Yes.
Funnily enough I have a spreadsheet setup just for that on the 4BD1T.

But the basics are quite simple, the big turbo must be capable of passing the total air consumption you expect, the small turbo must be capable of working alone as a single turbo.

My compound turbo setup is on hold until I can add more weight to the flywheel. I already have more torque than I can smoothly use below 2000rpm. More boost down low won't help me at all. In fact I'm about to swap a larger turbine housing onto my T25 to swap some low end boost for some better high rpm (like 3000rpm) flow.

Murray/John

do you have any more details on the GT2556V? I did a quick google. There seems to be different types with this model number. What sort of money is this turbo? GT2559V seems more widely available.

thanks

Pete

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REMLR # 137
Perentie 110 FFR ARN 49-107 GT28R Turbo
Perentie 110 PC FFR ARN 48-699 another project
Track Trailer ARN 200-117

Pete
waiting on a call from a truck wrecker with new and used prices for the GT2556V. Will post any info. Also try Saab wreckers as well.

Justin

__________________
I'm sorry

You've mistaken me for someone who gives a S..T !!

thanks Justin. I tried a couple of SAAB wreckers last time when considering a T3. Way over priced.

Pete

__________________
REMLR # 137
Perentie 110 FFR ARN 49-107 GT28R Turbo
Perentie 110 PC FFR ARN 48-699 another project
Track Trailer ARN 200-117

I think Dougal covered the basics.

Two turbos can be arranged in several configurations.

1. Twin turbos - 2 equal size turbos, each one for half of the engine and often used with V engines (one turbo for each bank)

2. Sequential turbos - a small turbo is used at low engine revs, then a larger turbo takes over at higher revs. Requires valves to control the change from one turbo to the other. The turbos are parallel. This has been used on some production vehicles in recent years.

3. Compound (or staged) turbos - the small turbo (sometimes called secondary turbo) is high pressure and the large turbo (sometimes called primary turbo) is low pressure.

The exhaust gasses from the engine flow through the high pressure turbine first, then through the low pressure turbine. Usually a wastegate is needed to bypass some exhaust around the high pressure turbine to the low pressure turbine at high engine speed - this reduces drive pressure and prevents overspeeding of the high pressure turbine. Generally no wastegate is needed for the low pressure turbine. The pressure at the inlet of the high pressure turbine drops on its way to the inlet of the low pressure turbine.

The inlet air flows through the low pressure compressor first (primary stage) where it's pressure, density and temperature increase before entering the high pressure compressor (secondary stage) where these values are increased further.

Compound turbos have a broader range than singles, and are capable of flowing more air and higher boost pressure.

4. The last configuration is a combination of sequential and compound. The 2 turbos operate as a compound set at lower boost pressure then as sequential at higher boost pressure. This is done for a broader range than sequential turbos, but does not produce the high boost pressure of compound sets. This is the configuration to be used on the new 3 litre V6 in the Disco 4.


I have a compound set for my 4BD1T. It uses 2 Borgwarner turbos. Pictures were posted in this forum some time ago.

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John

The 25 number relates to the turbine housing size. The 56 and 59 numbers relate to the diameter in mm of the compressor impeller.

But there are many other differences that can be made for particular engines, such as actuators for controlling the vanes, inlet and outlet differences etc.

So treat GT2556V or GT2559V like a family name. You won't usually find these designations on the identity tag of the turbo. There, you will find a number like 24652-0001 (this is from a GT2256V) the numbers to the left of the '-' is the main identity number, the numbers after the '-' are version (small changes/improvements that don't affect interchangeability).

The Garrett catalogues list different GT turbos with the the identity number and some other details, but not dimensions or inlet/outlet details etc.

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John

John
I do remember the set up you got. Did you ever fit it up and run it??.
Mate if I can fit my Switzer in and pipe it up with my Garrett I might just give it a shot. Got nothing to loose



Pete
Contacted an Iveco wrecker. GT2556V new $3000.00 + gst
he has 1 good s/h unit $1500 + gst these are both from the 3.0l Turbo daily truck

I would get the s/h unit but I have just given the local bitumen guy the go ahead to do 500m of our driveway/access road, so a bit on the no cashflow front for a while.

If you need his number I can pm it to you. Really good bloke to deal with.

Justin

__________________
I'm sorry

You've mistaken me for someone who gives a S..T !!

I have started fabricating a new exhaust manifold, but have been sidetracked.

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John

i have turbo's off a 3.0l daily, but they are GT2260VNT's going by the part number i got from thr turbotechnics website (753959-0005)
http://www.turbotechnics.com/docs/catalogue.pdf

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Damien
------------------------------------------------

Vern, are you selling them and if so how much are you selling them for?

Peter

__________________
REMLR # 137
Perentie 110 FFR ARN 49-107 GT28R Turbo
Perentie 110 PC FFR ARN 48-699 another project
Track Trailer ARN 200-117