OK, I started thinking about this on another thread titled "Boost Hold". https://dodgeforum.com/m_370480/tm.htm , but thought it was too far off topic for that thread.

The wastegate controls the flow of exhaust thru the "drive" impeller of the turbo, right?
First question; How exactly is this done? I figure it must be acting as a bypass type diverter. If so, is the impeller in a "side stream" (or auxiliary path), or is the impellar in the normal exhaust stream with the wastegate diverting exhaust thru a bypass sidestream to cut the boost. I guess by the same token, when the wastegate is energized (I assume by vacuum?) is it to create boost or cut boost? Sorry if I'm asking for too much detail here, but this will help me understand therefore mod / troubleshoot my newest addiction.

Boostjunkie! [sm=gears.gif]

Also, if the turbo glows red after periods of boosting, is there a reason (other than cutting costs) that it seems nobody has made a water cooled turbo unit? Wouldn't it help keep the air on the charge side cooler, as well as helping to extend the life of the turbo?

Scott

 

Our turbo is water and oil cooled. I believe.

 

our turbos are only oil cooled... there are a few upgreaded ones that are water and oil. its pretty rare to find a stock oil/water cooled. i think the sti is.

 

Im not sure what you mean about a “side stream� and I have not actually seen the plumbing of the exhaust manifold, but I would guess that the wastegate opens its own special path around the turbine. I think you are right about the wastegate being a bypass control diverting exhaust around the turbine when needed. I’m guessing that the way it works is that the wastegate is just a diaphragm with boost pressure on one side and a spring with the wastegate-valve on the other. When you overboost the boost pressure will overcome the pressure of the spring, open the wastegate-valve, and bypass exhaust around the turbine. This will slow down the speed of the turbine and compressor to maintain a safe boost pressure. So the wastegate could be considered energized when there is more boost pressure than spring pressure which open the bypass. Also, if you preload the spring in the wastegate it will take more boost to overcome the spring pressure so you will hold higher boost before you start to bypass.

Hope I’m not missleading you, im new to all this turbo crap too! I’m looking forward to more input on this topic.

 

All sounds correct to me chadsicle. I know Ford went to water & oil cooled turbos for their 2.3L turbo cars in 1985½. Before that they were only oil cooled. They used a way too small oil feed line to. FYI 2.3L turbos were in Mustangs, Tbirds, Cougars, Capris, Pintos, XR4TIs and I think I'm forgetting one.... oh well, all rwd an a lot of fun.