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rederic48
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Hello
I am building a 2.2 engine and was wandering if their is a difference between the 2.0 standard conrod and that required for a 2.2 crank using HC pistons. Can somebody please advise me on this matter?
Thanks

Esprit2
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Lotus 2.0 and 2.2 rods are the same... it's the pistons that are different.

If nothing else is done, the 2.2 crank's longer stroke will push the piston up higher, beyond the block deck, and it will collide with the head.

In order to prevent that, you must either...
1) install shorter rods, or
2) install pistons with higher wrist pin bores.
Usually one or the other, not both. Technically, there's no reason why you couldn't change both, as long as the 'total' change ended up being appropriate. However, changing two parts would increase a manufacturer's costs compared to changing just one part, so typically only one part is changed.

Lotus chose to use different pistons with higher wrist pins. As long as you're shopping for different pistons, also consider going with a higher compression ratio. 11.5 would be no problem in a performance engine. Or, stay with a lower compression ratio if you're building an easier to drive, better low-end torque motor.

Regards,
Tim Engel

Last edited on 04-22-2023 04:01 am by Esprit2

rederic48
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Many thanks Tim for the very informative information.
Regards



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