Blueprinted Engine

[triumphelan]

Could someone define "Blueprinted Engine ",I have seen this mentioned on this forum but am unsure exactly what it meens

[hatman]

Well, here goes....

A blueprinted engine is one that has been taken down, all parts checked, adjusted where necessary and set up exactly in accordance with the manufacturer's design specifications.

All mass-produced goods, engines included, incorporate a range of tolerances incurred during the manufacturing process whereby two engines, ostensibly the same, can produce widely different power outputs.

Blueprinting is a painstaking re-build to get back exactly to specification. It's used, I believe, where engine tweaks or other add-ons to give more power are prohibited. I believe that the removal of casting irregularities and a bit of mild port-polishing is permitted in blueprinting but no modifications beyond that.

Is that right, Rohan?

[rgh0]

Like most jargon "blueprinting" means different things to different people.

I have normally seen it used in the context of building an engine such that all dimensions or specifications are moved in the right direction within the specified tolerance range to maximise power output, reliability and / or smoothness.

For example - matching all the combustion chamber sizes so that each cylinder is the same and at the top end of the specified range of combustion ratio.

or

Matching the alignment of the carbs and exhaust headers to the ports to minimise any flow loss from missalignment

or

matching the weights of all the pistons to the minimum and exactly equal

etc etc for each element of an engine

All of this can be done within the context of the standard engine specification or within the context of allowable modifications for a particular competition class.

You see lots of people claiming to have a "blueprinted" engine for sale but rarely does anyone put in the time to do it properly and then sell an engine as they would never get their money back on the time spent to truely do every component in an engine to the level of detail and quality required. The guys who do it properly do it for their own purposes and dont sell the engines.

cheers
Rohan

[iain.hamlton]

I think the key is that advantage is made of the tolerances. So, for instance, the lift a cam is allowed by the manufacturing process to be between two limits, the larger one is chosen in the blueprinting process. This is applied to every parameter so friction is reduced; air-flow maximised; strength maximised; balance perfected; weight minimized, etc. So while the engine is in production tolerance in every way, the whole assembly makes quite a bit more power than any production engine.

As Hatman says, I am sure Rohan will know more about this.

best regards, iain

[mikealdren]

Hatman, Yes you're right. All production manufacturing is to tolerances. The idea of blueprinting is to optimise the dimensions to get the best performance within these production tolerances.

Methods include:

Lightening and balancing moving parts: crank, pistons, conrods etc.

Adjusting to optimium values within tolerance range e.g. skimming the head to maximise compression ratio.

Matching components: combusion chamber volumes, piston and con rods etc.

Surface finishing: Polishing sufaces, porting cylinder heads etc.

Optimising set up: Valve clearances, timing, carburation etc.

You can get significant performance improvements without changing the engine specification and this is particularly useful where competition rules limit modifications.

regards
Mike

[GrUmPyBoDgEr]

As far as I can remember the term "Blueprinting an engine" came about when Formula Ford came into being.
These cars were permitted to use only standard Ford Cortina GT engines of 1600cc.
As has been previously mentioned all of the engineering drawing (Blue prints) tolerances were used to a maximum in whatever dimension to improve the power of the engine.
No physical changes to the engines was permitted.
For example the weight of the con-rods could be optimised but shot peening or polishing was not permitted.
The idea was to provide a cheap racing formula where all drivers had (almost) identical hardware to compete with.
Blue printing became very much a "black art" & turned out to be an extremely expensive way of getting all you can out of an engine without "tuning" it.
By that I mean specially manufactured competition compoments in the engine.
I think that people who use the term "Blueprinted" for road cars today are not aware of the implications & I would be wary of them.
Cheers
John