G-Tec chip

[Freddan72]

Jari please add them to your photobucket so I also can see them

If I change the compressor wheel on the TB28 does this mean that the turbo can hold a higher boost pressure in the middle of the rev range say 4000 - 5500 rpm? Will it be a little more laggier compared to the OE turbo?

[per]

Interesting lecture about the bearings, it seems a GT28RS will be on the wishlist once my OE turbo fails.. (which by the way is strange why it hasn't happened yet, 155000km's, std. turbo and maxboost ca 1.4bar (since around 105000km)... Still no smoke! )

[GT28RS]

Sorry, I forget to answer to your other question .
Boost hold is not an issue with OE turbo, turbine wheel is the PROBLEM! It is so small 11 blade wheel, that this is the key point why you can not go very much higher with the power with TB28 turbo. Bigger compressor wheel together with machined housing will give more pressure in high rev's to win the back pressure of the turbine wheel.
With uprated OE turbo you can get higher peak power, but for example driving in track will cause very high exhaust temperatures just because of the turbine.
And now we come to the tricky point, why the OE turbo bearings won't last long.
OE turbo bearings are slide bearings and they don't like axial forces at all. Because higher boost works harder to get air flow past the turbine wheel, it gives quite a big axial force to the shaft and it will destroy the axial bearings quite soon. Like I explained my friend in Karleby.
This is why ball bearing turbo is much better, when we don't actually have turbo system in balance.
The modification of the OE turbo cost here in Finland around 600 Euro (ca. 5400 SKr), so if it won't last more than 10 000 km high boost run, it is not worth of doing. Surely if you run only with boost rate 1.2 bar it last longer and it gives you wider power band, but in high rev's you will see the same axial force problem. Okay modification of OE turbo is also almost half of the price and you don't need to modify anything other parts, that plus point to that choice .

It isn't laggier than OE turbo, you won't even notice the difference in low rev's, but better power is to be seen .

I have some where power graph, where I have manually added the uprated turbo curve + OE / Digitec and GT28RS with 1 bar boost. I try to find it and post as attachment here in Forum.

- Jari -

[Freddan72]

Originally posted by per
Interesting lecture about the bearings, it seems a GT28RS will be on the wishlist once my OE turbo fails.. (which by the way is strange why it hasn't happened yet, 155000km's, std. turbo and maxboost ca 1.4bar (since around 105000km)... Still no smoke! )

If you maintain the turbo (change oil regularly) and drive with common sense a turbo can last a lifetime.

Yes the plus side of modifying the OE turbo is that you don´t need to change downpipe, hoses etc.

Thanks for all the info Jari

[alx]

Originally posted by GT28RS
Okay modification of OE turbo is also almost half of the price and you don't need to modify anything other parts, that plus point to that choice

I think this is a strong point for many people (including myself). Not everyone is a skilled mechanic with access to a real mechanics garage. People tend to forget this when recommending turbo upgrade!
If I would be going for the GT28R (or RS) option it means a LOT of money need to be spent on labour for all the extras needed to fit the turbo, and also all the work for sourcing all the parts.

My turbo is smoking badly ( I have tried to convince it to quit smoking, but I guess it has became a habit for my car... )
Right now the car is in "winter rest" and I have not yet decided what to do... However, something needs to be done before spring arrives!

My choices as I see it:
1
Shipping the OE to a company that can put in 360 bearings, that I understand will last longer than the standard bearings.

2
Buying a GT28R and pay someone to fix everything brrrrr sounds expensive

3
We arrange a group hire of Jari He visits Gothenburg and fixes my, Per's and Freddans turbo upgrade.
We treat him with beer and ladies during the stay.
Brilliant idea! Agree?

[per]

Originally posted by alx
We treat him with beer and ladies

Is this something like PIMP my ride?

[Chorus]

per> Men du har orginal avagassystem med katalysator?
Min rykte ingenting med katten på, utan katt blev det ett stort moln bakom bilen när jag stog still ;D

[per]

Jag har 40cm av original downpipe 2.5", 3 tum till katten (2.5" Magnaflow), resten rostfritt 2.5tum.
Byggt av A-Alt-Avgas i Mölndal, downpipen av Togge.
Funkar fint, bra flöde o lagom tyst!

[GT28RS]

Hej,

Original downpipe is shit from start point . It is so narrow, the inside diameter is just some 50 mm, where the joint between turbo and downpipe is and that makes it very restrictive if you want to go above 280 bhp.
My friend, who has the GT28R turbo had in first place an adapter plate from the turbo to OE downpipe and the spool up was so slow that you could feel it. It was slower than my GT28RS. Then he did the full 5 bolt start from the turbo and the difference was so huge that it is even difficult to describe. With the adapter flange he got 280 bhp, after change the original downpipe to full 3" downpipe, he received the 312 bhp of power. With same setup the OE downpipe was restricting over 30 bhp.
Same kind of stories you can find also from UK forum.
With OE turbo this is not so clearly seen and felt, because there you have also the very small turbine wheel, which will restrict a lot when going high power, but spool up will be better and the power range is moved to higher rev's.


- Jari -

[pazzo]

De är säkert för att uppnå högre gashastiget vid låga varvtal = bättre verkningsgrad

Passar inte för extrema effektutag...

[Freddan72]

Originally posted by GT28RS
Sorry, I forget to answer to your other question .
Boost hold is not an issue with OE turbo, turbine wheel is the PROBLEM! It is so small 11 blade wheel, that this is the key point why you can not go very much higher with the power with TB28 turbo. Bigger compressor wheel together with machined housing will give more pressure in high rev's to win the back pressure of the turbine wheel.
With uprated OE turbo you can get higher peak power, but for example driving in track will cause very high exhaust temperatures just because of the turbine.
And now we come to the tricky point, why the OE turbo bearings won't last long.
OE turbo bearings are slide bearings and they don't like axial forces at all. Because higher boost works harder to get air flow past the turbine wheel, it gives quite a big axial force to the shaft and it will destroy the axial bearings quite soon. Like I explained my friend in Karleby.
This is why ball bearing turbo is much better, when we don't actually have turbo system in balance.
The modification of the OE turbo cost here in Finland around 600 Euro (ca. 5400 SKr), so if it won't last more than 10 000 km high boost run, it is not worth of doing. Surely if you run only with boost rate 1.2 bar it last longer and it gives you wider power band, but in high rev's you will see the same axial force problem. Okay modification of OE turbo is also almost half of the price and you don't need to modify anything other parts, that plus point to that choice .

It isn't laggier than OE turbo, you won't even notice the difference in low rev's, but better power is to be seen .

I have some where power graph, where I have manually added the uprated turbo curve + OE / Digitec and GT28RS with 1 bar boost. I try to find it and post as attachment here in Forum.

- Jari -

Jari

When you change the compressor wheel on the TB28 is this the same change that the kids in UK do on their STD turbos and call it a hybrid turbo?

Edit: I found the info on fccuk.org

[per]

Originally posted by GT28RS
Hej,
Original downpipe is shit from start point .
- Jari -

Although it seems the worst/narrowest bit is just before the catalyst, and the long bit where the pipes have double walls. Someone in UK measured his old OE system and it was under 2" before the cat.. So getting rid of this is still a good thing IMHO.

[alx]

Originally posted by Freddan72
Jari

When you change the compressor wheel on the TB28 is this the same change that the kids in UK do on their STD turbos and call it a hybrid turbo?

Edit: I found the info on fccuk.org

And the answer is?

[GT28RS]

Yes, this is what they call hybrid turbo.

Hybrid turbo is something where you mix bigger and smaller turbo parts together and it is not normally available.

In most cases they choose turbo according to compressor housing and add smaller turbine to get spool up earlier.

There are "hybrid turbos" from all kind of modells, for example one hybrid turbo you can nowadays read from UK Forum. Barbz is building GT28RS/R hybrid turbos. It has RS compressor housing, but quick spool R turbine housing.

In most of the cases these are good as long as you won't try to get all that is specified according to compressor map. For example if you could build GT28RS compressor housing together with original TB2810 turbine housing, you would have extra super spool GT28 turbo but no way it could give you more than 300 bhp, just because of the very small turbine.

- Jari -