engine weight reduction and 90 degree V10s

[aspetuck]

I have 2 questions:

What could be done to reduce the weight (and for that matter physical size) of an engine. I'd be willing to do almost anything, with the probable exception of replacing the block.

My second question was about 90 degree V10s. What is the possible advantage of this V angle? If, in theory, this engine was up at, say 12500 rpm, would the vibrations be significantly higher than a 72 degree V10? What are the disadvantages?

[Lycoming]

As I understand it, main point of high V angle is to lower center of gravity height. I won't comment on the effects on vibration.

What can be done to reduce engine weight? If the original manufacturer has done their job properly, there is not much that somebody with no engineering knowledge can do in their garage that will reduce the weight without somehow completely destroying the engine.

[aspetuck]

I would presume that after boring out an engine to a certain extent you would run out of sufficiently thick block to safely bore. Would it be possible, assuming you really wanted to bore out the engine, to lightly redesign the block to contain more material? If so, how much would this cost?

[Tommy Cookers]

.... about 90 degree V10s. What is the possible advantage of this V angle? If, in theory, this engine was up at, say 12500 rpm, would the vibrations be significantly higher than a 72 degree V10? What are the disadvantages?

their main value is commonality of production tooling with V8s (modern V6s also started this way)
the vibration should be the same, the difference will be that the firing intervals will be somewhat uneven
little disadvantage

[Tommy Cookers]

I would presume that after boring out an engine to a certain extent you would run out of sufficiently thick block to safely bore. Would it be possible, assuming you really wanted to bore out the engine, to lightly redesign the block to contain more material? If so, how much would this cost?

fit liners if there's none, or fit bigger liners
or sand cast a new block with smaller cores (cores are what determines the coolant passages and cylinder walls etc)
build up the walls of your present block with Stellite or similar, overbore as desired, then use it as a pattern for your new casting
(compensate for about 1% shrinkage if casting CI or about 1.3% if it's Al alloy)
most engines have coolant all round the bores, so have scope for bigger bores by 'siamesing' (locally joining cylinder walls)
EDIT with deference to the following poster, millions of siamese block engines have been made and won WRC etc
or a combination of the above (liners will allow cylinder walls to be much thinner, as porosity doesn't matter)

mask and acid dip the block
or cast an Al alloy block to replace Iron or a Mag alloy block to replace Al alloy, would need redesign at highly stressed points

stroking is rather easier, and potentially benefits maximum power as the max rpm falls less than the stroke increase
(rpm being fundamentally determined by piston acceleration not by piston speed)

of course the max power of your engine, however modified/redesigned engine is governed by the breathing ability of the head

[Scuderia Nuvolari]

The problem with Siamese blocks is that any overheating usually ruins the block, rings, pistons and turns it into a boat anchor