Okay so, quick question. Back in the days of the C3, the horsepower jumped all over the place...standard in 1970 was 300, standard in 1977 was 180...my question was, back then, were they still using gross horsepower measurements, or is this number the horsepower that's actually getting to the wheels.

i think 72 was first year of net horsepower

cthulhu said: i think 72 was first year of net horsepower

You are correct Sir...!!! Verified on page 65 of my copy of the "1953-2003 Corvette Black Book", 3rd bullet under the '72s option list.

The 1970 engine will still have more rear wheel HP. Somewhere in the 200 hp area. This is due to higher compression and no emissions. They really sucked the HP out of these cars trying to get the emissions down.

The change from Gross to Net HP figures took place in as others have said in 1972.....

In 1972 they actually rated the engines in a {"more" true world configuration).... They actually hooked up the
accesories (fan, water pump, and exhaust to the engine) then tested it...

This figure refers to HP at the Flywheel...not the rear wheels which is even less....

Bob Griffiths

The gross numbers were with the motor with no accessories and no exhaust. The net numbers had a full exhaust system and all accessories on the motor.

didnt unleaded gasoline have something to do with this too..

less octane and therefore it forced lower compression..

i wasnt alive in 72... so i dont know for sure..

but i thought leaded gas was also higher octane..

Lead was used as a valve lubricatant. It cushioned the valve seats and to a lesser degree, the guides. Some of the cars for leaded gas were okay with no lead, others would eat the valves, guides, and seats. Once replaced with new stuff, the engine never needed lead again.

Lead went away in 1975 for new cars. It hung around gas stations for several years after that, then went away complelely. The reason the lead went? It damaged catalytic converters. 75 was the first year for converters.

It really didn't have anything to do with horsepower.

|UPDATED|12/29/2004 9:07:59 PM (AZT)|/UPDATED|

I remember buying Sunoco 103 octane gas back in the early 70s. Was expensive, 40 cents a gallon! When unleaded first came out, there was only one grade, about the same octane as regular leaded(it may have even been lower octane than the reg.). If your 1975 or newer car was required to use unleaded, you know it had to be lower compression to run well. So much for "performance" back then.
Mike

My 2cents, Auto's emissions were required to comply with enactment of EPA, thank you tricky dick nixon, while lead was still around, ie super, you could "widen" your gas tank filler opening, put in the "super leaded" and burn the converter out in one maybe two tanks. Stunk for a bit, best was high RPM for some distance, interstate driving before the 55 limit was enforced in all states was the way to go.

MIkey and his beast.