Turbo modification - Anti Surge

[AndersS2]

I've heard some of this anti surge mod for the compressor housing on turbos, but i still dont get what it exactly does.
Can someone explain or do anyone know anything about it before i decide to do that to my current T-60-1 turbo?

(tried the search thing but came only up with this, though it explains some..)

Also, does this help in better spoolup or is it an extra portection for the axel/impeller and blades, and how can you feel the diffrence?

[twoqu]

Some info here. You will need to scrol down! Straight from Garrett!

http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech103.html

[Tommy200rs]

very good information in the link.

" Surge is most commonly experienced when one of two situations exist. The first and most damaging is surge under load. It can be an indication that your compressor is too large. "

- The reason for this might be that very "modern" engines nowadays produce very little exhaust fumes due to hard emission regulations. Therefore maybe Garret developed such small pressure turbos that wont produce such high amounts of exhaust gases. But anyhow if a turbo car, the air is needed into engine to make some mid rpm power anyhow and that is solved with big compressor wheel.

- that kind of balance between entry side and exit side is not optimal for high flow head , like the 20v turbo head allready as stock. If 20v head is equipped with flow increasing cams , the head channels are tuned , and some overlap the situation gets even worse with those earlier type Garret BBTs .

- I heared that Garret has produced some new BB turbos where the balance is so that entry is smaller in diameter compared to exit diameter (like rs2: ~ 47mm/54mm)
- delivery times for those ne BB turbos at the moment are with backorder status

- assumably these new turbos tolerate more boost at mid rpm 2800 to 4000 rpm but they most probably "weake up" slower at 2000 to 2800 rpm in 20v engine. Lets see when someone installs those new BBTs to Audi S2/RS2 and some first hand experience is received and not just speculating BS like my comments here.

If someone knows more about those new garret BBTs, please post some more info.

[Greg_S]

More links and info in this thread

http://www.s2forum.com/forum/showthread.php?t=16151