Search the Community
Showing results for tags 'Smallblock'.
Found 1 result
-
Chevrolet Speed - Sports Car for the People A Simple Formula 300 hp 3,000 lbs 30,000 Dollars The idea is not to build the best sports car in the world. It is to build the best sports car that the 20~40 demographic can actually afford. It is not the most powerful. It is not the lightest. And it is not the cheapest. But, it is powerful enough to equal a Boxster S at the stop light, it is light enough to approach the FT86 in driving dynamics and, most importantly, it is cheap enough to that a regular college grad can afford one. It is from this car that GM will graduate future Corvette and Cadillac-V owners. Design & Platform The Speed is heavily influenced by the Code 130R, but substantially different in most ways. It is not built on a standard Alpha Platform, but a heavily modified version called the Alpha SLC - Short Light Coupe. The wheelbase is shorten by 9.8 inches to 99.5 inches. Height is reduced by 3.8 inches to 52.1 inches. The belt line is dropped by 2.5 inches and the car is a full 23.1 inches shorter in length than the Cadillac ATS. Unlike the Alpha which is engineered to accommodate a wide variety of vehicle configurations and engine types, the Alpha SLC is tailor made for use strictly in 2+2 hardtop coupes powered by a Smallblock V4 engine. In fact, the engine compartment is so short, and the firewall is so far forward, that not even GM's upcoming 3-cylinder Ecotec will fit. Apart from the physical dimensions, the green house has a lot more rake and the nose is a lot shorter. It is almost difficult to imagine this as a RWD vehicle due the exceptionally short hood, but it is -- thanks to the V4 engine. Most importantly, the dramatic reduction in it's load carrying extents (mainly the wheelbase) and enveloped volume allows the vehicle to be approximately 400 pounds lighter than an ATS (300 lbs if you discount the disparity in equipment level and sound insulation). The Specifications Powertrain The design objective calls for maximum power output from the lightest, most compact engine. To this end, a 90 degree V4 engine that is basically a LT1 Smallblock V8 chopped in half is employed. Displacing 3.1L (188 cubic inches), the direct injected pushrod engine is about the same weight as a 2.5 liter DOHC Inline-4, but is only 2¼ cylinders long and significantly lower in height. The engine has two crank pins spaced 360 degrees apart and is supported by three main bearings. It exhibits the good overall balance of a 90 degrees full counter weighted engine, but is not an even fire design. With the crank pins spaced 360 degrees apart, the engine fires twice in 90 degrees of rotation then pauses for 270 degrees before firing twice again. This gives it a characteristically staccato exhaust note (1-1-0-0-1-1-0-0) at idle which turns into a guttural bellow when revved. The engine sounds almost like a Honda VFR750 motorcycle which has the same firing order. Synchronous cam phasing is used as on the Corvette V8 (LT1), but Active Fuel Management (Cylinder Deactivation) is not fitted owing to the impracticality of running the engine on just two cylinders. Direct Injection is employed using a combustion system identical to that on the LT1 V8. The engine offered in naturally aspirated form with 230 bhp @ 6000 rpm with 230 lb-ft @ 4600 rpm, or fortified with an Eaton TVS R1050 (1.05L) supercharger good for 300 bhp @ 6000 rpm with 300 lb-ft @ 3600 rpm. Eschewing the high costs of an 8-speed automatic or dual clutched manumatics, the transmission choices are relatively traditional. Both the base vehicle and the SS are available with either the GM Hydramatic 6L45 automatic or a Tremec 3160 manual -- both offering 6-speeds and automated rev matching. An electronically controlled active rear differential is optional on the base car, standard on the SS. Stability control is standard on both but launch control is featured only on the SS. Suspension, Brakes & Tires Suspension geometry is identical to the Cadillac ATS -- strut fronts, multi-link rears. Magnetorheological shocks are not offered to keep costs down and the Speed relies on traditional coil springs, tube shocks and anti-roll bars to keep vehicular motions under control. Brakes are lifted straight from the ATS with 11.8 x 1.0 inch front rotors on the base car and 12.6 x 1.2 inches on the SS. Both trims get 12.4 x 0.8 inch vented rears. The SS also gets Brembo floating calipers. Rubber on both trim levels are 225/45 R17 with alloy wheels. The base car is fitted with Goodyear Eagle GT All seasons while the SS gets Eagle F1 Asymmetric 2 Maximum Performance summer tires. The Competition
