L78 horsepower

[wheelhop]

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

[luzl78]

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.

[VintageMusclecar]

Originally Posted by luzl78

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.

When I built Donnie Cornelis' `69 L78 it made 462 HP and 439 lb.ft through headers (which were too big for that engine but were all I could get my hands on in time to test with) and ~430 HP and 411 lb.ft through the manifolds. However, the peaks don't tell the whole story. The engine lost 60+ lb.ft down low with the manifolds in place, and that you will definitely notice.