Knocking noise from engine maybe.

[SSbeast]

I've got a knocking noise that only seems to be there when engine is warm and under load like going up a hill or accelerating heavy. However when i park the car and free rev it in N or P the engine sounds fine no noise not even lifter noise. Is there anything else maybe exhaust system that can create a knocking noise? The noise isn't loud and you really have to pay attention to hear it. Cheers.Oh it's a VX SS LS1 4spd too.

 

[Drewie]

It may be Pinking or sometimes referred to as Pinging, which is actually detonation (very roughly explained if the fuel is a bad batch or of a low octane instead of a controlled burning of the fuel, it tends to detonate or explode in an uncontrolled manner and cause a knock which in extreme cases can burn a hole in the top of the piston), it could be a bad batch of fuel, it is usually not very loud though. Maybe try a tank of premium fuel 95 or 98 octane and see if it makes any difference. If it is a really bad knock it may be some thing more sinister like a bearing. I'd try the fuel first and see if it makes a difference. Have a read of the link below.
Is it a stock LS1 or has it been tuned, it may have been tuned to run on 98 octane fuel.

Engine knocking - Wikipedia, the free encyclopedia

 

[SSbeast]

It's been tuned mafless and i only run it on 98 either Vortex 98 or BP ultimate. Shouldn't the knock sensors pick up detonation and retard the timing?