1991 GMC Syclone - Double Time
This is a discussion on 1991 GMC Syclone - Double Time within the GM High Tech forums, part of the General Help category; 1991 GMC Syclone - Double Time The clock was ticking when we first caught up with New Jersey's own Ed ...
09-29-2007, 08:00 AM #1
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1991 GMC Syclone - Double Time
1991 GMC Syclone - Double Time
The clock was ticking when we first caught up with New Jersey's own Ed Hess and his 9-second Syclone. After easily clocking a 9.50 run by mid July, Ed was looking to become the first all-wheel drive Sy in the 8s--only to see this record taken by a Swedish competitor. Though slightly disappointed, an attractive consolation prize would be surpassing the current record holder to become the fastest AWD Syclone in the world, which is exactly what he intends to do. And just how, pray tell, will he manage that?
One very large advantage Ed has over his competition is the utilization of twin turbos, as opposed to a large single turbo, which was suggested by Ed's right hand man, consultant, crew chief, and tuner Harry Anderson. Or as Ed puts it, "Harry is the brains, I just put everything together." The welding and fabricating duties, though, are left up to Keith Mease of MPE Racing Fabrication in Pennsville, N.J. Mease is known for fabricating turbo headers, intake manifolds and intercoolers for a number of late model GM EFI applications including Turbo Buicks, F-bodies, and Vettes in addition to Sy/Tys. Ed and Harry commissioned him for a set of stainless steel manifolds with 1.75-inch primaries and dual 3.5-inch downpipes to accommodate the twins. Ed's current best run of 9.50 at 144 mph was owed to a set of 60mm "training" turbos set to only 20 psi, which have since been swapped out for Turbonetics T66s.
Typical of all upper echelon SyTys, Ed uses a Bowtie block with a .020 over bore. He had previously set the record for stock blocks a few years ago when he ran 9.93 at 137 mph. Unlike some of his competitors, he has chosen to stick with an even-fire crank made by Bryant Racing. The billet 3.48-inch stroke crank is complemented by Childs and Albert forged rods, and JE forged pistons. In combination with a set of Brodix (Pontiac) heads, compression is kept quite high at 11.5 to 1, but Ed and Harry contend that with a true race motor running 118-octane race fuel, lower compression simply isn't needed. The added efficiency from the higher compression, in addition to the reworked ports by Timothy John Racing Engines in Sewell, help the solid roller motor produce over 850 hp. These milled heads feature a 23-degree valve angle, welded and raised runners, 2.08 and 1.60 stainless valves, Del West titanium retainers, and high velocity shaping. COMP Cams offset solid lifters, 7/16-inch pushrods, and Jesel 1.6 ratio offset rockers actuate the valves in accordance with Harry Anderson's secret spec cam.
To match up to the custom raised runner heads, Keith Mease fabricated a raised runner sheet metal intake. When mated to an Accel 1,000-cfm throttle body and custom intake tubing, very little restriction is encountered post-turbo besides the MPE custom air-to-air intercooler. This large front mount unit is seamlessly incorporated into the radiator support. To keep up with the fuel demands, two Walbro 340-lph pumps are needed to supply the MPE high-flow fuel rails and Siemens 160-pound injectors governed by a boost-referenced Aeromotive regulator. An Accel dual sync distributor, MSD coil and Digital 6 box do the igniting as dictated by Accel DFI Gen VII+ and Harry Anderson. Harry uses the DFI also to control the two-step rev limiter and boost for optimum traction.
Speaking of traction, another unusual element of Ed's setup is the use of Hoosier 26x11.5-inch slicks. Originally, Ed had used an off-brand drag radial until switching to Mickey Thompson drag radials mounted on lightweight 15-inch Weld AlumaStars. However, as tire spin became a problem with increased power, the rears were swapped for Hoosier Quick Time Pros. In case you are wondering how the stock rear is holding up with slicks-the answer is, it's not. The 7.5-inch rear snapped and ejected an axle at launch toward the end of last race season, which caused a 540-degree spin and a slight grazing of the car in the opposite lane! This scary moment prompted Ed to install an 8.5-inch 10-bolt from an Impala SS with Moser 33-spline axles, C-clip eliminators, 3.08 gear and a spool. He also had Keith Mease put in a parachute that he knew would soon be required, in addition to the NHRA-certified rollcage Mease previously fabricated.
The rest of the driveline and chassis was dialed in with similar means--from either breaking something or scary moments on the track, also known as trial and error. The current setup includes a beefier front prop shaft, 3-inch chrome moly driveshaft, and a Rossler Turbo 400 that are near bulletproof. Thanks to the patience of Carl Rossler, a custom governor sets the shift points around 8,000 rpm. Pat's Performance Converters in nearby eastern Pennsylvania made a custom billet 9-inch torque converter to help the twin 66s spool up without a transbrake using a 3200-stall. Dual line locks are used to load the converter and turbos at final stage, stalling at about 3,000 rpm.
A Turbo Buick's Powermaster with a relocated motor establishes 2,000 psi of line pressure to clench the stock front brakes and aluminum rear drums. An incredible 1.42 short time has resulted from this launch method, also thanks to CalTracs traction bars and re-arched stock leaf springs. In the quest for 8s, Ed is now trading a bottomed-out set of Rancho shocks for QA1s and is considering adding an adjustable anti-sway bar. With still plenty more fine-tuning to go, it will be exciting to see if Ed can get this combo to hook and make history-or should I say, make history of his competition.
DATA FILECar: 1991 GMC SycloneOwner: Ed HessBlock:Bowtie V-6, 266 ciCompression ratio: 11.5:1Heads:Brodix, ported and polished by Timothy JohnRacing Engines, 2.08 intake, 1.60 exhaust valvesCam: Solid roller, custom grindPushrods:COMP Cams 7/16thsRocker arms:Jesel 1.7 ratioPistons: JE forgedRings:Speed ProCrankshaft: Bryant Racing billetRods: Childs & Albert forgedThrottle body: Accel 1,000 cfmFuel injectors: Siemens 160 lbs/hrFuel pump: Dual Walbro 340 lphIgnition:Accel distributor, MSD coil, MSD Digital 6 box,NGK plugsEngine management:Accel DFI Gen VII+Turbo:Dual Turbonetics T66Boost: 20+ psiIntercooler:MPE air-to-airWastegate:Dual Tial V44Exhaust system: MPE 1.75-inch turbo manifolds, 3.5-inchdownpipesTransmission:Rossler TH400Torque converter: PPC 3200-stall, 9-inchDriveshafts: HD prop shaft, 3-inch chrome molyFront suspension:Stock, removed sway barRear suspension: Stock leaf springs re-arched, QA1 shocks,CalTracs traction barsRear end: GM 8.5-inch 10-bolt, Moser 33-spline axles, 3.08gear, spoolBrakes:Stock front, aluminum rear drumsWheels:Weld AlumaStar 15x8.25 front, 15x10 rearFront tires:MT Drag Radials 235/60/15Rear tires: Hoosier 26x11.5 Fuel octane:118 Race weight: 3,650 lbsBest ET/mph: 9.50 at 144Best 60-ft. time:1.42Current mileage: 106,000
Photo Gallery: 1991 GMC Syclone - Double Time - GM High-Tech Performance Magazine
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