Rear wheel horsepower L-78 Nova ?

**1969L78Nova** · #1 08-15-2007, 03:22 PM

My Nova has been chosen as one to the finalist to be at the Cruise Nationals at the Canadian National Exhibition this weekend. As part of the events they are having the drivers guess the rear wheel horsepower of their vehicles prior to putting them on the DYNO. The winner wins a prize. Any guesses as to what my Nova will be. It's a stock L-78 bored over .60 (407 CI), balanced and blueprinted. I'm guessing 275HP?

**mockingbird812** · #2 08-15-2007, 06:46 PM

Auto or manual? Exhaust system? If she's dialed in you should be making at least 375 or better at the fly wheel. Deduct 15 to 20% by the time the drivetrain is factored in. Should be +/- 320 RWHP.

**1969L78Nova** · #3 08-15-2007, 07:55 PM

Manual Trans / 2.5 inch exhaust flowmasters ( No headers)

@wot · #4 08-16-2007, 04:32 AM

I read a dyno test of a L78 Chevelle with 60,000 plus miles on a stock engine. The car made 331 HP at the rear wheels with a semi tired motor.

bav70ss · #5 08-16-2007, 04:44 AM

A friend with an L78 which has been detuned for pump gas showed 275 hp at the rear wheels on the dyno.
John.

NCGuy68 · #6 08-16-2007, 05:15 AM

Lots of variables come into play on any given day. Ambient temp, humidity, type of gas, etc. Even rear tire width and the brand name of the Dyno will make a difference.

Guessing 280 +/- 10 HP.

**WILMASBOYL78** · #7 08-16-2007, 06:21 AM

A "real" blueprinted 69 L78 engine which "really" has 11 to 1..will make well over 400hp...those few extra cubes and headers will probably get you close to 425 horse...on the chassis that should get you in the 325-350 range....the factory 375 rating was creatively low....

wilma

Keith Tedford · #8 08-16-2007, 07:12 AM

A blueprinted and tuned L78 might make 400 hp. From the factory, the actual compression ratio was probably down around 10-1. Timing was retarded with a slow advance curve for emissions. The jetting was way lean for the same reason. Mid 14s was about all you could expect from one of these engines in this condition. 280 hp might be a generous number in this scenario. With tuning and headers 13.3s would be reasonable, at least from my experience. 320-340 hp might then be possible. We'll see what the dyno says. I'm usually wrong.

**JRSully** · #9 08-16-2007, 07:40 PM

My 30 over 70 L78 which was "blueprinted" and fully balanced, everything else being dead nuts factory (uncut 291 heads, 569 intake, 4557 Holley, stock distibutor 11:1 compression verified) dyno'd at 422 HP 5800 rpm w/Headers