Bad news. Threw a rod and blew up my RS2ed 3B engine

[AudiCoupeParts]

Thats a good trick, calling up Ford 289 rod bolts from ARP...

If the part numbers are different, does anything need to be done to fit them ?

Thats about 500Nm torque capability on Gazzas 16VGolf info - pretty much in line with the 500-550Nm commonly talked about here.

This spark jump appears to be the root cause though - seeing as we appear to have confirmation of use of the wrong / larger rotor arm.

Paul

Well, that really sucks! THe damn dealer sold me that POS rotor. I had no idea that there are two sizes!

What an expensive mistake. So does everyone agree that the wrong rotor brought me the expiration of my beloved 3B?

Any recommendations to the rebuilding of the next motor I find? WHat should I go with? AAN? Or just build the 3B bottom with all the bigger Scat rods, ARP bolts, and Rs2 crank bearings?

Thanks to all who have contributed to my motor's autopsy.


regards,
joe

[EspenW]

Thats about 500Nm torque capability on Gazzas 16VGolf info - pretty much in line with the 500-550Nm commonly talked about here.
Paul

Not quite... think about it

Regarding bolts. They only come into play when we talk rpm (higher rpm than stock rev limit), as they must hold up to strain, not compression (rods must withstand both types of force).

[waad_uk]

We use paschens law on a few of the products we make (Thyratrons and spark gaps). These use hydrogen or deuterium as the breakdown gas.

These babies will switch up to 250kV up to rep rates of 1000Hz. We use Pachsens law to ascertain the gap between anode and cathode.

It gets really weird as the paschen curve has two sides. At very low pressures you can decrease the gap between the electrodes to get a higher breakdown voltage, which goes against your instincts

I am not sure you will get cross firing in the dizzy cap, but you can get cross talk between HT leads, as you get a voltage induced in leads next to each other. If the pressure is high in a cylinder, the the voltage in the lead for that cylinder will be excessivly high, and you will get more induced voltage in the neighbouring lead, which could ignite whilst compressing.

You will always find on cars fitted with dizzys that there is a particular way you should arrange the HT leads. Cross talk is a big problem on LPG cars if you dont organise the leads correctly.

[EspenW]

Interesting. I also suspect that a dirty dizzy cap with traces of carbon can cause spark hop..

[EspenW]

Well, that really sucks! THe damn dealer sold me that POS rotor. I had no idea that there are two sizes!

What an expensive mistake. So does everyone agree that the wrong rotor brought me the expiration of my beloved 3B?

Any recommendations to the rebuilding of the next motor I find? WHat should I go with? AAN? Or just build the 3B bottom with all the bigger Scat rods, ARP bolts, and Rs2 crank bearings?

Thanks to all who have contributed to my motor's autopsy.


regards,
joe

Not the first time this has happened, and it won't be the last..
AAN or 3B with uprated ignition. RS2 bearings, ARP bolts and Scat's sounds like good thinking.

[S2central.net]

Not quite... think about it

Regarding bolts. They only come into play when we talk rpm (higher rpm than stock rev limit), as they must hold up to strain, not compression (rods must withstand both types of force).

No, I was just saying that the figure from the Golf guys is line with what I've commonly seen as the limit expressed here... Your info with some Nordic monsters running over 600Nm on these rods (with coilpack DI of course).

Now this has been a cool learning experience here for me and it sure backs up my ascertain that Direct Ignition (DI) is much better than dissys and such - I had never known they were sensitive to this stuff.

I feel bad for Joe with his engine destroyed though - guess we found the root cause just after the nick of time, but if has supplied the wrong part then *maybe* you have some way to get back something there to help pay for the rebuild.

[EspenW]

No, I was just saying that the figure from the Golf guys is line with what I've commonly seen as the limit expressed here... Your info with some Nordic monsters running over 600Nm on these rods (with coilpack DI of course).

The monsters mentioned were actually monsters from the land of frogs (even though tales abound of Audis hitting very low 11's on stock rods in Sweden).
What I meant was that it wasn't completely correct to compare the torque limit of a 4 with that of a five. 520Nm on a 16vt means 130Nm/rod, the equivalent is 650Nm on a five cylinder

[S2central.net]

Ahhhhhhh d'oh OK - lightbulb - gotcha now - its a Monday thing obviously.


Paul

[yodasfro]

Well, that really sucks! THe damn dealer sold me that POS rotor. I had no idea that there are two sizes!

What an expensive mistake. So does everyone agree that the wrong rotor brought me the expiration of my beloved 3B?

Any recommendations to the rebuilding of the next motor I find? WHat should I go with? AAN? Or just build the 3B bottom with all the bigger Scat rods, ARP bolts, and Rs2 crank bearings?

Thanks to all who have contributed to my motor's autopsy.


regards,
joe

Yup wrong rotor the first thing I changed when I got my 200 20v. Well at least you have a bunch of 7a stuff so you can now build a proper bottom end.

[20vQC]

When I was thinking about leave the stock motronic injection on my NM (very very similar as the 7Aengine) in my AAN, I found some interesting things in a link that was posted in the forum a long time ago. It explained the differences in the ignition system of the 3B setup and I wrote on my car's notebook this:

"Is a MUST to use the bosch part no. 1 234 332 414 R1 rotors on turbo setups with single coil distributor where the electrode tip designation is R1 and indicates the resistance of 1K from the center to the end of the tip. The width of this electrode is ~11milimeters. The rotors that must NOT be used on turbo setups are the Bosch 04170/1234 332 350R1 or the Audi 052 905 225C".

Hope this could help in a near future!

[Jamo]

disagree. nothing different between AAN rods and 3B rods, yet the AAN doesn't have this problem? The answer: pre-ignition.

Thats the beauty of life we can disagree.

I've seen 5 cars now on standard rods fubar by the Rs2 turbo irrespective of tuning all it takes is one spike.

The turbo is a torque machine, run it on standard rods at your peril.

[sal_s2]

The rods are all the same, aan, adu etc
I never had a problem on my rs2 turbo'd aby running almost 2 bar mapped by mihnea.

In fact I would recommend an rs2 set up highly, probably the most usable all round street/track power you could have out of a relatively simple bolt on job
BTW 3bs are cr@p :mischeif:

[AndyP]

BTW 3bs are cr@p :mischeif:

Cheey fecker, 3B's rule

[pastures16]

does this problem only lie with 3bs is the aby up to the job

[newsh]

Joe I'm really sorry to hear about this, it reminds me though of something I posted a while back, Tuned 3Bs have been known to bend rods after having the engine bay washed or steam cleaned, the culprit is the spark hopping to the wrong cylinder. Having said that I ran 26lbs of boost (with spikes of over 30lbs) for over a year on the stock rods and got away with it. I now have the SPM rods in though and feel a whole lot safer.