This Twin-Turbo Cadillac Packs a Surprise  Punch

October 4, 2017 / by Bradley Iger

This ain't your granddad's Caddy. Despite it geriatric exterior, the 1977 Cadillac of Shawn Gilbert is a twin-turbo sleeper ready surprise unsuspecting challengers. Lead photo credit: Dave Janu Photography.

“I've always liked them, especially the 77-79 body style, they have beautiful body lines,” says Shawn Gilbert of Elyria, Ohio. “My very first one was 79 Sedan Deville I picked up cheap when I was in my early 20's. It had a 425ci Cadillac power plant and would do burnouts with ease! Back then the thought didn't even cross my mind to hot rod one, I mean come on...who would?”

That changed in 2002 when Gilbert’s friend informed him of a ‘78 Coupe de Ville for sale in the local paper. “I called the guy, turns out it was a Florida car, no rust and he said it still had cold AC,” Gilbert recalls. “The next morning we went and looked at it, I put on my best game face trying not to reveal the excitement I felt. $900 dollars later I was driving home it home. My friends laughed their butts off when they saw the Caddy and I told them I was gonna make a street/strip car out of it.”

While Gilbert’s Caddy looks decidedly more performance-oriented than it did in showroom stock form, there’s little to tip off would-be contenders that this car is knocking out quarter mile passes in the high 8-second range.

Equipped with a 500-cube Cadillac big block pulled from a junkyard, Gilbert had the car running low 14-second passes with a decidedly lazy 2.28-geared rear end in it. The car continued to get quicker and quicker each year as Gilbert honed the big coupe on the backstreets of Ohio.

With weight being the enemy of performance in most situations, the massive late 70s Cadillac coupe isn’t a platform you’d expect to see in the staging lanes, and that’s one of the reasons Gilbert’s build gains so much attention. Gilbert’s latest build is actually his third Cadillac Coupe de Ville, after building a BBC-powered nine second car, and later a mildly built, LQ4-powered street car.

Eventually, he had the car ripping 10.30 e.t.s with the Cadillac mill before moving over to what he describes as a “mildly built” 540ci big-block Chevy motor in 2007, which brought the car into the high 9s. But Gilbert would sell off that car the same year, moving on to a brief stint with a mildly built white ’77 Coupe de Ville street car before picking up the Naples Yellow ’77 you see here, a car which ran consistent 8.80 passes all weekend at this year’s LS Fest.

Aside from the racing harness and McMahan Motorsports roll cage, the interior of the Caddy still looks much the same as it did when it rolled off the assembly line more than forty years ago.

“The current engine combo started as a 398,000 mile 2007 LQ4, I bought it as a core from a GM dealership I worked for at the time,” Gilbert tells us. “The cylinder walls still had cross hatch on them. My good friend/mentor and sales associate Vic Ellinger at Wiseco set me up with off the shelf .005 over 6cc dome pistons, 6.125-inch long K1 rods and they have been taking a beating with zero issues! It's making close to 1400 hp at the flywheel so I can only imagine how much power a dedicated Wiseco race piston and rod set up from them would be able to handle.”

Motivation comes from a twin-turbocharged LQ4 LS motor that Gilbert pulled from the junkyard with nearly 400,000 miles on it. While the crank is stock, the other internals have been beefed up to withstand the stresses of 1400 horsepower and include off-the-shelf Wiseco .005 over 6cc dome pistons and K1 connecting rods.

Gilbert’s combination still includes the original 400,000-mile LQ4 crank, which has been balanced and polished, while a custom-ground BTR camshaft, six-bolt Trick Flow cylinder heads, and a Holley Dominator EFI system are supplemented with forced induction by a pair of Borg Warner S366 turbochargers and a Treadstone A/T intercooler from Big 3 Racing in Hinckley, Ohio.

“I took it to LS Fest this year and people just fell in love with the car,” he says. “I ran a personal best of 8.79 @ 153mph that weekend with a soft 60ft tune, but it has been 1.26 in the 60ft with a more aggressive starting line tune. My goal is a sub-1.25-second 60ft, and I really think I can accomplish it before the 2017 season comes to a close. I never dreamed I would own and build a Cadillac that would be able to run consistent eight second passes yet still drive it on the street, but it happened. Motivation came from my buddy Poul when he pushed my old car into the sub 9 second zone with the help of a little nitrous.”

So what’s next for Gilbert’s luxurious street and strip terror? “The ultimate goal is to put the car into the 7s.”

Topics: FEATURES, CHEVY, featured

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Written by Bradley Iger