28-05-2012, 09:18 AM
Remember, an XU7JP4 is essentially a stroked down Mi16... Uses the same liners for certain.
Mi16 pistons should fit, if you get low comp 1.9 Mi16 pistons, they should fit fine - at least around the bore, you will have to get custom rods made up, but it's not too much of an issue...
Essentially your conrods will need to be 1.9 Mi16 on the little end (if you use low comp 1.9 Mi16 pistons) and then XU7JP4 on the other end, but the overall length of an XU7JP4 (that's only if the Mi16 gudgeon pin width is different, but I doubt it - if it's the same, just get them to copy an XU7JP4 rod).
You'll need to do some measurements of piston crown height from gudgeon pin centre on Mi16 vs an XU7JP4 - that'll tell you how long the rods need to be, since if the crown height of a 1.9 Mi16 is say lower, combined with the XU7JP4 rods, you might find that the piston top sits too low in the bore, meaning you've got shit all compression...
I would personally get the conrods modified to accept off the shelf forged pistons - that's much easier than creating custom pistons - in a boosted petrol that was once NA you can take pistons as an expendable item if you're pushing the engine...
But then if it were me personally doing this build... I'd probably just stick a set of forged pistons on stock rods as long as the gudgeon pin width is the same for an Mi16.
Mi16 pistons should fit, if you get low comp 1.9 Mi16 pistons, they should fit fine - at least around the bore, you will have to get custom rods made up, but it's not too much of an issue...
Essentially your conrods will need to be 1.9 Mi16 on the little end (if you use low comp 1.9 Mi16 pistons) and then XU7JP4 on the other end, but the overall length of an XU7JP4 (that's only if the Mi16 gudgeon pin width is different, but I doubt it - if it's the same, just get them to copy an XU7JP4 rod).
You'll need to do some measurements of piston crown height from gudgeon pin centre on Mi16 vs an XU7JP4 - that'll tell you how long the rods need to be, since if the crown height of a 1.9 Mi16 is say lower, combined with the XU7JP4 rods, you might find that the piston top sits too low in the bore, meaning you've got shit all compression...
I would personally get the conrods modified to accept off the shelf forged pistons - that's much easier than creating custom pistons - in a boosted petrol that was once NA you can take pistons as an expendable item if you're pushing the engine...
But then if it were me personally doing this build... I'd probably just stick a set of forged pistons on stock rods as long as the gudgeon pin width is the same for an Mi16.
