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I know that a few 3.X liter 12-valve V6s have been built. Out of curiosity, what is the maximum displacement possible for this engine? This assumes both a custom crankshaft (and probably connecting rods) and new pistons and liners. This also assumes no special machining of the block.

In other words, what is the maximum stroke and the maximum bore allowable? (As an aside, I'd be curious to find out what the maximum PRACTICAL bore & stroke might be.)

Thanks in advance!

-Joe in SoFla
 

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By installing larger liners I'm pretty sure you have to machine the block to accept the larger liners. Unless you do that, you can't begin to increase the displacement.
 

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I've heard of 3.5L conversions with custom sleeves, pistons, and machining. But certainly at some point one exceeds the limitations that the designers were imposing with other design choices they made. Somewhere along the line, you end up going the route that Greg Gordon took with certain kinds of forced induction. That's probably the route I'd recommend for more oomph. I've been considering it for after the Verde goes back on the road and has been there a while.

Michael
 

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Long story - buzz me at 425.941.4747 or email me and we can talk some more - but in short; you have the option to go a bit further with the 24 valve heads (more room between the edge of the combustion-chamber and the water-jackets that lead cooling up to the top to cool the tops of the combustion chambers...)

The problem with the 12 valve is that just as soon as you try to go as far as 101-102-103mm in the bore, you start to face other challenges, such as sealing the coolant and fire-seal (more long conversations here...) On a stock 3.0 litre crank you can get to 3.5 litres with more risk (and yes, with any of these options you have to machine the block to fit the liners!)

We have standardized on a 100mm bore barrel and a 99.90 piston (actually for both 12 valve AND 24 valve) just to be safe and head-ache-free - producing 3.45 litres and all the power/torque and flexibility you could ever want! On the 3.2 litre GTA crank, (78mm stroke), you get to 3.7 litres.
 
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