i recently bought a 98' sierra 1500 6.5L and it is both my first experience with diesel and with a turbocharger. Anyhow, when taking off from a stop, occasionally I'll notice a "whistle noise" (alot like a big rig) that lasts for a few seconds and then suddenly dies out. Is this turbo noise, and if so is it normal?. Thanks.

The whine is the turbo . . . always good sign . . . always fun.

the whistle you hear is a tell tale sign that you need bigger injectors more boost and a free-er flowing exhaust.. and you should probably get gagues just incase.

):h

hello cmb3366, yes that is quite normal. I assume you hear the high pitched whistle when you're on the pedal pretty good. It dies off because your computer is cutting back the boost pressure back into its 'safe' range (~6 psi). It spikes momentarily when you first yam on the accelerator.