H1C to HX40 Hybrid Question

[Cynic]

Hi!

So I'm not originally a DSM driver, but I (like so many others) have lurked on these pages due to the invaluable wealth of information about Holset turbos you all have made available. I am quite familiar with the benefits of Holsets, having rebuilt several and used HX/HY35's on my turbo MR2 project. However, I am only acutely familiar with the way hybrid setups work, and furthermore, I'm not sure what the EXACT differences between the H1C and HX35 frames are, besides the 8-blade compressor wheel vs. 7 (98+) and the way the compressor housings are mounted.

I've searched around, and haven't found an exact answer to my question. I know that in order to use an HX40 wheel on an HX35, you need to get an HX40 compressor housing and have the back plate machined to accept the larger HX40 wheel. Is the process the same for the H1C? Due to the differences in the way the H1C's compressor housing is attached to the CHRA, is it still possible to swap an HX40 housing and wheel over? I'm trying to find an H1C on the cheap and make a hybrid setup with a billet 60mm 6-blade wheel.

Thanks!

 

[JusMX141]

I've searched around, and haven't found an exact answer to my question. I know that in order to use an HX40 wheel on an HX35, you need to get an HX40 compressor housing and have the back plate machined to accept the larger HX40 wheel. Is the process the same for the H1C? Due to the differences in the way the H1C's compressor housing is attached to the CHRA, is it still possible to swap an HX40 housing and wheel over? I'm trying to find an H1C on the cheap and make a hybrid setup with a billet 60mm 6-blade wheel.

Thanks!

Nope- the compressor seal collar on the HX-series is thinner (wheel itself is thicker) so if you try to install a HX wheel on a H1 turbo, it will stick out from the backplate about 2-3mm.

If you want to pull this off, you'll absolutely need to get some material machined off the back of the compressor wheel and have it rebalanced. Next step would be to get the H1's seal plate machined to accept the 86mm HX40 wheel, and finally the compressor cover will also need machined. After you've spent all that money you'll still have a turbo that doesn't have the durable thrust system that a HX turbo has.

Basically, scratch this idea and buy a HX40.

 

[Cynic]

Oh okay, thank you for clarifying.

I'm not dead set on an H1C by any means, I just know they are cheap and readily available in rebuildable condition. However, an HX35/40 hybrid would be more desirable over an HX40 in most cases for me, simply because it can be difficult to find an HX40 with a useful exhaust housing size and I don't want to mess with swapping housings around. Aren't many HX40's T4 flange? I know I have seen some that use T3... perhaps I am just confused by the way people refer to the exhaust housing in cm... is that the equivalent to defining size by A/R?

 

[JusMX141]

There are 16cm2 (1.1 a/r) and 18cm2 (1.3 a/r) divided T3 HX40 housings.

What exactly are you planning to do here? You don't have to go too far before the HX35 turbine wheel and housing become a restriction even with a HX35...swapping to a HX40 compressor wheel can be a bad idea depending what boost level you're running.

 

[Cynic]

I'm trying to retain the spool up of a 60mm turbine and .89 A/R housing of the HX35 while getting the flow of a billet 60mm HX40 wheel. I'm not running any kind of shaft-breaking boost at the moment. I wouldn't think a .89 A/R housing would become a restriction at sub-600 power levels.