can someone please explain the difference between an internal and external wastegate and how each works. im not very familiar w/ turbo's in genearal, i was always an allmotor guy

is there a way to use a blow off valve on our trucks or is that the same thing as an external wastegate? i would like to install a sequential bov just for the sound

 

External wastegates are used on trucks with turbos that are non wastegated and are either connected to the manifold if you can weld cast most cant or most make a adapter flange that fits between the manifold and turbo and gets all 6 cylinders evenly then the part that is wastegated is sent down a pre fabbed usually 3/4" minirature downpipe into the downpipe. Boost line is attached from the turbo to the ex. wastegate and is adjusted like a fuel pressure regulator. lots of people use them to do more fine tunning and mainly in twin turbo setups allows for more adjustability. Whereas internal wastegates are more difficult to adjust the arm and some require you to pull the turbo out of the truck to do so on 3rd gens. Blow of valves most use them on twin setups to regulate the boost the bottom turbo is making and most use the small ones that go in the intercooler pipe and set them up in series usually too to wastegate down to the desired psi.

 

I'm no expert, but basicialy an internal wastegate is buildt in to the turbo and external is added on the drive side of the turbo and plumbed in to the exhaust. Both control the drive side of the turbo. A BOV is on the intake pressure side and is bleeding off access boost pressure. The one to worry about is drive pressure.

 

let me see if i understand this now. a bov works on the intake side to regulate intake boost pressure. a wastegate works on the exhaust side to regulate how much exhaust pressure is driving the turbo.

is that correct? if so, what controls how much intake boost is made w/o a bov? im guessing if the wastegate stays shut longer it will allow the turbo to build more boost? but i guess too much exhaust pressure would be bad for an undersized turbo correct?

and i guess if your turbo setup was making too much intake boost you could add a bov to drop it?

sooo, how much boost would be safe for the stock turbo? thanks guys, and please tell me if i am incorrect in any way or if i forgot anything. usually i am a quick learner but sometimes i can be a little slow

 

A BOV is absolutely required on gassers (patooie!) because they have a throttle plate(s) which slams shut every time the driver lets off the loud pedal - suddenly they got 30psi Boost dead-headed against that t\p(s), with resultant bent t\p(s) and possible compressor explosion - a Diesel has no t\p so that is not necessary, but can be used when pressures go up over 45psi to protect the compressor and turbine - easier to control Boost by controlling the exhaust-gas turbine motor driving the compressor: exhaust gas is bypassed around the turbine by opening the wastegate, reducing drive power - Boost is controlled with the BOV by an adjustable pressure regulator connected to the intake plenum: when Boost exceeds the adjusted pressure setting, the BOV opens to the atmosphere, dumping excess pressure = thus, the sound of a flatulent elephant - seems to fit right in with those overly large chrome f*rt tubes they all bolt on their little engines, eh..............

 

is that because the stock turbo isnt safe past 45psi? sorry if i am not understanding correctly.

 

Forget about BOV's all together. They aren't needed on diesels and don't really work properly anyway. If you want to regulate boost and/or drive pressure, a WG is the answer.

The BOV's Creed was talking about aren't true BOV's. Those are really just a "pop off" valve that opens at a certain boost pressure. I have them on mine to help keep the boost at a safe level (since I don't have head studs yet and the bottom turbo isn't WG'd). A real BOV opens when the throttle is slammed shut and relieves the excess pressure that has no where to go (that only happens with gassers though).

 

The racers and pullers (and I'm including the big tractors, here) use 45-60 and up over 125psi Boost pressures - a BOV can be used to protect the turbo and intake systems in those cases - you won't need that - and, yes, 45psi is unsafe for your oem factory stock turbo - even a BOV won't help, there.

ECM measures Barometric pressure and Boost pressure to determine the best fuel curve to meet demand (that's your right foot on the go pedal) - blow off some Boost erratically, and ECM is gonna blow off your demands, and the truck will be an erratic slug - not even good.

Wastegated turbos are used on engines with throttle plates, usually where oem pressures are limited to less than 10psi - a BOV becomes necessary as the engine is upgraded and Boost pressure is increased for greater power - again, the throttle plate slams shut and there's no place for all that high-pressure air to go = instant damage.

A BOV for entertainment sake is not worth the hassle, as mentioned above^, but you can find someone who'll sell you one and install it, if you persist - be a lot more functional if you just recorded one in operation on a Honda and played that on your stereo.

A BOV and a pop-off valve are essentially the same thing, but a BOV usually has a port for pressure control - both can be used where, for example, you miss a shift and Boost and rpm may increase drastically - the valve will dump Boost B4 it can damage the engine

 

thanks alot

 

45psi being safe on the stock turbo is debatable. Some say yes and some say no. I ran mine that way for 20k miles and when I removed it, it was perfectly fine.

 

so what are the pros and cons of internal vs. external wastegates?

does anyone offer a tubular stainless manifold for our trucks?

 

External is basically only needed if the internal cannot flow enough to control boost.

I have seen such a manifold, but not sure if it's been dyno tested or is actually in production. Send an email to John at flooritdiesel@sbcglobal.net. Tell him I (mike hoyt) let you know I saw one at his shop.