All critical high strength fasteners work by being stretched or what they are clamping going into compression. The different designs determine how much to achieve the required clamping load. Torque to yield is one method to compensate for thermal expansion. How much can you stretch the bolt before it breaks? Those special bolts allow more. For all those broken rods, the bolts weren't the failure. The bearings failed, then the shells turned and wedge in there and that blew the assembly apart. Why do we see it more on the 2.1L? There are more, they run harder, increased stroke made for a bad rod angle, oil pressure issues and temperature issues, etc. Rod failures are always a symptom of something else happening first. For the non-stretch bolts I have taken a part many a beetle engine where the rod nuts have actually come loose and I have even had some fall out with oil changes. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Chris Szpejankowski
Sent: Friday, November 13, 2015 12:24 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Power & MPG Summer/Winter

Non-stretch rod bolts in 1.9. 

Wysłane z iPhone'a

Dnia 10.11.2015 o godz. 20:55 Dennis Haynes <d23haynes57@HOTMAIL.COM> napisał(a):

> Stronger in what way? I guess if you read or heard it anywhere especially on the internet it must be true!
> 
> Only Tuesday, not Friday yet.
> 
> Dennis
> 
> 
> 
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Dan N
> Sent: Tuesday, November 10, 2015 8:51 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Power & MPG Summer/Winter
> 
> I heard that the 1.9 engine is stronger than the 2.1...
> 
> also you may want to add some of Lucas fuel treatment...
> 
> http://lucasoil.com/products/fuel-treatments/lucas-fuel-treatment