blow of valve ?

[ohiostroker17]

i was wondering if any of u guys have tryed puting a bov on ur 7.3s... if u did how diffuclt was it??

thx alot jon

[SEOHPowerstroke]

If your talking about a valve that blows the boost pressure off before it gets to the map sensor, it is extremely simple. You just cut the hose coming from hot pipe to the map sensor and insert your blow off valve, and connect the rubber hose to both sides and your good to go.

[Scooter's Roofing]

If your talking about a valve that blows the boost pressure off before it gets to the map sensor, it is extremely simple. You just cut the hose coming from hot pipe to the map sensor and insert your blow off valve, and connect the rubber hose to both sides and your good to go.

but how would you actuate it? I've got a design drawn up using solenoids, but I'm not convinced there's any benefit to one on a diesel

[SEOHPowerstroke]

I guess I was not talking about the same type of blow off valve as you, you must be talking about the ones on the little ricer cars right? I'm talking about the one on a diesel pickup, such as the PSD that you need to blow boost pressures off before they reach the map sensor and throw a code causing your Check Engine light to come on and your engine to defuel. This is just a mechanical valve, no wiring or solenoids necessary. As for the little blow off valves that you hear make that cool noise on the ricer cars I don't know of anyone having that type on a diesel, or why it would be necessary.

[SEOHPowerstroke]

http://www.dieselsite.com/index.asp?PageAction=VIEWPROD&ProdID=31
This is what I am talking about. Its the only Blow off valve you will ever need on a PSD to get to 800hp anyways.

[Jff24Gordn]

ricer valve like this??

[RideIcon]

I guess I was not talking about the same type of blow off valve as you, you must be talking about the ones on the little ricer cars right? I'm talking about the one on a diesel pickup, such as the PSD that you need to blow boost pressures off before they reach the map sensor and throw a code causing your Check Engine light to come on and your engine to defuel. This is just a mechanical valve, no wiring or solenoids necessary. As for the little blow off valves that you hear make that cool noise on the ricer cars I don't know of anyone having that type on a diesel, or why it would be necessary.


they are the same thing........

[n8ick]

They are mechanically similar, yes.

I dont think they both accomplish the same job though.

[Scooter's Roofing]

a blow off valve is mechanical too...

are you talking about a pop-off valve?

[RideIcon]

They are mechanically similar, yes.

I dont think they both accomplish the same job though.

yeah they do...

they release the pressurized air in the line before it hits the map sensor or intake manifold when you release the throttle.... they work mechanically through vacuum or other means,

there are fake non turbo ricer cars with speaker blowoff valves, those are just speakers... and faggot ricers, lol
ohh and some ricers grind their gears on purpose when they shift to get the blow off effect...

[Scooter's Roofing]

a pop-off valve relieves pressure when it reaches a certain point.

[n8ick]

yeah they do...

they release the pressurized air in the line before it hits the map sensor or intake manifold when you release the throttle.... they work mechanically through vacuum or other means,

there are fake non turbo ricer cars with speaker blowoff valves, those are just speakers... and faggot ricers, lol
ohh and some ricers grind their gears on purpose when they shift to get the blow off effect...

I was under the impression that the ricer version bleed off manifold pressure so that you will only have xx psi at the intake manifold (which is where the MAP sensor is).

The version in my truck bleeds of a small amount of boost in the map line only. I still have 26 psi in the intake manifold even though the MAP sensor thinks it is 22 psi.

[RideIcon]

the wastegate is used to control boost, but its on the exhuast side...
although the springs can be changed in the blowoff valves as they can only hold up to a certain amount of psi

[Scooter's Roofing]

blow off valves have boost pressing on both sides of the valve... springs won't effect how much they can hold, their sealing design will

[RideIcon]

no, one side directs the air either out to atmosphere or directs it back to the intake track before the turbo.
the blowoff valve is usually activated with vacuum on the top, yes when under acceleration the vacuum line is actually pressurized/ boosted, or at zero.
wheel the throttle is let up the vacuum comes and the valve opens...

the faster the blow off valve can release the pressure the less change that unused pressure will go right back into the turbo causing the turbo to stop spinning, thats why they are so important on manual vehicles, to keep spool when shifting..

searching.....
here
http://en.wikipedia.org/wiki/Blowoff_valve
pretty basic, i disagree with the disadvantage, although there are many like that, most cars use MAP sensors and therefore have no negative effects of having a blow off valve

[Scooter's Roofing]

a blow off valve is actuated with vacuum on the top, but that same line sees boost... so the signal boost pressure PLUS the spring pushes against the boost from the cold pipe. the reason you have a spring in there is to overcome the vacuum in the intake manifold behind the throttle body so that you aren't sucking in unfiltered/unmetered air.

on a diesel, you'd really only need just the very lightest spring you could find, and actually, you could probably get away with no spring if you ran your signal line off the compressor and put the valve after the intercooler as there will be higher boost at the compressor than at the cylinder head.

with that said a diesel doesn't have a throttle blade, and while the turbo slows way down and loses boost, my sps62 never drops to zero boost on shifts...

I have recently been thinking about rigging something up... with a couple solenoids, a hobbs or two, and a couple contact switches, I think I could put together a good working BOV. I'm just curious to see if it helps recovery on shifts on a diesel

[RideIcon]

a blow off valve is actuated with vacuum on the top, but that same line sees boost... so the signal boost pressure PLUS the spring pushes against the boost from the cold pipe. the reason you have a spring in there is to overcome the vacuum in the intake manifold behind the throttle body so that you aren't sucking in unfiltered/unmetered air.


i said yeah that line see's boost, but that small amount of boost will in no way hold that piston closed when your pushing boost through that intake pipe, the spring helps hold it closed. depending on how the sensors are set up, when the charge is let out it can go to atmosphere or to the intake track before the turbo

[Scooter's Roofing]

I know how a BOV/bypass works and how it effects a mass air vs. speed density system, but the spring is there to overcome vacuum... that line sees boost, so you have the same amount of pressure on both sides of the piston/valve

[RideIcon]

have you ever held a blow off valve? the boost from the pressurized side of the intake tube pushes right up against the piston on the bottom of the blow off valve, that piston is like a double sided thing, almost like 2 pistons with a rod between, the top one has the spring to hold the boost in but when vacuum pulls on it it compresses the spring..
grab a loose blowoff valve and try to push on that spring, you cant push it, its very strong, saying that there is no need for that spring is ignorance....

[Scooter's Roofing]

yes, the boost from the intake tube pushes against that valve... guess what pushes against the other side of that valve? BOOST from the boost port... 50psi on one side pushing against 50psi on the other = no problem

on a gas application while driving around off boost, there can be vacuum present in the intake manifold (behind the throttle body) which is where your signal line comes from that attaches to the top of the BOV. but there will be no vacuum in the boost tube leading up to it.

then you have a vacuum on the top side of the valve and no vacuum on the other side... if you didn't have a spring there, the vacuum would lift the valve open and you would draw in unfiltered/unmetered air.

there's a reason you can change springs on BOV's

[RideIcon]

there's a reason you can change springs on BOV's

to hold more boost!

that little tiny vacuum line on the top is not going to put enough pressure on the top piston to keep the boost from pushing the bottom up, and if the piston got pushed up that boosted air would be lost to atmosphere or the pre turbo side of the inkate

i can see what your saying and yes there is boost present, but that line doesnt not have the same force as the force of the boosting air going into the intake manifold... even if the psi's are similar, the cfm of that vacuum line can not hold that piston down, lol:bang

[Scooter's Roofing]

pressure is pressure...

note how TiAL instructs how to choose which spring to use:

http://www.tialmedia.com/documents/w3_tial_bov50_sp.pdf

[Jff24Gordn]

It wont open till there is a pressure difference between the signal line and intake. I have a 7psi spring in mine and it wont open at 100+psi, but it will open when I let off the throttle. I have the BD kit. It comes with a computer box that runs off the TPS/apps or the stick 12v version comes with a micro switch. The electronics flip an air solenoid to dump the signal line to atmosphere pressure.

[RideIcon]

still needs the spring, lol.
guess gas car ones are a bit defferent as they don't see nearly as much psi through the top, infact i don't think they see much if any...
My evo's blow off valve vacuum hose was pretty loose on there, just a rubber hose, no clamps or anything, never had any problems...