Blow-off or By-Pass

[max_s2]

Hello everyone!
First of all, sorry for my bad english, havent write in english for a long time..
Some weeks ago I brought Audi S2 2.2 turbo (3B engine code), very good car in very good condition! You can view some photos here if you want to -> http://foto.inbox.lv/maxz/S2
So, once I have this car I want to make a little engine upgrade. First of all, I want to decrease the turbo holle (I dont know is this right in english). I have readed that one of ways how to do this is to add a blow-off valve or upgrade the stock by-pass. Both of these valves seems ok for me, but some people told me that blow-off is not good for some turbo engines (how its with audi S2?). I mean.. blow-off can damadge lambda and other stuff because of the rich fuel. Is it true? Today my friend from car-store told me that lambda is right for that - if the fuel goes too rich, lambda sends some information to ECU un and so the fuel doesnt get so rich.. maybe sounds too lame, but I realy dont understand this all but if its right, then there should be no problem with blow-off!

In the end. What you guys sugest me to do? What valve should I install on my S2 - blow-off or replace the original by-pass with a better one? If the blow-off will not do some bad things to my engine, then maybe I should chose better it? And how about those blow-off's that goes PSSHHH and some of oxygen puts back in to the intake colector (dunno if I wrote right)?

uff.. it was hard for me to write this stuff, sorry for this long message. I hope that someone will understand my wishes and problems!

[alg]

Hello everyone!
First of all, sorry for my bad english, havent write in english for a long time..
Some weeks ago I brought Audi S2 2.2 turbo (3B engine code), very good car in very good condition! You can view some photos here if you want to -> http://foto.inbox.lv/maxz/S2
So, once I have this car I want to make a little engine upgrade. First of all, I want to decrease the turbo holle (I dont know is this right in english). I have readed that one of ways how to do this is to add a blow-off valve or upgrade the stock by-pass. Both of these valves seems ok for me, but some people told me that blow-off is not good for some turbo engines (how its with audi S2?). I mean.. blow-off can damadge lambda and other stuff because of the rich fuel. Is it true? Today my friend from car-store told me that lambda is right for that - if the fuel goes too rich, lambda sends some information to ECU un and so the fuel doesnt get so rich.. maybe sounds too lame, but I realy dont understand this all but if its right, then there should be no problem with blow-off!

In the end. What you guys sugest me to do? What valve should I install on my S2 - blow-off or replace the original by-pass with a better one? If the blow-off will not do some bad things to my engine, then maybe I should chose better it? And how about those blow-off's that goes PSSHHH and some of oxygen puts back in to the intake colector (dunno if I wrote right)?

uff.. it was hard for me to write this stuff, sorry for this long message. I hope that someone will understand my wishes and problems!

Replace with the S3 OEM Diverter valve. Cheap lasts longer than original. 'Blow-off' or vent to atmosphere valves are not suitable for this engine set up.
You will find lots of previous threads using search 'diverter valves' if you want a longer answer

[max_s2]

Thanks dude! Can you tell me in some words what's a diverter valve?

[alg]

DV=Diverter Valve= stock by-pass valve=automatic by-pass valve

[B3rggr3n]

Blow-off

Gfb has an open blow-off valve who is suited for our cars. It says so on the the homesite and i have heard of a few people who uses them here in Sweden and their opinion is that the valves work very good

[alg]

Gfb has an open blow-off valve who is suited for our cars. It says so on the the homesite and i have heard of a few people who uses them here in Sweden and their opinion is that the valves work very good

My understanding of the collected wisdom here (which is a lot) is that vent to atmosphere dump valves are not 'good for our cars'
I cannot recall all the details but the S2/RS2 system is designed as a closed system not open to atmosphere unless you have modified the induction system (as some have)
Check the previous threads for a more technical answer but my advice to a new owner of an unmodified S2/RS2 would remain an S3 DV...cheap, reliable and a quicker responding diaphragm design (rather than the piston aftermarket Forge et al)

[B3rggr3n]

gfb

yeah I've heard that to, but on GFBs homepage its says that it is made for cars who cannot use the regular open ones!

[WabTheKing]

i have a blow off valve on my car, works fine, no running problems

what are they suppose to do which is so bad?

either is better than non at all

[Greg_S]

The S2 and RS2 uses a closed loop system where all the air is metered into the engine and can confuse the engine when it goes missing, e.g. from a dump valve to atmosphere.

By using a recirculating valve the air is kept in the system and is ment to help keep the turbo spinning by sending the pressurised air back at the turbo on a gear change. The dump to atmosphere type valves do the same job but dont keep the air in the system.

But I have to agree with Wab either is better than none

[DJones]

If the MAF has been moved to the positive side and the dump valve is before it it will be ok, if not you will have slight hesitation as the ecu will over fuel when you put your foot down after changing gear. due to the ecu thinking there is more air than there actually is.

[Ski]

what are they suppose to do which is so bad?

I heard it gives u a oil leak

[WabTheKing]

yeah so never fit a dump valve to your power assist pump

[Ski]

Or to your starter motor

[WabTheKing]

or to the straps holding your car on the rollers

[Ski]

If you can get onto the rollers

oooh the fun never stops!