Archived posting to the Leica Users Group, 2001/01/19

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Subject: RE: [Leica] OT Blueprinting
From: Jem Kime <>
Date: Fri, 19 Jan 2001 17:24:45 -0000

Thanks John,
much appreciated.

- -----Original Message-----
From:	John Collier []
Sent:	19 January 2001 15:10
Subject:	Re: [Leica] OT Blueprinting

Blueprinting refers to the practice of taking a standard factory engine
completely apart and adjusting every part to its optimal spec; making it
match the blueprints. Similar parts are made dimensional the same and the
most advantageous weight and size. So the crankshaft bearing surfaces are
machined so that the crank is in exactly the right place, the bore centres
are machined to be exactly perpendicular to the crank centreline, combustion
chambers made exactly the same volume, piston deck heights the same, all
ports line up exactly.....etc. While in theory this will result in a "stock"
engine, it actually provides a significant power increase over a standard
production line engine as all the production line variances in individual
parts tend to reduce efficiency. This was common practice for factory test
cars in the sixties which is why the test cars always were much faster than
production line vehicles. I used to work on Russian Lada cars and there was
a huge difference in performance between similar new vehicles. We discovered
the "main" culprit one day by accident. The intake manifold ports on some
cars lined up so poorly that half the port was blocked! With today's modern
factory production methods and machining, there is not much difference
between a production line and blueprinted engine.

Certain classes of racing would allow certain modifications (or none at
all). For instance you could blueprint your engine but not balance it (all
rotational masses made equal and counterbalanced correctly). It is common
for race winners of restrictive classes to have to remove their heads and
have the bore and stroke checked.

"Gosh! I did not realise my engine was 20 cubic inches bigger than stock. It
must been a factory mistake!"

John Collier

> From: Jem Kime <>
> Jo,
> I have always thought of 'blueprints' as technical drawings (produced by
> the diazo process) for mechanical (and other) projects, but am aware of the
> phrase 'blueprinting' an engine which seems (to me) to have be used along
> the same terms as 'gas-flowing', ie. creating a more aerodynamic
> environment for the fuel and exhaust routes.
> Please could you explain exactly what 'blueprinting an engine' is and if
> you've any knowledge of how that phrase came to be used?
> regards,
> Jem
> -----Original Message-----
> From: []
> This is just like "blueprinting " one of my Drag car engines , I love that
> .
> Jo Goodtimes , France .