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Reynard38
02-20-2007, 09:46 PM
So ARP doesn't make rod bolts for the M20. Who does make upgraded bolts for our engines?

peerless
02-21-2007, 12:40 AM
To be honest the factory bolts are a very qaulity fastner and is used in M20 racing engines as well as stock engines.

I think alot of people think that 'torque to yeild' bolt are bad and prone to failure. This is simply not true. A 'tty' bolt is actually a very desirable fastener.

The initial torque, say 15 ftlbs in the M20 rod bolt serves to preload the fastener in a even and consistant fashion, then the additional angle/degree pull places the fastener at about 75% of its 'yeild' strength. This is considered its strongest point.

With the M20 rod bolts you do the initial 15ftlbs and then an additional 70* pull. This equats to about 45-48ft lbs. Consider the fact that the factory main caps are only torqued to 45-48ftlbs.

This is subsequently why you will not find any other manufactures of this rod bolt, it can't be improved apon. Its already pimptastic :)

The statements above are as I understand it. I am not claiming to be a bolt technician or specialist. I implore you to do a search of torque to yeild bolts. If you find any information that contradicts or adds to what I have said, please tell me and the others so we may all learn.

Reynard38
02-21-2007, 10:06 PM
To be honest the factory bolts are a very qaulity fastner and is used in M20 racing engines as well as stock engines.

I think alot of people think that 'torque to yeild' bolt are bad and prone to failure. This is simply not true. A 'tty' bolt is actually a very desirable fastener.

The initial torque, say 15 ftlbs in the M20 rod bolt serves to preload the fastener in a even and consistant fashion, then the additional angle/degree pull places the fastener at about 75% of its 'yeild' strength. This is considered its strongest point.

With the M20 rod bolts you do the initial 15ftlbs and then an additional 70* pull. This equats to about 45-48ft lbs. Consider the fact that the factory main caps are only torqued to 45-48ftlbs.

This is subsequently why you will not find any other manufactures of this rod bolt, it can't be improved apon. Its already pimptastic :)

The statements above are as I understand it. I am not claiming to be a bolt technician or specialist. I implore you to do a search of torque to yeild bolts. If you find any information that contradicts or adds to what I have said, please tell me and the others so we may all learn.

Thanks Peerless. I've got a new set of BMW rod bolts on the way. My engine builder concurred and said they are very high quality. Looks like the motor will come together next week (at least the long block)

chris325ix
02-22-2007, 12:22 AM
stock rod bolts are fine. they have been using the same design for ages all the way up to modern M cars. if the stock rod bolts are good enough for an E46M3, they are good enough for my lowly M20. ;)

Restoman
02-22-2007, 02:03 AM
What are your intentions with your motor. The M20 bottom end is pretty solid. I don't think the bolts would be the weakest link. Nor the rods. I would put some cash into the pistons though. But only if you wanted to spice things up.