Gross Horsepower LT-5 - ZR-1 Net Registry Forums

Hib Halverson · 10-25-2012

The only gen II LT1 which made 300 SAE net was the version in Corvettes and it was available from 1992-1996 with automatics and from 1992-1995 with manuals. That engine never made "377-78" gross at the flywheel. More like 340-350 on a good day.

The Camaro used a less powerful version (275-hp SAE net) of the Gen II LT1 from 1993-1997. There also was an even milder version (260-hp SAE net) used in the Caprice and Impala of the mid-90s.

The Gen II LT1 was, also, not the most powerful "traditional" (Gen 1/Gen II) SBC. That honor goes to the LT4, used in 1996 manuals. It made 330 SAE net about about 370-380-gross hp.

For the record, on SAE net vs. gross power ratings...

Up until the early 1970s car companies rated engines by measuring their torque output with an engine dynamometer than mathmatically deriving the horsepower.

Engines were tested in a manner which had them making the highest possible power output. They were set-up on the dyno with all accessories except the coolant pump removed. They were run with open exhaust. Prior to the early 1960s they used stock exhaust manifolds and after that, racing exhaust headers. The fuel and spark curves were optimized for highest performance. They were run with no exhaust emissions controls. They were run in high-octane, leaded fuel. The intake air temperature was as cold as possible.

In the early 1970s, all the car companies agreed to abide by a new SAE standard which required them to measure "net power". Once again, the ratings were arrived by measuring torque output on an engine dyno, but the engines were run the same way they were configured when installed in a production vehicle. This meant with all accessories (power steering pump, A/C compressor, alternator, etc) installed and operating along with any exhaust emissions controls the production engine may have used. Full stock exhaust systems were installed. The fuel and spark curves were calibrated to production intent. Unleaded pump gas was used. Intake air temp. was 77°F.

The difference in testing methods could amount to 50-hp.

10-25-2012	#11
Hib Halverson Join Date: Jun 2005 Location: CenCoast California Posts: 899	Re: Gross Horsepower LT-5 The only gen II LT1 which made 300 SAE net was the version in Corvettes and it was available from 1992-1996 with automatics and from 1992-1995 with manuals. That engine never made "377-78" gross at the flywheel. More like 340-350 on a good day. The Camaro used a less powerful version (275-hp SAE net) of the Gen II LT1 from 1993-1997. There also was an even milder version (260-hp SAE net) used in the Caprice and Impala of the mid-90s. The Gen II LT1 was, also, not the most powerful "traditional" (Gen 1/Gen II) SBC. That honor goes to the LT4, used in 1996 manuals. It made 330 SAE net about about 370-380-gross hp. For the record, on SAE net vs. gross power ratings... Up until the early 1970s car companies rated engines by measuring their torque output with an engine dynamometer than mathmatically deriving the horsepower. Engines were tested in a manner which had them making the highest possible power output. They were set-up on the dyno with all accessories except the coolant pump removed. They were run with open exhaust. Prior to the early 1960s they used stock exhaust manifolds and after that, racing exhaust headers. The fuel and spark curves were optimized for highest performance. They were run with no exhaust emissions controls. They were run in high-octane, leaded fuel. The intake air temperature was as cold as possible. In the early 1970s, all the car companies agreed to abide by a new SAE standard which required them to measure "net power". Once again, the ratings were arrived by measuring torque output on an engine dyno, but the engines were run the same way they were configured when installed in a production vehicle. This meant with all accessories (power steering pump, A/C compressor, alternator, etc) installed and operating along with any exhaust emissions controls the production engine may have used. Full stock exhaust systems were installed. The fuel and spark curves were calibrated to production intent. Unleaded pump gas was used. Intake air temp. was 77°F. The difference in testing methods could amount to 50-hp. __________________ Hib Halverson Technical Writer former owner 95 VIN 0140 current owner 19 VIN 1878 Last edited by Hib Halverson; 10-25-2012 at 12:51 AM. Reason: added content.