Anyone have specs for the Rod Bearing clearance’s for the CFSA motor? I can find it for the regular 4.2FSI, and for the 3.0t V6, but not for the CFSA. I’ve also got the specs for the Main bearings. I know I can probably ballpark it but due to the high revving nature, and the fact that the CFSA doesn’t share the same Rod Bolt Torque specs as either the 4.2FSI or the 3.0t I’d rather have the exact specs. Thanks
Lemme see if I can find something. BRB.
From the 26.5k mi engine with the seized #3/7 Rod bearings. This is Rod Bearing #8 below. I did use some Plastigauge and they showed what is probably within spec…still need to find out the spec, about .035mm, about .0014". They look like new on the two outer sides and in the middle they show wear which is where they receive oil from the Crankshaft.
.0014” is a little skinnier than I thought they’d be. I was hoping for at least .0020”. For reference, the s65 in the M3 turned out to be a nominal of .0009” and as little as .0004” leading to their abysmal engine life. I’m looking too, trying the 5.2L research route.
What’s the CFSA journal diameter?
Found it. WOW the range is big (.0008"-.0027") and yours is right in the middle. Can you perhaps get all of them, for science?
Some more thoughts on this…typical bearing clearances are .0075"-.001" PER INCH of rod journal diameter. Our journals are 54mm or 2.126". Can you verify that for me? If that number is true then our clearances should be around .0016"-.0021" (says basic engine building guides) vs the .0008"-.0027" (says audi). It’s also said that high RPM cars should add .0005" to the clearance, giving around .002" clearance minimum that I mentioned before. My concern is twofold: i hope that these clearances aren’t the root cause of failure because after all the M3’s S65 clearance issues, fixing the issue will be very expensive for us, and that supercharged cars will put even more stress on the rod bearings. .0014" won’t cause failure like the .0009" nominal bearings on the S65, given that you bearing has 50% more clearance than the average S65 bearing, AND we don’t use 60W oil like they do from the factory. Getting more clearance data from the CFSA motor will help us understand a bit more…
First of all, thanks RS5. I have the damn manual and must have looked through it twice and still didn’t see it.
Second of all, I did Torque to 40NM but then I did the additional 120’ that is the normal Rod Torque procedure. That extra 120’ does make those bolts tight, kind of scary tight.
Thirdly, the Plastigauge I used was very old, probably still good but you know how plastic degrades with age. I have a new set of Plastigauge and a Rod Bolt strain gauge on it’s way. I’ll check a couple of the Rods again and while I’m at it to get an idea I’ll check a couple of the Rods on the 99k motor.
So my plan is to use the King Rod Bearings, ARP fasteners, Plastigauge every one of them on install, and use a Strain gauge rather than Torque for more accuracy.
The 99k motor definitely looked like: Oil Breakdown, dirty oil, contamination? I really wish at the time I had sent a sample out for oil analysis but I knew the engine was seized when I got it. The 26k motor had come from a wrecked car and sat for a couple of years and who knows how it was stored, condensation? Old oil that turns acidic? Also wish I had tested this one before failure. Third engine from wrecked car I purchased. Started right up and drove it up on my trailer, oil analysis sent and came back with flying colors. Even with the Oil analysis I still want to inspect and change the bearings.
Good to know we can take that .0014” with a grain of salt right now. Very much looking forward to seeing a full engine of clearances for a better idea of the design. The King bearings are some of the best but they like to have +-.001 and coatings. It’s probably a good idea to get OEM clearances and variance before you order.
I was also looking at determining a more appropriate oil weight based on the bearing clearance. The chart I’ve attached has some basic values on it. Currently I use Castrol 0w-40 euro and I’ve had great results with it. I drive the car very hard on occasion, pushing oil to 240+. I like the 0W for cold start protection and the 40 for extra high temperatures. I ran this oil in all my turbo BMW’s that would reach 250+ on 20 psi of boost regularly and it was very good. However, during cruising, which is 90% of my driving, oil temps barely get over 200. Perhaps 40 is too heavy for tight clearances, but so far I’ve got no evidence to support that, quite the opposite in fact.
Specs seem a little tight but the spec for the older 4.2’s is shifted just a little tighter:
Clearance when new 0.015 … 0.062 mm
Wear limit 0.12 mm
And checked with 30Nm Torque on cap instead of the CFSA 40Nm Torque on the cap.
On my #2 engine #1/5 Rod journal I measure 2.129" with a cheaper dial caliper.
Crankshaft bearing / Crankshaft conrod
j
Basic dimension
67.000 – 0.026
– 0.042
54.000 – 0.024
– 0.040
Repair undersize
66.750 – 0.026
– 0.042
53.750 – 0.024
– 0.040
How’s the new engine and bearings? I will most likely have a shop replace rod bearings if I supercharge mine. I can never get enough preliminary information to ease my mind. Also what did your last post mean exactly?
Been lazy in my free time lately. Finally went out and used my new fancy Digital torque wrench and torqued the rod bolts a few days ago, also installed the plastic oil splash shield under the crankshaft. Was ready to install the upper oil pan but realized I was missing one odd shaped O-ring (there are around 4 specific shaped O-rings). The engine schematics from Audi are not the easiest to read. Waitng for that single O-ring to hopefully get the engine buttoned up. Then I’ll need to still transfer over the JHM Headers, LWCP kit, and install the new S6/S5/RS6 Flexplate.
The last post is just the Rod Bearing journal size specs for the Crankshaft, somebody PM’d me about posting the specs from the manual.