Turbo comparison S55 vs S58

[Track/S]

I had the opportunity to disassemble s58 turbos, and I decided to take some pics to compare it with s55, I hope you like it.


Compressor housing









Exhaust housing













CHRA Shaft & Wheels















Size of the wheels, both compressor wheels are billet.

S55
Compressor wheel
Inducer 40mm
Exducer 51mm

Turbine wheel
Inducer 42.5mm
Exducer 37mm



S58
Compressor wheel
Inducer 45mm
Exducer 56mm

Turbine wheel
Inducer 47mm
Exducer 41mm


It's a shame that the s58 turbos don't fit on s55 otherwise it would already have them installed on my car with a small mod on the wheels

[SYT_Shadow]

the headers are beautiful on the S58.

I wish someone bothered to make a nice header for the S55 instead of the typical garbage we get.

Do you have weights of the hot&cold side for both engines?

[Track/S]

Originally Posted by SYT_Shadow

the headers are beautiful on the S58.

I wish someone bothered to make a nice header for the S55 instead of the typical garbage we get.

Do you have weights of the hot&cold side for both engines?

Everything about the s58 turbos is wonderful, I love them, the first time I fall in love with turbos

I will weigh them tomorrow, but there is a big difference, the wheels of the s55 are small.

[Wanted_M]

Nice comparison, the upgrades are abounded. Our wheels are small, and you can see the compressor/turbine AR are much larger. The manifold design is way better. Now we know why the G80/82 can push 700+ whp.

Can we adapt the turbo mani/housing!!

[SYT_Shadow]

Originally Posted by Track/S

Everything about the s58 turbos is wonderful, I love them, the first time I fall in love with turbos

I will weigh them tomorrow, but there is a big difference, the wheels of the s55 are small.

BMW did a beautiful job on the S58, but I still find those turbos a bit too big and laggy.

It would be really interesting to see a comparison of S55, S58 and then a few aftermarket options in terms of weight

[M3SQRD]

Originally Posted by Track/S

I had the opportunity to disassemble s58 turbos, and I decided to take some pics to compare it with s55, I hope you like it.


Size of the wheels, both compressor wheels are billet.

S55
Compressor wheel
Inducer 40mm
Exducer 51mm

Turbine wheel
Inducer 42.5mm
Exducer 37mm



S58
Compressor wheel
Inducer 45mm
Exducer 56mm

Turbine wheel
Inducer 41mm
Exducer 47mm


It's a shame that the s58 turbos don't fit on s55 otherwise it would already have them installed on my car with a small mod on the wheels

Thanks for the great side-by-side comparisons.

The s58 turbos are beautiful compared to the s55 turbos.

[McBobby Jr]

The manifold port size delta is interesting. It’s cool to see these turbos side by side so props to you.

[Track/S]

Originally Posted by Wanted_M

Nice comparison, the upgrades are abounded. Our wheels are small, and you can see the compressor/turbine AR are much larger. The manifold design is way better. Now we know why the G80/82 can push 700+ whp.

Can we adapt the turbo mani/housing!!

I also understood why they produce so much power when I saw them, I have to look at the ways to adapt the manifold.

Originally Posted by SYT_Shadow

BMW did a beautiful job on the S58, but I still find those turbos a bit too big and laggy.

It would be really interesting to see a comparison of S55, S58 and then a few aftermarket options in terms of weight

Later I will upload more pics with the modifications of each one.

[Rob@RB]

Good comparison shots and cool the S58 is MHI.

The OE S55 "base" setup is no slouch and has some good potential for upgrades. I'd say our S55 Stage 2 based offering still has a bit of a nudge on the OE S58 setup. The S58 already being a TD04L is great but it is hard to see what kind of material is available for a larger turbine, especially around the diffuser/tip height areas.

The problem with the S55 turbine housings is there is no significant material available beyond where we are currently at with our Stage 2 setups custom turbine (a bit larger than TD04L). So if you want a properly fitted larger wheel you really need to start drastically increasing the tip height of the turbine, which unfortunately means you end up with a terribly responding turbo. Hopefully for the S58 crowd that is less of an limiting issue inherent to the castings, because while the S58's TD04L(R in this case) is a great start it definitely is a limiting factor for large power.

All in all the OE S58 setup is a great base setup and should have even better room for growth, they appear to be a very good start to a very potent set of bolt-on upgraded turbos.

[chetrickerman]

What a difference in the port diameter and the turbine housing A/R! This is great information, thank you for sharing

[mike@x-ph.com]

Thank you for sharing; the S58 is a significant upgrade over the S55. ]

Im glad BMW made a big change in this area.

[wheela]

Very interesting to see, thanks for sharing!

Tough to tell from pics, but the s58 manilfold appears to more directly route the pulse energy into the turbine housing than the s55 manifold. Probably helps mitigate any spool loss or responsiveness loss due to the increase in wheel size.

[Track/S]

Originally Posted by Rob@RB

Good comparison shots and cool the S58 is MHI.

The OE S55 "base" setup is no slouch and has some good potential for upgrades. I'd say our S55 Stage 2 based offering still has a bit of a nudge on the OE S58 setup. The S58 already being a TD04L is great but it is hard to see what kind of material is available for a larger turbine, especially around the diffuser/tip height areas.

The problem with the S55 turbine housings is there is no significant material available beyond where we are currently at with our Stage 2 setups custom turbine (a bit larger than TD04L). So if you want a properly fitted larger wheel you really need to start drastically increasing the tip height of the turbine, which unfortunately means you end up with a terribly responding turbo. Hopefully for the S58 crowd that is less of an limiting issue inherent to the castings, because while the S58's TD04L(R in this case) is a great start it definitely is a limiting factor for large power.

All in all the OE S58 setup is a great base setup and should have even better room for growth, they appear to be a very good start to a very potent set of bolt-on upgraded turbos.

I am not in favor of using huge wheels, in the s55 I use a turbine with a 44mm exducer and a compressor with a 44mm inducer, and with the same power as any other hybrid turbo, and practically the same spool as the oem turbos, in the s58 I plan to do the same no greatly increase size of the wheels.

Originally Posted by chetrickerman

What a difference in the port diameter and the turbine housing A/R! This is great information, thank you for sharing

I was also impressed with the A/R, both compressor housing and turbine housing.

Originally Posted by wheela

Very interesting to see, thanks for sharing!

Tough to tell from pics, but the s58 manilfold appears to more directly route the pulse energy into the turbine housing than the s55 manifold. Probably helps mitigate any spool loss or responsiveness loss due to the increase in wheel size.

Yah, the shape is more direct without closed curvatures











PD:

S55 upgrade version vs S88 upgrade version


S55
Mod compressor wheel
Inducer 44mm
Exducer 56mm

Mod turbine wheel
Inducer 49mm
Exducer 44mm














S58
Mod compressor wheel
Inducer 49mm
Exducer 63mm

Mod turbine wheel
Inducer 53mm
Exducer 48mm

[Rob@RB]

Originally Posted by Track/S

I am not in favor of using huge wheels, in the s55 I use a turbine with a 44mm exducer and a compressor with a 44mm inducer, and with the same power as any other hybrid turbo, and practically the same spool as the oem turbos, in the s58 I plan to do the same no greatly increase size of the wheels.

Your S55 offering is nearly identical to my own, I personally designed a particular 44/56mm compressor back in 2016 which I believe some use the same unit until this day, and they are what I use in the S55 too. From my experience a 49/44 turbine could be a bit much for the S55 housing, unless you have a very large tip height (ie. 11+mm), or your wheel positioning within the housing will not be most ideal. I have included an internal pic of the prototype S55 setup I did back in 2020 with a custom 47/42 turbine, where you can see the positioning of the enlarged turbine within the machined housing. Based on past experience this fitment was a great matchup, and the only option to further enlarge the turbine while retaining great fitments would yield and increasingly lazily responding turbocharger.

Overall I am with you on the fact that there is a point where you cant just keep cramming larger wheels into housings that are tapped out, while many seem to just keep at it for that snapshot in time dyno chart the performance and reliability will suffer. This is why I probably will leave well enough alone with the S55 units, leaving an offering that is very tastefully designed and to give a much larger power potential over OE. Beyond that point some full custom setup would be the recommendation, or some other vendor that one feels comfortable with using.

On the other hand the S58 units appear to be quite awesome in OE form and based on your new specs should be some serious units, with a base housing foundation that could very likely accommodate it well. I have had some larger MHI TD04 reverse turbines for a long time now, was going to use for the N20 but would be nice if they could be purposed into these S58 housings someday. Good luck with this upgrade venture and thanks for sharing.

[SYT_Shadow]

if only we could find TiAl wheels that are reverse scroll!

[Track/S]

Originally Posted by SYT_Shadow

if only we could find TiAl wheels that are reverse scroll!

Yes, it would be hell

Originally Posted by Rob@RB

Your S55 offering is nearly identical to my own, I personally designed a particular 44/56mm compressor back in 2016 which I believe some use the same unit until this day, and they are what I use in the S55 too. From my experience a 49/44 turbine could be a bit much for the S55 housing, unless you have a very large tip height (ie. 11+mm), or your wheel positioning within the housing will not be most ideal. I have included an internal pic of the prototype S55 setup I did back in 2020 with a custom 47/42 turbine, where you can see the positioning of the enlarged turbine within the machined housing. Based on past experience this fitment was a great matchup, and the only option to further enlarge the turbine while retaining great fitments would yield and increasingly lazily responding turbocharger.

Overall I am with you on the fact that there is a point where you cant just keep cramming larger wheels into housings that are tapped out, while many seem to just keep at it for that snapshot in time dyno chart the performance and reliability will suffer. This is why I probably will leave well enough alone with the S55 units, leaving an offering that is very tastefully designed and to give a much larger power potential over OE. Beyond that point some full custom setup would be the recommendation, or some other vendor that one feels comfortable with using.

On the other hand the S58 units appear to be quite awesome in OE form and based on your new specs should be some serious units, with a base housing foundation that could very likely accommodate it well. I have had some larger MHI TD04 reverse turbines for a long time now, was going to use for the N20 but would be nice if they could be purposed into these S58 housings someday. Good luck with this upgrade venture and thanks for sharing.

Well, there are companies that use turbines with 45.5mm exducer...
I have used several measurements on s55 and the one I like the most is 44mm.

[Rob@RB]

Originally Posted by Track/S

Well, there are companies that use turbines with 45.5mm exducer...
I have used several measurements on s55 and the one I like the most is 44mm.

An overly big Inducer is the main concern, then it ends up hanging wide out into the volute exhaust flow due to housing design. If one is using a 45.5mm exducer that would mean they more than likely have a 50.5+mm inducer. While they may make good power and flow more they likely fail well more often along with it, thus it is a huge push and a risk not worth taking IMO. I've seen some vendors mass produce literally hundreds upon hundreds of these types of builds that flop and are essentially worthless boat anchors in very short order. A very large tip height can help null this issue a bit, but these S55 housings are not too forgiving about it. Hopefully the S58 housings have more potential.

[Sedgehammer]

Originally Posted by Track/S

I had the opportunity to disassemble s58 turbos, and I decided to take some pics to compare it with s55, I hope you like it.


Compressor housing









Exhaust housing













CHRA Shaft & Wheels















Size of the wheels, both compressor wheels are billet.

S55
Compressor wheel
Inducer 40mm
Exducer 51mm

Turbine wheel
Inducer 42.5mm
Exducer 37mm



S58
Compressor wheel
Inducer 45mm
Exducer 56mm

Turbine wheel
Inducer 47mm
Exducer 41mm


It's a shame that the s58 turbos don't fit on s55 otherwise it would already have them installed on my car with a small mod on the wheels

I'm new to the BMW S58 & the B55. We build tractor pulling tractors and the manifold isn't part of the turbo. That makes upgrades much harder. I'm wondering about cutting the turbo off and putting a flange on it to make the turbo upgrades easier. Anyone dong this?

[Track/S]

Originally Posted by Sedgehammer

I'm new to the BMW S58 & the B55. We build tractor pulling tractors and the manifold isn't part of the turbo. That makes upgrades much harder. I'm wondering about cutting the turbo off and putting a flange on it to make the turbo upgrades easier. Anyone dong this?

There is little space to do this, it is better to use single turbo

[D_SheerDrivingPleasure]

Originally Posted by Sedgehammer

I'm new to the BMW S58 & the B55. We build tractor pulling tractors and the manifold isn't part of the turbo. That makes upgrades much harder. I'm wondering about cutting the turbo off and putting a flange on it to make the turbo upgrades easier. Anyone dong this?

Wow. For ahich tractor class do you build? As a young boy I attended a tractor pull at a local Ag center. It was thrilling to see the crowd erupt in cheers at a full pull. Motorsports at it's finest.

[rad_name]

Originally Posted by SYT_Shadow

if only we could find TiAl wheels that are reverse scroll!

The Evo 6-9 RS turbos ran a reverse titanium turbine wheel, but it's a TD05 size wheel.

[SYT_Shadow]

Originally Posted by rad_name

The Evo 6-9 RS turbos ran a reverse titanium turbine wheel, but it's a TD05 size wheel.

Very interesting, thank you!