What's a "blueprinted" engine?

[robroy]

Good evening,

I've heard of "blueprinted" engines for years but have never known what that meant. What's a "blueprinted" engine?

Thanks!
-Robroy

[robroy]

I'm guessing that it means an engine that's assembled using an exact formula, including all internal dimensions and properties, to yield a known outcome. But I really have no idea.

[fordman]

it means that its put back to the factory specs. they uusally say balanced and blueprinted.

[robroy]

Oh, I see! So do they put the engine back to the factory specs to ensure that it runs with the exact same characteristics that it did when new? For an ideal, true restoration?

Thanks Fordman!
-Robroy

[HOWDY69]

I think it is a little like saying a car was detailed. Which basically means they cleaned the car better than usual. A builder who blueprints a motor will carefully measure and check tolerances. For balancing they will remove a little bit of material from each set of pistons and rods so they weigh about the same. They may also check the volume above the pistons when they are at top dead center so the compression can be calculated with some precision. In general it means the engine is built with some care and certain measurements were taken and documented. How much care depends on the builder and the intended purpose of the engine.

[kaptnkaos]

Technically, "Blueprinting" is the machining of components to tighter tolerances to achieve better balance.
Better balance means less engine stress and ultimately better performance.
Performance engine builders will have an engine "blueprinted" to optimize it's potential HP output.
Tolerances, determined buy engineers, are given to machinists who machine each part to it's optimum tolerance before the builder assembles the engine.
Is it worth it for a street engine...
Not really, but if yer building one for racing, it could be the difference that means a paycheck...
Any engine can be balanced, which will give it better performace, but it isn't nearly as good as a blueprinted one

KaptnKA S

[saidyene]

Blueprinting isn't always to factory spec. Its just being exactly to the spec that is planed for. If you think about it you cant get an engine to exact spec in a factory. It just takes too much time to make it profitable. You get a "blueprinted" engine by having it machined to the exact spec you want.

[FORD428CJ]

Blueprinting is a little more then what has been mentioned. Its truing up the deck, boring out the cylinders to the relation of the crank, truing up heads (resurfacing). The factory is a little rough compared to a Blueprinted engine. Check out the Poor Mans 427! That will give ya a little more detail on blueprinting an engine. JMHO

[fireguywtc]

Is your new 390 blueprinted Robroy?

[fitzwell]

wowsers.... i remember the day when a motor that was "balanced & blued" was the thing...mainly 'cause it sounded cool & 90% of the yokels standing around had no idea EXACTLY what it meant.

My interpretation is...assembled to an exacting specification. All piston rings the same end clearance, all bearings the same clearance, oil pump "worked". So on & so on...There are a number of specifications that people will check, recheck, and test before/and during assembly. Assembled valve height, spring rate, etc.Cam degreed in, block de-burred, all bolt holes chased & chamfered, casting flash removed. Balanced goes without saying. Being horribly anal about detail is a good way to sum it all up.
There are a number of "tricks" specific to each engine that can be performed, both to ensure longevity & performance.

[robroy]

Is your new 390 blueprinted Robroy?

Hey FireGuyWTC,

That I don't know! I could call and ask, although it sounds like the definition of a blueprinted engine varies--at least based upon this thread--and it doesn't seem to be black and white. Meaning that it sounds as though two engines can both be blueprinted, yet one received far greater attention to detail than the other (and could perform better).

Thanks for all the interesting responses!
-Robroy

[FORDification]

Blueprinting means machining the engine components to match the factory blueprints precisely, and carefully and methodically maintaining all factory-specified tolerances, which eliminates all the normal production variances. In other words, "close enough" ain't good enough....it has to be exact. It takes a little (lot) more time to achieve, but the end result is worth it.

[robroy]

Hey Keith! I think one of the key differences between the various definitions of blueprinting is whether or not the engine is returned to factory specs, or some other exact set of specs (like the known specifications for a particular hot rod engine build).

Other than ensuring that the engine behaves exactly like the factory setup, is there any benefit gained by returning it to the factory specs? Versus returning it to known good, hot rod specs?

Thanks Keith!
-Robroy

[fireguywtc]

Probably debateable, but I believe the blueprinting applys to an exact spec build wether it's factory specs or something totally unique. Keep all the specs exact no matter what specs are called for. Clear as mud??

[robroy]

That answer makes sense to me, since this kind of build is probably very different from approximating all the way through the engine.

-Robroy