turbohcar
TTypes Taste Like Chicken
- Joined
- Jun 30, 2004
I got to talking with a member here that frequents the forum and we couldn't come up with an answer for my question so, here goes.
Why don't the GN cars have a blow off valve? Every factory turbo car I've ever seen has had one, and from what I know, for good reason. The idea is that when the turbo is making positive manifold pressure (i.e. boost) and you let off the throttle, air is going to back up against the throttle plate. Now, that air has to go somewhere, so it progressively backs up through the intercooler and plumbing and back to the turbo. When this happens it causes compressor surge which is essentially when the two wheels stop spinning instantaneously because it cannot create any more pressure on the intake side and causes the turbo to "stall". This is the reason blow off valves were created. When a turbo "stalls" it can significantly increase the risk of bearing failure and decrease turbo life. The blow off valve gives the pressurized intake charge somewhere to go instead of backing up. You simply hook it up to vaccum port on the intake, attatch it to an intake pipe (between the turbo and throttle body), and when the intake sees vaccum (i.e. when you let off the throttle) it opens the valve.
Now, after that novel, why is it the GN cars can get away with this and I can't? Thanks
Why don't the GN cars have a blow off valve? Every factory turbo car I've ever seen has had one, and from what I know, for good reason. The idea is that when the turbo is making positive manifold pressure (i.e. boost) and you let off the throttle, air is going to back up against the throttle plate. Now, that air has to go somewhere, so it progressively backs up through the intercooler and plumbing and back to the turbo. When this happens it causes compressor surge which is essentially when the two wheels stop spinning instantaneously because it cannot create any more pressure on the intake side and causes the turbo to "stall". This is the reason blow off valves were created. When a turbo "stalls" it can significantly increase the risk of bearing failure and decrease turbo life. The blow off valve gives the pressurized intake charge somewhere to go instead of backing up. You simply hook it up to vaccum port on the intake, attatch it to an intake pipe (between the turbo and throttle body), and when the intake sees vaccum (i.e. when you let off the throttle) it opens the valve.
Now, after that novel, why is it the GN cars can get away with this and I can't? Thanks