I'm after some info on Turbine selection and housing A/R sizing for making up a hybrid turbo for 2.0 diesel.

it currently has a GT1549 with a .35 turbine housing spools roughly at 1700rpm and is known to cause high EMP at high boost.

from what I've seen of other peoples hybrids, people seem to bore out the housing and fit a GT17 turbine from a 2.0 Petrol SAAB in the .35 housing, but this still creates high EMP.

the other ones i have seen have used a .47 housing from what i think to be a 2.5 litre Transit (also a GT1549) but that too has been bored out to accept a GT17 turbine and then spools at around 2300rpm.

the .47 housing comes from a 2.5 litre Diesel so I'm wondering if its original turbine would be more suited for earlier spool than the GT17 from the petrol SAAB.

Here are the specs from what I'm able to find off of the internet..

Current turbo .35 A/R
Gt15
Inducer: 41.5mm
Tip Height: 7.21mm
Exducer: 33.99mm
Trim: 67
Part Number: 434713-0007


GT1549s Transit .47 A/R

INDUCER DIAMETER 41.5mm

EXDUCER DIAMETER 35.2mm

TIP HEIGHT 7.1mm

BLADES: 9

Gt17

Exducer "ØA" Tip Height "B" Inducer "ØC" Journal "ØD" Stem "ØE" blades
37.5mm 7.7mm 44.3mm 7.88mm 5.08mm 9


I'm planning to use either a 52mm or 56mm Compressor depending on what i can get, that come from a 2.5 diesels, so using the .47 A/R exhaust housing is going to be the obvious choice but which turbine to use?

any one give me some tips or pointers in making a selection?

looking for driveability but also to use up all the fuelling i have that the original turbo cant flow air for.

many thanks..

 

Let's take this one step at a time, we know it's a 2L diesel, what hp are you after and at what rpms will it make it at?

For some reference, do you know how much hp your at now, and how much drive pressure your creating?

 

Its 2.0 8v non crossflow fully mechanical TDI using a "modified" Bosch VP21 (basically the guts of the vp21 installed into a NON ecu dynamic timing controlled pump)

unfortunately i can only estimate power atm..
The engine originally started out as an 85hp non intercooled TD but I've added an intercooler from a later model SDI spec car and then increased the fuelling and turned the boost up to 18psi. On the current turbo that probably good for about 115-120 hp, the later spec turbos have visually different Compressors but same specs as the TD compressor, and they make 105-135 stock at 15-17 psi (depending on model of car)
After 19psi the efficiency of the compressor drops off to where its just beating the air to death.

I'm looking for around 150 if its able to do that, but with out the smoke.
Its got a good haze to it in the summer and in the winter (due to the dense air) its much lighter on the smoke and definitely has more power, it actually makes the clutch slip on hard acceleration when it hits 2000rpm as i guess its starting to make peak torque here. After a couple pulls its noticeably less enthusiastic, Probably down to heat soak from that crap compressor.

I don't have any data atm on EMP, only from what I've managed to gain from reading on the MG-Rover forums and that EMP and head lift is a factor when tuning these engines with stock turbine housings and bigger Compressors.

Some Back story

Unfortunately for me, I'm about 10-15 years late to the party and don't get any replies on the MG-Rover forum posts when I've asked questions, also alot of info has been intentionally held back on turbo specs, especially ones that do well on the dyno.

the one hybrid turbo that made 181hp on the dyno used a "secret" turbine housing that also was a direct bolt on upgrade on a stock manifold and down pipe, and after sifting through 10+ years of forum, no one ever divulged what it was from.

Its took me best part of a year but i finally worked out what it was off of.. really rare TD version of a transit from the 90's but what was even more difficult to find was the A/R of the housing as Garrett didn't list it.. So after a lot of emailing of turbo refurbishers, i managed to find out its a .47A/R

Thanks to the Chinese they still reproduce the housing, (but with the A/R ground off for some reason) so i can get one these, but I'm not after 180 hp.

this where i come back to picking turbines so i can try to get spool somewhere in-between the stock 1700rpm and the "hybrid gt1752" 2300 rpm.

I don't know enough, to know if what I'm trying to achieve is physically possible using this particular size of housing and just changing turbine wheel size to get the desired out come.


If you've read this far, its appreciated lol, any advise would help, granted there's not a lot of hard data to go on but hey, just theory would help at this point.

 

I've built alot, alot, alot of gt17 and gt20 turbos for diesels. For 150hp the gt15 turbine itself would be sufficient. Gt17s are good for 220ish hp, gt20s we've pushed~300hp.

What flange is on the turbine inlet? I know there's a .63 a/r housing that would also work, I would change the compressor wheel to something more suited for pressure. Those older compressor were not designed for the speeds and pressures that we run now.

 

Its an unequal sided triangle...but only just, one through hole on the top and two m10 threaded holes on the bottom.
The flange is orientated so the single through hole is inline with the centre line of the housing, and the scroll of the housing hangs downwards... if that makes sense with the waste-gate actuator rod going over the top.

here's the drawing for the Gasket: https://www.turbomaster.info/eng/gaskets/gaskets_model.php?nombre=210293

So if i end up using the .47 turbine housing, then the stock Turbine that matches that housing is the one to use.
That's great news as i don't need to machine anything!

as for Compressors..

theoretically would i be right in assuming id need something like 20lbs/min to get close to the 150hp?

if that's the case then
(provided I'm reading a compressor map correctly)

Something like a 56mm 55 trim compressor is pretty much bang on 20lbs/min at a PR of 2.2 and in the highest efficiency island of the map.

 

Its an unequal sided triangle...but only just, one through hole on the top and two m10 threaded holes on the bottom.
The flange is orientated so the single through hole is inline with the centre line of the housing, and the scroll of the housing hangs downwards... if that makes sense with the waste-gate actuator rod going over the top.

I did list the link for the drawing of the gasket, but for some reason this forum hasn't posted this whole message for nearly 24 hours now, and just flagged it up as awaiting moderator approval and is invisible..!?
The part number is 210293
you can find the drawing if you look under the gasket tab on the Turbomaster website

So if i end up using the .47 turbine housing, then the stock Turbine that matches that housing is the one to use.
That's great news as i don't need to machine anything!

as for Compressors..

theoretically would i be right in assuming id need something like 20lbs/min to get close to the 150hp?

if that's the case then
(provided I'm reading a compressor map correctly)

Something like a 56mm 55 trim compressor is pretty much bang on 20lbs/min at a PR of 2.2 and in the highest efficiency island of the map.

 

You'll need to be close to 21lb/min, but otherwise your almost bang on.

Running the numbers, the gt17 in the .47 housing would definitely be the best route, followed by gt15 and .63 housing (has t25 flange tho), and last gt15 in the .47 housing.

Not sure where your located, but if your in the US I could work the gt15 turbine wheel over to flow more like a gt17. The advantage of this is you'll have a lighter turbine wheel, better spool with close to the same flow. Or swap to gt17 and bore out the turbine housing. I have loads of gt17 turbines and 37mm compressor wheels. Also have vsr balancer so you'll know its balanced.

 

Im in the UK im afraid, but otherwise that would be very kind of you.

The gt17 wheel would be the better bet in the long run then,
is this down to the fact that its physically bigger and would have higher shaft torque to spin the bigger compressor or would it just be down to the fact it flows more. Or does housing geometry / AR ultimately control the amount of flow through the hot side until the wheel becomes the choke point? if that makes sense?

when you mentioned about modifying the gt15 turbine wheel, is this what's known as a clipped wheel? or clipped turbine?

 

The 17 flows more, it better matches the engines breathing at the level you'll be running it at.
Housing a/r choke only controls the point at which it can't flow anymore without a substantial increase in drive pressure. If you kept going up housing sizes you would eventually get to the point where the turbine chokes instead of the housing.

Yes, clipping is where you grind away the outlet portion of the turbine wheel, there is a calculated approach to how much to go. This opens flow up but can also affect spool. There is some flow potential to be had grinding on the inlet side as well.

 

How critical is wheel diameter compared to the inducer diameter?

Reason i ask is Garrett list several GT17 wheels of 43mm and 44mm diameter but then they have the same inducer sizes.

For example
A (434533-0002) has 43 wheel size and 35.80 inducer / 69 trim
A (434714-0007) has 44 wheel size and 35.80 inducer / 66 trim

i know the differences are minimal but what effect would i expect to see between the two?

 

The lower trim (66) will make more boost at the same shaft speed.

I wouldn't use a 60+ trim wheel on a diesel. I would go with the 36x52mm (48 trim), the turbo won't have to work as hard, and will be less likely to surge than a 60+ trim.

Bigger trims are better for gas engines where they have alot of flow potential and don't need alot of boost.

 

This is turbine wheel size and trim where talking about right? cause other wise looking at the turbine wheel page on the Garrett website we're getting out of the GT17 sizes at 52mm and into the GT22 and T25 turbine wheel sizes..?

(For the Compressor i was looking at 56mm dia / 41.55 inducer, 55 trim)

 

No, I was talking about the compressor wheel.

 

I'm talking about turbine wheels, as there are roughly 7 different sizes of GT17 turbine wheel to pick from on the Garrett website and they have a range of inducers from 35.40 up to 39.40 and two wheel dia sizes

also looking at the compressor map for a 52mm 48 trim wheel you mentioned, 20lbs/min is almost off the top of the map..