blow off valve - Ford Powerstroke Diesel Forum
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post #1 of 10 Old 09-21-2007, 03:48 PM Thread Starter
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blow off valve

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???



03 F250 4wd auto strait pipe quad cab lariat 33x12.50x18

84 K5 blazer CUCV M1008 dana 70 front and rear, detroit lockers front and rear, 45" tractor tires, 6.2 diesel

1978 cj5 built 304 lots and lots of rust
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post #2 of 10 Old 09-21-2007, 03:56 PM
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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.


DITTY

Brisco:-White 2000 F-350 PSD CrewCab/SRW/LongBed/4x4/6spd Manual/HUGE Powerstroke.Org Vinals!

Favorite Mods: Baby-seat mod/Girlfriend delete/6pos on Xtreme!

Repairs since bought: both batteries/alternator/3 transmissions/4 clutches/entire front axle/new steering stabilizer/power steering pump

Still broken: cracked windshield/all glowplugs/glowplug relay/4WD still out/trailer harness no power

Current Best: 16.149@84.13MPH (Est.7800lbs)
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post #3 of 10 Old 09-21-2007, 04:03 PM
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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...

Sold it for the Vette Now Want Another!
06F-250-6.0 CC SB 4"TB Silverline No Cat SCT XCal2 DJ'S Econ, Street Smoke, Looney! Innovatives Xtreme Race, Xtreme Street Quadzilla Commander A-Pillar Mount 2 12" Solobaric L7'S & Kicker 1000 watt amp. High Idle Mod, CFM+Intake Elbow...............Coming Soon! Injectors, Turbo, ARP Head Studs
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post #4 of 10 Old 09-21-2007, 04:06 PM
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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.


DITTY

Brisco:-White 2000 F-350 PSD CrewCab/SRW/LongBed/4x4/6spd Manual/HUGE Powerstroke.Org Vinals!

Favorite Mods: Baby-seat mod/Girlfriend delete/6pos on Xtreme!

Repairs since bought: both batteries/alternator/3 transmissions/4 clutches/entire front axle/new steering stabilizer/power steering pump

Still broken: cracked windshield/all glowplugs/glowplug relay/4WD still out/trailer harness no power

Current Best: 16.149@84.13MPH (Est.7800lbs)
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post #5 of 10 Old 09-21-2007, 04:06 PM Thread Starter
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on ebay it is saying it will help with turbo surge



03 F250 4wd auto strait pipe quad cab lariat 33x12.50x18

84 K5 blazer CUCV M1008 dana 70 front and rear, detroit lockers front and rear, 45" tractor tires, 6.2 diesel

1978 cj5 built 304 lots and lots of rust
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post #6 of 10 Old 09-21-2007, 04:06 PM
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ditty explained it good....i wouldnt of typed that if i saw that he already explained it..sorry bout that...

Sold it for the Vette Now Want Another!
06F-250-6.0 CC SB 4"TB Silverline No Cat SCT XCal2 DJ'S Econ, Street Smoke, Looney! Innovatives Xtreme Race, Xtreme Street Quadzilla Commander A-Pillar Mount 2 12" Solobaric L7'S & Kicker 1000 watt amp. High Idle Mod, CFM+Intake Elbow...............Coming Soon! Injectors, Turbo, ARP Head Studs
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post #7 of 10 Old 09-21-2007, 04:08 PM Thread Starter
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I have my wastegate unplugged anyway so I dont think it would even do anything on mine



03 F250 4wd auto strait pipe quad cab lariat 33x12.50x18

84 K5 blazer CUCV M1008 dana 70 front and rear, detroit lockers front and rear, 45" tractor tires, 6.2 diesel

1978 cj5 built 304 lots and lots of rust
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post #8 of 10 Old 09-21-2007, 04:12 PM
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Quote:
Originally Posted by onecrazyblackredenck View Post
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.


DITTY

Brisco:-White 2000 F-350 PSD CrewCab/SRW/LongBed/4x4/6spd Manual/HUGE Powerstroke.Org Vinals!

Favorite Mods: Baby-seat mod/Girlfriend delete/6pos on Xtreme!

Repairs since bought: both batteries/alternator/3 transmissions/4 clutches/entire front axle/new steering stabilizer/power steering pump

Still broken: cracked windshield/all glowplugs/glowplug relay/4WD still out/trailer harness no power

Current Best: 16.149@84.13MPH (Est.7800lbs)
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post #9 of 10 Old 09-21-2007, 04:15 PM Thread Starter
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You are the man Ditty!!! Thanks for the info, saved me from wasting my money like I always do.



03 F250 4wd auto strait pipe quad cab lariat 33x12.50x18

84 K5 blazer CUCV M1008 dana 70 front and rear, detroit lockers front and rear, 45" tractor tires, 6.2 diesel

1978 cj5 built 304 lots and lots of rust
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post #10 of 10 Old 09-21-2007, 04:16 PM
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Quote:
Originally Posted by onecrazyblackredenck View Post
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.


DITTY

Brisco:-White 2000 F-350 PSD CrewCab/SRW/LongBed/4x4/6spd Manual/HUGE Powerstroke.Org Vinals!

Favorite Mods: Baby-seat mod/Girlfriend delete/6pos on Xtreme!

Repairs since bought: both batteries/alternator/3 transmissions/4 clutches/entire front axle/new steering stabilizer/power steering pump

Still broken: cracked windshield/all glowplugs/glowplug relay/4WD still out/trailer harness no power

Current Best: 16.149@84.13MPH (Est.7800lbs)
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