Jump to content
SAU Community

Recommended Posts

On 25/04/2022 at 8:13 AM, joshuaho96 said:

Is the GTIII-SS actually mismatched between compressor and turbine? I've never been able to find any information on it. Only thing I know is the exhaust housing a/r is 0.54. 

Yes if you consider every other low monut offering. 0.54 a/r turbine housing ? - This in itself is quite ridiculous with a reduced in size 52mm turbine wheel. Nissan moved to a 0.64 a/r on the N1 and Nismo turbine housing in the 90s, so even Nissan themselves realised a 0.64 turbine housing was a more appropriate size. Going any smaller than 0.64 on turbine housing is a bad idea regardless of what you do with the compressor side.

Regarding specs the MHI GTIII-SS which I have found is a smaller turbo overall compared to the HKS GT-SS or Garrett-9. The GTIII-SS falls into the trap of using a billet compressor wheel as its selling point and then makes both wheels smaller and uses a journal chra ?! WTF were they thinking doing this as an improvement ?

Specs on all, noting original HKS GT-SS is slightly bigger on comp wheel than -9 so not exactly 100% equivalent but close.

Garrett-9 ball bearing chra

Compressor: 0.42 a/r, Inducer - 44.5mm, Exducer 59.4mm, trim = 56t

Turbine: 0.64 a/r, Inducer - 53.9mm, Exducer - not listed, but has to be 47mm as trim = 62t

HKS GT-SS ball bearing chra

Compressor: 0.42 a/r, Inducer -  46.6mm, Exducer - 60.1mm

Turbine: 0.64 a/r, Inducer - 53.9mm, Exducer - 47mm trim = 62t

HKS GTIII-SS journal bearing chra

Compressor: not listed a/r, Inducer - not listed, Exducer 56mm

Turbine: 0.54 a/r, Inducer - 52mm, Exducer - not listed

  • Like 1
On 4/24/2022 at 7:20 PM, BK said:

Yes if you consider every other low monut offering. 0.54 a/r turbine housing ? - This in itself is quite ridiculous with a reduced in size 52mm turbine wheel. Nissan moved to a 0.64 a/r on the N1 and Nismo turbine housing in the 90s, so even Nissan themselves realised a 0.64 turbine housing was a more appropriate size. Going any smaller than 0.64 on turbine housing is a bad idea regardless of what you do with the compressor side.

Regarding specs the MHI GTIII-SS which I have found is a smaller turbo overall compared to the HKS GT-SS or Garrett-9. The GTIII-SS falls into the trap of using a billet compressor wheel as its selling point and then makes both wheels smaller and uses a journal chra ?! WTF were they thinking doing this as an improvement ?

Specs on all, noting original HKS GT-SS is slightly bigger on comp wheel than -9 so not exactly 100% equivalent but close.

Garrett-9 ball bearing chra

Compressor: 0.42 a/r, Inducer - 44.5mm, Exducer 59.4mm, trim = 56t

Turbine: 0.64 a/r, Inducer - 53.9mm, Exducer - not listed, but has to be 47mm as trim = 62t

HKS GT-SS ball bearing chra

Compressor: 0.42 a/r, Inducer -  46.6mm, Exducer - 60.1mm

Turbine: 0.64 a/r, Inducer - 53.9mm, Exducer - 47mm trim = 62t

HKS GTIII-SS journal bearing chra

Compressor: not listed a/r, Inducer - not listed, Exducer 56mm

Turbine: 0.54 a/r, Inducer - 52mm, Exducer - not listed

Isn't the trim for the GTIII-SS listed somewhere? The tag for it says 5652 55T 01786 on mine. I'm guessing the 55T is for the compressor.

I don't understand, I thought when you make a smaller turbo for smaller power output everything gets smaller. 0.64 a/r on a -9 but 0.83 or 1.01 a/r on a single turbo is not unusual. Stock is 0.48 turbine a/r so it's pretty much right between stock and an N1 or GT-SS. I was never really interested in it for "billet", I just want a tiny turbo to make very pedestrian levels of power. Pretty much stock, just without the ceramic turbine wheel. Each turbo only has 1.3L of displacement to work with after all. I think more than anything my concern is I make an irreversible change to the car that really affects reliability or driveability. It would've been nice to have the same turbo but ball bearings instead of journal bearings but I'm willing to bet that a larger ball bearing turbo is ultimately going to have more lag than a smaller journal bearing turbo. Even if there's more drag from the bearings, the issue is more the inertia of the turbine/compressor wheels.

On 4/24/2022 at 5:10 PM, Dose Pipe Sutututu said:

A few twin turbo advocates here turned single turbo activists.

That's saying something. One guy *cough* Pig.. *cough* gaz famously said "I wouldn't change a thing" on his twin GT-RS RB26 with Tomei brap cams.

Well not sure whatever happened to that setup.

I don't know if I'd ever recommend a bolt-on turbo for the kind of power that the GT-RS turbos are targeted at.

Edited by joshuaho96

Exhaust housing are one area that shouldn't be underdone. If that is compromised the whole turbo / engine package is compromised.

Seriously i give up dude, you just dont grasp what I'm trying to get across. Dot points:

-standard ceramic turbos suck

-trying to imitate the standard turbo results with something else also sucks.

-Gt-ss or -9 is only an improvement over the standard ceramic turbos everywhere in reality - there is no downside however you might think to the stock units.

Post results when GTIII-SS installed and tuned please.

On 25/04/2022 at 7:16 PM, joshuaho96 said:

I don't know if I'd ever recommend a bolt-on turbo for the kind of power that the GT-RS turbos are targeted at.

Single turbo realm mate, as Piggaz above.

On 4/25/2022 at 3:44 AM, BK said:

Exhaust housing are one area that shouldn't be underdone. If that is compromised the whole turbo / engine package is compromised.

Seriously i give up dude, you just dont grasp what I'm trying to get across. Dot points:

-standard ceramic turbos suck

-trying to imitate the standard turbo results with something else also sucks.

-Gt-ss or -9 is only an improvement over the standard ceramic turbos everywhere in reality - there is no downside however you might think to the stock units.

Post results when GTIII-SS installed and tuned please.

Single turbo realm mate, as Piggaz above.

Genuinely confused here, I've never seen a dyno result where -9s/GT-SS didn't give up a pretty substantial amount of response relative to stock turbos. I figured staring at turbine maps that you want to size it to the actual amount of exhaust CFM you expect or else either you have really awful response or the turbo becomes entirely backpressure limited. Everything I can find suggests that for the same exact turbine wheel, adjusting the turbine a/r moves the choke point up and down. The turbo definitely chokes somewhere around 18-21 psi up top from what I've seen but for my purposes that's actually ok.

Funny enough looking at the BMW S55 the turbos they use stock are comparatively tiny. 51mm compressor exducer, 43mm turbine inducer:

696092999_ScreenShot2022-04-25at10_35_24AM.thumb.png.378baa3e3eeb9e32c87c9b593a713693.png

On 4/25/2022 at 9:20 AM, BK said:

Yes if you consider every other low monut offering. 0.54 a/r turbine housing ? - This in itself is quite ridiculous with a reduced in size 52mm turbine wheel. Nissan moved to a 0.64 a/r on the N1 and Nismo turbine housing in the 90s, so even Nissan themselves realised a 0.64 turbine housing was a more appropriate size. Going any smaller than 0.64 on turbine housing is a bad idea regardless of what you do with the compressor side.

Regarding specs the MHI GTIII-SS which I have found is a smaller turbo overall compared to the HKS GT-SS or Garrett-9. The GTIII-SS falls into the trap of using a billet compressor wheel as its selling point and then makes both wheels smaller and uses a journal chra ?! WTF were they thinking doing this as an improvement ?

Specs on all, noting original HKS GT-SS is slightly bigger on comp wheel than -9 so not exactly 100% equivalent but close.

Garrett-9 ball bearing chr

Compressor: 0.42 a/r, Inducer - 44.5mm, Exducer 59.4mm, trim = 56t

Turbine: 0.64 a/r, Inducer - 53.9mm, Exducer - not listed, but has to be 47mm as trim = 62t

HKS GT-SS ball bearing chra

Compressor: 0.42 a/r, Inducer -  46.6mm, Exducer - 60.1mm

Turbine: 0.64 a/r, Inducer - 53.9mm, Exducer - 47mm trim = 62t

HKS GTIII-SS journal bearing chra

Compressor: not listed a/r, Inducer - not listed, Exducer 56mm

Turbine: 0.54 a/r, Inducer - 52mm, Exducer - not listed

On 4/26/2022 at 12:35 AM, joshuaho96 said:

Genuinely confused here, I've never seen a dyno result where -9s/GT-SS didn't give up a pretty substantial amount of response relative to stock turbos. I figured staring at turbine maps that you want to size it to the actual amount of exhaust CFM you expect or else either you have really awful response or the turbo becomes entirely backpressure limited. Everything I can find suggests that for the same exact turbine wheel, adjusting the turbine a/r moves the choke point up and down. The turbo definitely chokes somewhere around 18-21 psi up top from what I've seen but for my purposes that's actually ok.

Funny enough looking at the BMW S55 the turbos they use stock are comparatively tiny. 51mm compressor exducer, 43mm turbine inducer:

696092999_ScreenShot2022-04-25at10_35_24AM.thumb.png.378baa3e3eeb9e32c87c9b593a713693.png

Looking at HKS GTIII-SS specs and as they are MHI based, then 56mm compressor exducer and 52mm turbine inducer should be from TD004H or HL turbine family :

TD04H turbine : inducer 52mm exducer 44.2mm.

TD04HL turbine inducer 52mm exducer 45.6mm.

TD04 turbines are usually 12 blades fom MHI, but also available aftermarket upgrade with 11 blades and 9 blades.

Compressor exducer 56mm can be 15T (inducer 41.9mm), 16T or 15G (same inducer 43.4 mm but different blade profile), which compressor maps show max flow of around 29-31 lb/min at 1-1.5 Bar of boost. However its possible that HKS uses newer TD04 compressor from MHI which may flow a bit more.

That BMW S55 MHI upgrade should use similar compressor as above with TD04L turbine inducer 47mm exducer 41.3mm. I have read TD04L maxes out about 220-250whp in other engines on e85 or pump gas + methanol mix.

OEMs such as Volvo, Saab, uses these sizes TD04s for engines around 220-280 max hp usually at lower boost than 1 bar. Biggest OEM TD04HL is a TD04HL-19T which has 46mm/58mm compressor with max flow around 37 lb/min at 1.3 Bar of boost

Garrett turbo closest in wheel sizes to TD04HL is GBC22-350 which has 44mm/56mm compressor max flow 37 lb/min at 1.7 Bar of boost and 50mm/46mm 9 blade turbine and also journal bearing as TD04s or next step larger GT28 series in journal or ball bearing.

Other close sized option is Holset HE221W which has 43.4mm/61mm compressor max flow 38 lb/min at 2 bar of boost and 52mm/45.7mm 11 blade turbine, with T2 internal gated turbine housing sized at 5cm/6cm/7cm, so will bolt on to RB26 stock exhaust manifolds, but piping and downpipe will need to be custom made.

Compared to GT28 ball bearing turbos, TD04s has smaller turbine inducer, exducer, shaft and compressor bore diameter so should have lower inertia which may allow it to spool comparable to GT28 ball bearing turbos, dependent of housing sizes. I have read infos from various platform which said TD04HL-19 T is close to GT2860R in response and max power.

So my take on HKS MHI based GTIII-SS is it should work well if hp target around max 500-600 engine hp. Although if insisting on twin turbos then GBC22-350, TD04-HL-19T and HE221W will work just as well if not better and definitely cheaper.

However, if no legal/emission compliance reasons, instead of upgrading twins, going to a similar rated power twin scroll single turbo such as GTX3071R/GTX3576R Gen 2, GTW3476, S257SXE, Holset HX35/HE351W, will be simpler and lighter although likely similar cost wise as need to buy proper t3/t4 divided manifold and external wastegate, and with similar HP should be faster car. This is what I would do.

  • Like 1
On 4/25/2022 at 5:25 PM, CefiroA31 said:

Looking at HKS GTIII-SS specs and as they are MHI based, then 56mm compressor exducer and 52mm turbine inducer should be from TD004H or HL turbine family :

TD04H turbine : inducer 52mm exducer 44.2mm.

TD04HL turbine inducer 52mm exducer 45.6mm.

TD04 turbines are usually 12 blades fom MHI, but also available aftermarket upgrade with 11 blades and 9 blades.

Compressor exducer 56mm can be 15T (inducer 41.9mm), 16T or 15G (same inducer 43.4 mm but different blade profile), which compressor maps show max flow of around 29-31 lb/min at 1-1.5 Bar of boost. However its possible that HKS uses newer TD04 compressor from MHI which may flow a bit more.

That BMW S55 MHI upgrade should use similar compressor as above with TD04L turbine inducer 47mm exducer 41.3mm. I have read TD04L maxes out about 220-250whp in other engines on e85 or pump gas + methanol mix.

OEMs such as Volvo, Saab, uses these sizes TD04s for engines around 220-280 max hp usually at lower boost than 1 bar. Biggest OEM TD04HL is a TD04HL-19T which has 46mm/58mm compressor with max flow around 37 lb/min at 1.3 Bar of boost

Garrett turbo closest in wheel sizes to TD04HL is GBC22-350 which has 44mm/56mm compressor max flow 37 lb/min at 1.7 Bar of boost and 50mm/46mm 9 blade turbine and also journal bearing as TD04s or next step larger GT28 series in journal or ball bearing.

Other close sized option is Holset HE221W which has 43.4mm/61mm compressor max flow 38 lb/min at 2 bar of boost and 52mm/45.7mm 11 blade turbine, with T2 internal gated turbine housing sized at 5cm/6cm/7cm, so will bolt on to RB26 stock exhaust manifolds, but piping and downpipe will need to be custom made.

Compared to GT28 ball bearing turbos, TD04s has smaller turbine inducer, exducer, shaft and compressor bore diameter so should have lower inertia which may allow it to spool comparable to GT28 ball bearing turbos, dependent of housing sizes. I have read infos from various platform which said TD04HL-19 T is close to GT2860R in response and max power.

So my take on HKS MHI based GTIII-SS is it should work well if hp target around max 500-600 engine hp. Although if insisting on twin turbos then GBC22-350, TD04-HL-19T and HE221W will work just as well if not better and definitely cheaper.

However, if no legal/emission compliance reasons, instead of upgrading twins, going to a similar rated power twin scroll single turbo such as GTX3071R/GTX3576R Gen 2, GTW3476, S257SXE, Holset HX35/HE351W, will be simpler and lighter although likely similar cost wise as need to buy proper t3/t4 divided manifold and external wastegate, and with similar HP should be faster car. This is what I would do.

I do have legal/emissions compliance to keep in mind unfortunately. But even if there were no such concerns the things I want out of a single turbo RB26 doesn't really exist as far as I know. Short runners, low-mount, proper heat shielding instead of just having an exhaust manifold + turbo inches away from heat-sensitive components, real thought given to minimizing the changes to things other than the turbo + manifold + intake piping, and twin scroll. Basically look at a BMW B58 or N55, that's the goal in my head. I know that's a really tall order but this is a street car, not a track build. Someone I know has gone through stock turbos -> HKS GT-SS -> GTX3576R gen 2 and he absolutely loses power at the critical ~3000-4000 RPM area where I spend a lot of time at on the street contrary to what Motive found. 

  • 1 month later...
On 27/4/2022 at 7:46 AM, joshuaho96 said:

I do have legal/emissions compliance to keep in mind unfortunately. But even if there were no such concerns the things I want out of a single turbo RB26 doesn't really exist as far as I know. Short runners, low-mount, proper heat shielding instead of just having an exhaust manifold + turbo inches away from heat-sensitive components, real thought given to minimizing the changes to things other than the turbo + manifold + intake piping, and twin scroll. Basically look at a BMW B58 or N55, that's the goal in my head. I know that's a really tall order but this is a street car, not a track build. Someone I know has gone through stock turbos -> HKS GT-SS -> GTX3576R gen 2 and he absolutely loses power at the critical ~3000-4000 RPM area where I spend a lot of time at on the street contrary to what Motive found. 

I had HKS gtss with cam gears dialled, stock cams, 3800rpm all in @22psi, night and day difference over stock turbos and any perceived “response” loss

8374 efr + vcam is another level of ass kicking again if you inclined 

On 6/1/2022 at 6:14 AM, R.3.2.G.T.R said:

I had HKS gtss with cam gears dialled, stock cams, 3800rpm all in @22psi, night and day difference over stock turbos and any perceived “response” loss

8374 efr + vcam is another level of ass kicking again if you inclined 

From what I have seen/heard the oil control issues involved with huge power is just too annoying to deal with, I'd rather keep power targets conservative for that reason. I am planning on running VCAM whenever I finally get around to it though. I have seen enough charts to conclude that within the bolt-on turbo design space there is no free lunch, more power up top means worse response down low. Doing the same optimization with a stock turbo would yield better response than GT-SS. Emissions and OEM engineering validation are issues that I need to be concerned about so going single turbo isn't really something I want to do either.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • For these last 7 years of ownership, I've always had to use a small scissor jack under one of the front tow hooks to raise the front just enough so my low-profile jack fits under to reach my subframe jack point. I'm beginning to get annoyed of always having to do this. Are there any lower low-profile jacks that fit under the gtr lip on a dropped car?
    • Seat of the pants assessment of the new intake: The car is way less "doughy" when hitting the loud pedal, especially off idle when stopped or in traffic, I did use a cheapo lazer thermal thingo to measure the temp around where the pod filter got its air, it was between 55 - 60°C, in saying this the car was shut off and not moving, so the OEM intake pipe was not supplying any fresh air to where the pod was when the car was at least moving A weird bonus was induction noise on the throttle in the cabin increased a bit,  I was worried that I was actually going to lose some of that induction noise I love so much, outside though, when I got the daughter to do a WOT drive by pass for me, the induction noise has increased alot when on the throttle, not quite ITB doort, but well up there I'm extremely happy with the results and have been exploring the country roads in the region  As for house mods: 1.New front fence is up and is awesome, it really upgraded how the joint looks from the street, and the added security is nice 2. Electricians have replace some interior lights, and with more lighting in the garage, a few new motion detecting lights out the front above the garage, front room, and at the front door, which I have already found heaps helpful coming and going, also now has fancy pants CCTV all round the house The only hold point for power though is the solar and batteries due to supply issues, although this will happen over the next few weeks 3. I have done a heap of landscaping out the front and I'm almost ready to do a new small retaining wall with some nice blocks to replace the brick and cemented in rocks around the raised garden beds cemented in river stone "was the fashion at the time" the house was built. I currently have a pallet of retaining wall blocks and 2 bulka bags of 20mm blue metal to replace the wood chip that is in the raised garden beds around the house 4. I now have 3 big raised garden beds for out the back to grow some vegetables, about 70cm high, 200cm long and 100cm wide 5. My 2 compost bins are already pretty full with brown, green and kitchen waste from the landscaping I'vedone so far, but they will probably take a few months to break down, so anything else that gets chopped, trimmed, and kitchen waste will just start filling the base of the raised garden beds to about 30cm before I start throwing 40cm of good compost, and stuff, for the vegetables to grow in, I'll need a few ton of compost and soil, but the local supplier can sent me bulka bags of the stuff Basically the logs, wood chips and a few strategically placed rocks for drainage, will give the beds some good organic materials down low to break down over time, and they will hold moisture during the warmer months to save the water in my big arse water tank if we don't get alot of rain So, all in all, the car and house mods are going well, and I'm really enjoying being retired, I sleep in too 0700 and slowly plod around inside until I feel like actually doing anything, and only work in the yard for as long as want, which has actually been alot over the last few weeks,  although when you look at it, it seems that not a huge amount of work has been done,  until I look at the before I started the work pics Happy days and good times indeed 
    • hahaha yeah. Plan is to get side skirts and probably just rear pods. But going to do them one-by-one. I've got a set that I really like from RHDJapen, but that one isn't shipped to AU. So need to find someone who can get it for me
    • Here's an idea, answer the questions I asked you as they are trying to work out WHY the LSD will be binding up in a straight line.
×
×
  • Create New...