Words: Tommy Parry
Frank found this glimmering example of a ‘75 Monza collecting dust in the garage of the original owner’s family and, seeing it was one of the original 5.7-liter cars, he had to see it. Excited to get his hands on one of just 3,300 made, Frank was predictably disappointed when he realized the original 350 had been swapped for an LT1. Seeing as the motor was no longer factory, he held no reverence for the machine.
That didn’t stop him from buying it though. Due to the lack of originality, he saw no problem in swapping an LSx motor into the pristine Monza, and strapping on a massive turbo while he was at it.
It turned out that the LT1 wasn’t working terribly well, and so he towed the car an hour back to his house to begin swapping the 4-lug setup for the traditional, 5×4.75” bolt pattern hub. The platform would have to handle big torque, so the footwork got some much-needed attention. Drop spindles and slotted/crossdrilled rotors from an S10 updated the front axle, as did braided brake lines and bigger calipers.
From the same donor S10 came a set of axles for the rear, and while he was back there, Frank had a friend weld to the new lug pattern on the rear drums.
After hoisting the LT1 from the bay and selling it to a friend, Frank rebuilt the TH350 and strengthened it with a 10” billet converter. In the corner of his garage, forming a new home for several nests of spiders, was an 5.3-liter LS with an LS6 cam and a set of hot heads.
Frank grabbed the heads and took them to the machine shop for a quick valve job and the installation of BTR .660” valve springs. While he was there, he went for the full enchilada: the heads got a set of 2” intake valves and stainless 1.57” exhaust valves. While he was at it, he shaved .003” off the heads. With some LS9 head gaskets and a set of new studs, Frank slapped the heads on and doused the block in coat of classic Chevy Hugger orange. To help contrast that iconic blaze orange, Frank laid down two layers of Krylon black in the tidied engine bay.
To help put the force-fed V8’s power down cleanly, Frank tubbed the rears to accommodate a 275-section rear tire and held onto the factory 7.5” 10-bolt until it popped, and then upgraded to a narrowed 9” with a 3.50 gears.
A half-cage and some subframe connectors came next. Not only would they stiffen the chassis and help put that colossal amount of power down, but they’d also keep it reasonably safe and accessible. This is a road car, after all, and so climbing into a chromoly jungle to go to the restaurant makes little sense. It seems Frank got the compromise perfect with this cage.
At 7 pounds of boost and a custom log manifold, the motor made an impressive 400 horsepower at the rear wheels with a wide powerband, reaching full boost at 3,500 rpm. With 12 pounds of boost and a little methanol, Frank saw an impressive 550 wheel horsepower! Not bad for a junkyard motor with a basic turbo setup.
As you might imagine, a stock TH350 struggles to handle that sort of shove, and so it grenaded promptly after dyno tuning. Not willing to see his project collect dust in the garage, he built a new transmission with a 36-element sprag conversion, a hardened input shaft, a TransGo kit, a direct piston machined for an extra clutch pack, Alto Redo Eagle and Borg Warner clutches, Koleen Steels, dual bushed Vega lightened sun shell, dual feed drum, a TH250 gundrilled/hollow output shaft, a roller pump, roller first gear planetaries and a few other goodies to harness that torque.
Frank then louvered the hood for better engine temps and a bit of flair, and gave the hood a coat of gloss black. Without any dyno tuning, he moved the methanol injection to inject a 60/40 methanol/water concoction into the compressor impeller, and found he could make the same horsepower after lowering the boost pressure to 11 pounds. Finally, he scrapped the plush, red leather seats and replaced them with something a little more functional.
With a fresh coat of yellow and his custom plates, Frank had a setup that could churn up the pavement without attracting the fuzz. He found the perfect combination between flash, speed and subtlety, and best of all – he didn’t break the bank. It deserves the nickname “Monzarati.” Let’s just hope it’s a little more reliable than the name would suggest.
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