Set filter to bandpass 4 pole , resonance to 80 % percent , cut off around 100hz and slightly modulate by lfo , the higher the resonance the nastier the effect
Here's an audio clip
https://app.box.com/s/p9p6s9469d8wflk20u9vrisrcqndm6fx


Wooww , here the filter is totally bypassed , just sine osc direct to out
Could it be the engine itself ??



