I recently uprgraded my turbo with a 62mm compressor wheel and housing along with a 14cm n/wg turbine housing. I have started to get coolant puking out of the overflow under high boost situations and am assuming the hg has let go. I had a 16cm turbine housing with the HX35, but i only see 5lbs more boost (40 total) with the new combo. My question is are the drive pressures higher with the new turbo combo than with the old, and if so is it enough to be worried about putting another stock hg in?

If i do need more than a stock hg and bolts what would you recomend?
-A stock gasket with 12mm studs?
-Or would a cometic gasket be something i should look into?

 

I don't want to comment on your DP because I don't really know what your particular turbo will be at but I would have guessed lower with the new one?
You might want to do a line torque on the engine and see if it seals it up for a little while longer to buy you some time. A new gasket and a set of studs should hold fine, I personally don't think the MLS gaskets are the way to go unless you are resurfacing both the block and the head.

 

So you don't think that high drive pressures would have been the cause of the headgasket failure, maybe it was just time for a new one?

 

I would think that your TIP increased when you changed to the smaller turbine housing -especially since it's non-WG'd.

Based on your reported compressor boost increase of 5psi, however - it's hard to guesstimate the increase (if any) in drive pressure... since you now have a more responsive, higher-TIP 14cm and a larger, higher-boosting 62cm (as opposed to what - 58cm?) compressor wheel.

In any event, IMO if you trashed your HG it was due to running a tighter, non-WG'd turbine - while not monitoring TIP - with the same engine tune...

 

In my opinion when we decide to up the anti and run more fuel and higher boost pressures like we do it's only a matter of time until the HG fails. I have hit 50 psi on several occasions and have since dialed things back a bit,at least until I can get some studs and a better gasket.