If there is one universal truth, it’s that every serious gearhead has had the same dream; to build a car, from scratch, by hand, in their garage. It could be for drag racing, autocross, a street car, or in the case of Don Stellhorn, a race car to tackle road courses. Instead of taking the easier route and buying a late-model sports car like a Corvette, Porsche, or BMW as his starting point, he chose a classic American muscle car to put them in their place on the track. This is not a show car, this 1964 GTO race car is a homebuilt corner carver.
The Stellhorn household is no stranger to the early GTO and its street-performance image. Don’s dad was one of roughly 32,000 Americans that bought the brand-new GTO in 1964. Then from 1965 to 1967 threw it around the corners at local time trials and gymkhana events. Even when the GTO was replaced with a 1968 427 Corvette for track duty, the GTO was still used to flat-tow the Corvette to and from the races and handle daily family tasks. When Don was born, his first car ride was being driven home in the family GTO. The family 1964 GTO was eventually sold, but Don’s dad continued racing and wrenching. Don became the official tool fetcher when he was five years old and started working on cars with him at the age of six.
In a sea of modern performance cars at the track, this ruby-red 1964 GTO grabs everyone’s attention.
While everyone loves straight-line speed, Don never really got hooked into drag racing. He felt that the big wait in the pits and staging lanes to make a single quarter-mile pass wasn’t worth it compared to whipping a car around a road course like his dad. The half-hour adrenaline-fueled racing session chasing down an opponent while being chased by another was much more appealing. When Don turned 15, Don’s dad started putting the bug in his ear that he should get his first project car. After six months of hunting, Don finally found his first car for an affordable $1,100 — a 1964 Pontiac GTO.
Don’s GTO was no showpiece, it was a project car that needed work. The body was beat up, but the non-original Pontiac 400 was at least road-worthy. Don’s dad helped him bring it back to life with an acetylene torch and some homemade patch panels. The original “Cameo Ivory” white color was substituted for a dark maroon that Don sprayed himself in the driveway. It wasn’t perfect, but Don at least had a GTO he could call his own. Shortly after high school, the Goat was involved in a minor fender bender. Now it was time for Don to give his pride-and-joy an exterior makeover it deserved and desperately needed.
The GTO race car has come a long way since Don bought it at 15 years old. The overall width grew by several inches to fit the 335-wide Hoosiers.
No more bodywork in the driveway with an acetylene torch, this time Don found a professional to handle the bodywork. Once that was sorted out and Don painted it dark maroon in the driveway again, it was time to tighten up this Goat’s handling. This stage of Don’s build was limited to the budget of a typical 20-year-old. He started with lowering springs front and rear, along with polyurethane bushings in the stock control arms that he boxed himself. As the years went on, additions like 245/50/zr16 tires on 16×8 inch American Racing wheels, Koni adjustable shocks, and fatter sway bars helped this 3,500-pound muscle car feel like it was finally riding on rails.
The LS3-based 416 cubic inch V8 pushes over 650 horsepower to the tires through an Autogear 4-speed.
By the mid-’90s Stellhorn and his dad were becoming regulars at time trials and track events in the GTO. The car was still in street form but was proving to be a competitor with further improvements in weight reduction and some seat time. But unfortunately, at an event in West Virginia in 1998, Don lost brakes and went off the track. While Don escaped unscathed, the old Goat was another story. It wasn’t a complete loss, but needed to be rebuilt once more. On the long drive home that day, Don asked himself a pivotal question “Should I quit this and return the car back to a street car after I fix it? Or shoot for the moon and build a race car?”.
Should I quit this and return the car back to a street car after I fix it? Or shoot for the moon and build a race car? — Don Stellhorn
It was finally time for his GTO race car to receive the build it deserved. By now it was the late ‘90s and Don’s passion for motorsport had landed him a job at SLP. Don had never built a car from the ground up, but had a vision for his Goat. He enlisted help from one of his coworkers, Ken Guyer, who worked as a fabricator for SLP and had experience racing, building racing chassis, and designing suspension. Ken provided the knowledge and education to get Don started and SLP loaned him a frame table to build the GTO chassis. Don found a bare 1964 GTO convertible frame for a good deal in need of a little rust repair. He fixed his new foundation to the borrowed frame table, cut off all the stock suspension mounting locations and rust, and boxed the frame to make it a rigid starting point.
The brake ducting for the front Wilwoods is Don's design. It forces cool air onto the calipers as well as both inner and outer rotor surfaces.
Don started at the rear with a new Speedway Busch Series 9-inch Ford axle, ordered with full floating hubs with 1.0 degree of negative camber built in. The aluminum third member is from Strange Engineering and is filled with an Eaton Truetrac torque biasing differential and 3.25:1 gears. Don designed and fabricated the new rear suspension, which is a three-link design with a Watts link to keep the axle centered in the frame. A 7/8-inch diameter sway bar and coilovers from Aldan American with Eibach 375-pound springs keep the ass-end of this muscle car planted at the track.
For the front end, Don bought suspension simulation software that allowed him to use his home computer to figure out where all the mounting spots should go for the upper and lower control arms. This saved him time because he could simulate different designs to dial in the exact camber gain he wanted in the front suspension, instead of the hard way of trial and error in the garage. Don chose to design and fabricate his own lower control arms and pair them with AFCO 10-inch upper control arms, attached to Sweet Manufacturing spindles. Aldan American 12-inch coilovers were used up front as well, this time with Eibach 700-pound-per-inch springs and a 1-1/4-inch-diameter sway bar. Steering this GTO race car around corners is a CJR power steering box with a 12:1 ratio and a center link and tie rod end setup designed and fabricated by Don to keep bump steer to zero.
Project car pro tip: Your neighborhood HOA can’t fine you if they can’t describe the year, make, and model.
Suspension that will stick a ton-and-a-half muscle car to the pavement like glue while carving corners is all well and good, but the gains will be for nothing if it takes Don half a football field to slow down for every turn. Don turned to Wilwood brakes on all four corners. TA2 Grand National GN6R six-piston calipers are mounted in the front with 13.00 x 1.38 inch GT48 rotors. In the rear are TA2 Forged Superlite4 Radial mount four-piston calipers in the rear with 12.19 x 1.25 inch GT48 rotors. Don designed and fabricated one-off brake ducts to the front calipers and rotors. At speed on the track, cool air is forced to the inner and outer surfaces of the rotors and caliper. The race-spec brakes are hidden behind a set of CCW Classic 3-piece forged wheels measuring 17×12.5 inches front and rear with Hoosier A7 road race DOT slicks measuring 335/35R17.
Don used a wood wheel well template to help him fabricate the fender flares. After positioning the template where he wanted it, he then took strips of construction paper to connect the template to the fender to shape the flare.
Now that his GTO race car had a new rolling chassis, it was time for Don to flex his fabrication skills with the body. He didn’t build the new suspension to fit inside the stock sheet metal, he built it to perform the best on the track. This meant some serious work was needed to flare the fenders to fit rubber that’s more than a foot wide at each corner. Starting with wood as a template for how he wanted the outer wheel well to look, he then took construction paper, carefully trimmed it, and then transferred it to steel metal sheets to fill the gap.
This same process of fabricating each new body part out of metal by hand l was used throughout the car from the custom front air dam up front and side skirts to the rear spoiler and diffuser. No more paintwork in Don’s driveway, this time the finish work and paint were handled by the local Macco Auto Body using the beautiful Ruby Red metallic you see here.
Don built every piece under the hood for function, not form, but it’s still a work of art.
Don has always been adamant about his GTO race car retaining a Pontiac V8, so it hit the track once again after the redesign with a 455 cubic-inch Pontiac V8 backed by an Autogear 4-speed. But as the GTO racked up miles on the track, it became clear this was going to be a difficult conviction to uphold. The 455 suffered from a cracked head during a pre-race practice and banished Don to the pits for the weekend. It was time for the engine to also be replaced with modern track-ready tech and something a lot lighter; an LS.
Don turned to Dave Kogan of Kogan Motorsports in Island Park, NY for his next engine. Machine work started with a new 6.2-liter LS3 bare engine block from Chevrolet Performance, that has been honed with a torque plate, notched for the stroker crank, and had the oil passages radius profiled. Kogan then welded AN bungs on the external oil passages for the dry sump oiling system. It was filled with an all-Manley balanced rotating assembly consisting of forged pistons, forged 4340 steel H-beam connecting rods, and a forged 4340 steel 4.000-inch stroke crankshaft. Compression comes in at 11.5:1 and the final displacement comes to 416 cubic inches, 40 more than a stock LS3.
The stock dash is long gone. In its place is a handmade carbon fiber panel housing eleven gauges and half a dozen switches.
To match the new 416’s airflow needs, Kogan utilized a pair of Chevrolet Performance’s CNC ported LS3 heads with Manley valves and dual valve springs replacing the out-of-box components. Comp Cams custom-ground a hydraulic-roller cam to keep this stroker LS’s powerband high in the RPM range. Duration comes in at 258 degrees on the intake and 266 degrees on the exhaust at 0.050-inch with lift at 0.623-inch for both intake and exhaust and 109 degrees of lobe separation. A hydraulic roller valvetrain keeps the maintenance down and allows Don to utilize the simple-but-rugged factory GM LS3 rocker arms with Straub Technologies bronze bushing trunnion upgrade.
The simplicity follows with Don deciding against EFI and sticking to a carburetor. A Pro Systems Billet Venom VX 850 cfm carb, tuned by Don himself, tops an Edelbrock Victor Jr. intake manifold Don hand-ported to match the CNC intake runner of the heads. Don decided to stick with the factory coil-near-plug ignition system using stock GM LS9 coils, sending spark to the NGK spark plugs and controlling the timing curve with an MSD timing box. Since nobody makes an off-the-shelf pair of headers to fit an LS in Don’s custom chassis, he welded his own out of 1-3/4-inch stainless steel that was ceramic coated to keep the heat where it belongs, in the exhaust and out the side pipes.
By now it should be no surprise that Don also designed and fabricated the roll cage and interior sheet metal on the GTO.
The all-aluminum 416-cubic inch LS small-block fits well between the frame rails, no surprise since it was once home to a monster iron Pontiac V8. The LS’s smaller size allowed Don to mount it behind the centerline of the front wheels and run an Aviaid three-stage dry-sump oiling system and shallow metal dry-sump pan, drastically improving the Goat’s weight balance and center of gravity. The new power was a welcome improvement as well, making 652 horsepower and 529 pound-feet of torque with a 7,000 rpm redline. That power is transferred to an Autogear M23X 4-speed through a 10.5-inch Spec Stage-5 clutch with a solid hub, a lightened pressure plate, and an aluminum flywheel. Don has been running this setup for the past several racing seasons without issue. His current personal best lap time is 1:12.0 flat on the Lightning Circuit at the New Jersey Motorsports Park, besting modern performance cars like ZL1 Camaros, Shelby Mustangs, Corvettes, Porsches, and Ferraris.
Four 335mm wide Hoosier slicks keep the GTO planted in the corners. They’re mounted on 17×12.5 inch CCW Classic wheels.
By January 2025, Don will have owned his 1964 GTO race car for forty years. In that timeframe, he took a beat-up old Goat as a teenager and turned it into his own creation as an adult. Don believes one’s car is an expression of their personality, and he built his to reflect exactly what he believes a 1964 GTO race car should look like. In Don’s case, the genesis of American muscle cars on the outside but with modern tech under the hood and his race-spec chassis underneath.
