12 replies to this topic

[minivan2007]

I have looked on google and can't find the info on the factory spec of the 998 engine does any one know where to find the info I need so I can blueprint my engine , thanks

[mk1leg]

the Blueprint engine well you would have to source many parts so basically every con rod is weighed and you choose the four that are the sane weight then theres the head valves and springs and the collets rockers and basically thats a blueprint engine no tuning is involved........

[Cooperman]

Quite simply you can't.

To 'blueprint' you need the manufacturing drawings for each individual part so that you can optimise to the upper or lower tolerance limit as appropriate. Blueprinting is only for competition cars where the regulations are critical and you don't want to get disqualified for having dimensions outside those designed for.

For example, a crankshaft will have a tolerance on diametric 'throw' and when blueprinting the journals are ground to be at the maximum throw allowed. Also, the big-end journals will be exactly opposite for 1 & 4 compared to 2 & 3. In practice they won't be exactly right, so 'blueprinting corrects this. It is known as 'indexing'.

Then there are the tolerances on cylinder head thickness and you combine this with the maximum service amount which is allowed to be skimmed off to give best compression ratio without cheating.

The same applies to rocker shafts, camshafts, pistons, etc.

In the 'works' competition dept's it was common practice for a selection of production components to be taken off the line, then accurately measured to select the ones with the very best sizes. They were the ones used. Alternatively blank castings and forgings were taken and precision machined, at huge cost, to give the optimum dimensions allowed for on the detail drawings.

Blueprinting really only applies to what was/is Group 1/Group N, as higher groups allow more modification and machining of components.

[Spider]

When you say 'Blueprinting' do you real mean 'Optimise'?  Not necessarily making it any 'Hotter' in it's state of tune, just making what's there work with as least losses as possible and  possibly increasing engine life?

[minivan2007]

Building an engine by following a set of factory specs. Ie making sure tolerances are .00275" main bearing clearance where as a the factory specs say anything from .0015 to .0030"

[Cooperman]

Machining tolerances are so much tighter nowadays with full CAD/CAM techniques. But think what it was like back in the 60's &70's, which is the Mini's era.

BY using parts with tolerances at maximum or minimum, the maximum power was achieved without breaking the Gp 1 or Gp N regulations.

For example, a Group 1 Ford Mexico with a fully 'blueprinted' works engine would have a lot more power than one straight from the showroom by as much as 5% to 8%. That is enough for a class win without it being illegal.

Bearing clearances were normally set to the maximum stated to reduce crankshaft drag. It mattered not if the engine needed rebuilding sooner.

Camshafts were specially ground and pistons were selected to get the minimum and equal weight, the same going for the con-rods.

It was a very expensive procedure and could cost as much as a more highly tuned Group 2 engine if done properly.

The class-winning aspect of a Group 1 car was important and I once rallied in a full 'works' Hillman Avenger with a factory 'blueprinted' engine. It certainly went well and beat all the Mexicos, even the 'works prepared' ones, which was the object of the exercise.

There is no point in blueprinting unless entering competition where standard engines are mandated. The current 'Endurance 1400 cc Rally Class' is one place where this would work, although these days more is achieved by 'tweeking' the electronics.

[minivan2007]

I am building a high revving engine I have already had con rods balanced etc I just wanted something to do with my free time as I've got a rather long holiday and I have excess to cnc machine and lathes etc

[Fast Ivan]

I'm not sure the factory specs will give you the info you want, if your building a high revving performance engine then the clearances aren't going to be the same as a standard factory spec engine, I'm not sure where you would get this info other than from top engine builders 

[ACDodd]

PM me I have the info you will need.

AC

[minivan2007]

Pm'ed

[mk1leg]

I don't think I was far off the mark with My answer.....

[lawrie124]

PM me I have the info you will need.

AC

 

AC

 

Is his something you would be prepared to share on here?  ... or shall I PM you?

 

Mike

[ACDodd]

The answer is not what you think. It is not a list of factory sizes. It is a list of tolerances that you as the engine builder must set inorder to maximise the success of your build. That's info that won't be going on here.

AC