Chevrolet Chevelle Forum : “whats the hp ratings for a 396 high output engine?”

The standard 1966 Chevelle engine (RPO L35) was rated at 325 horsepower at 4800 rpm and 410 lb-ft of torque at 3200 rpm.  The RPO L34 was rated at 360 horsepower at 5200 rpm, and 420 lb-ft of torque at 3600 rpm.  Ready for the top-of-the-line?  It was an RPO L78, rated 375 horsepower and 415 lb-ft of torque at 3800 rpm.  0-60 in 6.5 seconds, man.

Woooooah.
=) CarGrrl

1965 z16 425hrspwr which in fact could have been much more

The L78 was usually rated at 375 HP...  There were "supposedly" some "listed" as "425 HP"...

However, these were the EXACT same engines (375HP vs. 425HP), same cam, same heads, same carb, same distributor, etc...  Only the "rating" (on paper) changed...

As far as I know, the highest "rating" was 375.  That's a joke though.

The L34 produced 360hp, 415ft/lbs of torque. It was possible to get the 375hp motor option but few were made.

The 375hp motor was "underrated" in chevelles for insurance purposes!  The likely output of the L78 motor was in the neighborhood of 425-450hp.  The car reported 0-60mph at 6.5 seconds, on 1966 hard rubber tires. My 1967 ss396, L34 stock except for a solid cam/lifter setup, modern wide radial tires and a tighter suspension was hitting 0-60mph in under 5 seconds, you get rid of wheel hop and wheel spin and when you can shift at 6800 rpm's instead of 5500 rpm's time improves greatly!

the LS5 396 which was in the '70 SS was advertised at 390 horses.

the LS5 is a 454

There were four 396 engine options offered in 1969. (#1) The base 396 engine was rated at 325 HP for the basic  SS package (in '69).  This was also teamed up with the 3 speed transmission as standard issue, the four speed and automatic were an option. (#2) The 350 HP version was an option, as well as the (#3) 375 HP (Known as the L78).
The original '69 brochure for the Chevelle did not list the L78, but the El Camino brochure did. If you had a knowledgeable sales person, he would  have been able to order the L78 engine for you in a 1969 Chevelle SS. The other (4th) option was the L78 with Aluminum Heads. This was the rarest option. The HP was not rated higher, but the weight was a considerable improvement over the cast iron heads. Both versions of the heads on the L78 were big rect port heads and both the 350 HP and two 375 HP versions had an aluminum intake, which the 325 HP version did not come with. the 325 HP version and 350 HP versions had the smaller oval port heads as well. Later in the 1969 production year the bore of the 396 changed to a 402, however, the car was still called an SS 396, then the 454 arrived in 1970. All SS 396 Chevelles were 402 CI in 1970 with the  SS 454 as an option.

The 396 in 1965 was rated at 375 HP in a Chevelle SS 396. 415 lbs of torque. ONLY 201 Chevelles in 1965 were SS 396 engine cars. The Corvette did offer the 396 engine for one year only 1965 and it was rated at 425 HP. This might be the engine that you were refering to, but it was not offered in a Chevelle.

5 versions of the big block was offered in 1970.
3 402's (still marketed as 396 engines).  
#1 was the L34@360 hp
#2 was the L78@375 hp  
#3 was the 375 hp (with the additional option of RPO L89) This was Alumn Cyl heads.
RPO Z15 the 454 options :
#4  LS5 454 rated @ 360 hp
#5  LS6 454 rated @ 450 hp

That is correct Travis. So was the LS7.