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lewie wrote:pretty sure the standard one is a gt25 of some type. And the fact that vn15 on here has put one of the larger gt28s on his 2.8 and has worked well just thought maybe the smallest of them would be an upgrade seeing as i think its already got a 25 on it...???
as with the GT28 series the GT25 has more then just one turbo.
lewie wrote:pretty sure the standard one is a gt25 of some type. And the fact that vn15 on here has put one of the larger gt28s on his 2.8 and has worked well just thought maybe the smallest of them would be an upgrade seeing as i think its already got a 25 on it...???
as with the GT28 series the GT25 has more then just one turbo.
How much power do you want to make?
Not all T25 turbos are actually ball bearing cartridges either remember. Big difference.
If you want to use a GT28 then keep your exh housing below .64
A 2.8 should spool a disco pretty quick anyway. It's probably not the ideal turbo for the job though. Easy to get hold of though
lewie wrote:pretty sure the standard one is a gt25 of some type. And the fact that vn15 on here has put one of the larger gt28s on his 2.8 and has worked well just thought maybe the smallest of them would be an upgrade seeing as i think its already got a 25 on it...???
as with the GT28 series the GT25 has more then just one turbo.
How much power do you want to make?
Of course there are far more factors to consider than simply "how much power".
It's very easy to size a turbo for max power, simply find the biggest turbo that will provide the necessary boost at the highest rpm.
But unless you're building a dyno queen, that's pointless.
Drivability is a big concern to most, keeping a usable amount of boost over most of the rev range is a big part of that.
Besides, to get big power from a small engine requires high boost, the disco potato isn't suited to high boost, the compressor map stops at PR 2.5 (22 psi).
The original turbo on the 2.8 will be a TB25, the exhaust housing may be as small as 0.49 A/R.
I'd like low to mid range power, how much you ask? f*kin heaps! hmm a very hard question to answer... umm i want how much power a suited BB turbo will add onto the mods ive done and weather a BB turbo upgrade will even give significant power changes with a retune after installation for the money spent. Mainly i want to do this to improve the low to mid range power with a faster spooling turbo than what i have now and then get it retuned as ive also installed the intercooler since getting the original fuel/boost tune done. Like i said if i was going to get a GT28 id get the smallest of them but some saying it would work and some saying it wouldnt and the fact the someone has used 1 of the larger sizes and its worked. Its just that the BB 25 series look like far more modification than installing a 28 because of the triangular flanges etc instead of the normal circular for fitting silicone hose.
ledgend80 wrote:lewie what are these triangle flanges that you talk about on the 28
The outlet from some of the 25 and 28 compressors have a three bolt flange.
It's easy to make an adapter back to the pipe of your choice, nissan also have a lot of factory pipes which fit those and head off in different directions.
Here is what a correctly sized bb turbo will do over a std hitachi turbo on a patrol. These graphs are from the same vehicle as the boost graphs that were posted earlier.
First is power, std GU ute, fact i/c, desert duellers, 4.1 diffs. Red graph is untouched except for a 3" system, blue is as above with boost and fuel adjustments, yellow untouched except for bolting on a Garrett bb, pink is with Garrett and boost and fuel adjustments.
Hope this helps with decision making.
Andy
www.diesel-tec.com.au Ph 03 9739 5031
Ball bearing turbo upgrades for factory turbo vehicles. Got a diesel question just ask.
Home of the twin turbo shorty and many 150rwkw+ patrols.
Yeah andy thats very good but havnt seen anything on a rd28t as yet and the reason id like to stear clear of the three bolt flange is there is very little room for the compressor outlet into the intercooler silicone hose so id really like to get one with a similar compressor housing design to the exsisting. If its slightly larger that will be fine and i can get it rotated to suit the angle of the exsisting turbo.
I'd like to go through andy as i certainly trust his knowledge etc, but ive only seen his work on 4.2s and like i said its hard to fork out over a grand for something he wont tell you 1 thing about. I could buy and have it rock up and need far more modification than what im prepared to do. Thats why id like some thing reasonably similar in regards to compressor and exhaust housing designs but not nessisarily size as they will vary slightly no doubt.
The turbo on it is already both water and oil cooled so thats not an issue just have to make/ buy new lines with fittings.
ledgend80 wrote:ok so i am down to either he gt2860rs, gt281r 48 trim or the gt2871r 56 trim. has any body fitted one of these toa landcruiser or a patrol.
not keen on the gt2871r 52 trim due to the bolt on flanges unless someone knows that you can get it in the normal barb style
You're down to two turbos which vary in flow capacity by 25%?
As asked earlier, what are your goals?
Do you intend to go with intercooler upgrades and fuel pump upgrades? Will you be happy with what the stock pump can put out or will you just leave it at factory fuelling?
yes that maybe true but the gt2560r has the flange type inlet and outlets not what i am after and arent all the hp calculations on the garrett site for petrol engines not diesel engines
ledgend80 wrote:yes that maybe true but the gt2560r has the flange type inlet and outlets not what i am after and arent all the hp calculations on the garrett site for petrol engines not diesel engines
I do my own power/torque calculations. The maps are good for required airflow and pressure ratios. That's it.
If you want 200hp at say 3200rpm, then you need ~430Nm at that rpm.
Assuming a VE of 80%, compressor 60% efficient and intercooler 60% efficient then you only need a little over 15psi.
Total airflow required is 25 lb/min, the 2560 can push a total of 33 lb/min so it's going to run out of puff around the same time your engine runs out of revs.
There are a range of turbo sizes suitable for your engine, it all depends what the required outcome is. This is just one turbo that is suitable.
I wouldn't let compressor flanges dictate choice at all.
ledgend80 wrote:well seems to be running ok yet to have the pump adjusted only had 3 inch exhaust done and still need to fit the water to air intercooler.
it would be good to hear how it goes once you have the pump etc tweaked.
It would be very interesting to see how much the boost/RPM figure you posted on ih8mud change once its been tuned.
it will be interesting as some shops have told me that once the pump is adjusted it sill wont supply enough fuel for it and will require internal mods. how do they tell that it isnt suppling enough fuel when the tune them. (egts to high maybe running to lean i guess) has any one had tghere 1hdt pump modified internally and if so what do they do to it. and is the cost worth it. what peoples opions.
if it is not getting enough fuel, the EGTs will be lower, excess fuel create excess heat in a diesel.
If it is being dynoed they should be able to measure the air/fuel ratio to determine if it is getting the right amount of fuel. EGTs are an indicator too.
they can be modified, but I think you are talking $thousands. The distributive head and plunger can be changed from 12mm to 13mm (1hz uses 11mm) from what I know, it becomes hit and miss with a bit of trial and error to get things right, so I dont think it will be cheap.
From memory Dzltec did this to the pump on his own 80series, I dont think it was straight forward.
