I’ve never had an engine “blueprinted” but I think I have an idea what it is about. This is done on special engines, mostly racing engines. The engine is taken apart and all the key moving parts are weighed and “balanced” to make sure pistons are within very tight tolerances. Usually the block and heads are “magnafluxed” which is like a CT scan for metal.
This means the block and heads are free off any defects from the manufacturing process, and the pistons and other moving parts are matched for balance. Such an engine can handle much higher rpm’s than a stock motor of the same displacement. All this means more power, more rpm, and a motor that won’t explode under racing conditions.
Here’s a run through of assembling a modified Miata engine:
It hints at all the work needed to ‘blueprint’ an engine, where all specs and clearances are brought to their ‘blueprint’ value (all components balanced, all clearances matched, all cylinder displacements matched(cc the heads)). Of course, there’s all degrees of ‘blueprinting’.
Maybe it’s been stated already but motor replacement I believe is no different then replacing most any appliance instead of repairing it. As the years go by, the manufacturing process is so specific and computer driven on assembly lines with literally one way, one time assembly, it’s just too time consuming and too many man hours involve in repair and rebuild. The casting processes makes it almost impossible for the average dealer mechanic to do much more then walk through a manual on most major repairs. It started with electronics and everything is so modular now, the motor is one big module as far as manufacturers are concerned. Bent rod, replace the motor, a ticking noise, replace the motr won’t be too far off.
So IMHO, the motors are much better and longer lasting, just less repairable.
@MG Good point-I’ve always been in the rust belt, so I forget some people are blessed with a corrosion-free existence. Even outside the rust belt, the rest of a car now holds up much better than it did many years ago.
I believe much of the reason you’re hearing engine replacements more is tribute to the longevity of today’s bodys and chassis along with today’s more stringent requirements (emissions and safety testing). It was common in the days of old for cars to be driving down the street with a cloud of smoke behind them. Nobody cared, they just said “oh, he needs a ring job”. And when a car approached 100,000 miles it was considered shot. Today, 300,000 miles is common, and even then the bodys are in good shape with many cars. So the engine gets changed.
Also, by participating in the Cartalk community one hears about all the problems, which can skew your opinion about how often they happen. Kind of like trying to judge people’s health by hanging out at the Emergency Room…
Blueprinting is most useful in a racing class that calls for a stock or :spec" engine. When everyone has to use the same parts, the difference in winning and losing is how those parts are prepared. Balancing is a must, so is making sure everything is straight and true and that all clearances meet specifications and are closely matched and at the optimum edge of those specifications.
But I would add that because of the Statistical Process Control and other advancements, today’s engines come off the production line much more balanced and with parts that fit far more consistantly than ever before. And many even use counterbalance shafts to add to the smoothness.
A few things to add:
No one seems to have mentioned that the usage of fuel injection has significantly improved cylinder and ring life, and no doubt reduced oil contamination.
Along with SPC (mentioned above,) some engine parts are classed dimensionally to match better with mating parts thereby making better use of the normal manufacturing tolerance band to get more precise end fit.
Cars these days are amazing value in terms of quality. I can’t think of any other consumer product that contains so many industrial-quality components.
Kiwi, I agree. The list of improvements to vehicle design and manufacture that make engines run longer than ever would be a very long one. There’s improved casting techniques, better alloys, better nonmettalic materials, bonding methodologies and products, robots, conformal coating technologies, far better control over the coombustion process, etc. etc. etc.