Blow-Off Valve and Flange
09-01-1999, 06:54 PM
#2
Guest
Posts: n/a
Why oh why oh why would you do this???
Maybe its my limited understanding of the Motronic control and the 1.8T turbo, but I don't see what you guys expect to gain from the installation of a BLOWOFF valve. Hear me out:
First of all, your 1.8T is equipped with a BYPASS valve, not a BLOWOFF valve. A bypass valve is necessary to protect the turbo compessor from the surge of high pressure that occurs under boost when the throttle closes. When the throttle closes, the resulting mainifold vacuum actuates the bypass valve dumping the excess boost back to the intake side of the turbo. In this manner, the energy is recirculated and not lost nor dumped to the atmosphere. Don't replace or mess with your bypass valve.
A blowoff valve is typically used in bolt-on aftermarket turbos where there is no external wastegate or electronic control to modulate the wastegate to limit boost pressures. They are a necessity in these applications to limit the boost and prevent engine damage.
The Bosch motronic control in your 1.8T does not regulate or control to boost set-points, it is an air-mass based system. The control doesn't even know the absolute boost levels, there is no manifold pressure sensor input to the control. This means that for a given engine load, the boost level will be different based on ambient conditions.
So, what boost level are you going to pick for your blowoff valve. You have two choices: higher than the peak boost the control would ever develop, or lower. If you choose higher, your wasting your money as the blowoff will never activate. If you choose lower, then your just dumping precious energy that the control is commanding, ie you're pissing away power and performance.
This applies if your chipped or not.
Don't look at a blowoff valve as a performance enhancement for your 1.8T, it is not.
First of all, your 1.8T is equipped with a BYPASS valve, not a BLOWOFF valve. A bypass valve is necessary to protect the turbo compessor from the surge of high pressure that occurs under boost when the throttle closes. When the throttle closes, the resulting mainifold vacuum actuates the bypass valve dumping the excess boost back to the intake side of the turbo. In this manner, the energy is recirculated and not lost nor dumped to the atmosphere. Don't replace or mess with your bypass valve.
A blowoff valve is typically used in bolt-on aftermarket turbos where there is no external wastegate or electronic control to modulate the wastegate to limit boost pressures. They are a necessity in these applications to limit the boost and prevent engine damage.
The Bosch motronic control in your 1.8T does not regulate or control to boost set-points, it is an air-mass based system. The control doesn't even know the absolute boost levels, there is no manifold pressure sensor input to the control. This means that for a given engine load, the boost level will be different based on ambient conditions.
So, what boost level are you going to pick for your blowoff valve. You have two choices: higher than the peak boost the control would ever develop, or lower. If you choose higher, your wasting your money as the blowoff will never activate. If you choose lower, then your just dumping precious energy that the control is commanding, ie you're pissing away power and performance.
This applies if your chipped or not.
Don't look at a blowoff valve as a performance enhancement for your 1.8T, it is not.
09-01-1999, 08:53 PM
#4
Guest
Posts: n/a
VERY good statement, your 1.8T's turbo system isn't a Integra aftermarket system...
HKS and Blitz manufacture blowoff valves designed for cars that do not share similar turbo system characterestics that the 1.8T engine has (in manners mentioned above). It's engineered for turbo bolt on upgrades, or stock turbo systems such as on the Supra. Just because your 1.8T is a turbo aspirated car, doesn't mean that you should apply the common upgrades used for other turbo cars - especially asian ones.
Sorry to seem **** about this, but people keep thinking that a turbo car should have a blowoff valve and it's just because of ignorance that they think they're going to need a blowoff valve for their engine. Why not go buy a Weapon-R intake for your A4 too? Or how about a POWERED BY HKS sticker across your front windshield? The point is - your car isn't part of the import scene and should be treated like that either.
This isn't just geared just towards you Roger, so don't take it personally. Ok, I'll stop venting now.
-mF
99.5 1.8tqm (tomorrow!?)
Sorry to seem **** about this, but people keep thinking that a turbo car should have a blowoff valve and it's just because of ignorance that they think they're going to need a blowoff valve for their engine. Why not go buy a Weapon-R intake for your A4 too? Or how about a POWERED BY HKS sticker across your front windshield? The point is - your car isn't part of the import scene and should be treated like that either.
This isn't just geared just towards you Roger, so don't take it personally. Ok, I'll stop venting now.
-mF
99.5 1.8tqm (tomorrow!?)
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