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5/16 vs 3/8 rod bolts (experiences welcome)

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Old 01-08-2023, 10:58 AM
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Default 5/16 vs 3/8 rod bolts (experiences welcome)

Just wanting peoples experiences using 5/16 and 3/8 rod bolts. I read 3/8 is recommended and that makes sense. I'm thinking of buying some Chinese rods with the 5/16 for my goal of 325hp e85 only build. Has anyone here seen or heard of a failure that was related to the smaller bolts? In my build I don't plan to rev more than 7200rpm.

Also if I do get Chinese rods where can I source 3/8 rod bolts that will work with say maxpeedingrods?
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Old 01-08-2023, 12:32 PM
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I've never heard of a rod bolt failing on any Miata with aftermarket rods. Just run what it comes with. Nice to have and need to have are two different things.
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Old 01-08-2023, 12:46 PM
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The only failed rod bolts I've heard of are the ones that people forgot to torque properly...

I have 5/16 bolts in mine and it's gone to 360+ at the wheels. I don't rev it past 7500 though, and they're Carrillos, not no-name eBay rods.

--Ian
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Old 01-08-2023, 01:31 PM
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Originally Posted by codrus
The only failed rod bolts I've heard of are the ones that people forgot to torque properly...

I have 5/16 bolts in mine and it's gone to 360+ at the wheels. I don't rev it past 7500 though, and they're Carrillos, not no-name eBay rods.

--Ian
For sure thanks for the info. It seems that the 5/16 are fine for what I plan. As long as they are arp I should be ok.
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Old 01-08-2023, 06:47 PM
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Originally Posted by Hernj65
For sure thanks for the info. It seems that the 5/16 are fine for what I plan. As long as they are arp I should be ok.
Agreed. My thoughts, if going over 8K, I'd want the stronger bolts, but otherwise the lighter ones are fine.

With Carrilo's 5/16 bolts (which are $$$$ bolts) mine have seen 93XX RPM and are fine.
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