GMC

Car Feature: Sonoma Savior

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photos by: the author

Brad Smith Turned his Small Pickup into a Corner-Carving Menace

When you want to build something a little out of left field that’s from the late-model GM contingent, what do you go with? A Grand National? A GTO? Meh, both albeit rare, have been done so many times that’s it’s ridiculous. What a about a GM S-series pickup? Sure, V8 swaps date back to the truck’s inception but those were largely small-blocks and for drag racing purposes.

Obviously LS-swaps have slowly crept into the fold, but very rarely do we see one built for the autocross and the road course. Brad Smith’s ’97 Sonoma is a perfect example of breaking away from the fold, and carving its own path.

We first heard of Brad’s Sonoma during a previous gig at another publication a few years ago, but it wasn’t until we spotted it at LS Fest 2014 that it fully caught our attention. Over the course of time since then, a lot of work and a few dollars spent, the truck was competing at the same event this year at a much higher level.

lssonoma-13You see, Brad’s introduction to LS power came by way of  taking the slow-rolling process from the original 4.3L V6, to swapping in a ’97 Camaro’s LT1, to a C5’s LS1, then eventually to the LS7 that’s sitting under the hood now. It’s been a journey of continual engine swaps, transmission swaps, bolt-ons and engine power but the effort was well worth it.

This all started when he realized that the automatic-equipped 4-cyl. S-10 that he previously owned wasn’t going to cut it, and found this Sonoma on a S10 forum packing the Vortec 4.3L V6 and 5-speed. Content for a year, the aforementioned years of engine upgrading ensued until he arrived to the point that he is today.

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No longer relying on anything from the ’90s, the Sonoma’s current LS7 is a welcome upgrade from 190hp — up to 535 hp to the tires, in fact. There’s 500-lb ft. of twist hitting the pavement, too, thanks in part to a PCM of NC hydraulic camshaft upgrade, that specs in at  230/246 duration, .644/.652 lift and a LSA of 114.

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The stock LS7 heads have been lightly massaged and milled, too, thanks to the folks at C&S Performance. Brad himself reassembled the heads, using the stock 1.8 ratio rocker arms that only benefit form a COMP Cams trunnion upgrade.

You won’t find any form of boost or nitrous under the hood of the Sonoma, but the induction is left entirely up to a custom-made cold-air induction kit, featuring a K&N filter, TPIS 90mm throttle body and the stock LS7 intake manifold. Exiting the exhaust gases just as quickly as they come in are a set of Stainless Works 1-7/8-inch long-tube headers, 3-inch pipes, X-pipe and Magnaflow mufflers. The sound is incredible.

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The a spark is produced through the stock coil packs, plug wires and NGK TR6 plugs. The 93-octane pump gas is fed through the stock fuel rails, 42-lb injectors, C5 filter/regulator and an Aeromotive 340 fuel pump. Dialing the tune in is made possible with a Current Performance Wiring swap harness HP Tuners software and the clever fingertips of Jesse Riggle at Late Model Throttle.

Now with the power straightened out Brad knew that he wanted to maintain the manually-shifted capabilities of the Sonoma, so when he went to upgrade the transmission, he decided to do so with a TREMEC T-56 paired with a Centerforce DYAD clutch and flywheel, attached to a MGW shifter.

The power is then sent through a custom steel driveshaft into a GM 8.625-inch rearend  sourced from Blazer Xtreme. It’s been modified with the help of Moser axles and a 4.10 gear set, which it will most certainly need with that level of power.lssonoma-6

In addition, the stock suspension that was in the Sonoma to being with was more in-tuned with the day-to-day commute to the feed store than it is for the autocross of LS Fest, so Brad put together a nice package comprising of Hotchkis sway bars, UMI upper and lower front A-arms and Viking coil-overs at all four corners.

Speaking of the all four corners, the GMC rides on a set of Forgestar F14 wheels, measuring in at 18.9.5 in the front, and 18×10 out back. The F14s are wrapped in Bridgestone rubber; RE-71Rs specs’d in at 275/35/18 — and they provide plenty of grip on the track surface, and real-world durability to survive for a decent amount of miles on the street.

The C5 Corvette front brake calipers, paired with S10 Blazer units help bring the truck to a halt, but it surely can’t do it without Baer Eradispeed rotors up front, Powerslot rotors in the rear and Hawk HPS snug inside each caliper. Pro-touring is largely about balance, and if you don’t have competent brakes or handling, then what’s the pointing having big power?

Cosmetically, it looks like a stock Sonoma at a glance, but Brad has injected some small, subtle details that make it stand out form a more traditional S-series truck. Obvious among them is the custom roll pan, billet grille and steel cowl hood. The aforementioned Forgestar rollers and Viking coil-overs allow for a lowered ride stance.

If you look a bit closer, you will also notice that the tailgate and radio antenna have been shaved for a smoother appearance, which continues inside the interior, where the subtle but effective approach also lives. An Auto Meter oil gauge and temp gauge, fire extinguisher and Momo racing seats with racing harnesses ensure that the occupants stay in place and safe while well-infomred on engine vitals.

The results of all of the efforts translate to 11.8 at 124.95 in the quarter mile, which is amazing for a vehicle that has no weight over the rear wheels and a wheel/tire setup more in tuned for the autocross circuit. Although he still has a lot to work out to put him in the top-tier of the pack, we think he’s doing very well for a homegrown guy with a twenty year-old pickup!

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TECH SHEET:

  • CAR: 1997 GMC Sonoma
  • OWNER: Brad Smith
  • ENGINE BLOCK: LS7
  • CRANKSHAFT: LS7
  • PISTONS: LS7
  • CONNECTING RODS: LS7
  • CAMSHAFT: PCM of NC; hydraulic, 230/246 duration, .644/.652 lift, LSA 114
  • CYLINDER HEADS: GM; LS7 milled .030 by C&S Performance, reassembled by the owner
  • COMPRESSION RATIO: 11.8:1
  • ROCKER ARMS: LS7; COMP Cams trunnion upgrade
  • INDUCTION: LS7 intake manifold, AIRAID cold-air kit, Nick Williams 102mm drive-by wire TB
  • IGNITION: Stock coil packs, GM wires, NGK TR6 plugs
  • EXHAUST: Stainless Works 1-7/8-inch long-tube headers, 3-inch pipes, X-pipe and Magnaflow mufflers
  • FUEL DELIVERY: 42-lb injectors, Aeromotive 340 fuel pump, C5 filter/regulator
  • OILING: Chevrolet Performance pump, Holley pan and racing baffle
  • TUNING: HP Tuners; tuned by Jesse Riggle at Late Model Throttle
  • TRANSMISSION: T-56
  • CLUTCH: Centerforce DYAD; twin-disc
  • DRIVESHAFT: custom-made; steel
  • REAREND: GM; 8.625 from a Blazer Xtreme, Moser axles, 4.10 gears,
  • SUSPENSION: Hotchkis front and rear sway bars, Viking coil-overs, UMI adjustable upper and lower front A-arms, custom “one-off” rear
  • BRAKES: C5 Corvette calipers, Baer Eradispeed rotors, Hawk HPS pads (front), Blazer calipers, Powerslot rotors, Hawk HPS pad (rear)
  • WHEELS: Forgestar; F14 (18.9.5 front, 18×10, rear)
  • TIRES: Bridgestone; RE-71R 275/35/18 (front & rear)
  • HP/TQ.: 535/496
  • BEST 1/4-MILE ET: 11.8 at 124.95
  • BEST 60-FT.: 2.0

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