CALE12 Posted March 3, 2009 Report Posted March 3, 2009 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 ? Quote
philbey Posted March 3, 2009 Report Posted March 3, 2009 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. Quote
CALE12 Posted March 9, 2009 Author Report Posted March 9, 2009 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 Quote
styler Posted March 9, 2009 Report Posted March 9, 2009 yeah what philbey said, look up static vs dynamic compression ratios too Quote
Teddy Posted March 9, 2009 Report Posted March 9, 2009 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 Quote
philbey Posted March 9, 2009 Report Posted March 9, 2009 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 Quote
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