Larry McIntosh

I was wondering when hp was changed. I had a 1962 340hp 327, 1966 350hp, 327 a 1978 L82, 350 I think it was around 220hp, all bought new. I now have a 1996 LT4 CE 340hp, and was wondering if, and when did they change. What would the 96 compare to my 1966. Thanks in advance.

MavsAK

Pre 1972 cars were rated in gross hp. That is, rated with just the waterpump and open exhaust.

Your 96 in gross horsepower ie pre 72 ratings would be like 400 to 410hp.

Your pre 72 cars, the 66 for example would be like, 250 to 270ish hp in net hp (that is fully dressed and with full exhaust)

kg4fku

This should explain.
HP ratings

And your LT4 is rated at 330HP.

Silver96ce

Here's a pretty good article that answers most, if not all, of the questions on horsepower ratings from the '50s to now.

http://ateupwithmotor.com/terms-tech...et-horsepower/

Silver96ce

You got to it before me. Sorry for the double post.

MavsAK

Under rated at that. In reality the LT4 apparently makes 340 to 350hp

kg4fku

I don't believe that. I have read a lot of articles and looked at every LT4 DYNO graph available online and I am not a believer in the LT4 under rating theory. However, that is not the topic of this thread.

Tom400CFI

Then why post?

I think Mavs is right. What have you seen stock LT4's typically put down?

Tom400CFI

Ateupwithmotor is awesome. Fantastic articles!