What's a "blueprinted" engine?

[fordman]

i agree that i disagree about agreeing. any further agreeing or disagreeing with my above statment is to not agee that you are disagreeing. huh?

[fireguywtc]

What the heck are you smoking Fordman J/K but you did make my head hurt!

[fordman]

i was just commenting on the slightly varied opinions. i think kieth has it right. they go back to the ford blueprint and get everything back to the orginal specs.

[td]

alot of full on race engines are blue printed, i would think most of the specs wouldn,t be near original.

[Happy_Camper]

This is a great question!
With excellent answers

My understanding (which may or may not be right ) from decades of bench racing and factory experience is that the term "Blue printing" has evolved as builders gain more knowledge and experience.
The factory builds to a "tolerence range" to get each part into the tolerence range there is a specific target (i.e. if the gap range is 0.003" to 0.009" the target could be 0.005"). The target may or may not be the "optimum" sweet spot, but allows the factory to get the largest number of pieces built correctly somewhere in the specified tolerence range.
So originally the engineering blue print sheets would have the target listed, and engine builders would build to the target spec.
As builders became proficient at modifying engines to extract maximum performance, they find that factory "targets" are not always the real sweet spot of the engine. Talk to any good builder, and they've got all kinds of note books they've kept over the years on specs they've found to produce maximum power, or efficiency, or longevity, and then combinations of the three. So depending on what the customer wants they build the engine to their specs. So realistically, Blue printing should be redifined as "notebooking" an engine, unless a builder is working to build the perfect "factory spec" engine.

Just my highly unscientific for your reading endurement

[averagef250]

Blueprinting is an overused term with different ideals on it's definition in relation to engine building.

A better idea of an engine's caliber is the degree to which it is blueprinted. Simply plastigauging engine bearings to ensure they're within proper spec can easily be defined as blueprinting. The opposite end of the spectrum is a high-end competition engine that's being pushed far beyond factory output and must have upgraded parts and tolerances that are differing and more precise than your standard engine.

Wrap your head around the idea of the 4 crank throws of a V8 engine and how they have to be machined at exactly 90 degree intervals. Or how crankshaft journals are ground, not turned and a grinding wheel is consumed as it grinds. A ground cylindrical part has a taper to it, how small this taper is is a function of machinist skill and machine quality. Your typical crank throw ground on a manual grinder tapers .0002-.0003". In a full on race engine this means the rod and main bearings have an unequal oil film to distribute the load. Block deck parallelism to crank centerline is only one aspect of it. Consider with the crankshaft installed how the stroke of each rod journal can be a few ten thousandths of an inch off, usually this is closer to .005"-.008" on a factory crankshaft. A V8 camshaft has 16 lobes, 8 pairs of lobes that are expected to be ground to precisely match in timing and profile.

No engine is perfect. High end engine builders go to lengths to ensure the parts they're using are the highest quality and the spec they want for the engine's application. The engine shop I use holds main and rod tolerance to within .0001" on their race engines. Taking measurements accurately down to a tenth requires not only good tools and the skills to use them, but a temperature controlled shop. An iron engine block grows several tenths depending on temperature, aluminum grows several thou. Assembling an engine's bottom end to have each bearing journal match with a tenth requires several sets of the highest quality racing bearings just to get everything as close to perfect as it can be.

The difference between a $5K race engine and a $25K race engine is in the details. In the search for perfection I've seen men spend $30K on a pair of 302 cylinder heads. But 950 real, reliable HP from a pushrod V8 is pretty darn untouchable in a 5.0 liter 110 octane naturally aspirated engine class.

[FORD428CJ]

Get you crank blue-lined! Most stock cranks are off from the factory...

[fordman]

very well said dustin. i was trying to say that in my wierd post but i could not come up with the correct words.

[averagef250]

Buying a race engine or choosing a shop to build an engine I want to see the shop myself and talk to the people doing the work. A good shop will figure out exactly what you want and fit the work/parts to the application. That's what you're paying for. A good shop will have a waiting time. You won't get your engine back in 3 days dyno tuned and ready to go and forget about race season.

Engine builders have turned from a refined black art to more of an assembly line with marketing and a snow job about how great the work they do is. High quality engine builders are a dying breed.

[DuckRyder]

Scott (happy camper) and Dustin (average 250) have this one, although Keith’s technically correct. It is most appropriate to ask "what (or whose) blueprints" when someone says blue printed.

Usually when it is to factory blue prints it is for some particular racing class that requires it.

For instance the SuperSport 600 motorcycle class requires a stock engine further with no after manufacture machining. Ever wonder why those bikes are so much faster than a totally showroom one? Because when they need a part they will get 20 or 30 of them and use the one that measures out like they want it, whether it be the head with the smallest champers or the cam with the highest lift... That is a form of blueprinting.

Anyway, blueprinting is one of those terms that you really have to ask what exactly was done to "blueprint".

[shrektruck]

And here I thought "blueprinting" was when they stamped that Ford oval on the valve covers and painted em Ford blue