Thread: Waste gate ???

I thought waste gate was something to do with turbo talk and how the excess pressure is got rid off?

Originally Posted by loopy111

Someone referred to a waste gate in a previous posting.
What is a waste gate, where is it located and how can that cause "misfiring" under load.

In a turbo the engine drives the turbine wheel with exhaust gas.

The waste gate bleeds excess pressure off to prevent the compressor side from boosting too much.

A "gate" that releases the "waste" energy that is not needed to maintain the boost level desired.

in a TD5 it is pressure operated using a rod fed boost pressure from the outlet side of the turbo.

Once boost reaches a desired level the gate opens (slowly based on boost) to maintain the desired output, dumping residual exhaust down the exhaust pipe without using it to drive the turbine wheel.

Clear as mud hey!

If the wastegate (or its modulator in ECU controlled engine) jams or fails, then the turbo can produce too much boost and the ECU cuts power to protect the engine.

When did Landys become so technical?

Originally Posted by landyfromanuthaland

When did Landys become so technical?

About the time the 200TDI came out or if you include the Isuzu LR's then much earlier.

All Forced induction engines have to have a waste gate to control the amount of boost the engine recieves.

Originally Posted by mcrover

About the time the 200TDI came out or if you include the Isuzu LR's then much earlier.

All Forced induction engines have to have a waste gate to control the amount of boost the engine recieves.

before that was the Turbo D 2.5

Originally Posted by mcrover

<snip>

All Forced induction engines have to have a waste gate to control the amount of boost the engine recieves.

Not true. A lot of large engines (eg agricultural at least) don't have a wastegate. None of my header or 2 turbo-ed tractors have wastegates.
I'm told that Saab invented the wastegate so that their engines could use a higher boost, so had to design a way to limit turbo output. Prior to that, turbos didn't have a wastegate.

Originally Posted by mcrover

...All Forced induction engines have to have a waste gate to control the amount of boost the engine recieves.

No they don't.

A waste gate is not required if the turbo is matched correctly to the engine.

When a small turbine is used, so the turbo spins up earlier, they often produce high boost pressure at high turbo revs. This is usually associated with high back pressure at the turbo, which apposes flow into the cylinder.

The waste gate reduces the back pressure and avoids the high boost pressure.

Originally Posted by Graeme

Not true. A lot of large engines (eg agricultural at least) don't have a wastegate. None of my header or 2 turbo-ed tractors have wastegates.
I'm told that Saab invented the wastegate so that their engines could use a higher boost, so had to design a way to limit turbo output. Prior to that, turbos didn't have a wastegate.

There are some turbo's that dont have an external waste gate controler, some CAT engines (I cant rattle the models of the top of my head) dont have any visible signs of having a waste gate but still have one that is controled by a Vane and weight internaly.

If they dont have a waste gate and you get an engine over run as can happen with an oil leak into the intake or an injector that may fail to shut off (both are more common in large industrial engines than automotive type) then the engine will just keep increasing in revs thus increasing boost until something goes bang.

Im not saying your wrong but I havnt seen a forced induction engine without boost control of some sort but you may be right in that it isnt called a waste gate.

There was an early turbo on a detroit 2 stroke that I once did some work on that had a blow off valve on the turbo that when it hit a certain level it would start to open until it would be passing the complete charge above atmospheric pressure and I think that is the only one I have seen that didnt actually have a waste gate as such.

Maybe the header and twin turbo tractors have blow off valves?

I dont know what equipment you are running so I cant really comment on what you have.