Batfink 201 Posted March 21, 2008 i'm looking at the wossner website and they list mi16 pistons at 11.8:1 compression with a 2.45cc dome volume. Now i'm a little confused. Standard unswept volume is 50.65cc with the pistons its 476.133/10.8 = 44.086cc 50.65-44.086=6.564cc chamber volume difference. Thats a lot more than the dome volume affecting the compression ratio. Even if the new piston TDC matched the deck height of the block that still only gains an extra 2.2cc So whats the bit i'm missing? Share this post Link to post Share on other sites
ginjaspeed 0 Posted March 21, 2008 i'm looking at the wossner website and they list mi16 pistons at 11.8:1 compression with a 2.45cc dome volume.Now i'm a little confused. Standard unswept volume is 50.65cc with the pistons its 476.133/10.8 = 44.086cc 50.65-44.086=6.564cc chamber volume difference. Thats a lot more than the dome volume affecting the compression ratio. Even if the new piston TDC matched the deck height of the block that still only gains an extra 2.2cc So whats the bit i'm missing? Sorry to correct your calculation but it's 476.133/11.8 = 40.347cc This is more missing than you thought! Maybe they just expect anyone who's ordering these pistons will also skim there heads! Share this post Link to post Share on other sites
ginjaspeed 0 Posted March 21, 2008 sorry, my bad forgot to minus the one because the head volumes not included Share this post Link to post Share on other sites
Issam 0 Posted March 21, 2008 How much you guys paying for wossner's? Share this post Link to post Share on other sites
B1ack_Mi16 67 Posted March 21, 2008 My calculations on the Wössner pistons lead me to a comp. ratio at approx 12.3:1. Piston sits 0.5mm over deck at TDC. Volumes: Head volume: 40cc Headgasket volume (1.3mm thick, 83,5mm bore (anyone know for sure what the standard gasket thickness for the Mi16 is?)): 7.1cc Upwards piston dome: -2.45cc Reduced volume due to piston sitting 0.5mm above deck at TDC: -2.7cc Swept volume: 476cc Total unswept volume: 40 + 7.1 -2.45 - 2.7 = 41.95cc Comp: (476 + 42)/42 = 12.3:1 Share this post Link to post Share on other sites
Batfink 201 Posted March 21, 2008 I worked out the standard gasket is roughly 1.2mm - 6.49cc Where did you get the overdeck info? Share this post Link to post Share on other sites
B1ack_Mi16 67 Posted March 21, 2008 I worked out the standard gasket is roughly 1.2mm - 6.49ccWhere did you get the overdeck info? It says 38mm comp height in the piston spec. So... 224.5mm (block height) - 143mm (rod length) - 44mm (crank throw) - 38mm (comp height) = -0,5mm Voila... You worked out the std gasket is like 1.2 is fair engough, same as I worked it out to be 1.3mm. But if anyone has measured one after it's been clamped that would be the best I think Share this post Link to post Share on other sites
