assuming headgasket

[joelk2010]

Was going to say, if you tighten the pd150 bolts to "normal" specs you are wasting your time from my experience.

 

From memory, I think we added another 90 degree which prevented the head lift for good

Edited 22 May, 2015 by joelk2010

[alex_e3]

Bloody hell I would be really worried they'd snap if I went another 90!

 

I spoke to Darkside about the problem (who actually answered my email very quickly!), and they suggested doing another 90, but warned that they may break.

 

Personally I don't fancy having to get a snapped bolt spark eroded from the block. Although I'd like to not have to spend nearly 200 quid on something that the PD150 bolts would do just as well!

[coskev]

Was going to say, if you tighten the pd150 bolts to "normal" specs you are wasting your time from my experience.

 

From memory, I think we added another 90 degree which prevented the head lift for good

The pd150 bolts are a higher tensile, so not wasting your time upgrading to them.

Not a sniff I would try an extra 90degrees on new pd150 bolts,even if the bolt could take it it would either snap the bar your using or round off the torx part in bolt imo.

[silky16v]

Th common practice in the cosworth tuning circles fit the small turbo head gasket with standard bolts with an extra 90deg turn on them

did many many engine builds this way never had an issue

Alex th if your going bigger setup I'd be removing your cylinder head and inspecting it anyhow for cracks and heat damage

[joelk2010]

From my experience I ran them at normal spec and got head lift after running 2.7 bar for a few k miles.

Changed them out and torqued to spec plus the extra 90 and never had a problem in the rest of my ownership.

[coskev]

Th common practice in the cosworth tuning circles fit the small turbo head gasket with standard bolts with an extra 90deg turn on them

did many many engine builds this way never had an issue

Higher torquing figures though as standard on the pd engine than a cosworth, so not really a good comparison.

[sepulchrave]

Additionally the YB suffers from block distortion when using bolts which is why long-stud conversions are essential for higher boost applications.

 

So all in all a truly terrible comparison. 

[SKYHAWK]

studs kit it is :(

[Lofty]

An extra 90 degree turn on the already high torque setting on a PD150 head bolt seems mad.

 

How long is your breaker bar LOL!!!

[sepulchrave]

High tensile steel has a yield point dangerously close to its ultimate tensile strength, hence the danger of the magic *plink* sound.

 

Stretch bolts work by using the the material's inherent elasticity to apply the clamping force without reaching the yield point, the elastic limit is not really that much higher and once the bolt starts to yield the clamping force can actually reduce.

 

It is impossible to judge these things by feel, once a bolt yields it is effectively useless because the elasticity is gone and with it the clamping force.

 

Feel can only tell you if the bolt is good or no good.

 

I HATE angular torque settings because they're so inexact, they're designed for mass production so reliable assembly can be performed by idiot robots.

 

It's perfectly possible to use a torque wrench on stretch bolts and you'll get much more even clamping if you do, but it needs to be a GOOD quality calibrated torque wrench.