cookstar

iTrader: (6)

Have heard this term when peolpe talk about rebuilds and other stuff

I have never known what it means, anyone care to educate

Ben v7

A standard engine is built within certain tolerances, allowing a degree of variance from perfect, which would be exactly as designed. Blueprinting is where an engine is assembled such that it matches the optimum settings to a much higher level than from factory.

scooby-k

when making engines at a rate of 20 per hour the tolerences have to be fairly wide to accomadate production. thats why you get some cars that appear quicker than others. I had a 98 uk 2000 and it flew! much quicker than others I have driven. I grind gears for gearboxes and the tolerences mean that one gear assembled on a mainshaft can have 0.005m clearence and another 0.03m As Ben says blueprinting is making sure these tolerences are the optium size required.
ken

cookstar

iTrader: (6)

Thanks guys

I kinda understand it a bit better now

TonyBurns

iTrader: (3)

As above but will add a bit
Basically, if you have say an engine Blueprinted, it wont be for a production road car (so the old saying that STI's have blueprinted engines is a myth).
First of all, it takes tollerances down to the absolute minimum to gain the best out of the engine, secondly, it doesnt last as long as people think, ie 1k and your rebuilding.
One example of a blueprinted engine is an F1 cars engine, but the engineering work needed to get it to such close tollerances is very expensive, hence they cost quite a lot more than your normal run of the mill engine.

For:- more efficient
Against:- considerably more expensive

Tony

cookstar

iTrader: (6)

Bob Rawle

Early STi engines were blueprinted, my STi2 wagon was a case in point, the original documentation confirmed.

bob

NotoriousREV

Jesus, 3cm clearance?!

Tim-H

When I was a boy a few years ago, working on the escorts , mini`s etc , blueprinting was getting the original factory "blueprints" ( they were blue :-) which was the original spec for the engine , the getting everything as close to spec as possable , without going over the sizes , ( to adeare to regs) something like a mini head could be as far as 3mm smaller on an inlet port than spec`d to be, pistons were quite often under and different from one and other . other things like opening the stud holes then "doweling" the manifolds, as often they did not line up from new, oh and my all time favorite job (NOT!) matching head chamber capacities and lapping valves.
as factory tolurences and casting qualities (sp?) back then they were,,,,,, hmm dependant on if it was monday , wednesday , or last thing on friday, (my Dad worked for BL :-)
modern cars are a lot better and I would say don`t need it unless you are building a race car, most of them probably get better standard tolurences now, than we did by hand back then, things have come a long way , running an engine without first balencing all the bit`s back then would not have been good,
Have a good xmas all
Tim

Chelspeed

An example explains best.

Say pistons come with a nominal diameter of 86mm, the engine maker will tell his piston maker I want 86mm +/-0.1mm. So he gets pistons between 85.9 and 86.1mm diameter.

Say he needs 0.1mm clearance between piston and bore. If he therefore tells his block maker to make bore sizes a nominal 86.1mm then the same +/-0.1mm tolerance will mean the bores range from 86.0mm to 86.2mm. Some of the pistons will be bigger than some of the bores. Not big or clever.

So he tells the block maker I want 86.3mm +/-0.1mm. This means he can just build engines by sticking any piston in any bore (quick and cheap) and he will never get less than 0.1mm clearnance. But he may get as much as 0.5mm clearance (85.9mm piston, 86.4mm bore). It won't blow up but it won't be the quickest.

Enter the factories race team, they use the same block and pistons but they "blueprint". They go through the parts bin and measure everything. From the million blocks in store they pick the one with four off 86.2mm bores. Then they measure a zillion pistons and pick 4 off at the upper tolerance of 86.1mm so optimising the 0.1mm clearance.

It was this 0.1mm clearance that the engine designer was aiming for. He quoted this clearance on his original engineering drawing which was copied and given to the machine shop and engine builder. Old style, pre cad, drawings were copied by a process that produced copies that were blue, hence "blueprint".

An aftermarket engine builder can do similar but he's likely to pick the first four pistons he gets (but from a race piston builder who does better than +/-0.1mm tolerance). Then he bores the block undersize, measures the piston diameters exactly and then hones each bore to exactly the right size to get the required clearance.

Blueprinted engine will have exactly the same life as an off the shelf engine since clearances etc are the same as some of the factory engines, the best ones, just they are all the best ones.

The only way engine life would be compromised would be if you chose tighter tolerances and pushed the metallurgical limits of components by increasing revs, reducing weight of components. This is why some race engines need 1k miles rebuilds (but usually measured in hours rather than miles) and not because they are blueprinted.