blow off valve

[onecrazyblackredenck]

found a blow off valve on ebay for my 7.3, I didnt think we could put one on our trucks for some reason. What exactly do they do? Are they worth it? Are they loud???

[Ditty]

Diesels do not have, or need BOVs. Diesels do not have a throttle plate, therefore no need for a BOV.

A BOV is used to vent any access boost pressure to atmosphere when the throttle plate is closed on a gasser. This stops the boost pressure from flowing backward through the boost tubes, back through the turbo compressor and slowing/stopping/reversing the turbo.

In short, you do not need a BOV...and anyone that says you do, does not know what they are talking about.

That being said, you might hear a "WHOOSH" when you are at full throttle, high in the boost, when you let off. This is normal and is the sound of the boost pressure lowering in the boost tubes.

[06F-250-6.0]

i think you can put one on any turbo with a wastegate....you know the turboed imports that have that real loud pchoooo or the loud sound when they shift gears or let off after hard acceleration....its hard to explain the sound so bare with me on that explanation...i think they sound good on imports but all the different brands sound different....some sound good and some sound horrible...i have never heard one on a diesel....u should put it on and put a sound clip on here...i think the purpose of them is to releive excess boost pressure.... not for sure on that so somebody correct me if im wrong...

[Ditty]

I already explained it. It won't work. It's a waste of money. You can do it, but it's either going to BlowOff before the WG opens, venting your boost, or it's just going to sit there...doing nothing.

Ohh, yeah...btw...the reason a BOV works on a gasser is that when the throttle plate closes, it causes a vacuum in the intake plenum, (between the throttle plate and the head), this vacuum is what opens the BOV, causing the boost pressure to vent.

[onecrazyblackredenck]

on ebay it is saying it will help with turbo surge

[06F-250-6.0]

ditty explained it good....i wouldnt of typed that if i saw that he already explained it..sorry bout that...

[onecrazyblackredenck]

I have my wastegate unplugged anyway so I dont think it would even do anything on mine

[Ditty]

Originally Posted by onecrazyblackredenck

on ebay it is saying it will help with turbo surge

A BOV has nothing to do with surge. Surge is something that is built into the turbo design. Factors that cause turbo surge, or stall are:
Compressor housing size
Compressor wheel size/design
A/R ratio on the exhaust housing
Overall speed of the turbo shaft. (Shaft speed)
AND total boost relevent to atmospheric pressure.

When you look at a turbo "map", (graph that shows info about the turbo's capabilities), there will be a dotted line on the map...that is the surge point. It is different for all turbos.

[onecrazyblackredenck]

You are the man Ditty!!! Thanks for the info, saved me from wasting my money like I always do.

[Ditty]

Originally Posted by onecrazyblackredenck

I have my wastegate unplugged anyway so I dont think it would even do anything on mine

WasteGates and BOV's are two completely different things. A BOV has already been explained. (Vents boost when the throttle is closed...aka...no foot on gas pedel.)

A WG re-routes the exhaust past the exhaust side of the turbo...limiting the amount (and speed and pressure) of the exhaust gasses that drive the turbo...limiting the overall amount of boost.

In short, the WG will open while your foot in IN the throttle...a BOV will open when you take your foot OFF the throttle.

The only simularity to the two is that they regulate boost pressure. They just do it 180degrees from eachother.