Waste gate twitter on over run

[Bengarzy]

It would seem that Kawasaki have silenced the wastegate on the 2019 SX, a closed loop system as on most turbo cars would be used now in all probability....... to be honest after watching a few road tests I was getting sick of it anyway warbling away every time the throttle was closed.

[JonTheChron]

Waste gate is silenced on every H2 model from factory.

I changed mine out to a Turbosmart that's really the only way to hear it.

[Snakes709]

Think you are confusing blow off valve with wastegate. To my knowledge, there is no wastegates on our bikes as its a chain driven supercharger.

[Bengarzy]

Aren’t wastegates and blow off valves one and the same, on a mechanical driven compressor it won’t slow down until the crank slows down and if the throttle valves are shut suddenly the compressor will continue to pump as if it’s on full chat so it would have to have a blow off valve to reduce that. On a turbo when the throttle is closed the exhaust gases that drive the compressor will stop and the thing will only free wheel down, this causes a spike of pressure but is not as constant as a mechanical compressor, particularly on the over run with constant down shifts into lower gears.
The fairy tail that it is the blade tips going through the sound barrier is just that, other wise you would hear it all the time not just when the throttle is closed........ there has to be a blow off/waste gate to get rid of the excess pump pressure when the engine isn’t taking it in.
In the old days the carburettor was on the intake side of the supercharger so when the throttle was closed it starved the supercharger of air so no over pressure valve was needed as it was pulling a vacuum against the carb butterfly.

[cOoTeR]

Aren’t wastegates and blow off valves one and the same, on a mechanical driven compressor it won’t slow down until the crank slows down and if the throttle valves are shut suddenly the compressor will continue to pump as if it’s on full chat so it would have to have a blow off valve to reduce that. On a turbo when the throttle is closed the exhaust gases that drive the compressor will stop and the thing will only free wheel down, this causes a spike of pressure but is not as constant as a mechanical compressor, particularly on the over run with constant down shifts into lower gears.
The fairy tail that it is the blade tips going through the sound barrier is just that, other wise you would hear it all the time not just when the throttle is closed........ there has to be a blow off/waste gate to get rid of the excess pump pressure when the engine isn’t taking it in.
In the old days the carburettor was on the intake side of the supercharger so when the throttle was closed it starved the supercharger of air so no over pressure valve was needed as it was pulling a vacuum against the carb butterfly.

Wastegates dump excess exhaust gases to prevent over boosting. Blow off valves relieve excess boost pressure that is built up.

[Bengarzy]

So both doing the same job then

[cOoTeR]

So both doing the same job then

No the wastegate is in the exhaust side of the turbo dumping the exhaust (waste) gases to prevent the turbo from creating too much boost. The blowoff valve is on the intake side dumping intake air that has been compressed but not needed, such as when the throttle is closed.

Since the H2 bikes don't have turbos there is no need for a wastegate.

[Bengarzy]

But what I said is true, both protect the intake side from over pressure, just do it slightly differently.
Wrong choice of word by myself in the first place I guess
Anyway I don’t get the chirp on the over run and not a great amount of grunt up to 6 k, any ideas?

[Snakes709]

As cooter already said. Wastegates are on the exhaust side and will dump excessive gases. I had my turbo set for 29psi on my evo. So any after that, the wastegate would dump when under load/building boost. The bov would dump all boost when opened (when you let off the throttle). There are 2 types of bov and wastegates. Atmospheric and recirculates. If its atmospheric, when they open it will be louder but depending what your are driving and how the maf sensor is calibrated, it could run shitty. When its recirculates, like our bikes are and how my evo was, when they open, the pressure goes back into the intake (bov) or the downpipe (wastegate).

Our bikes dont start making the flutter/chirp until 5000epm which is the superchargers blades breaking the sound barrier apparently. To hear the bov, you gotta be in boost and have built alot of pressure for it to make any noise.

[JonTheChron]

But what I said is true, both protect the intake side from over pressure, just do it slightly differently.
Wrong choice of word by myself in the first place I guess
Anyway I don’t get the chirp on the over run and not a great amount of grunt up to 6 k, any ideas?

The chirp is from the supercharger

the blowoff valve makes a loud phhhssss (just like opening of bottle of soda) which you cannot hear on the stock bike since its rerouted to the internals,

you can hear them in my video, I have an aftermarket BOV



0:45 is the Supercharger chirp + some BOV
0:55 is only the Blow Off Valve