dhess

All you experts out there i need your help.

Thanks,

Dominik

marcucci

Not that I can think of. I can't think of any engine that would sustain damage in an overrev that wouldn't be valvetrain related.

S2KYSK

Is AHM trying again to blame owners again for mechanical failure?

Over-rev causes valves to float resulting in piston(s) coming contact with valve(s). other than that what I gather from various sources F20C1 is capable of revving past 9K with different valve springs.

Disclaimer: I am not an expert.

chris_barry

DHess,

Been following your threads on the Aussie forum. Have you had your rods, rod bolts and pistons crack tested. I'd put money on an insufficiently torqued rod bolt, or a failure in one. Honda uses bolts that are ordertorqued, and the bolt elastically deforms ( stretches to longer than their original length) to a design clamping pressure. The bolts can develop cracks, or stretch more than intended leaving the rod cap only clamped properly by one bolt. The rod cap will eventually fail and the insides end up on the outside. ( without an overrev)

I have seen these failures on Toyota 4age engines that use the same bolts. When you crack test the remaining bolts they all have cracks starting to develop. I normally replace them with APR bolts during a rebuild. The ARP bolts are not plastic deformation style.

chris_barry

Let me correct myself before I received a deluge of corrections.

Toyota uses plastic deformation rod bolts. The design and shape is completely different, but they operate the much the same way as honda bolts.

Elastic deformation returns to it original length when you remove the load, plastic over stretches the bolts so they end up longer when you remove the load. The bolts are designed so the plastic deformation load, is the same as the intended clamping pressure.