well I didn't answere this earlier because I was in a hurry and though some one else would. Looks like you got a little help and some smart ass coments. I have a little 400lb 360hp ricer rocket if you would like to race some time.
I don't know much about turbo diesels. This is my first and I just got it 6 months ago, but I am learning.
I do know my turbo systems for street bikes. A blow off valve is to relieve the extra pressure built up when letting off the gas. It is not as important on a diesel because you do not have a throttle blade that is being close. On a gasser your turbo is spooling up and making 15lbs boost and all of a sudden you let off the gas. Where does all of that boost go? It stops and slows down the compressor. A blow off valve relieves all of the excess pressure when the blades are closed and does not slow down the turbo as much for when you get on it again. I do believe a blow off valve could be benificial in a diesel and get rid of turbo bark, just not needed as much as on a gas engine.
A wastegate controls how many lbs of boost you are running. The variable vane turbos they ran in the lly can control their vane position to adjust how many lbs of boost you are running. A wastegate has a spring in it. That spring controls how much boost you run. A stiffer spring holds the waste gate shut and allows more boost. I run a boost controller on my turbo bike. The boost controller applys air pressure on opisite sides of the gate to control the opening and closing of the gate to control your boost.
diesels dont need blow off valves. The intake is open all the time....no throttle body or butterfly valve or anything to restrict the intake when you "let off the gas". The turbo bark was fixed with the latest software update...
and turbos do not blow up on diesels either right..
or maybe you meant LLYs with stock chargers do not need one.
Any ways sometimes it depends on how much air you can get. the blow off valve on mine has worked flawlessly on the street needs some tweeking for sled pulling but has definetly prevented some monster barks, I do have a larger then stock charger and with that i wanted to protect it however I could here is some pics.
First pic is the actual BOV the second pic is the sol that activates the BOV it is tied into the compressor housing and when it is turned off it allows air to pass thru holding BOV shut along with an internal spring, then when the throttle activited switch is turned on it applies voltage to the sol, closing it and allowing boost pressure to overcome the spring in the BOV and blow off pressure till the spring pressure exceeds air pressure and returns the BOV to the closed position. I got this BOV from BD and in the kit it comes with several different springs and shims to allow it to blow off more or less boost, right now for instance with the spring I have in there(the largest in the kit) the BOV closes again with about 20#s of boost and burps are still possible but I can adjust it down and use a smaller a spring and the BOV will remain open longer.
the only time i have had a complaint is on a roll hammering down there is some lag giving the other guy some breathing room but even with my truck not living up to its expectations(problems in the fueling system) it usually quickly overcomes my opponent.
by the time I had it figured out that there was definitly a problem the season was over and since i am upgrading anyways i just left well enough alone, it could be fueling it could also be mechanical ie rods ...the fact is my truck just flat underperformed after installing the turbo, inj, and such and there was no point in trying to get to the bottom of it when i will be running a different setup next season
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