Fake BOV's and high boost
- Thread starter Trip
- Start date
Makaveli_se7en
Member
who needs a BOV? why dump all that hard aquired boost pressure into the atmosphere?
red reading
Active Member
Hopefully a plug,your cock would be very painfull:lol::lol:
darkyGTI-R
New Member
I love the noise the dv makes!Each to their own I suppose!
Purely to reduce noise as most manufacturers do with turbo cars ;-)
Makaveli_se7en
Member
There are two potential issues with running without a dump valve:
1. When you close the throttle you drive the compressor to the left hand side of the comp map. This is were the highest thrust loads towards the compressor are found. Therefore if you are running high boost levels you can cause excessive thrust bearing wear. As far as I'm aware this is not such an isuue with BB turbos as the thrust carrying mechanism is different. I would also argue that at the boost level the standard T28 is capable of I would not expect it to be an issue but I do not know the thrust load capacity of the T28. It could also be overcome with a 360 degree thrust bearing. But normal journal bearing turbos can be rebuilt cheaply enough for it not to be too much of a concern either way imo.
2. Compressor stall. A very misunderstood term. It does not mean that the turbo stops turning as many would have you believe. It refers to the flow separating from the impeller and re-cirulating within the blade passage. This causes what is technically referred to as transient surge (the fluttering noise) where the compressor starts to perform in an unstable manner (gulps air rather than a smooth flow). In extreme cases (very high boost levels) this can cause damage to the impeller blades, normally at the tip of the inducer and destroy the turbo. However I am yet to see evidence of this on a road car application.
As for the functionality of BOV, there are the above mentioned potential increased of turbo life features but I would contest the idea that it imporves transient reponse of the turbo, as there are aguements fro and against:
For- keeps turbo operation nice and smooth (no surge) so in theory could potentially keep the turbo spinning faster and therefore doesn't require as much initial engergy to spool it up again.
Against - vents all positive pressure from the intake, so have re-pressurise the intake system, which with a big FMIC could create a lot of lag.
As I said I don't run one, I don't believe with modern turbos that the life is greatly reduced running without one and I have quite a big FMIC and want as little lag as possible. Also if my GT3071 dies I have a GT 3076 lined up to replace it
Sorry if thats a bit long winded
1. When you close the throttle you drive the compressor to the left hand side of the comp map. This is were the highest thrust loads towards the compressor are found. Therefore if you are running high boost levels you can cause excessive thrust bearing wear. As far as I'm aware this is not such an isuue with BB turbos as the thrust carrying mechanism is different. I would also argue that at the boost level the standard T28 is capable of I would not expect it to be an issue but I do not know the thrust load capacity of the T28. It could also be overcome with a 360 degree thrust bearing. But normal journal bearing turbos can be rebuilt cheaply enough for it not to be too much of a concern either way imo.
2. Compressor stall. A very misunderstood term. It does not mean that the turbo stops turning as many would have you believe. It refers to the flow separating from the impeller and re-cirulating within the blade passage. This causes what is technically referred to as transient surge (the fluttering noise) where the compressor starts to perform in an unstable manner (gulps air rather than a smooth flow). In extreme cases (very high boost levels) this can cause damage to the impeller blades, normally at the tip of the inducer and destroy the turbo. However I am yet to see evidence of this on a road car application.
As for the functionality of BOV, there are the above mentioned potential increased of turbo life features but I would contest the idea that it imporves transient reponse of the turbo, as there are aguements fro and against:
For- keeps turbo operation nice and smooth (no surge) so in theory could potentially keep the turbo spinning faster and therefore doesn't require as much initial engergy to spool it up again.
Against - vents all positive pressure from the intake, so have re-pressurise the intake system, which with a big FMIC could create a lot of lag.
As I said I don't run one, I don't believe with modern turbos that the life is greatly reduced running without one and I have quite a big FMIC and want as little lag as possible. Also if my GT3071 dies I have a GT 3076 lined up to replace it
Sorry if thats a bit long winded
shroom
Active Member
ah its alright for some :lol:Also if my GT3071 dies I have a GT 3076 lined up to replace it
thanks for the info, I run one but tbh might try it without, the hks does give a nice novelty noise value but thats already worn off