Turbo for low/med performance, GT2052 or CT26(12HT)

[Dougal]

I own "Maximum Boost" by Corky Bell and was able to find a copy of the book "Diesel Engine Reference Book" chapter 2 can be found here: https://forum.ih8mud.com/ca-bc-coastal-cruisers/283634-diesel-reference-book.html
Both discuss sizing the turbine, also the garrett website has turbine curves as you know. I can't say they answer your specific question but there is good technical information in there.
I think you said it best in one of the many posts of yours I've read, something to the effect of "you look at comparable turbines used on existing engines and can scale by rpm and displacement if necessary"
However there is discussion on turbine size in the book that indicates that too small is just as bad as too big.
Chris

I have the DERB and Baines "fundamentals of turbocharging" which is even better. But the specific question of turbines goes beyond those.
I have done water turbine design, but the whole cooling and compressibility of exhaust makes it not directly comparable.

With a 2H I don't see the TD05 turbine as too small, they will also all be wastegated to keep boost down. This is more a question of which is better and why.

 

[Chris Wilcox]

Dougal,
I enjoy the research and discussions you and others have on such topics. I usually research stuff too much and try to learn much more than is necessary. It is all part of the project for me. Thanks for the lead on another good turbo book.
Chris

 

[gbentink]

The percentage of torque (where) is heavily turbine design dependant in addition to housing), where pure radial developed mosty at inducer, or axial developed mostly at exducer... When you look at turbine designs, you will see there is a compromise between the two and that is what governs the temp gradient that works best (i.e: target AFR). You will also see compromises where turbo manufacturers are limited by frame size, so they keep wheels same dims but change clipping of turbine to get more axial flow and fit a larger A/R housing (or vnt).

I reckon if you put the intake back on it will pick up in the power stakes

Seriously though - if you can make a vnt controller - fit one of my 1KD turbo upgrades. Bolts the 1KZ flange, designed for 30psi to 3400, then ramp down to 24psi at 4200rpm.

Ive just had test results - posted here for first time . See graph attached (no tuning at all, and factory turbo is fine condition). Totally stock 2005 vehicle (std exhaust, intercooler, 220,000kms)

Look at the AFRS even though boost follows original closely without rising!!! I think both readings are slightly on rich side - 17:1 seems low. But in any case, its inference by difference

I ran up results in excel - most of the increase in power is simply higher turbo efficiency - you can do this yourself comparing increase in boost to increase in AFR's. Its a steller result.

This will put down 220hp at wheels after rail and timing and inj duration mods. Bottom end will rise too.

So on a turbine, what percentage of the torque is developed at the inducer compared to exducer?
I know if we reduce exducer size, we get higher gas speed and more resolved force, but less torque due to the reduced radius. But is this minor compared to the accelerated flow already turning the outer fins at the inducer?

BTW, may need to talk to you about a 1KZ turbo. We ripped an intake hose on a hilux. Haven't looked at the turbo yet, but one driver thinks power is down.

 

[gerg]

I remember when I ordered forced induction and performance tuning to the local library. When I came to pick it up, the librarian made fun of me and said "well I bet your just going to snuggle down with a glass of wine by the fire with this one!" Well... I felt like smashing him in the face, but then I just felt bad cus he wasnt a he at all, she was just a super ugly chick. Was a good book too.

 

[Dougal]

The percentage of torque (where) is heavily turbine design dependant in addition to housing), where pure radial developed mosty at inducer, or axial developed mostly at exducer... When you look at turbine designs, you will see there is a compromise between the two and that is what governs the temp gradient that works best (i.e: target AFR). You will also see compromises where turbo manufacturers are limited by frame size, so they keep wheels same dims but change clipping of turbine to get more axial flow and fit a larger A/R housing (or vnt).

Do axial have a bigger flow or speed range than radial?

I reckon if you put the intake back on it will pick up in the power stakes

Seriously though - if you can make a vnt controller - fit one of my 1KD turbo upgrades. Bolts the 1KZ flange, designed for 30psi to 3400, then ramp down to 24psi at 4200rpm.

It split the boot into the turbo. I'm suspecting the wheel got dusted. But I haven't taken a look and I'm not sure I want to.

I won't be fitting a VNT to my brothers work ute any time soon. I've got a 4wd and a work car to do that to first. More looking for the best way to get back up and running. Something like a swap in core if it is buggered. Bigger wheels possible.

 

[HayMaker]

But back to the task at hand....

What about the 2h.

I know Dougal does sniff around on the other diesel forums..how do you think a holset he22w with the 6 or 7 cm housing would work on a 2h. I know you would have to adjust the hell out of the wastegate, but shouldn't a turbo sized to fit a 4 liter diesel work on the 2h??

Hay(former)Maker

 

[Dougal]

What about the 2h.

I know Dougal does sniff around on the other diesel forums..how do you think a holset he22w with the 6 or 7 cm housing would work on a 2h. I know you would have to adjust the hell out of the wastegate, but shouldn't a turbo sized to fit a 4 liter diesel work on the 2h??

Hay(former)Maker

You'd need a much softer wastegate actuator on the HE221 to stop it over-booosting. But otherwise I'd expect it to be very good.

The HE221 is a TD04HL MHI core and turbine with a special compressor. Since you don't need the huge boost and flow range, a more common TD04 might work. Gerg is the person to ask about those.

 

[gerg]

Turbine is 46.6/52mm put it almost exactly the same as a td04hl (largest td04)
Compressor is a large 44.2/60mm puts it almost exactly a 50/55 trim t3 garett compressor diameter for maping. Id have to look a bit more but gotta drive the kids to school. Really nice turbine compressor ratio.
Comes in a 6cm housing.

Dougal is right, it would spool hard and fast and you would be limited to low operting boost and revs. It is designed for 4.5L motors, but these are not Toyotas that love to rev. Many of then cant get past 2600 rpm in stock for due to the governor.

 

[Dougal]

Here is the HE221 comp map with the 4BD1T (24psi and 60% intercooling) overlaid.

This is enough air for this sort of result:

Which makes me think even a 56mm TD04 compressor would have plenty of spare capacity for most of us.

 

[gerg]

13t, 16t and 18t td04 compressors are all 56mm but I am quite interested in the 19t as it is a 58mm but the neat thing is that it maps almost vertical for low hard boost and would be ultra surge resistant. The only thing is you would need a pretty good turbine to run it. I think the td04h or td04 hl are the only candidates as they produce the greatest torque of the td family (diameter and trim wise)
Here is a 2H map just playing with boost numbers (guessing) dots start at 21psi is 1200rpm. I think a 6cm housing would choke hard with high numbers ike that, but you can get stock turbos in different housings. It is a neat idea. I personally think its small on a 4.2, but would be a nice small turbo for a compound 3B

 

[Dougal]

13t, 16t and 18t td04 compressors are all 56mm but I am quite interested in the 19t as it is a 58mm but the neat thing is that it maps almost vertical for low hard boost and would be ultra surge resistant. The only thing is you would need a pretty good turbine to run it. I think the td04h or td04 hl are the only candidates as they produce the greatest torque of the td family (diameter and trim wise)
Here is a 2H map just playing with boost numbers (guessing) dots start at 21psi is 1200rpm. I think a 6cm housing would choke hard with high numbers ike that, but you can get stock turbos in different housings. It is a neat idea. I personally think its small on a 4.2, but would be a nice small turbo for a compound 3B

Last weekend I went back from my DIY T2560 to a straight T25 with a heavily preloaded 22psi wastegate which holds 20psi through the mid-range.
I'm much happier with boost response, much further from surge and with the wastegate working it will rev out to the rev-limit.

I was never perfectly happy with the 60mm T28 wheel and this plot sealed it's fate for me:

Even intercooled, it doesn't have the surge margin that I'd like:

The T25 is limited to ~25 lb/min airflow (approx 300CFM) and that's enough to deliver ~140kw and 550Nm on my engine. It'll do less on a 2H because the IDI is less efficient at converting fuel and air into power and torque.
Most importantly, it feels good, it sounds good and it runs clean. Drivabililty is massively improved.

I've just plotted out the 19T wheel (thanks for that) and it's looking pretty close to the HE221. Not surprising really. But I'd be inclined to go smaller to get more surge margin and run closer to the middle of the efficiency range. My 4BD1T 20psi plot only makes it to the middle of the map at the rev limit.

 

[gerg]

you know its weird. Ive been thinking alot lately about exducer diameter and effeciency islands. I, as usual, have no time to build lots of turbos and fool around withthem, but am cureous about larger then optimal compressors used for low rpm boost and trade off the less than optimal effeciency at cruise. I know the rotating mass will lagg, but static spool would be increased with larger exducer (up to a pojnt) and when I calc outlet temps with lower effeciencies you dont seem to gain as much heat as you migh expect. At 10pis for example going from 75% effecient to 65% you net somehting like 30F which isnt that bad. The other thing which is neat is looking at the turbine rpms at higher boost and you can open the wastegate sooner (at the same pressure) as the larger exducer often runs dramatically lower rpms. This might not make sences, and I will clean up what im trying to say, but im in the middle of cooking dinner and it gets crazy here with my kids.

 

[Dougal]

I've just mapped out a few more of the TD04 compressor wheels.

The 19T has the best surge margin. No doubt due to the higher tip speed of the bigger wheel.
The 13T (unknown 6 or 4 variant) and 15G about the same.
The 16T and 18T are not looking that good. If you want 20psi at 2000rpm they are crossing the surge line there.

Mellett show a 51 and 56mm variant of the 13T wheel (13T-6 is the bigger). I can't tell which map I have.

 

[Dougal]

you know its weird. Ive been thinking alot lately about exducer diameter and effeciency islands. I, as usual, have no time to build lots of turbos and fool around withthem,

Me neither, but I can steal 5min every now and then to talk about them on the interweb.

but am cureous about larger then optimal compressors used for low rpm boost and trade off the less than optimal effeciency at cruise. I know the rotating mass will lagg, but static spool would be increased with larger exducer (up to a pojnt) and when I calc outlet temps with lower effeciencies you dont seem to gain as much heat as you migh expect. At 10pis for example going from 75% effecient to 65% you net somehting like 30F which isnt that bad. The other thing which is neat is looking at the turbine rpms at higher boost and you can open the wastegate sooner (at the same pressure) as the larger exducer often runs dramatically lower rpms. This might not make sences, and I will clean up what im trying to say, but im in the middle of cooking dinner and it gets crazy here with my kids.

I know what you are saying. I did just that with my DIY T2560 build. But I went too far with the compressor. From a 51.3mm wheel to a 60mm wheel.
Somewhere closer to 56mm would be almost perfect.

I found enough lag with the 60mm that I had to wind in the boost-compensator to stay smoke free. I also had rougher running at high boost and low rpm, which was not helped by running into surge.
But I also couldn't get the fuel economy I could with the little compressor. There wasn't much in it, but I wasn't hitting 10km/l unless I drove it really really carefully. With the 51.3mm wheel I could plant foot everywhere and still get it on the odd tank.

With the temperature, I've gone from 24psi peak boost to 20-21psi peak boost and my EGT's are the same. A combination of slightly cooler intake (more effficient spot on the comp-map) and less exhaust drive pressure.

I have a GT2256V VNT turbo here to try. But life keeps getting in the way. Compressor maps aren't available, but I think it'll deliver around 28 lb/min and far better surge resistance than the T28 60mm wheel.

 

[gerg]

There is a td04hl 19t that is twin scroll off of liberties. Looks interesting, but would be expensive to get as a stocker. Fortunatley, chesbay has lots of MHI aftermarket suff and you can pretty much lego your own turbo toether for very reasonable prices. I would of cource start with a genuine MHI center housing. The housings come in varying sizes as well.

 

[Dougal]

There is a td04hl 19t that is twin scroll off of liberties. Looks interesting, but would be expensive to get as a stocker. Fortunatley, chesbay has lots of MHI aftermarket suff and you can pretty much lego your own turbo toether for very reasonable prices. I would of cource start with a genuine MHI center housing. The twin scroll housings come in varying sizes as well.

With an appropriate sized/shaped turbine housing that would be an excellent swap. I recall the original flange shape on those being pretty strange!

My country is full of turbo subaru parts. Every town has a subaru parts wrecker.
Muppet owner wants to go faster, turbos go up for sale.
Muppet owner drives subaru into tree, turbos go up for sale.
Subaru gets stolen, turbos go up for sale.

Over here the legacy (liberty) were sequential twin turbos with IHI RHB5 turbos. The WRX got the big singles. But our cars were mostly JDM spec and quite different to north american spec.

 

[gerg]

Yeah that is the MHI normal rotation twin scroll set up. I just bought a td05h evo 8 twin scroll turbo that is reverse. Im looking to use a divided manifold (1-4, 2-3) I had laying around after my failed MR2 turbo set up, which you cautioned me not to do and you were right... bastard. Anyhow, I think the td05 might be an interesting fit. It would be the large first off manifold with a small turbo below it, sort of a sequential semi compound. The end result might be very tunable for all sorts of different types of boost levels. Cource I bought the turbo, yet have no time to build it. The divided manifold took quite a while to build and I dont just want to chuck a single scroll turbo on it.

Specs are:
td05h reverse rotation 49/56 for... driving on the other side of the road or.... sheer kewlness I guess.
16g Large compressor 48/68
9.8cm divided housing which spools inbetween a 6cm and a 7cm housing acording to solid internet gossip.
360 thrust bearing stock. Even the internal wastegate is set stock to 19psi I think.
It gives a .82 exducer to exducer ratio on the gerg scale which is pushing it closer to max, but has lots of room to breath.
.76 is the max holset I have seen, but only on the newer turbos such as he he351cw.

You guys might get nice JDM stuff, but we do not. I had to club a seal to get this deal.
By the way, Canada loves seals. We make all sorts of very useful materials out of them.
Here is what it looks like.

 

[Tapage]

Here is a 2H map just playing with boost numbers (guessing) dots start at 21psi is 1200rpm.

it's this ^^^^^

really realistic .. not that I'm planning to go there .. but sounds tempting .. !

 

[gerg]

Please dont misunderstand what I was trying to do with that map tapage. I was just chosing some crazy boost number at an extremly low rpm to show that it would be almost impossibel to get that compressor to surge on a 2h. That is all. Im not saying that the turbo would perform that way.

 

[Tapage]

too bad .. I was entering in " child " mode ...