General Motors Rotary Combustion Engine※※※
GMC V6 engine
For the 1969 model year the ZL1 option was offered featuring an all-aluminum 427 cu in (7.0 L) big-block engine listed at 430 hp (321 kW) gross, it propelled the ZL1 through the 1/4 mile in 12.1 seconds. The option cost $4,700 (the ZL1 was a $3,010 option that consisted of aluminum cylinder block and heads on top of the $1,032.15 L88 option). Though generally believed to deliver at least 100-hp (75 kW) more, this has been proved as only rumors, proper testing of the engine revealed closer to 460 hp (343 kW) gross and net rating of only 376 hp (280 kW).
According to Motor Trend in a late 1968 road test, the Corvette ZL1 was the fastest production car ever produced (up to that time). For decades, automotive experts believed only two were built (yellow and white coupes), however Car and Driver in December 1969, revealed a third red ZL1. It was purchased by a Gulf Oil engineer who still owns and occasionally races it.
The ZR1 special engine package was a $1,221.00 option available exclusively with the LT-1 engine option. It included the solid-lifter small-block engine, heavy-duty four-speed transmission, power brakes, aluminum radiator, and a revised suspension with special springs, shocks, stabilizer bar, and spindle-strut shafts. Since it was competition equipment, the ZR1 could not be ordered with power windows, power steering, air conditioning, a rear-window defogger, wheel covers, or a radio. Only 53 1970-1972 ZR1's were built (25 in 1970, including 8 convertibles, 8 in 1971, and 20 in 1972).
The ZR2 special engine package was a $1,747.00 (1 year only) option originally planned for 1970, but officially released in 1971. It included the special equipment in the ZR1 package, but for the 454 LS-6 engine. Per GM policy, 1971 Corvette engines were detuned to run on low-lead fuel, except for the LS-6 V8, which was rated at 425 bhp (317 kW) on premium fuel. 188 cars in the 1971 model included the LS-6 engine, with only 12 with the ZR-2 package, including only 2 convertibles. Some believe the "ZR" lettering to stand for "Zora Racer", named after chief Corvette engineer Zora Duntov, but in 2008, Corvette Production Manager Harlan Charles said, "the reality is the codes are usually random and get meaning from enthusiasts."
Posted at 2016/10/17 01:44:33