O2 dumptubes and external wategates?

[brokencpsd95tsi]

Ok I know nothing about O2 dumptubes or external wategates....could somebody please explain them or point me to a web address that will.

 

[candela]

You know its so funny how many of the same questions are asked. Ive been here since may and have seen the same questions soo many times, its funny.

First, just to be basic, a wastegate controls boost...simple and plain. If that confused you, all a boost controller does is trick the wastegate.
There are internal wastegates and external wastegates, they both do the exact same thing, just one does it in a little more efficient way than the other. External wastegates are usually mounted on the exaust manifold befoe the turbo so it can remove spent gases to control boost. Sometimes people have a seperate pipe coming off of the collector that goes to the wastegate, and in this case, the w/g releives gases from all cylinders instead of just one as the manifold mounted w/g does. Another way is to mount the w/g as part of the o2 housing which I think is pretty cool personally. The w/g is mounted where the spent gases would normally go if you had an internal w/g (more on that later), thus providing maximum pressure on the turbine (good) instead of having a cylinder robbed of flow or something

An internal w/g is mounted in the turbine housing, and uses a w/g actuator to open up a valve/flapper on the turbine housing an dlets the gases flow out of the turbine housing thus controlling boost again. There are two ways to have the gases exit, either by routing it back into the exhaust or having it "dumped" into the atmosphere. The rerouting is nice an quite, and doesnt shoot out all kinds of exhauts into the atmosphere like the dump does. The dump has the passage from the w/g flapper seperate from the rest of the o2 housing/exhaust, and usually has some type of its own tube that just points to the ground (or whereever) and releases the exhaust into the air when the flapper opens. The advantage of an o2 dump over a rerouted internal gate, is that it, for the most part, eliminates any instability in your boost. You dont get boost creep or anything like that, that some do with a rerouted w/g. The advantage of an external gate is that the flow and release of gases from it is much more direct and smoother than that of an internal gate. It controls boost much better, and will enable larger turbos to run lower boost levels without creeping (so long as its big enough). If you have a large turbo (20g +) and a small internal w/g sometimes it is not efficient/large/direct enough to release all of the pressure built up in the turbine housing, so the normal is to slowly have boost pressures rise above what you want them at....creep.

There are many improvements on internal gates, and many company's swear by them and promise no creep with there large turbos. Personally I have a 16g with a 34mm flapper that works perfectly for me. I would bet that if this 34mm flapper were used on something larger than mine, like a 20g, that it would creep if boost setting were at anything lower than say 19psi or so. Tis why, there are larger flappers, for example our lovely moderater John aka "L2RtsiAWd", I beleive has a 39mm w/g with his turbo that is fairly large. Its apparantly large enough to where he doesnt get any creep at 18psi or so. Anyhow, if its better its usually more expensive. Internal gates are usually cheaper, quite and good for emissions. Internal gates with o2 dumps are loud (just like externals, as they both blow exhaust into the atmosphere), perform a little better than internals, but are usually only a tiny bit more money (unless you make your own). External gates are desired by most as they provide the best boost control, and usually provide better sppol up with any turbo, but are always more expensive. They can be rerouted back into the exhaust if one wanted to, but I have never seen it done before.

I know this was long, but i hope I made some sense.

 

[brokencpsd95tsi]

that made alot of sense...thanx alot