blueprint porting

[PowerJunkie]

blueprint porting is the same as port and polished heads?

[wilkin250r]

Not quite.

Everything inside your engine has a tolerance, a range of sizes. For example, your piston isn't exactly 85mm, it can range anywhere from 84.95mm to 85.05mm.

The piston usually has a pretty tight tolerance, but other engine components will have a much larger tolerance. A large variation on one part, and a small variation on another part can create some very tight or very loose-fitting assemblies, certainly not ideal.

The term "blueprinting" usually refers to inspecting all parts and changing them to ideal dimensions and tolerances, as close to "perfect" as possible, the same as blueprint specifications. For example, a typical bore for a 85mm piston would be 85.05mm, but what happens if you have that same bore, but your piston is only 84.95mm? Your bore is too large, you have too much clearance and thus you will lose power, you need to replace the piston with a slightly larger one.

Blueprinting is taking everything back to original stock ideal specifications. If you've got blueprint porting, they clean up all the burs, fix any mis-matches, and the result is a "perfect" stock porting, obviously different than a full race porting and polish.

[PowerJunkie]

thanks for the help