Hp limit for main bolts

[Zrain25]

I'm going arp head studs, arp rod bolts and resizing the rods and should I do main studs also I'm shooting for 450whp

Can I just drop in the main studs or do those need to be resized also

 

[Dirgle]

Yes, when moving to ARP main studs you are supposed to align hone the main bores. People have gotten away without doing it but they made sure that the bores were still within spec after torquing to the new higher values with the ARP hardware. But the recommendation is still to get the block align honed. For most shops it's a simple and cheap piece of machine work so why not.

 

[Zrain25]

I know head studs are a must but are the rod bolts and mains really needed for 450hp

 

[Dirgle]

Concerning the need, my personal opinion is, for rod bolts, yes. For the mains, no. The factory hardware is already pretty robust on the mains. As far as the rods go my trust in them is not near as high, and arp hardware is cheap insurance. But at 450hp you're approaching the edges of the envelope for virgin factory rods. In addition to arp hardware they should go through some kind of stress relieving as well.

 

[Zrain25]

Ya rods have already been shot peened I was going to just get arp rod bolts. Now when I get those pressed in and get the rods resized I will have to go with a bigger rod bearing correct?

 

[Dirgle]

No, a good shop will be able to resize them to std. spec. Oversize bearing are only for if you need to get the crank ground.

 

[Zrain25]

Ok thanks

 

[Prism11]

No, a good shop will be able to resize them to std. spec. Oversize bearing are only for if you need to get the crank ground.

Undersized. The I.D. of the bearing gets smaller since the O.D. of the journal gets smaller. Oversized bearings are used in "cracked" or "broken" connecting rods since they can not have the bores made smaller, the O.D. of the bearing must get bigger for the new bore size.

Otherwise, correct.

 

[Dirgle]

Undersized. The I.D. of the bearing gets smaller since the O.D. of the journal gets smaller. Oversized bearings are used in "cracked" or "broken" connecting rods since they can not have the bores made smaller, the O.D. of the bearing must get bigger for the new bore size.

Otherwise, correct.

You are quite correct, thanks for the catch.

 

[supraguy@aol]

I don't see the need to align bore the mains simply because one switches to ARP's. Unlike rod bolts, there is no stress placed on the main saddles by switching to studs from bolts. You're just threading them in by hand after all, not pressing them in. However, I do think that align bore should always always be checked/corrected when rebuilding an engine, for the general sake of confirming clearances.

 

[Dirgle]

Some people don't. But since the new torque value is higher than the old one, there is the possibility for deformation. Just look at what tightening the idler pulley bolt can do to the roundness of the cylinder bore. Thousandths of an inch matter when you're talking about bearings. Metal is elastic and can change shape if you apply more force to it, like going from 75ft-lbs in oil to 90ft-lbs in ARP lube. Now they don't go out of round by much, and people have gotten away without align honing them. So just make sure you check you clearances. Of the three blocks I've done two needed, but only just barely, align honed for one reason or another.

 

[supraguy@aol]

Ahh. Gotcha.
That makes sense.

 

[Poodles]

450WHP = ~517 crank HP. Over 500 I'd start throwing nice parts at it (as you're over double the stock power)