David,
Does the crack start from the bottom and go up? Can't tell from the pic but is that bracket not crack completely through?

 

RT, You are correct on both counts... the crack starts from the bottom and works its way up and in this case i caught it before it broke all the way thru... It is now as big as when i discovered it. At that point i reinstalled the check valve setup and the crack has not grown any larger...

 

Thanks for the Pics David!

That crack looks like what you'd expect if you were to load the bracket in the up direction toward the passenger side
I'll go stare at my engine for a while and see if I can

 

Just saw the SC dyno #'s on Comptech website. Does anyone notice a slight improvement in hp/torque in this pdf?
http://www.comptechusa.com/images/dyno/s20...upercharger.pdf
I remember an old thread talking about the SC actually loses a few hp/torque below 3,500 rpm.

 

Well, looking closer at the way the bracket is rotated to line up with the top of the mounting plate, the load direction seems normal (tangent to the system's rotational center) for a fatigue type failure from the rotational vibration of the whole assembly.
Can't explain why the failure happens sooner to the Ghostboosted cars but I'm pretty confident it will eventually happen on the other installations as well.
I think it's just a matter of time. We'll see I guess.

Idea:
I wonder if that same exact bracket were made from a different material (different inherent spring rate) if the whole system would suffer less from the harmonic we've all learned to love/hate (you know, the vibrator on steroid stick shift effect; see: http://www.s2000online.com/forums/showthre...p?threadid=9336 )
It maybe time to fire up the milling machine.
I think I am willing to part with that crazy harmonic vibration and having the piece of mind that the bracket won't fatigue "can't be hurt'n neither".

Definitely don't want to go off half-cocked,................... but,.......... what do ya guys think?

 

>>Can't explain why the failure happens sooner to the Ghostboosted cars but I'm pretty confident it will eventually happen on the other installations as well. <<

I agree.

* It still seems to be too early to tell if this is a GB only issue. Low sample size. And maybe the GB owners are more carefully scrutinizing their cars and/or driving them harder as a group which may accel the discovery.

* Apparently various brackets are failing. Not just one bracket which always fails in the same place.

* Aluminum has an endurance limit of ZERO. Eventually it will crack even under light loads if it sees enough cycles. Conversely steel can handle certain loads pretty much indefinitely. High revving I4s are buzz bombs - this is hard on the bracket longevity. Lots of E30 M3 I4s have broken cast iron and steel brackets after many years of use. And these are pretty beefy brackets. Stress riser issues or sometimes a fastener loosens up a bit from the vibes which loads the bracket improperly. Perhaps it would be a good idea to check the comptech bracket fasteners from time to time for adequate torque.

* As RT says, perhaps ALL of the SC brackets will eventually fail. Maybe the GB'd car's bracket failures are simply an early warning red alert thing.

* Specialty cars tend to have unusual useage patterns. Some S2ks are driven 2000 miles per year while others see constant vtec and lots of open track action.

* From what I am reading so far, it appears that a bracket redesign may be needed. Aluminum could still work well if the endurance limit issue is considered. Perhaps steel would be the path to a complete fix.

* Maybe some crank damper work would be beneficial too.

Stan

 

so maybe something as simple as a harmonic damper would fix the prob - read: rubber grommet

 

or maybe a titanium bracket?

 

heh yeah, but a grommet would be like 50 cents and maybe some milling to adapt the size.

I love Ti!

 

SixthGear,

That is the same dyno chart we've always had on the site. It's the one from the guy in Phoenix who got our first production kit.