Last week’s travel through time revealed that Banks wasn’t always only about twin-turbos with its single turbo kit installed in an ’81 Chevy Corvette, which was reviews in Popular Hot Rodding’s March 1982 issue. Another Banks turbocharged Vette was also reviewed in that same month, this time it was a ’69… and twin turboed. The big difference here (besides the additional turbo) was that it wasn’t just a Banks kit on a stock engine powering the Vette, but instead a fully-built and blueprinted Banks twin-turbo 350 small block engine.
Back then Gale Banks added street engine availability to his already legendary line of powerful marine engines. These engines were available in three “series”: Series 1 was a fairly mild build that churned out 500 hp. Series 2 was a more performance-oriented and blueprinted build that made 600 hp. Series 3 was a competition engine that made 700 horses. The owner of the Vette opted for the 2nd series engine. All engines were boosted through a blow-thru carburetor (specific CFM for each build), which was pretty different compared to the draw-thru for the day. The benefit to this was an almost instant throttle response, the turbo not needing to deal with compressing both air and fuel, and because the design of the intake chamber incorporated a “shuttle valve” (commonly referred to as blow-off valve) the turbos remained at full speed without stopping due to the throttle valve closing.
When all was said and done, the customer’s Corvette was an absolute beast. The magazine took it to the track where they made several runs on drag slicks, and with an overlay of Gale’s water injection system running on the engine. In the end, the Vette bested a quarter-mile time of 10.95 seconds @ 129.12 mph. And here’s the thing: This monster could transition easily to everyday street use. And, since there was more in it with a little extra tuning, it could be even faster at the track. It’s a duality that remains a part of every Banks performance engine to this day.