? on hp rating

[rayfan]

Is the 70 350-300hp about the same real horsepower as the 71 350-270 hp when you consider the 70 was measured as gross hp and the 71 was net hpOr is the 70 actually a truly higher hp even considering the difference that the hp was measured.

[fatherlarry]

Hi Rayfan,

The '71 350/270 Turbo-Fire (base) was gross horsepower 270 at 4800 rpm and net horsepower was actually 210 at 4400 rpms. So 270 is actually the gross hp, not the net. The compression ratio for the '71 was 8.5:1 and the combustion chamber volume was 6.08 cu in.

The '70 300/350 compression ratio was 10.25:1. So comparing apples to apples, it stands to reason that if compression is higher than hp is increased. In '71 the gov't started to institute emissions regulations.

I don't know how true GM's horsepower readings were back in the '60's and '70's. Sometimes they had to deal with insurance companies to keep the horsepower down for insurance reasons, so they would naturally underrate the hp. This of course, is just my guess.