Turbo Question

**isuzuscott** · 18th April 2012, 07:48 AM

Gday,

My mate has a 2.8 diesel GQ patrol and is upgrading the turbo. Since he can only run one turbo his standard one is up for grabs. It is a Garret T25.

I read that the budget turbo thread where he uses a T25/T28 hybrid (same as a GT2560R but with ball bearings) off a s14 silvia. Is it possible to use a normal T25? And if so what would be the diffrence between an S14 hybrid T25/T28 and the standard T25?

Adaptor flanges for the manifold and other stuff is not a worry. Just checking to see if a T25 suits the 4be1?

**ScottW** · 18th April 2012, 08:02 AM

As far as silvias go, the T25 is generally off the S13 silvias. The T28 is off the S14 and S15 silvias. The T28 ball bearing version is off the JDM S15 and are harder to come by. Of course these turbos were available on a number of other cars with different A/R ratios etc.

**isuzuscott** · 18th April 2012, 08:39 AM

Originally Posted by ScottW

As far as silvias go, the T25 is generally off the S13 silvias. The T28 is off the S14 and S15 silvias. The T28 ball bearing version is off the JDM S15 and are harder to come by. Of course these turbos were available on a number of other cars with different A/R ratios etc.

Thanks. In the budget turbo thread here OldBushie says he gets a GT2560R or T28/T25 hybrid off an S14 Siliva, SR20DET engine. Because of the hybrid he says it will spool up quick with good flow.

I want to know if a basic T25 will spool up and have good enough flow to suit the 4be1?

**Bush65** · 18th April 2012, 09:28 AM

T25 is a generic size that can have many options to suit the aplication.

On the turbine side, the housing A/R is an important consideration - diesels normally require a smaller A/R compared to petrol engines, or they can be slow to spool.

On the compressor side, inducer (inlet) and exducer (outlet) diameters of the wheel have the most influence on air flow and efficiency (heating of charge air), and depend on how much boost pressure you want to run.

**c.h.i.e.f** · 18th April 2012, 10:38 AM

Also consider why is he taking it off a 2.8 and upgrading to something else !! I didn't know that Nissan patrols came out with Garrett's I thought they were hitachi ht15's and ht16's ?? i do not like hitachi turbos I recon they are not as good quality IMO....

**isuzuscott** · 18th April 2012, 11:27 AM

Originally Posted by Bush65

T25 is a generic size that can have many options to suit the aplication.

On the turbine side, the housing A/R is an important consideration - diesels normally require a smaller A/R compared to petrol engines, or they can be slow to spool.

On the compressor side, inducer (inlet) and exducer (outlet) diameters of the wheel have the most influence on air flow and efficiency (heating of charge air), and depend on how much boost pressure you want to run.

Thanks mate.

Do you have any figures which suit the isuzu engines in terms of housing A/R, inlet and outlet dia?

**isuzuscott** · 18th April 2012, 11:33 AM

Originally Posted by c.h.i.e.f

Also consider why is he taking it off a 2.8 and upgrading to something else !! I didn't know that Nissan patrols came out with Garrett's I thought they were hitachi ht15's and ht16's ?? i do not like hitachi turbos I recon they are not as good quality IMO....

He was thinking about upgrading because the current one was leaking oil so i had quickly thought of the idea to use his old one but from I am reading it appears that a turbo off a s14 silvia will suit the isuzu better.

**c.h.i.e.f** · 18th April 2012, 01:07 PM

Auh i see so you were going to rebuild it yourself then and use it ? I cannot comment wether it will be suitable as I'm no expert but can you post up the cold and hot side AR's ? It will be written on the housings somewhere...

**Dougal** · 18th April 2012, 03:06 PM

Originally Posted by isuzuscott

He was thinking about upgrading because the current one was leaking oil so i had quickly thought of the idea to use his old one but from I am reading it appears that a turbo off a s14 silvia will suit the isuzu better.

Chances are his turbo is passing oil because his engine is poked and the crankcase is pressurising. So if you hold off you might get a whole series of used turbos that he thinks are no good.

**isuzuscott** · 19th April 2012, 08:44 AM

Originally Posted by Dougal

Chances are his turbo is passing oil because his engine is poked and the crankcase is pressurising. So if you hold off you might get a whole series of used turbos that he thinks are no good.

I think he has fiddled with the injector pump fuel screw so that would explain why.

Dougal you are the man to talk to aren't you?

Will a t25 of a patrol suit the isuzu though in terms A/R, turbine and compressor diameters? Do you need these numbers to give an answer or can you give me a rough answer by knowing that it is off a 2.8 6 cyl patrol diesel? There isn't much similarity between the patrol and isuzu so i would assume the turbo wouldn't be very effective on a 4be1.

It is all well and good getting a cheap turbo off him but whats the point if it isn't going to work well.

Isuzurover uses these specs which are from the silivia turbo so I am aiming to find a turbo similar, is this a good idea?

First thing I did, was track down a turbo from an S14 Silvia (SR20DET). This is a hybrid T28/T25 turbo, exactly the same as the GT2560R, except that the S14 turbo has a journal bearing rather than a ball bearing. It should have a fairly quick spool up, and quite good flow.
The specs are:
Compressor: T-28, 60 trim 60mm BCI-1 compressor in T-04B housing
Turbine: T-25, 62 trim 53.8mm 0.64 A/R turbine housing.

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