Turbo Question

**isuzurover** · 19th April 2012, 08:56 AM

Originally Posted by isuzuscott

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.

If you want the same turbo as me, just look around on the nissan/ricer forums or ebay.

I bought mine sh from a nissan guy for a couple of hundred. I have put >>100k km on it and no problems yet. IME it is a good option for highway/touring work for a 4BD1. For an E it should be fine too, but you may want a slightly smaller turbo if you do a lot of slow speed / offroad work and want it to spool earliier.

**Dougal** · 19th April 2012, 10:15 AM

It all depends what you want. Ben's turbo is running a similar compressor to my current one, but I run a lot smaller exhaust housing. The reason being I like to get the max benefit in the 1500-2500rpm range.
My current setup is choking the exhaust by 3000rpm and that is where my power band ends, mainly because I'm pushing 24psi boost through it. Lower boost extends your operating range.

I don't know the specs of the patrol RD28 turbo. See if you can find any numbers.

**isuzuscott** · 19th April 2012, 11:44 AM

Originally Posted by Dougal

It all depends what you want. Ben's turbo is running a similar compressor to my current one, but I run a lot smaller exhaust housing. The reason being I like to get the max benefit in the 1500-2500rpm range.
My current setup is choking the exhaust by 3000rpm and that is where my power band ends, mainly because I'm pushing 24psi boost through it. Lower boost extends your operating range.

I don't know the specs of the patrol RD28 turbo. See if you can find any numbers.

I want to add the turbo for similar purposes such as touring, towing etc and in particular the cape trip which is planned for september. I don't want it to spool up too quick but i don't want it spool up after 2500rpm. So between 1500 and 2500rpm sounds perfect for what i want.

I need a clutch and rear main first so I will continue to search around the ricer forums and ebay and look for one.

Should I stick with garrett for quality? There are various shops selling T25/T28 silvia turbos brand new for sale but I don't want to buy rubbish.

I had a quick stickybeak around for Patrol info and the best I can get is this photo which only gives the A/R value. Now A/R stands for Area/Radius doesn't it? Therefore a smaller A/R value means its spools quick therefore power lower in the rev range

**Dougal** · 19th April 2012, 12:10 PM

Yes, but the A/R you are looking for is on the exhaust housing. The one on the compressor housing isn't quite as useful.

Most of the T25/T28's for sale on ebay and the like have large A/R exhaust housings for ricers to hit max boost at 8,000rpm.

**Bush65** · 19th April 2012, 01:18 PM

Yes A/R is the cross section area in the housing, divided by the radius from the axis of the impeller shaft to the centroid of the cross section area.

With the compressor cover (housing) A/R change makes little to no effect. With compressors the most effect comes with changing the impeller (wheel). The turbo manufacturers offer different wheels (which need a matching cover) to suit variations in engine sizes and types.

With the turbine, the impeller that the manufacture chose for the series (T25, etc.) is not changed, but the housing A/R makes most difference for matching to engine size and type.

With petrol engines the exhaust is much hotter and flow is greater because rpm's are much higher than for diesel engines - these need a larger A/R housing so as not to choke the exhaust at high speed.

The operating rpm range of diesel engines is smaller (and lower rpm), and exhaust gas temp is much lower.

Many manufactures state a HP figure for their turbos. This is based mainly upon air flow requirements for petrol engines.

I don't know the sizes of a turbo from a 6 cylinder 2.8 litre Patrol - these rev fairly high for a diesel so the size may be suitable for a much lower revving 4BD1. The A/R should be suitable, since it is for a diesel.

From memory, the 4 cyl 3 litre Nissan diesels have a Garrett VNT GT2052V. These would be suitable providing you don't want high boost pressure for much higher power and rpm than a stock 4BD1T. The 52 mm compressor impeller is too small for best results, but a larger impeller should do the trick.

On Garrett turbos from some stock vehicle, the tag will have the Garrett number along with the vehicle part number. If you know the Garrett number, there are enough publications to find most details.

Turbo repair kits are available on ebay for little cost.

**isuzuscott** · 20th May 2012, 05:57 PM

Alright, I got my hands on the RD28 turbo i was talking of two weeks or so ago. The reason I got it was because it was a great price, it was rebuilt 40,000k's ago, no shaft play at all and runs a journal bearing.

It is a garret TB2527 which from what I know is a water cooled and oil cooled journal bearing turbo. The TB stands for a flapper valve waste gate which makes sense, see the photos. It also has a T2 flange.

I got some numbers off the turbo, see photos.

TB2527
465941-6
TT171007-2

If anyone can elaborate on the details of this turbo it would great.

**Dougal** · 21st May 2012, 06:27 AM

That's a T25, the tag that's on it isn't factory, suggesting it may have been rebuilt at some stage.
Look for A/R numbers on the turbine housing near the inlet flange and take the compressor cover off to check which compressor wheel is in it.

It's basically the same as the CA18DET T25 I ran for a long time, but the exhaust housing will likely be a different size. The CA18 turbo was 0.49 A/R on the turbine housing and worked very well up to 15psi. Past 15psi it choked the top end before the rev limit. I ran it at 20psi for a long time.

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