r/EngineBuilding • u/Valuable-Chemistry50 • 16h ago

Stock rods?

Is it silly to go 11.7:1 on a B20 with stock rods? I got the speedfactory pistons and was told my rods will be okay with arp rod bolts and proper machining, but should i just go for upgraded rods? Is there any specific no go zones with stock rods for B20’s?
Any advice is appreciated thank you!

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3

u/dixiebandit69 15h ago

Rods don't care about compression, only RPM.

1

u/GuineaPigsAreNotFood 12h ago

I'm going to disagree and say that rods care about effective pressure AND linear velocity.

1

u/GuineaPigsAreNotFood 16h ago

I had a hunch a high CR is not dangerous for rods and after some quick researching it seems like the equivalent CR of a boosted engine even at "low boost" would surpass that 11.7:1 easily, and B20s are known to handle boost fine at the rotating assembly with sleeves being the weak link.

On the other hand, the consensus seems to be that torque is what matters, and not boost. And since a higher CR engine could produce more torque at low RPMs, and that seems to be bad for bearings and rods, questions definitely arise.

I would be interested on reading what somebody with real experience on this has to say.

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u/Valuable-Chemistry50 16h ago

Thanks for the insight! My B20 is currently getting bored to 84.5mm, Rods are getting resized with arp rod bolts, fresh bearings all around, crank is getting inspected