Cajun_LS3

I know that hp ratings were calculated differently in the early 70's (gross vs net). So, is there a real difference in a 300 hp 1970 Vette and a 270 hp 1971? It seams like torque is also reduced from 70 to 71 (although calc'd. At a lower RPM).

early shark

The compression ratio drop would most likely account for the biggest real world drop in power output. 10:25 to 1 versus 8:5 to 1

Alan 71

Hi C,
I agree with early shark.
The 70 and 71 engines were rated by the same method
The change in hp rating method occurred for the 1972 cars thus the larger published hp difference was evident then.
Some 71 literature lists the GROSS and S.A.E. NET hp rating too. 210 hp.
This is a chart in the Nov.1970 Corvette News, in an article about the new 71.
Regards,
Alan

Notice this chart would have you believe there was a 115 hp difference between the L48 and the LS6…. I think it was probably a couple more hp than that.

1974ta

Alan,

That difference is pretty laughable. I got a good kick out of the chart.

Bill

Cajun_LS3

Good info. Thanks. I did some more research and it looks like a good rule of thumb is about a 20% decrease from gross to net.

Hammerhead Fred

The real answer is "it depends".
Try this for some depth of information on the topic.

Cajun_LS3

That was a great read. Thanks for sharing.