To conquer and rule, you must first believe. No matter how large the obstacles may get, you must still believe. When your friends say you are crazy, you must still believe. When your best sense tells you otherwise, but a voice so primal and deep in your soul tells you to go forward, you must believe. That is how some of the best things in life are created with our own hands–whether a song, business, or a '98 GMC Sonoma that runs 8.70s.
To say that Troy Marburger's Sonoma was a labor of love would be an understatement, purchased new from the dealership where the 39-year-old technician works. Troy originally spotted this very truck on display while taking his children to the Texas state fair, it wound up on the dealership lot and became the very first new vehicle he had ever purchased for himself. Starting with the basic bolt-on modifications, Troy truly became hooked after being invited to Texas Motorplex by a coworker. And soon he swapped in a six-speed and was running 12s with nitrous. By 2001 he was ready for an engine swap, and with prices for LS1 parts still sky high the LT1 became an easy solution for someone accustomed to working on them. With just a CC306 cam, the six-speed truck was running 12.80s until nitrous ended the stock engine's glory. After building a 383, the truck ran 11.40s on motor and 10.20s on juice while still being daily driven. Eventually gas prices relegated the truck to mostly weekend and track duty. Speaking of money, Troy had also been rethinking his nitrous usage between the charge to refill and a few pistons he burnt up.
Though initially intimidated by rumors of the cost, Troy crunched the numbers himself and found a turbo system to be well within reach. The first step was pulling the scorched motor and dropping in some -22cc JE slugs to go from 12.5 to a more boost friendly 8.9:1 compression. The TrickFlow heads that had been ported by Lloyd Elliot were reused along with the Scat H-beam rods and crank. Lloyd Elliot helped spec out another custom solid roller cam to replace the previous with a more turbo-friendly 255/251 duration split on a 114 LSA. Again Troy topped off the motor with a converted Edelbrock single plane SBC intake and an Accufab 1,300cfm throttle body. This time, though, a hat would be used to grab charged air from an air-to-air intercooler and a Borg Warner S480 turbo purchased off eBay. Troy fabricated 1.75-inch primary turbo manifolds with 3-inch collectors to route the exhaust up to the turbo. Fueled by E85 and backed by a TH350 he found locally, this setup eventually enabled the truck to run a 9.30 at 135 mph after sorting through some converter issues. Before the next race season began, Troy advanced the cam a few degrees to help the engine come up on the transbrake and bought a thrifty air-to-water intercooler (off eBay again). With an ice tank stashed in the bed, the truck went 8.84 at 158 mph.
Now most people would have stopped there. But this is where things started to get interesting. Since the TH350 was no longer reliable at this power level, the Powerglide was the preferred solution to broken input shafts and drums. So Troy called up Pete at Hughes Performance (on several recommendations) for a two-speed and a converter. It took a few adjustments to the stall speed and suspension, but eventually Troy was back into the high 8-second range before spending the next winter installing a three-nozzle methanol injection from AIS and ditching the intercooler and ice tank. With 23 psi of boost the Sonoma hit a new best of 8.72 at 160. And this set Troy upon a new path, to push the stock LT1 block to its limits. The following winter the budget turbo was ditched for a Precision PT-98, purchased used off a forum, and the hot side piping was redone to accommodate the large hairdryer. A Griffin radiator was pushed to the side and clearance was made to the front end where necessary to source induction air from behind the grill. The 5-inch downpipe coming out the front bumper also took an all-business attitude. With an AMS-500 commanding 19 psi, the new turbo has already equaled the previous with an 8.76 at 160 and plenty more to go. Troy expects this turbo will make around another 5-7 psi of boost and easily surpass his previous best.
None of this would be possible without a stout fuel and ignition system, and a skilled man at the helm. That man is Steven Kan at PRT Performance who has dialed in the FAST XFI system at every step, with a three-bar speed density tune commanding 160-pound injectors with a boost referenced Aeromotive Eliminator pump gulping E85. An MSD cam sync makes the Opti a distant memory, as an MSD Digital 6 and HVC-2 coil conspire to deliver precise spark tables.
Of course the credit is only half-owed to the powertrain with the rest going to Hansen Race Cars who built the 10-point cage, installed the Lexan rear window, and helped set up the chassis. The TRZ anti-sway bar, Caltracs, and split mono-leaf along with a quartet of QA1 shocks allow some impressive 1.33 short-times on 28x10.5-inch Mickey Thompson stiff-sidewall slicks. Weld 15-inch drag wheels, TRZ front control arms, and race seats shed a few unwanted pounds. Wilwood brakes are currently the only method for haulting the GMC from 160 mph, but the rear end is SFI legal with Moser 33-spline axles and spool fortifying the stock 8.5-inch 10-bolt.
Though it was the new front end on the '98 model that really made Troy fall in love with this truck new, eventually it even needed some updating. An Envoy front bumper and a Goodmark cowl hood gave the Sonoma a facelift, meanwhile the body was smoothed out and shaved of door handles, the tailgate handle and rear step by Sewell Cadillac before coating the body in PPG paint. As a self-proclaimed "professional test and tuner," owning an extremely clean, fast and unique truck sets him apart from the hundreds of Mustangs and Camaros sitting in staging lanes across Texas (and the country). "It's different from most anything that you will see at the track on any given weekend, and it does not look like a race-only vehicle."
In fact, the only place this unique truck looks at home (besides Troy's garage) is at the LTX Shootout, which is exactly where he intends to take the truck this year. "I tried to make it last year, but broke the torque converter a few weeks before the show." With a little luck and a lot of hard work, we're sure Troy will make it this year to unite with many like him, to hear that familiar sound. Those that have beaten their heads against a wall, pouring blood and sweat into a seemingly losing venture, only to come out victorious, know it all too well. May we all be such believers.
Car: 1998 GMC Sonoma
|Heads:||TrickFlow LT1, ported by Lloyd Elliot, 2.08 intake, 1.65 exhaust valves|
|Cam:||Custom solid roller, .688/.645-inch lift, 255/251 duration at .050, 114 LSA|
|Pushrods:||Comp Cams, 5/16-inch|
|Rocker arms:||Jesel, 1.6-ratio|
|Throttle body:||Accufab 4-barrel|
|Fuel injectors:||160 lb/hr|
|Fuel pump:||Aeromotive Eliminator|
|Ignition:||MSD Digital 6, MSD HVC-2 coil and billet cam sync|
|Engine management:||FAST XFI, tuned by Steven Kan at PRT Performance|
|Power Adder:||Precision 98mm turbo|
|Blow-off valve:||JGS 56mm|
|Exhaust system:||1.75–inch turbo manifolds, 2.5-inch crossover, 5-inch downpipe|
|Transmission:||Powerglide, built by Hughes Performance|
|Converter:||Hughes Performance 5000-stall|
|Front suspension:||TRZ control arms, QA1 coilovers, removed sway bar|
|Rear suspension:||Calvert Racing split mono-leaf and CalTracs, TRZ anti-sway bar, QA1 shocks|
|Rear end:||Stock 8.5-inch 10-bolt, 3.42 gear, Moser 33-spline axles, spool|
|Brakes:||Wilwood 4-piston, front and rear|
|Wheels:||Weld Rodlite 15x3 front, 15x10 rear|
|Front tires:||Mickey Thompson 26.5x4.5|
|Rear tires:||Mickey Thompson slicks 28x10.5|
|Fuel:||E85 + methanol|