Hi,
I need to chime in here. Albeit weeks in arrears...
Blueprinting is certainly not providing zero tolerance. What it is: taking
care within the limits of the design spec. of tolerances to get the most
power. If you compete with your car, a blueprinted engine will almost
always produce more power than an engine that is not blueprinted.
Blueprinting is not porting and polishing. In fact many rules and guideline
prohibit porting etc. but allow for blueprinting. Blueprinting a stock
engine provides you with a stock engine that has the most power available
with the stock components. Similarly, lightening reciprocating components
may provide more power due to lower reciprocating loads, but in some
classes in some rules books lightening is illegal. For example in SCCA
Street Prepared Solo II, it is legal to balance an engine, but you must add
weight to balance, not remove weight.
However, if you weigh all your connecting rods from several engines and
find that one set is a few grams lighter than the other sets, you would
want to use those lighter rods in your blueprinted motor. This sort of
thing is sometimes referred to "stretching the rules", but it is almost
universally accepted as still being "legal" in the rules sense.
As an example, if the design spec for the crank calls for a journal
diameter of some number +/- .0005, if you want a motor to rev a lot, you
pick the cranks with the journal diameter that is .0005 under. By doing so,
the motor will turn more freely.
Another example is that rules bodies usually allow for "port matching".
This is a process whereby you make the ports for the intake/exhaust line up
in the most optimum manner by carefully cutting and grinding the manifolds
and/or the head. However, in port matching there is almost always a rule
that indicates that the grinding is only legal is it is done withing an
inch of the manifold interface. The result is - you get the same amount of
fuel/air flowing through, but it is less turbulent and therefore you can
derive more power.
The point is that even with design tolerances in the .0005 inch range,
there is plenty of variation between components that can make a motor more
or less powerful, and careful attention to detail will allow you to build a
motor to its real potential.
And as you may have figured, to do this properly takes a lot of time and
patience. If you are paying for these services, that translates to $$$.
Like they say: "Speed costs, how much do you want to spend?"
regards,
rml
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