What's the difference between wastegates and blow off valves? And which kind of wastegate is better, internal or external? Thanks.

Well. Wastegate and BOV's are two different things entirely. Wastegate's vent excess exhaust gases away from the turbo so that you do not overboost. The wastegate controls boost essentially. BOV vent compressed air (boosted air) away from the turbo when the throttle plates close.



As far as internal vs. external...depends. Internal wastegates are for cars who use external actuators to open up the wastegate flapper door. External wastegates are used with single turbo FD's. It's not possible (unless a new manifold is made) for you to run stock twins and external wastegate.

so what's the difference between a wastegate and a manual boost controller?

Sorry, I'm still pretty new to the whole turbo thing. I've just started really looking into the mechanical side of these cars. Before I was all about bodykits and that kind of stuff.

http://auto.howstuffworks.com/turbo.htm



Sorry man, but you've got to get the basics down first.



A boost controller is controlling the signal to the wastegate.

Manual boost controller is a boost controller that is not controlled via any electronics. Essentially you want more boost you turn the knob manually :P



Wastegate was explained in my above post. Wastegate's have a boost/vacuum source connected to them (usually on the side) that comes from the motor. As the engine build's boost, that boost pressure will open up the wastegate. They will open up at different boost levels dependent upon manifold design and wastegate spring(different springs vent at different boost levels). When you add a manual boost controller to a wastegate you normally connect a boost source to the MBC and then the MBC to the top of the wastegate.

Couldn't you do the same thing with stiffer springs in the wastegate?

Yes. But that's MUCH harder than simply adding in a boost controller. And if you want to lower boost ....well you can't if you do that.