Blueprinted engine

[Zef]

Excuse my ignorance...but what is a blueprinted engine ???

[Milu]

One built to the tightest tolerances shown on the original design. I.e. as close as possible in manufacturing terms to zero tolerance.

[charleskieffner]

every rod/piston is weighed and all match. tightest tolerances held on every part. truly the way all motors should be built, but very time consuming.

[Zef]

Thank you very much to light up my knowledge...

[livi]

As an example, I think Porsche blue printed the 88-89 Carrera Club Sport. They still claimed original 231 ponies but apparently they usually bench 240-250 bhp.

[charleskieffner]

bottom line. motor will last a very very very long time if not abused. when my 3.2 takes a dump, we will balance and blueprint it. ya get what you pay for.

example .........build SCORE 1600 motor w/hecho en mexico/brazzilia parts it will run but it will not last under severe service. build same motor out of german parts(tighter tolerances) and motor will last entire season of beating the living snot out of it! WFO throttle PINNED ALL DAY AND NIGHT LONG racing off road.

[Nine9six]

Originally posted by charleskieffner
every rod/piston is weighed and all match. tightest tolerances held on every part. truly the way all motors should be built, but very time consuming.

What is described above, is actually some of the efforts performed on a balanced and blueprinted motor. You can add all the fasteners on the rotating assy. to be match weighted. The crank gets balanced as well. Threads on the fasteners get prestretched, and then torqued to spec. You can go to the engine building section, to see some of the detail, these guys get into. Its quite facinating.

[livi]

So, if I understand correctly, a blue printed engine will not only produce more power but also last longer/wear less ?

So this is perhaps one reason why one engine will last very long, the other needing a rebuild early ? By coincidence every stock engine is assembled more or less close to blue print ? I wonder how Porsche in general stack up against other marques in this regard ?

[Dan in Pasadena]

All factory parts are produced from a design and all designs have tolerances. Obviously, the designer intended the part he spec'd to be produced as close as possible to the specified dimension but gave a tolerance in recognition of mass production reality. Same applies for weight.

If a given engine is produced pretty much "nut on" the specificed dimensions and weights, then the highest reliability and power production THAT DESIGN IS CAPABLE OF PRODUCING is what youl will likely get. You might even exceed the designed power output levels. But not be too much. And since it is very, very close to specificed values you will get outstanding reliability - but only if the specified maintence (at a minimum) is religiously kept up. And of course assuming the car is not abused with regularity.

[charleskieffner]

it really comes down to a time issue. assembly lines work w/one set of tolerances. race engines have tighter tolerances and more time is expended. to make every assy line engine to balance blueprint specs would be cost/time prohibitive. ask your shop cost on total engine rebuild. then ask them cost of balance blueprint engine costs. more time more bucks. a FAT RACING SCORE 1600 motor(all blueprinted/german parts) can easily hit 15K. thats a piss ant 1600!!! but they will live an entire off road race season until a teardown is needed.

translated to just street use.............the motor should with proper care..............OUTLIVE YOU!

[Tyson Schmidt]

Like Dan in Pasadena said there are tolerances.

The extra power in a blueprinted engine comes from getting the cams on the high end of the spec, (lift and duration) the compression ratio nuts-on, and the ports free from any flaws or irregularities that would cause them to flow less.

American V8's benefit immensely from this, since the tolerances are very wide compared to a Porsche. But there's still a little on the table.

[Dan in Pasadena]

Tyson, How're things going in the Bay area?

I forgot to mention your comment about how American engines can really benefit from extra attention but less so for Porsche parts. Couldn't agree more.

[randywebb]

Yeh - make us up some ceramic rotors for 15" wheels...

[Zeke]

Tyson was the first to touch on the compression issue. Not only are the heads cc'd for volume, but the deck heights of the pistons are made to be equal. You can balance the rods, but that doesn't ensure they are all the same length. The list goes on: Valve springs are matched, spark plugs are indexed so they all sit the same way and all ports are matched in diameter to the manifold that bolts up. It goes deeper than that. All angles are checked for square like the piston pins to the bore.

You can check as you go building an engine and before the rings go on the pistons, it's surprising how easy the motor will turn by hand. That's one of the major points for blueprinting. You get more HP just because the motor uses less power to overcome its own friction.

This was a good question and there's lots of info on the Net about blueprinting and building engines.

[Wil Ferch]

At least during the air-cooled era...Porsche engines were about as "blueprinted" as they could come from a series-produced factory...certainly much better than the average US car.

- Wil

[john70t]

At 5,000 rpm(measured at the crankshaft) the piston is accelerating, stopping, accelerating and stopping again. Very quickly, again and again.

Any extra space in any of the bearing surfaces would mean the oil layers seperating the metal surfaces might collapse when they "slap" together, and start making the engine into a self-propelled internal mill. Same goes for any unbalanced weight, etc.
More shows up with badly-manufacturered parts, but they usually show up after 100K miles with proper use. The quality of oil these days is excellent and makes up for a lot of it.

[BK911]

The way it was explained to me was...

To blueprint an engine you take everything to factory specs. For instance, if a setting is x mm +/- y mm, you set it for x mm, minimizing or eliminating the tolerance y.

One difference between American and Porsche engines is that Porsche spec'd a tighter tolerance. ie the y values are much smaller.

[A Quiet Boom]

I think Milt summed it up nicely. And yes American V8's really benefit a lot from blueprinting. My limited experience with Porsche engines lends me to believe they are of much tighter tolerance than most, about like a mildly blueprinted street engine. Believe it or not indexing the sparkplugs is worth a few ponies. CC'ing the heads, matching deck height etc. it all adds up in the end.

It costs more up front but the pay off in reliability is worth it, at least for the V8's I've built. With the initial cost of a 911 engine plus a rebuild I wouldn't even think twice about blueprinting and balancing, cheap insurance IMO.

[randywebb]

Wil - Weren't there some cars (or rumors) where they put out motors that were beyond the avereage by observing closer tolerances?

[dd74]

Excellent thread. I do wonder about rebuilt motors, and if it is a common practice with respected rebuilders to balance and blueprint engines as they rebuild them. In short, is this practice included in the rebuild as they already have the engine in pieces in front of them?

FWIW, I've heard the same as Wil about stock Porsche motors. I even once recall hearing ALL air-cooled engines are balanced and blueprinted in the factory, which could be a reason it is so difficult to obtain huge amounts of reliable aftermarket horsepower from these engines w/o swapping out p/cs, cams, and induction.

To illustrate what b&b can do for an American car, one only needs to look at the '85 Buick Regal Turbo, which when supplied to C&D and R&T magazines, the testers were astounded that the car went from 0-60 in 4.9 seconds and developed over 300 hp, when it should have developed in the low 200 range.

Yep...it was a ringer car with a balanced and blueprinted V6 Turbo who also had its electronics and boost levels fiddled with.

That car spawned the Buick Regal GNX.