Sometimes at the pulls I go to there will be a hopped up tractor or a diesel truck that is building boost and once they begin to launch POOF The smoke changes to white and just fogs out. What is this? I saw one Cummins that did this and he came back for the next class... so that seems to rule out my suspiscion of blown turbo... any ideas?

 

I think it was a 12ver with the timing set high.
I like to watch the smoke change colors

 

I thought white smoke was raw fuel, and black smoke was partially burned fuel

 

Fuel or a combination of fuel and water.
High timing will get the white smoke at idle or even just increased fuel delivery. Or a decompressed engine etc.

 

Sorry I didn't specify too well... I should point out that this ended their runs, definitely not supposed to happen so something went wrong. I've seen some that have the heavy gray smoke while it's loping away waiting for more RPM, but what I'm talking about is a failure of some sort. Pourin, I see you said decompressed engine... so would that mean an intercooler boot or blown turbo?

 

Well that is a possibly...or even a blown turbo.
But what I meant was that they have fly cut or shaved the pistons to lower the final compression ratio of the engine to allow for more fuel delivery or boost etc.

 

They didn't get the turbo to "Light" They were running a huge amount to Water, and didn't get enough fuel / RPM to make everything launch like it should. 2 try's is what they should get, unless past 50, or 75 ft, and then wait till next time. Maybe they had too big of a water jet in place, and flooded.