What does X look like. Cylinder bore Addition

B6/7 S4/RS4
#1

Well if you have a B6 or B7 S4 your worried about a smooth cylinder wall. The scoring of the cylinder walls looks to be one of the biggest issues with the B6 and B7 motors. So what are people talking about when they say you might have a scored cylinder wall.

Generally your healthy cylinder walls should look like this.

http://audirevolution.net/addons/albums/images/791288284.jpg

Sure there shouldn’t be oil in the cylinders but its a good picture. Lets look a little closer at the walls.

Looking closer the walls should be smooth like this. Note: there is a long piece of hair in the cylinder so disregard that. Other then that its a text book great looking cylinder

http://audirevolution.net/addons/albums/images/128136538.jpg

So this motor if you compression tested it, should do quite well, given the other components are in great shape. The walls of this cylinder should be holding strong. This is a big issue when making power. You want to keep the oil below and the air and fuel trapped in the cylinder. So you want the walls to be smooth and make sure the piston rings seal.

This picture is from what might be a semi damaged motor, from a cylinder stand point.

http://audirevolution.net/addons/albums/images/911798652.jpg

You can see the scratches on the wall. There is even a chip missing. This is semi light, chances are the car was eating oil. Not a ton but it was getting oil past the rings. The scratches allowed oil to get into the chamber, from there it gets burnt with the gas. Not great for power.

This next one is just bad. This is a large scratch. From inspection you could see oil was easily getting by. It wasn’t flowing past it wasn’t stopping the car from running. It wasn’t eating oil every day but it would consume oil every 800+ miles or so.

http://audirevolution.net/addons/albums/images/838678569.jpg

This is where we will stop for today. Ill get more up tomorrow.

#2

Wow, really a great comparison. Thanks a lot! I’ll be very interested to see this thread develop as this is obviously one of the prime issues on our motors as they age.

#3

How close is this motor to my S5 FSI motor?

I would think my motor is closer to the Rs4 then the S4. Its the power levels that have me unsure if my block is more S4 or RS4

#4

I don’t recall exactly, but the RS4 is the “Sport FSI” motor, and the S5 is the “Comfort FSI” motor. They share certain aspects, but still quite different. The “Comfort FSI” motor is what is also used in the Q7 and other Audi platforms with the 4.2 FSI. To some aspect, it’s been described as a B6/7 S4 bottom end and a RS4 top end, but it’s not really that cut & dry or simple, but that gives you kind of a mental image to think about. All that said, the S5 should have a fair bit more potential then the B6/7 S4 did based on the motor design, time will tell though. Hopefully someone else can come in and correct me as well as post some more info about the differences. I think beemecer knows a fair bit more about them.

#5

Well put maddog.

To be simple. The New aluminum FSI motors are more Stout then the FI S4 motors. The S5 is lacking lots of the RS4 goodies in the chain system. Its not however missing anything in the block so your good there.

#6

x2, similar bottom end as the RS4 (not the same, but still all forged), but not the nasty cylinder heads the RS4 uses to make power at 8000rpm

#7

CountVohntastic - any advice on preventative steps to avoid wall scoring?

Also, any thoughts on a ‘cure’ for scored wall engines? People like to imagine re-honing or sleeving could solve all of our problems if our block turns into the one above, but of course then you might also need your pistons/rods replaced (to eliminate the cause) so costs skyrocket.

Are scored wall blocks simply destined to be…

http://www.superuse.org/images/1906.jpg

#8

^I wouldn’t mind one of those, ya think I could pick one up cheap from a PES car, I’m sure there are a couple trashed/blown motors out there we don’t know about by now haha.

#9

mmm pushrods

#10

Great post. Ill update this with more when I can.

In short the best thing people can do is OIL CHANGE AND MAINTENANCE and OIL change and maintenance.

The parts that tend to fail are oil supplied and essentially oil driven. If the oil gets compromised so will the supporting parts. A noisy chain rattle on start up can in some cases be fixed with just a oil change and use of a better oil.

Also the number 1 killer of this motor. The PRECATS. This is the main monster. The removal of this is going to extend the life by miles. While removal of the precats isn’t going to fix damaged components, it will help slow or stop it from getting worse to a certain extent.

This isn’t just a B6 S4 thing. Trace this back to the B5 S4. The ko3 turbos were known to blow early if you still had a precat on. Cars that removed the precats has ko3’s that lasted 10x longer. This was due in large part to the removal of the heat that gets trapped in the precat. That heat will sooner or later start to back up into the cylinders if the motor is pushed hard enough.

That is what I would call my check list.

What options are there if the motor is bad. It depends on how bad the motor is. Being that this block is all true aluminum if you get damage to the cylinder walls your going to have to gauge how bad it is and if they can be filled. There are options out there, till all the tests are done Ill have to reserve giving more advice.