L78 horsepower
 

Made our first dyno run on the L78 engine for my 67 Camaro. It's bone stock carb to pan. Generated 397hp at 5,500. Was running a little lean, so re-jetting tonight and run again tomorrow. Anyone have input on what HP a stock L78 should put out?

Was the session with headers or exhaust manifolds? Ours with a little lower compression made 450 with the shops carb, headers and dist. but almost 70 less with the stock carb and distributer.

The answer is.... has Eric laid his hands on it or not!!

Mine made 420 with shop headers but, was not "dialed in" all the way

How much do you think headers add over manifolds? Eric is gonna build my 402 for me and I am going back and forth. It's in my Monte Carlo.

Eric did the carb. Ran on dyno with headers, stock dist and carb.

Seems impressive to me. Was max HP at 5500? Seems to me there would had been a little more runway left for more HP?

Should take roughly a 74 primary jet with headers on the dyno, will want the 71 with manifolds in the car. Secondary jetting should be good as is.

L78 Horsepower..
 

When the L78 was introduced in 1965 it was rated at 425hp...this was based on 6400 rpm's...almost 1,000 rpm lower than the engine being discussed. Most folks would agree that the later 375hp rating was low...headers, properly tuned distributor/carb and blueprinted assembly all make a huge difference.

Last one we did was a 70 402 version...pancake intake, Eric prepared 4492 and run thru headers...it made north of 430hp.

Again, the real power difference in these motors is in the details.

-wilma

My 69 L78 was just a basic build,trw pistons,bullet stock spec camshaft,it was balanced.heads are stock 840 castings.with headers it made 415@5500 and 400ft lbs from 2000 to 5500. My nova ran a 13.02 off the trailer at scr with headers 4.10's and street tires