I'm wondering if the cover survives a thrust failure. Because I have a fap on my 71 and the 599 garage sale doesn't appear to have a fap. Or is it a matter of case by case ?

 

turbine pressure is always higher than boost pressure. so turbine always gets pushed toward compressor cover. depends on how bad the thrust play was and for how long. so yeah case by case basis. I like non shrouded covers better. far better low end boost response. really enhances drive-abilty.

 

Ok I've heard that there's a hit down low for some up top but.. I need a turbo and trying to find the best course of action ... Thx I'll have to pop the snap ring

Next time I have it anodized maybe it helps lol

If the pressure goes that way wouldn't the turbine try to escape ? Robert said it goes back and forth exacerbating the issue.

 

on my recently fail hta grn, the cover survived.

did the comp wheel touch the housing, yes, but just slightly....can barely detect it with your finger nail, but the wheel did touch the housing. comp wheel isnt re-usable.

as close as the tolerances are, your results will most likely vary.

I to have a 71hta & i went from the oem cover to the surge ported model. surge ported housing definitely did its job. There is a definate difference in spool-up & low rpm response when going from the oem cover to the surge ported unit.

so much so, i am toying with the idea of modifying the oem cover to help relieve some pressure, but not as much as the surge ported cover.

For example, i easily made 27psi @ 5k for example on the oem cover, with similar preload after swapping to the surge ported cover & the same ebc settings, the boost @ 5k was now ~24.8.....that cover is simply a intentional boost leak.