Can a Blow Off Valve be installed on a Diesel?

[KOOPDADDY]

I have just gotten the HTB2 installed on my truck and I am hitting around 50PSI, the amount of boost that is being created and then released scares me. I used to have numerous turbo cars i. e. Toyota Supras. Whenever a mod was done that increased boost a blow off valve was required so that the boost would not reenter into the turbo. They are normally mounted on one of the intercooler pipes. So anyways, can you do this on a diesel, and if not, why? I am having problems getting rid of excess boost when coming to a stop after I have given it a fair amount of throttle.

 

[lmills]

BD power makes a valve

 

[mattymac]

I would rather use an external wastegate on your exh. manifold. I think that the blow off valves can overspeed the turbo becase you still retain drivepressure on the hot side and loose boost on the cold side which I thought would put less pressure on the vaines causing it to spin faster at those boost #'s.



If you are just wanting to dump boost from WOT and max boost then yes a BD blow off valve would work but when you lift from wide open throttle you loose alot of boost and its hard to recover, thats why they say its for 1/4 mile or sled pull use.



I think that 50 lbs is at the top of the map for the B2 and wouldnt run it there everyday (but dont know for sure). Its more reliable to control boost on the hot side of diesel turbos than the cold side. Plus gas motors need to control max boost for detonation reasons while diesels dont.

 

[KOOPDADDY]

Thanks for the input!!

 

[nickleinonen]

I would rather use an external wastegate on your exh. manifold. I think that the blow off valves can overspeed the turbo becase you still retain drivepressure on the hot side and loose boost on the cold side which I thought would put less pressure on the vaines causing it to spin faster at those boost #'s.



If you are just wanting to dump boost from WOT and max boost then yes a BD blow off valve would work but when you lift from wide open throttle you loose alot of boost and its hard to recover, thats why they say its for 1/4 mile or sled pull use.



I think that 50 lbs is at the top of the map for the B2 and wouldnt run it there everyday (but dont know for sure). Its more reliable to control boost on the hot side of diesel turbos than the cold side. Plus gas motors need to control max boost for detonation reasons while diesels dont.

i think blow off valve [BOV] and Bypass valve are being confused with a pop off valve/poppet valve.





#ad


poppet valve is a dumb device that is a simple pressure relief valve that is preset by adjusting the spring tension. they come in sizes from 1/8"npt to 1"+ npt. they are good for things like aircompressor relief valves...





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a blow off valve/bypass valve is commonly used on all gasoline turbo engines. it is actuated by intake manifold vacuum during shifts to dump the intake piping boost pressure. it actually keeps the turbo spooled up so you build boost quickly when you get back on the throttle...



if you get creative with some plumbing and an electric vacuum pump and some hobbs switches and a vacuum solenoid and microswitches, you can make a gas engine BOV work...

 

[soslow91]

Although it wouldn't supprise me if most blow off valves are vacuum actuated they are still blow off valves without this feature. Most poppet valves for air compressors stay open if they are popped to release all or almost all of the pressure and often need reset.



BOV's in general are to prevent damage to either the engine or the turbo by preventing overboost say if your wasgate stuck or to release the compressor side pressure when you lose drive pressure on the exhaust side so the turbo doesnt quickly turn the opposite direction often breaking in the process.



A simple bov on a gas engine will pop when you release the throttle because there is usually a throttle plate after the turbo when you close it the air has nowhere to go and pressure rapidly builds past whatever point the valve is set for. On most diesels their is no throttle plate so the pressure doesn't spike so you would need some sort of control built into it. If you used boost pressure to open it with a diaphram and a switch that sent boost to the diaphram only when the throttle was closed it would release the pressure and then close again because it no longer has the power to stay open so you wouldn't be prone to sucking unfiltered air in through it or not having boost the next time you open the throttle.

 

[Blakers]

A poppet valve is a valve that opens to admit air and or air/fuel, or opens to expel exhaust gasses by lifting from a seat. This is the type of valve that is used in your truck's cylinder head.



What most of you are refering to is a "pop" valve, or a safety valve that opens from pressure exceeding the set point of the valve.