Mythbuster: continuing project thread of my 1303 '75 - Page 18

paul_f · #1 March 6th 2010, 12:40

Excellent news!

The settings would be very useful.

Humble · #2 March 6th 2010, 14:23

I'm an hour away from Laguna Seca, Jason you should stop by on your way down. It'll give you a chance to drive on my favorite roads

70Turbobug · #3 March 8th 2010, 04:41

Hi Wally! Great video! You said you were running on the wastegate only? Still very fast..

Wally · #4 March 8th 2010, 04:52

Thanks, well, yes on wastegate, but mind you, this is already 14.5 psi wastegate

Acceleration was very fast, but cornering speed was just so-so as I didn't want to take any chances

Sandeep · #5 March 8th 2010, 12:03

Great news about the PID and great video Wally !

My brother just bought a 2007 Audi RS4, so I have to keep up with that now, track day is scheduled for June 26th !

Looking forward to more incar video from you

Sandeep

**NO_H2O** · #6 March 14th 2010, 22:10

Scatching my head too. Glad you didn't hurt anything but the rockers.

**owdlvr** · #7 March 14th 2010, 23:45

I guess the rest of your rockers are suspect now?

I wonder if a dye kit would help confirm the rest are good to use. http://www.indanc.com/flawfinder_layout_ink.php

-Dave

wrenchnride247 · #8 March 14th 2010, 23:52

You are very lucky Wally! Glad that's the only damage done.

Sandeep · #9 March 15th 2010, 08:17

Wow ! I'm glad there was no other significant damage to your engine ! That is a very puzzling break for sure.

Sandeep

Jim · #10 March 15th 2010, 08:45

I'm glad you have past this with the less cost effectiveness.

70Turbobug · #11 March 15th 2010, 14:28

It is odd that 2 broke on the same cylinder.I´ve seen that happen on V8 cars that ran into the rev limiter on their burnout,it happened to my Mustang back in 1992.I broke 3 rocker arms due to valve float when I ran into the limiter (set it lower after that

),but they were all on different cylinders.Other than that,I would say that they just wore out and broke,stress cracking and fatigue. But very lucky indeed that it didn´t take a bunch of other parts with it!

Clatter · #12 March 17th 2010, 03:49

It's just too coincidental that they are both on the same hole side by side...

Detonation?

Evil Detonation, specifically?

Wally · #13 March 17th 2010, 05:56

Quote:

Originally Posted by Clatter

It's just too coincidental that they are both on the same hole side by side...

Detonation?

Evil Detonation, specifically?

No, its not from detonation, that I know for sure as I had the vid running showing the knock sensor not sensing knock when it happend.

Mark, its not from 'worn out' reasons either as no wear is visible. Wear by definition should always be measurable/visible. Not likely either as they run on DLC treated rocker shafts...
But I do also think pure metal fatique could be the most likely cause, probably combined or caused by a does of bad luck from coinciding ignition and/or fuel cut-outs all at once and overboost cut-outs during the tuning I did the days before. These are/can be rather violent.
I have no other explanation as these original rockers are really considered as 'unbreakable' otherwise.

Steve C · #14 March 19th 2010, 00:18

Hi

I'm no metallurgist, could you take them to maybe a local aeronautical engineer and ask their opinion.

Steve

**owdlvr** · #15 March 19th 2010, 01:42

I've done a bit of failure analysis in the past, doubtful I could tell from photos but if you post closeups of both sides (broken side) I can at least take a look.

-Dave

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