ARP rod bolts and main studs. Worth it?

[E30arsen]

So I'm almost done with my 3.1 stroke build and was wondering if it's worth spending the extra change on arp rod bolts and main studs or would I be fine with oem bolts?
I plan on running a redline between 7/7.5K

[ak-]

At that rev I would say absolutely.
The stock ones will hold nicely imo, but while it's un-assembled I'd do it for peace of mind. Cheap insurance.

edit: talking about rod bolts, not mains.

[Northern]

I've never heard of either of them failing. I'd say it's a waste of money for a stroker, maybe worth it for some sort of high boost monster.

[digger]

Standard oe bolts work fine

But Imo Rod bolts yes because of rpm do you get good insurance , pretty much all aftermarket rods come with them and the 24v rods you can get them. Must resize rods if you do change the fastener or torque method from when rod was originally honed to ensure they are still round as different methods produce different distortion.

Mains not needed but it's convenient for assembly as they are reusable where as BMW claim you need to replace cheap enough to replace. You are also recommended to line hone when doing this.

[E30arsen]

Then I think I'll just get ARP bolts for the connecting rods. Thanks for the help. I've been struggling to come to a conclusive decision.

[ak-]

I've never heard of either of them failing. I'd say it's a waste of money for a stroker, maybe worth it for some sort of high boost monster.

Boost wouldn't be much of a multiplying factor of stress on the con rod bolts.
It's change in piston direction (TDC and Bottom DC) where the load is greater as RPM goes up - so being stroked, I'd say it's more worth it for a stroker rather than bewst.

[apostate]

^ True.

So I'm almost done with my 3.1 stroke build and was wondering if it's worth spending the extra change on arp rod bolts and main studs or would I be fine with oem bolts?
I plan on running a redline between 7/7.5K

These RPMs are senseless unless you are using a 300+ camshaft with a big overlap and CR over 12:1.

OEM bolts would hold up with no problems up to 7-7.2K RPM.

[E30arsen]

^ True.



These RPMs are senseless unless you are using a 300+ camshaft with a big overlap and CR over 12:1.

OEM bolts would hold up with no problems up to 7-7.2K RPM.

Well I'm running a 288 cam and 11:1 CR. So I'm on the edge of what you're saying. I have a feeling the stock bolts would hold up, but since I have the engine apart I just did the rod bolts. From what I've heard from members, the main bolts are super stout.

[digger]

a 3.1L with that cam with itb kit will make peak hp about ~7000rpm so redline at 7500rpm seems reasonable

[Northern]

Boost wouldn't be much of a multiplying factor of stress on the con rod bolts.

Thinking more about peace of mind of ARP's protecting $10k+ worth of turbo gear vs stock bolts.

[ForcedFirebird]

Main bolts are not TTY and can be reused, if they are replaced I would suggest an align hone. Some people think it's ok to swap in ARP, but it will distort the bores a measurable amount. I have yet to have a rod bolt fail, and most of our builds use new stock bolts. Again, ARP will distort the bores, so they will also need to be resized (check with the product, a few of the new stuff matches OE specs so rod bearings can be done in the car on the newer recalled bearings).

[E30arsen]

Main bolts are not TTY and can be reused, if they are replaced I would suggest an align hone. Some people think it's ok to swap in ARP, but it will distort the bores a measurable amount. I have yet to have a rod bolt fail, and most of our builds use new stock bolts. Again, ARP will distort the bores, so they will also need to be resized (check with the product, a few of the new stuff matches OE specs so rod bearings can be done in the car on the newer recalled bearings).

Thanks for the info, never would've thought there would be any issue with swapping bolts. I ended up keeping stock main bolts and just swapping to ARP bolts for the connecting rods.

[digger]

Main bolts are not TTY and can be reused, if they are replaced I would suggest an align hone. Some people think it's ok to swap in ARP, but it will distort the bores a measurable amount. I have yet to have a rod bolt fail, and most of our builds use new stock bolts. Again, ARP will distort the bores, so they will also need to be resized (check with the product, a few of the new stuff matches OE specs so rod bearings can be done in the car on the newer recalled bearings).

the BMW TIS says to replace but i agree there wouldn't be any issues reusing. i checked prices and they are actually expensive for what they are