So I just measured the stock pistons and they come in at 302 grams bare. Bare meaning no clips, rings, wrist pin. 405 grams fully dressed.
JE says their 10.5 compression (apples to apples) is 261 grams. Thats a pretty nice weight savings.
Anyone measure the CP's? I always prefere CP pistons but dont expect them to be any less weight than that JE.
Wrist pin wall thickness plays a big role in weight as well. Theres a fine balance between strength and weight there.....
I also notice CP makes a 2mm shorted rod. That gives us 4mm of extra stroke. Judging by the head shim I ran in the turbo, the cam chain, at least on my machine, is good for about 1.25mm of added deck height (base shim) before its out of slack entirely. Thats good for another 2.5mm of stroke. Thats 6.5mm of total stroke you could add without much trouble....except.....
How low can you go on the cylinder! These slipper pistons can only take so much rod angle as well, and we are now compounding the increased rod angle with a shorted rod AND a longer stroke. My magic number that I never wanted to go lower than was 1.6 rod ratio. Maybe 1.55 but thats cetainly my limit but would rather higher. Also depends on what your intention is on the engine.
So I need to either go measure the stock length rod or have someone who already knows the stock rod length tell me so I can come up with a ratio. CP does not say what the 2mm shorter rod length is so I need to do more homework.
Ive also used a "similar" piston with a smaller wrist pin and bushed the small rod end to gain a little more stoke in certain builds.
Of coarse you could have some custom stroker pistons made but that usually take 10+ pistons
Heres some #'s:
98mm bore with 6.5mm added stroke: 1070cc's
98mm bore with 4mm added stroke: 1032cc's
96mm bore with 6.5mm added stroke: 1026cc's
96mm bore with 4mm added stroke: 990cc's
JE says their 10.5 compression (apples to apples) is 261 grams. Thats a pretty nice weight savings.
Anyone measure the CP's? I always prefere CP pistons but dont expect them to be any less weight than that JE.
Wrist pin wall thickness plays a big role in weight as well. Theres a fine balance between strength and weight there.....
I also notice CP makes a 2mm shorted rod. That gives us 4mm of extra stroke. Judging by the head shim I ran in the turbo, the cam chain, at least on my machine, is good for about 1.25mm of added deck height (base shim) before its out of slack entirely. Thats good for another 2.5mm of stroke. Thats 6.5mm of total stroke you could add without much trouble....except.....
How low can you go on the cylinder! These slipper pistons can only take so much rod angle as well, and we are now compounding the increased rod angle with a shorted rod AND a longer stroke. My magic number that I never wanted to go lower than was 1.6 rod ratio. Maybe 1.55 but thats cetainly my limit but would rather higher. Also depends on what your intention is on the engine.
So I need to either go measure the stock length rod or have someone who already knows the stock rod length tell me so I can come up with a ratio. CP does not say what the 2mm shorter rod length is so I need to do more homework.
Ive also used a "similar" piston with a smaller wrist pin and bushed the small rod end to gain a little more stoke in certain builds.
Of coarse you could have some custom stroker pistons made but that usually take 10+ pistons
Heres some #'s:
98mm bore with 6.5mm added stroke: 1070cc's
98mm bore with 4mm added stroke: 1032cc's
96mm bore with 6.5mm added stroke: 1026cc's
96mm bore with 4mm added stroke: 990cc's