd come running for sure.

We ran the car on three occasions. The first time out, the car sucked down so hard at the eighth mile that it bottomed the rocker panels and inner skirts on the track. It also did minor damage to the rear wheel tubs. We built some solenoid activated suspension snubbers and returned the following week to pound out a 7.33 at the astounding speed of 190 mph - one mph less than my projected target. The following week we made some fuel system changes (the tank vent needed to be 5/8" in diameter)!! The result was a 7.17 at 195 and change. It took the top of the class almost ten years to duplicate that performance.

The demand for our heads and other products caused me to make a decision regarding running the car or "running racing" and the later was the choice. We sold all the engines to "Uncle Bob" Glidden and dug in to create controversy with out swirl technology.

The car was cut apart and destroyed. As the program had been one of those rarities, where you could honestly look at the final product of your hard work and say "If I build another, I won't change a thing", and that doesn't happen often in life. This was also an instance where I wasn't anxious to have others copy the designs and the notion of sitting back and watching "progress" was appealing. They still haven't caught up yet.

- Larry Widmer


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The Last Gasp - the final time the engine would be in place.


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The Last Picture Show - last pictures before meeting the metal cutting chain saws.


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The revolutionary Pro Stock ThunderBird Program