Chevy Makes an Easy 550+ Horsepower on the Dyno

You’ve got to love old school grunt.

Today we have a naturally aspirated small block Chevy built by Keith Dorton at Automotive Specialists. It’s been punched out to 400 cubic inches, and naturally aspirated with a carburetor still manages to make over 550 horsepower on pump gas. Maybe best of all, this engine is built to be able to handle those power levels for years with no stress on the components.

There’s no secrecy or trickery here. All the components used are readily available from Summit or all the other places you normally source your performance parts. Granted, it’s all nice stuff, but if money is tight you can swap in less expensive components and still get similar results.

So please check out the video and let us know what you think!




Engine builder Keith Dorton of Automotive Specialists makes a timing check while breaking in our 400 cid small block on the dyno.


Checking bearing clearances on the Dart SHP block.


The forged Molnar crankshaft has a stroke of 3.750. Combined with the 4.125 diameter cylinder bores, that makes this engine 400 cubic inches.


Six inch Molnar connecting rods link the crankshaft to the pistons.


A mild dish in the Mahle pistons helps keep the compression ratio pump-gas friendly.


The valvetrain is controlled by a hydraulic roller from Crane Cams


The Crane roller rockers have the Chevy stock 1.5:1 ratio.


Jeff Dorton setting up the engine on the dyno.


4 Responses

  1. Love that 400 CID 550 hp build what is the price tag on that engine
  2. I want to know the full price of the engine 400CID 500 Hp
  3. Can you put up the full list of parts and part numbers?
  4. I have a 1971 Chevrolet Nova with a 350 small block try to decide which route to go enjoy your video 550 plus horse yes looking for a low budget build I would appreciate your help looking forward to hear your reply

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