Tsunamix
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Let me settle it for you -
There are technically only 2 ways to break/bend a rod. Application of excessive acceleration (Brute force) and Work hardening (brittle shatter due to to strecth).
Fact one. Material governs stretch and stretch recovery. Choose your materials well. Bear in mind that EVERY material has a limit on how much stretch it can handle, and how often it can handle it. The amount of stretch is generated by piston head acceleration. This comes from a mixture of cubic capacity of the combustion chamber, compression ratio, fuel being burnt and the length of stroke. The higher any one of these numbers is, the higher the acceleration (and deceleration) forces are.
Fact 2. Revs themselves do NOT kill a rod. Run at 6.5 to 1 compression ratio at rev to 20,000 rpm and your accelerative forces aren't as high. However - run at High revs, Hi compression ratio and long stroke and your rods better be the best in existence.
Fact 3. The weakest point in any conrod is the smallest point of contact. This can be the rod bolts, or possibly the small end journal. In these instances - bigger is better - but you CAN go too big and have no material holding the bolt/journal in place. So pick the very best quality.
There is a long stroke ducati motorcycle engine that has an oval piston, that runs at 13:1 compression ratio with a turbocharger, and revs to 20,000 rpm all day. It has 2 conrods per piston. Maybe thats the best explanation righ there.
There are technically only 2 ways to break/bend a rod. Application of excessive acceleration (Brute force) and Work hardening (brittle shatter due to to strecth).
Fact one. Material governs stretch and stretch recovery. Choose your materials well. Bear in mind that EVERY material has a limit on how much stretch it can handle, and how often it can handle it. The amount of stretch is generated by piston head acceleration. This comes from a mixture of cubic capacity of the combustion chamber, compression ratio, fuel being burnt and the length of stroke. The higher any one of these numbers is, the higher the acceleration (and deceleration) forces are.
Fact 2. Revs themselves do NOT kill a rod. Run at 6.5 to 1 compression ratio at rev to 20,000 rpm and your accelerative forces aren't as high. However - run at High revs, Hi compression ratio and long stroke and your rods better be the best in existence.
Fact 3. The weakest point in any conrod is the smallest point of contact. This can be the rod bolts, or possibly the small end journal. In these instances - bigger is better - but you CAN go too big and have no material holding the bolt/journal in place. So pick the very best quality.
There is a long stroke ducati motorcycle engine that has an oval piston, that runs at 13:1 compression ratio with a turbocharger, and revs to 20,000 rpm all day. It has 2 conrods per piston. Maybe thats the best explanation righ there.
