Help needed! Crankshaft differences!

[EBR]

Hi all.

I know this has been discussed before but I didn't find the answers I'm looking for.

I have three crankshafts, one AAN, one 3B and one probably from a 7A. The AAN and 3B are identical but the third crank is a bit different. It is cross drilled, just like the one on the right in the picture here in this thread:

http://www.s2forum.com/forum/showthread.php?t=18969

And its oil pump collar only has two keys, the other cranks have 4 (opposite to the cranks in the picture where the non cross drilled only has two keys!).

I have been trying to search for info about the cranks to see if the one that is cross drilled is worse in any way. By using google I have found something about cross drilled cranks in general and it seems like it is not a good thing to have them cross drilled but usually it doesn't matter.

I still haven't checked if they weigh the same, but the counterweights look smaller on the cross drilled crank.

Has anyone here used the cross drilled 5 cyl cranks for high hp, high reving engines? Are they any worse than the 3B/AAN/ABY cranks?

Thanks in advance, Eiríkur

[Pirvu Eugen]

The one you think is from 7A...is not...is from old 10v engines...KV, HY...i had that in my engine....yes, the one with big rods journals...as there are some with smaller diameter rod journals. I am sure that, in few minutes, UrS4Boy will let us know from what engines the old type crank was and if they were used on early 7A engines.
IIff it was me...i will choose the old one iff is in good order.
Goodluck!

[UrS4boy]

... I am sure that, in few minutes, UrS4Boy will let us know from what engines the old type crank was and if they were used on early 7A engines.

Don't hold your breath on this one. Last time I checked, there was only one crankshaft PN left in the system and unless I have the old PN to start with, I can't search to see what else it came in. That said, I will give it a shot.

[EBR]

Don't hold your breath on this one. Last time I checked, there was only one crankshaft PN left in the system and unless I have the old PN to start with, I can't search to see what else it came in. That said, I will give it a shot.

I know that now the crankshafts all have the same PN in Kate. But that doesn't change the fact that some changes were made at some point in the past, for example they stopped using cross drilling. And I would like to know if the cross drilled cranks are suitable to be used in high hp, high reving engines

[UrS4boy]

Don't hold your breath on this one. Last time I checked, there was only one crankshaft PN left in the system and unless I have the old PN to start with, I can't search to see what else it came in. That said, I will give it a shot.

This is all that I am going to take the time to find:

MC, MB = 034105021K

RT = 034105021G

WR, GV, WX =035105021

KW = 035105021K

KV, HY, JT, NG, KU, NF, 7A, RR, 3B, AAR, AAN, ABY, ADU
= 034105101S

[UrS4boy]

... And I would like to know if the cross drilled cranks are suitable to be used in high hp, high reving engines

I think you need to ask yourself which crank did Audi decide to install in the later generations of the inline-5 engine and why (cost? reliability?). Alternatively, which cranks have people used in high hp, high revving I-5 20VT engines?

To me, cross drilling has the potential to weaken the crank.

I will let others finish this discussion.

I'm gone.

[Pirvu Eugen]

Can you post the numbers from both cranks? 034K...etc...
I have both in garage..but i have to dig alot for them...
Is interesting the cross drilling thing..never thought at this...this maibe is the answer why Audi changed the oil path inside the crank...
Again...thank you UrS4Boy!!!

[EBR]

Can you post the numbers from both cranks? 034K...etc...
I have both in garage..but i have to dig alot for them...
Is interesting the cross drilling thing..never thought at this...this maibe is the answer why Audi changed the oil path inside the crank...
Again...thank you UrS4Boy!!!

Both the AAN and 3B cranks do have 034K on them but the cross drilled crank has 034A.

Here are some pictures that show the difference.

1. picture: 3B crank, the oil passage goes straight from the main journal to the rod journal.

2. picture: The main journal is drilled all the way through.

3. picture: The rod journal is also drilled all the way through.

4. picture: For each oil passage to a rod journal the crank has to be drilled 3 times and one hole needs to be blocked.

[blackS2]

Both the AAN and 3B cranks do have 034K on them but the cross drilled crank has 034A.

Here are some pictures that show the difference.

1. picture: 3B crank, the oil passage goes straight from the main journal to the rod journal.

2. picture: The main journal is drilled all the way through.

3. picture: The rod journal is also drilled all the way through.

4. picture: For each oil passage to a rod journal the crank has to be drilled 3 times and one hole needs to be blocked.

I have a spare crank from 7A engine with exactly the same cross drilling...

[EBR]

Is there no one that has any experience with the cross drilled cranks, good or bad??

[quattro84]

In theory better because oil distribution is more homogenious (if the oilpump can supply enough flow but i reckon it is fine to use )

[Tonks4x4]

I have had and used the cross drilled cranks without any issues and know of others on here with high HP using the same cranks.

I think even Jeffer with 1005bhp is using a standard crank too.


Tonks4x4 - The Land Rover Specialist

[EBR]

At first I also thought it would just mean better oil distribution. But I started having doubts after reading this for example:

" There's a lot of things that were all the rage over the years that when modern analysis was applied, were proven to be not effective or harmful. There have been things that became "standard" that are still done to cylinder heads that actually hurt them as far as flow is concerned. I actually debated with myself before posting as this is one of those subjects that's a lot like politics or religion. Arguments almost always ensue. One side says "I've done it and it hasn't broken therefore it is good" and the other side picks it apart and asks "why is it good or bad."

The common consensus in the OEM and racing world is that you lose oil volume and pressure to the rod bearings at higher RPM's. There's some good, published work by TRD engineers out there on the net, but there's also a lot of info that trickles from the racing industry. The bottom line is, if you don't have an oiling problem, cross drilling is not needed and will not help the situation. If you have an oiling problem, before you cross drill you need to figure out why you have the oiling problem. What cross drilling can cause is aeration of the oil and reduction of volume to the rod bearings. Overcoming centrifugal forces getting oil to the gallery connecting to the rod journals requires higher pressure and increased volume to overcome that tendency.

Mind you, this is an issue that comes at much higher levels of power than many people see. There have been a number of cross drilled crank engines in high levels of competition over the years that did well. There are also engines that had problems that resulted from using one. The key is, if you aren't having problems, don't try to fix something that isn't broken. Cross drilling was originally done to try to help with flow to the rod bearings. At high RPM it starts to take away flow from the rod bearings unless the pressure and volume are increased. If the pressure and volume are increased, the rod bearings get more oil at an increase of parasitic loss required to make more oil pressure.

It's an argument with no end as it can be made to work either way. In a "stock" type oiling system, running a cross drilled crank will decrease oil to the rod bearings at higher RPM. If you use a full groove main bearing, you get more oil to the rods at the expense of hydrodynamic wedge in the mains. If the power level is such that full groove main bearings work, then it's all a moot point. If you start to kill main bearings, then you can experiment with 210 degree bearings or try more volume through the system.

It's like anything else in the performance world. You trade something for something. Nothing is a magic bullet unless all the ramifications are allowed and compensated for. A lot of things in engine building get done simply because "so and so said so". I've done things that customers wanted simply because they were listening to their friends and people on the forums. I'll do them as long as I don't feel they'll hurt anything, but try to steer them away if I think it will end up hurting things in the end.

I attended the School of Automotive Machinists a year and a half ago to learn what industry was doing and try to keep abreast of the state of the art while learning to build current tech race engines. I subscribe to Race Engine Technology and read everything I can get written by Gordon Blair and Don Terrill. I'm by no means an expert on engines, but I do analyze everything to try to understand the "why" when someone says to do something. I'm one of those born skeptics that wants a reason for everything I guess!

I don't want to step on anyone's toes, as there are plenty of people on both sides of the issue. Like I said, I debated before posting in the first place. "

Taken from: http://theamcforum.com/forum/cranksh...734_page1.html

And this: http://rehermorrison.com/tech-talk-5...calls-part-ii/

So now I'm not sure if it is such a good idea to use if you want to rev the engine past the original 7300 rpm Although there they are talking about cross drilling cranks that aren't cross drilled from the factory.