Another Corvette question...

[ChronoT150]

What happened to the C3's after 1971? They go from ~300HP to ~200HP. Is this because of pollution laws or something?

[Ecordeddie]

yup.... and even worse...I think the 1976 hit rock bottom at 180 hp. The '74s were the last of the big block 454s.... so they really didn't drop hard until after that. I just picked up a '79. It's rated at 230hp stock. Not great but still a damn fun car. The previous owner must have taken alot of the emmision controls off my car (shhhhhhhhh!)... I've got a question out in this forum as to what is really needed for emmisions control as well.

[ChronoT150]

Originally Posted by Ecordeddie

yup.... and even worse...I think the 1976 hit rock bottom at 180 hp. The '74s were the last of the big block 454s.... so they really didn't drop hard until after that. I just picked up a '79. It's rated at 230hp stock. Not great but still a damn fun car. The previous owner must have taken alot of the emmision controls off my car (shhhhhhhhh!)... I've got a question out in this forum as to what is really needed for emmisions control as well.

Good to know...

Are the early models still street legal despite the lack of emission controls, or do you need to get them retrofitted?

[mike2004tct]

Originally Posted by ChronoT150

Good to know...

Are the early models still street legal despite the lack of emission controls, or do you need to get them retrofitted?

That depends on your state's laws/rules.

Here in Wi., in order to register a car in certain SouthEastern Counties, the car has to pass an emissions test if newer than 1965. The car must have all factory specified emission equipment (smog pumps, air pumps, catalytic converter, etc). Other less populated Counties in the State don't require these tests, so the emission stuff isn't required to get license plates.

Again, check with your State's/Province's Motor Vehicle department to see what's required.(I found mine 0n-line)

I recently got my '85 licensed as a "Collector" car (20 years old or older vehicle), which means as long as I own it, I'll never have to take an emissions test agian, or pay registration fees. The only draw back is I can't drive it in the month of December. I can now do whatever I like to the drivetrain

[ChronoT150]

God I love you guys so much. It's so easy to learn things

Shameless brown-nosing aside, I'll look into that. Thanks for the info.

[Joe Wilson]

Originally Posted by ChronoT150

What happened to the C3's after 1971? They go from ~300HP to ~200HP. Is this because of pollution laws or something?

I think that about that time they started computing the horsepower at the rear wheels rather than at the flywheel.

[ChronoT150]

Originally Posted by Joe Wilson

I think that about that time they started computing the horsepower at the rear wheels rather than at the flywheel.

I can't find anything to prove or disprove this. Can anyone cite any information on this?

[ChronoT150]

This is from a Corvette dealer who finally offered an answer via email. Figured I should share.

"According to the 2005 edition of the Corvette Black Book (1-800-826-6600 or www.motorbooks.com ), "Power ratings for all engines (1972 and thereafter) were reduced due to a change in measurement technique. Instead of "gross," it became a more realistic "net," which included losses from such things as accessories, air cleaners, and mufflers" (page 20). Hence, power reduced from 270 gross to 200 net. The hp probably decreased by only 20 actual hp, whether measured gross or net..

Additionally, the same source says "1971 engines were detuned variants of 1970 engines. GMs' intent in reducing octane requirements to 91 (research) was to give oil companies phase-in time for the unleaded fuels needed for future use of catalytic converters. Hence power reduced from 300 to 270."