Bob Sirna is automotive enthusiasm personified. A Notre Dame grad, mechanical engineer, and award-winning designer from Rochester, Michigan, he started at Ford Design, switched to IBM, and then started an IT staffing company. He’s been car crazy his entire life.
Sirna, now 77, has owned two Mercedes-Benz 300SL Gullwing coupes and three 300SL roadsters. He is a past president of the Gullwing Group International. He completed a recreation of the W194 roadster that Mercedes factory team driver John Fitch drove in the 1952 Carrera Panamericana, then raced it with Fitch at Lime Rock and at the Goodwood Festival Of Speed in 2000. A few years ago, he restored and starting vintage racing the 1958 D-A Lubricants Kurtis/Offy that Johnny Thomson drove at the Indy 500.
He bought his silver Gullwing in 1983. He’s vintage-raced it at Laguna Seca, Seattle, Portland, San Diego, Road America, Lime Rock, and Waterford Hills, and with John Fitch at the 2002 Mille Miglia Storica (Fitch won the Mille Miglia GT class with a factory Gullwing in 1955.)
Catching salt fever
In 2001, a trip to Bonneville with Gullwing racers Lynn Yakel and Roberta Nichols Yakel gave Sirna a case of salt fever; that affliction that grabs you and won’t let go until you come back to The Great White Dyno with a race car.
Sirna made all the necessary changes to his silver Gullwing for the F/Grand Touring (three-liter engine) class at Bonneville. He took it to the salt three years in a row, 2003-2005, with Mercedes-Benz legend and Mille Miglia winner John Fitch driving. Fitch became the oldest driver, at 87, ever to challenge the place (the award-winning documentary film, A Gullwing At Twilight, recalls the Sirna/Fitch adventure at Bonneville).
During a TV interview, when Fitch was asked if, at his age, he wasn’t a bit concerned about going faster than 172 mph, he replied to the female reporter, “I’ve driven faster than that, at night, in the rain, on public roads!”
Sirna worked with Katech, Diamond Racing, Kinsler Fuel Injection, Monkey Wrench Racing, and Precision Racing Services to get the most power and reliability out of the M198 50-degeee canted inline six designed for the 1955 production cars.The last attempt at the F/GT record with the original engine came in 2013. The heavily modified single-overhead-cam, two-valve design simply couldn’t breathe deeply enough to make power at Bonneville’s 4300-foot altitude in 100-degree temperatures.
Updating for performance
To overcome the limitations, Sirna consulted with the Bonneville rules makers and found that, in GT, it’s permissible to use any Mercedes-Benz engine of 3.0 liters displacement. He acquired a 1996 Mercedes-Benz sedan, and sent its 3.0-liter DOHC 24-valve engine to Bud and Kirt Bennett at RM Motorsports in Wixom, Michigan, to be fitted into the Gullwing chassis. Then he approached Roush Competition Engines for help. After a comprehensive analysis of the Mercedes M104 sedan engine, Roush agreed to take on the project.
Roush and Sirna decided to build the Mercedes M104 inline 24-valve DOHC six with dry sump oil scavenging, 11.6:1 compression, 3.59-inch bore, 2.99-inch stroke, Diamond pistons, Carrillo rods, and a Chevy Fluid-damper on a modified Mercedes crankshaft with billet main caps. Roush also ordered special custom Comp Cams camshafts. Roush designed custom chain guides patterned after the OEM plastic guides and did their porting magic to the cylinder heads. Port electronic fuel injection, six Accel ignition coils, and a crankshaft-driven high-capacity water pump completed the package. The car carried a MoTec ECU and data logger; six exhaust O2 sensors to read each cylinder and twin O2 sensors for ECU fuel tuning.
The first engine produced 430 horsepower at 9500 rpm and 278 pound-feet of torque at 8700 rpm. A second engine was built “just in case.”
Setting records
The testing program continued at the East Coast Timing Association Ohio Mile meet in Wilmington, Ohio, in June, 2015. A shifter malfunction spun the engine to 12,000 rpm, so it went back to Roush for post-event inspection and maintenance. There was no Bonneville event in 2015 because the salt was under water.
In June of 2016, Sirna went back to The Ohio Mile with the backup engine installed in the car. It ran flawlessly, and the silver Gullwing set six records in F/GT, F/GMS, F/FMS, E/FMS, E/GMS, and D/FMS, running 160.54 in the measured mile in F/GT, the target class for Bonneville. The F/GT record was 172.974 mph, set in 2010 by Victory Motorsports from Wisconsin with a Datsun 240Z.) After years of trying and failing, the path to a Bonneville record was looking more like The Yellow Brick Road.
In July, Sirna traveled to Loring Air Force Base in Limestone, Maine, where the car set six more records, three apiece on the 1-mile and 1.5-mile courses in F/GT, E/GT, and D/GT, reaching a top speed of 190.884 mph. In August, Sirna loaded up the race car, hooked the trailer to his Chevy Suburban and headed west to Bonneville with crew chief David Decker, who runs Precision Race Services in Davisburg, Michigan. Decker had worked on GM’s Indy racing programs since the Buick V-6 turbo days, and on the factory Corvette racing effort at Le Mans.
Unexpected adventure
On the way into Laramie, Wyoming, Decker noticed the Suburban’s oil pressure gauge wobbling, and by the time they reached Laramie GM Auto Center, it was clear that the engine in the 177,000-mile Suburban had expired. But Bonneville was waiting, and a new engine would not be installed until Bonneville was over. The dealership then offered Sirna an amazing deal so he could get to the salt. For $1, he rented the dealership’s snowplow truck for the duration of the event in Utah.
It was a generous offer, except that the dealer's truck didn’t have the mounts for Sirna’s Bonneville pushbar. A call from the dealership to Big Pete’s Welding in Laramie fixed that. Sirna and Decker hooked the Chevy diesel up and headed for Bonneville.
In nearby Wendover, the crew started to assemble. Dean Johnson, a fellow Gullwing owner and mechanical engineer, came from California because he knows the car well. Earl Miller from Kinsler Fuel Injection came in from Michigan to do the final calibrations. Matt Price arrived from his MonkeyWrench Racing operation in Michigan.
Supporting them were former GM designer and Corvette racing team crewmember Randy Wittine, who did the graphics on the car and would drive the push truck; Corvette racing team veteran Les Talcott from Kentucky; and the Michigan trio of retired Ford designer Dennis Reardon, engine builder Denny Hummel, and crew physician Dr. Henry Carels.
On the salt
The Sirna Gullwing, by now so familiar to the SCTA tech crew that it was featured on the 2011 event t-shirt, breezed through tech and was readied for its first run. Fitted with a big, long NHRA Pro Stock-style hood scoop and an ice-powered engine-cooling system recommended by Roush and fabricated by RM Motorsports, Sirna’s Gullwing was truly unique.
The first run down the salt produced mixed results. The car smashed the record with a pass of 188 mph, with Sirna reporting that the salt at the five-mile mark was “like driving through slush in a Michigan winter.” But the engine, tired out after its dyno runs and all the runs in Ohio and Maine, was off-song. So the record run was aborted and it was decided to put the spare engine in the car. That's where Tall Mike enters the story.
The very first auto shop you see when entering Wendover, Utah, west of Bonneville, is the CarQuest on the south side of Business 80. Dr. Carels noticed it had a garage door on the side, and thought it might be a better place to work than out on the hot salt. He inquired within.
Mike Crawford, the 6-foot, 8-inch tall owner of the CarQuest shop, told the guys to bring the car right on in. They could stay as late and as long as they needed, he said.
Crawford comes from a family that has been in the auto parts business since 1960. The Crawfords helped the legendary Burt Munro, immortalized in the movie The World’s Fastest Indian, when he was at Bonneville.
Tall Mike owns a show-winning silver Corvette, a trick Chevy pickup, and his daily driver is a customized red big block 1966 Corvette with two four-barrels sticking up through the hood. His shop is absolutely slathered with Corvette memorabilia, logos, photos and models. He also happened to be the mayor of Wendover, so he knows where to go for anything you might need.
With an engine hoist borrowed from the Speed Demon streamliner team, the gang got to work stripping all the accessories off the engine, swapping them onto the new one, and putting it into the chassis, an exercise that took all of Saturday and Sunday because the bigger, taller, vertically mounted M104 engine has almost no wiggle room in the engine bay, and the air box, headers, oil and water lines form a very complex matrix under the hood.
At the end of the swap, Sirna discovered that, while the new engine was running perfectly and there were no leaks anywhere, the hydraulic master and slave cylinders for the triple-disc 7-inch Tilton carbon clutch were not communicating, so the clutch was not disengaging at all. Push-starting the car, with its custom-built Italian 5-speed transmission and Brooklyn Motoren Werke spool rear end, was going to be a little different this time.
After a few practice push-starts away from the course, and a critical two-hour electric warmup for the engine oil, using a Honda generator hung off the back of the pickup bed and a long extension cord, the car was pushed into position at the starting line.
One hundred yards down course, the silver Gullwing fired and Sirna got through all five gears very quickly, pushing it to 9,500 rpm in high gear, where the power lives.
Hundreds of people clustered around the PA speakers and FM radios heard it before Sirna heard it: 189.714 mph. A new world record was in hand.
Wittine and Decker chased him down, bundled the parachute and towed the car directly to impound, where it stayed overnight. Routine maintenance discovered that the right rear tire had only 20 psi in it, the other three 90 psi. A valve stem fix and more nitrogen solved the problem.
The entire crew, including Tall Mike, his wife Anne, and their son Kasey, enjoyed a champagne dinner that night at the Peppermill casino.
Impound was cleared by 6:15 the next morning and the car was in line for the required second run, hooked up to the generator/oil heater rig, and ready to go by 7 am, when the cooler temperatures would help.
The second run was even faster than the first, 191.805 mph, for a record average of 190.759 mph, nearly 18 mph over the old F/GT record, after only 15 years of trying. The Gullwing again sailed through post-run tech and the record was certified.
Think about that. More than one mile per hour per cubic inch from a naturally aspirated engine in a car that was almost 900 pounds heavier than a stock Gullwing, about 3700 pounds wet with driver.
Looking for 200
Sirna then opted to change to F Gas Modified Sports, obtained the number 1658, and the crew went to work modifying the car for an attempt at a second record and membership in the 200 MPH Club. They removed the front bumper, taped over the grille and fender vents, removed the side windows, and Randy Wittine changed the graphics to reflect the class change. But the car, even with slicker aero, wasn’t strong enough to get to 200 mph on that day.
Next day, the crew packed up the trailer and dispersed, headed back home. Sirna and Decker drove the rig back to Laramie, swapped the borrowed pickup for the Suburban with its fresh engine, and headed home to Michigan filled with the satisfaction of accomplishment that only Bonneville can provide.
Two months later, Mercedes-Benz Powertrain Engineering presented Sirna with a framed, official factory proclamation that his car was The World’s Fastest Gullwing.
Sirna decided to retire the silver Gullwing after 33 years and put it on the show circuit. It was later sold to a collector in Oregon, without the engine.
Next year, Sirna and his crew will reappear at Bonneville with an M104 engine in the original donor Mercedes-Benz C280 sedan for an attempt at the F/PRO production sedan records. He also plans to install another M104 engine in his Ford roadster for F/Gas Roadster, with truck, trailer and both cars all painted in Sirna’s Italian-flag color scheme.
A version of this story first appeared in Vintage Motorsport Magazine.
