D3 Test Drives

[Teejay1]

Originally Posted by ChrisE

Shortening the connecting rods would not reduce the swept volume. If we assume that you want to use the same block casting then you need to change the crankshaft so that it doesn't move the pistons so far up & down the bore & then INCREASE the length of the rods to get the height of the piston up the bore at top dead centre to be the same as before changing the crank to keep the compression ratio etc the same. This would use the original pistons. As an alternative you could increase the height of the piston above the gudgeon pin & then use the same rods as before.

The D3 engine is going in the new S60. Are they due before the D3 XC60's? At least you could try the engine.

I would have thought they'd reduce the size of the block and corrosponding metal work making the whole engine more compact and lighter. Then retune the engine and turbo to suit?

[Daleman]

I was amazed the other day when a Volvo salesman said to me the D3 engine will be great ,have you noticed how the SC60 is nose heavy? Well it wont be with the D3 engine because it’s a lighter unit better suited to the car .Oh I said surely it’s the same 5 cyl engine that’s already in the D5 basically so the weight will be much the same ? No he said it’s a lighter better engine .Oh I said !!!!

[ChrisE]

When motor companies make a range of engines cost is normally of critical concern as are the number of different parts that they need to make/ supply etc.

Traditionally the cheapest way to make different engine sizes has been simply to drill different sized holes in the block casting. This means that the engines are pretty well identical apart from the pistons. Easy & cheap but the long stroke smallest engine often isn't the best.

The second way is to reduce the stroke using a different crank & rods but everything else is the same including everything that bolts to the engine. That is a lot of parts!

The most expensive way is to reduce the height of the block with a new casting, change the crankshaft but keep the rods & pistons the same. Hopefully most of the parts that fit bolt to the engine will still fit. This isn't common, to the best of my knowledge but would make a lighter engine which the others don't.

I have no idea which way Volvo have done this but we know that it is 2, 3 or some method that I haven't thought of. My money is on 2.

My original point was that changing the length of the con rods alone does NOT change the engine capacity.

I do wonder if the much lighter unit is the new 2.0 petrol engine that is being supplied in some markets.

[Daleman]

Yes got the message changing the length of the connecting rods does NOT alter the engine capacity.