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75mm crank VS 79mm crank purposes

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Old Mar 6, 2020 | 06:52 PM
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Default 75mm crank VS 79mm crank purposes

Hello all,

Forgive me for the newbie question but what is the difference between the 75mm stroke crankshaft and the 79mm stroke crankshaft?

Which one is used for which engine? What are the pros and cons of each one and why would one use that or the other?


Thanks,
ET
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Old Mar 7, 2020 | 09:01 AM
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75mm stroke relates to 2.0 and 2.2 engines / 79mm stroke is used for the 2.5 engine...............

if you have an early <98 centre thrust block then to use any of the later higher spec cranks you would need to convert to "rear thrust" by correctly machining the block cases
if you wished to "stroke" either the 2.0 or 2.2 block then you can use the 79mm crank with suitable custom pistons / rods to achieve this
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Old Mar 7, 2020 | 09:08 AM
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Originally Posted by stockcar
75mm stroke relates to 2.0 and 2.2 engines / 79mm stroke is used for the 2.5 engine...............

if you have an early <98 centre thrust block then to use any of the later higher spec cranks you would need to convert to "rear thrust" by correctly machining the block cases
if you wished to "stroke" either the 2.0 or 2.2 block then you can use the 79mm crank with suitable custom pistons / rods to achieve this

Thank you for the info!

Are there any performance differences between centre thrust and rear thrust or is just a modification done for the crank type?
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Old Mar 7, 2020 | 12:34 PM
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later rear thrust 'heat treated' or 'nitrided' cranks have greater strength than the original design
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Old Mar 7, 2020 | 01:51 PM
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Originally Posted by stockcar
later rear thrust 'heat treated' or 'nitrided' cranks have greater strength than the original design

Got it.

Thanks a lot!
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Old Mar 9, 2020 | 09:47 AM
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all really depends on what you are trying to achieve as the original centre thrust cranks are generally reliable if not abused too highly.......
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