March 3, 200917 yr comment_324327 What is the max psi can you got to before running into trouble :| i want to push the limits !!!!!! (i am running 211psi with NGK bp6eys)no probs yet ? Report
March 3, 200917 yr comment_324343 Why do you want to know? PSI doesn't give you compression ratio if that's what you're getting at. MY 5K Runs ~200 PSI but the compression is about 11:1. That isn't a relationship though as the comp ratio is a Volumetric function. Report
March 9, 200917 yr Author comment_326035 Why do you want to know? PSI doesn't give you compression ratio if that's what you're getting at. MY 5K Runs ~200 PSI but the compression is about 11:1. That isn't a relationship though as the comp ratio is a Volumetric function. OK i thought the psi was the main Table to work from ? how do you work out ratio then Report
March 9, 200917 yr comment_326057 yeah what philbey said, look up static vs dynamic compression ratios too Report
March 9, 200917 yr comment_326128 Swept volume (size of motor - ie 1300cc) = Pie r squared x stroke of motor Engine capacity = swept volume x no of cyl Compression ratio = (Swept volvume + Clearance volume ) divided by clearance volume Report
March 9, 200917 yr comment_326195 You also need to factor in things like ring land to piston crown, piston diameter, dish volume, deck clearance. This is the list I sent my engine builder to calculate my compression ratio: Bore Diameter: 3.248 inches Stroke: 2.874in Cylinders: 4 Combustion Volume: 18cc Crown-Deck distance: -0.0118in Piston Valve Relief: 0 Compressed Gasket Thk: 5 thou? Gasket Bore Diameter: 3.268in Piston Dish Volume: 8cc Outer diameter of piston at crown: 3.177in Piston crown to ring land distance: 0.276in Report
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