BMW E90 M3, Audi RS4 & C63 AMG Battle CT4-V Blackwing: Which Is Best?

[25 V8 IS]

This is just really, really, good stuff right here. Enjoy!

[pbonsalb]

I remember when I was shopping back in 2011.I bought a CPO 2008 E90 M3 6MT and kept it 10 years. It was my first car engine that revved over 7200 rpm. I tuned it so the limiter was 8600 and did other performance mods. It was wild from 5500-8500 rpm.

The Audi tempted me due to the AWD since I live in the Northeast. The C63 AMG tempted me with the bigger, higher torque V8.

[BlkGS]

An E90 6MT is hard to argue against. Other than that motor not being very reliable.

BMW doesn't make great cars like that anymore, that's for sure.

[pbonsalb]

My E90 M3 was very reliable. The only failure I had was throttle actuators. I bought one new and one rebuilt. I changed the rod bearings as preventative maintenance myself at 60k miles. Sold the car at 110k.

The next owner did have one repair and he could not DIY so he had to pay a shop a few thousand. I forget what it was. He sold the car at 130k miles.

[25 V8 IS]

With the rod bearing issues, I'm assuming replacing the stock ones with something better is the way to go, right? How much can that cost?

[Mingwan]

Hard to beat the E90 M3. The performance from the V8 in the merc always impresses, even by modern day standards.

Maybe it doesn't make sense in this comparison, but it would've been interesting to see the ISF in there.

[spazzyfry123]

Originally Posted by 25 V8 IS

With the rod bearing issues, I'm assuming replacing the stock ones with something better is the way to go, right? How much can that cost?

Oversized like BE Bearings seems to be the choice. That’s what I used on my last E90 M3; haven’t changed them on my current one yet but am due. Depending on market, but paying a shop to replace can swing anywhere from high $1k (SoCal) to high $3k (everywhere else )

[Toad]

Originally Posted by spazzyfry123

Oversized like BE Bearings seems to be the choice.

Oversized? Wasn't the whole reason for the rod bearing issues on the S65 because the OEM bearings were oversized?

[pbonsalb]

I used the new non-lead stock bearings with WPC treatment, but this was before BE and others offered thinner bearings to increase clearance. The most popular theory for the S65 rod bearing issues is the tight factory clearance that goes beyond industry norms.

Today, I would use one of the extra clearance bearings. A few companies make them. I would also use ARP bolts because the factory torque technique for stock bearings is painfully precise and long — 3 stage torque repeated 3 times for each bolt. I helped a friend do his S65 bearings and we used Vac bearings and ARP bolts and the bolt torquing was much simpler.

[spazzyfry123]

Originally Posted by Toad

Oversized? Wasn't the whole reason for the rod bearing issues on the S65 because the OEM bearings were oversized?

The inverse is the common reason for failure that most have arrived at, but I think we may be chasing the same tail in different language. I say "oversized" in the sense of oversizing the clearance in line with what pbonsalb shows below. Perhaps you are thinking that I mean to oversize the material, which in turn would create a tighter clearance to the rod. Apologies for any confusion.

Originally Posted by pbonsalb

I used the new non-lead stock bearings with WPC treatment, but this was before BE and others offered thinner bearings to increase clearance. The most popular theory for the S65 rod bearing issues is the tight factory clearance that goes beyond industry norms.

Today, I would use one of the extra clearance bearings. A few companies make them. I would also use ARP bolts because the factory torque technique for stock bearings is painfully precise and long — 3 stage torque repeated 3 times for each bolt. I helped a friend do his S65 bearings and we used Vac bearings and ARP bolts and the bolt torquing was much simpler.