Thursday, June 30, 2011

GMC Truck's AWD turbo Syclone...


When GMC collaborated with Michigan's Production Auto Services in the early '90s to create a niched performance market for their mid-sized models, they could not have chosen a better platform to build from then a short bed/cab, Sonoma/S-10 truck on top of an all-wheel-drive chassis transplanted from a relatively standard Astro/Safari van. This, along with an upgraded body kit, paint and interior package, sport-tuned suspension, and a now legendary 4.3 V6 fitted with a water-cooled turbo from Mitsubishi. Though radical by late '80s/early '90s standards, the TD06 turbo originally found on all Syclones and Typhoons is very crude in the realm of today's market.


Why a twin-turbo motor from TA-Duttweiler would work on the "SyTy" platform:


* The Sonoma/S-10 platform is light and nimble, even in standard form


* The slightly smaller displacement allows for a higher-winding powerband


* Because it uses forced induction to build power, the motor is built with a low compression ratio and less-aggressive cam, allowing the motor to run smoothly and accurately, while making room for various tuning possibilities ranging from a high-boost/octane running dynamic to a low-boost/octane dynamic that allows the motor, even with twin turbos, to run legally on pump gas.


* The blow-off valves can be calibrated electronically


* Turbo lag can be overcome by using a twin setup; the primary unit helps the motor get past the lag that usually occurs while the engine's exhaust spools-up the turbo, and activates the secondary turbo to keep the powerband progressive


* The passenger van-based, all-wheel-drive system that allows the Syclone--and eventually the Typhoon--to propel forward with near perfection works in a way that makes the midsize truck hook-up with minimal wheelhop.


* Even with a twin-turbo configuration, the AWD system can be re-mapped to hook-up almost flawlessly under any driving conditions. This also applies to the factory fuel injection, though an aftermarket unit would probably work better under these conditions.