Dave951

I haven't seen the Holset variant in person but I can speak from experience with garret GT30R.

Using the K24/K26 replica hotside will ASSIST in bolting up the stock crossover but it will not eliminate modification. The GT turbo is going to sit lower and slightly different angle at the crossover mating flange then what was originally present. Therefore you'll have to make some accommodations to the crossover. This will also depend on how you mount it since that will also change how high or low it will sit. Lightly grinded stock mount with appropriate oil drain adaptor (Like ATP sells) is one route.

On the downpipe side that will just bolt up.

odonnell

Thanks for the info. I'll need to take measurement of the HX35. It bolts to the stock mount (once clearanced) so oil drain is not an issue. The feed will be custom of course.

Dougs951S

I don't follow the turbo forums too closely right now; I just finished a successful NA engine rebuild and am gearing up to build a new 951 engine, but I'm still in the planning stages. Michael, myself and another one of our buddies have been discussing the HX35 turbo for some time. We all want to use this compressor; but this thread is not the proper place to discuss our reasons for that choice. We have been discussing dual scroll for a long time, and that is ultimately how we will eventually go, I think. In the mean time, the think tank has apparently come full circle and I too am keen on a bolt on HX35 solution. I believe the issues with the turbo sitting too low or high and therefore requiring mods to the crossover are unique to the GT series turbos. I have spoken to Sid (blown944) at length about running this turbo some time ago; he assured me it was a bolt on affair aside from the aforementioned slight grinding to the turbo mount, the clearancing of the throttle body/intake, the custom oil feed, and sourcing an appropriate replica kkk hotside and modifying it to fit the holset CHRA. A production kkk hotside will not work, it must be a replica since these are designed for use on garrett CHRA's which happen to be ~1mm smaller OD from a holset. The stage 5 (T350) garrett turbine is nearly identical in dimensions to the holset HX35 turbine, so a slightly clearanced replica housing made for the stage 5 wheel effectively lets one have a bolt on HX35. A TRUE garrett hotside would actually flow even better, but of course then you need T3 up and down pipes and at that point, it just makes sense to run the factory holset dual scroll hotside and fabricate a dual scroll hotside or do something really crazy and move the turbo onto the passenger side and just be done with the crossover entirely.