BOV'S

S

smokeisfun

still learnin
Joined
Oct 14, 2007
Messages
230
where can i find blow off valves...all the ones on ebay are for gassers...i dont know if it makes a difference or not....but gassers wont build as much boost as i will...i need one to let off at 65#'s
 
smokeisfun said:
where can i find blow off valves...all the ones on ebay are for gassers...i dont know if it makes a difference or not....but gassers wont build as much boost as i will...i need one to let off at 65#'s
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They don't really make blow off valves for diesels. Diesels and gassers operate completely different when it comes to that! About the closest you can get to one is from BD...http://www.modsfortrucks.com/product.php?w=P.Brand='BD'&d=141
 
We have one with a considerably lower price and all mechanical. Drive pressure and spring pressure over come boost pressure until drive is removed then boost overcomes spring to release.
 
on our trucks we use those Watts air regulators they adjust from 50lb's to 125lb's
 
inline6359 said:
What blow off valve do you use? Any issues with 60+ psi?
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I am not sure if you were directing this to me.

About the BOV, There is a selection of springs to set initial seat pressure. As drive builds it adds to the spring pressure to keep the valve closed as the boost builds. For example: Drive is at 70 and boost is at 60, you back out of it and drive drops below the 60 PLUS the seat pressure (8-20lbs) the valve opens and dumps to the atmosphere. You would want to dial in the amount of spring you need in each application so you can keep the reaction time minimal. The more spring you run the longer it takes to drop below the boost level and open the valve. This type of scenario would apply to pressures 150+. The limiting factor is the amount of drive pressure you can push on top of the piston and keep in the cylinder effectively, pressures close to 200psi may overcome the cylinder seals and bleed out. If boost builds above the amount of drive you can contain, the valve would open.

Short version: 60psi is no problem.

Chris
 
I plan on running the BOV like bd does, not with a DP signal but a boost signal.
 
I did my own drive pressure BOV, works well even @ 60psi with low drive press. twins.
 
the bd bov comes with a second spring and shims. I run near 80psi of boost and the bov stays closed until it is suppose to open.

The others are speaking about a wastgate which is boost contol as well as drive pressure
 
onetun said:
the bd bov comes with a second spring and shims. I run near 80psi of boost and the bov stays closed until it is suppose to open.

The others are speaking about a wastgate which is boost contol as well as drive pressure
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I'm not!:umno:
 
ok...BD is insane if he thinks he can get $600+ out of one those things...i just want a simple blow off valve...not so much for compressor surge...but just so i dont run out of the compressors map...or maybe you guys will know if i even have to worry about it...i run hx35 (18cm housing) over a bht3b (26 cm housing)...and more fuel than i can burn...so could those chargers push over 70psi...i dont want to go over that...


thanks for the replies too
 
carfichris said:
I am not sure if you were directing this to me.

About the BOV, There is a selection of springs to set initial seat pressure. As drive builds it adds to the spring pressure to keep the valve closed as the boost builds. For example: Drive is at 70 and boost is at 60, you back out of it and drive drops below the 60 PLUS the seat pressure (8-20lbs) the valve opens and dumps to the atmosphere. You would want to dial in the amount of spring you need in each application so you can keep the reaction time minimal. The more spring you run the longer it takes to drop below the boost level and open the valve. This type of scenario would apply to pressures 150+. The limiting factor is the amount of drive pressure you can push on top of the piston and keep in the cylinder effectively, pressures close to 200psi may overcome the cylinder seals and bleed out. If boost builds above the amount of drive you can contain, the valve would open.

Short version: 60psi is no problem.

Chris
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If I am reading this right, the boost wants to open it, and the drive wants to keep it closed. What about when you chop the throttle closed? My drive and boost drop almost at the same rate, so its hard to see a lower drive than boost? I run 55 boost and 57-58 drive.

Jeffrey
 
B18B1LS1 said:
If I am reading this right, the boost wants to open it, and the drive wants to keep it closed. What about when you chop the throttle closed? My drive and boost drop almost at the same rate, so its hard to see a lower drive than boost? I run 55 boost and 57-58 drive.Jeffrey
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Yes, its the short time that the drive is radically lower than boost that the boost air is trying to stop the compressor wheel that used to shear shafts off. The newer "fat shaft" S300 type turbos handle that abuse quite well but a gain is to be had esp. in a stick truck between shifts when the throttle/drive press. drops boost is vented the turbo doesn't spool down and back up every shift, it can stay fairly high rpm wise. thus aiding in response into the next gear. If you've ever had a "scary" moment where you had to jump off the pedal and back on it, the forces on the turbo shaft are severe to say the least.:blahblah1:
 
carfichris said:
We have one with a considerably lower price and all mechanical. Drive pressure and spring pressure over come boost pressure until drive is removed then boost overcomes spring to release.
Click to expand...

I'm very interested.

Can you get into design/function/specs either in this thread or start a new one?

If you have re-invented the wheel, I might be interested in giving it a shot.
 
What's the diameter of the typical blow-off valve?

Seems like I could make a pretty good one out of a $40 200 PSI water fumigation solenoid and a $60 eBay wastegate... Provided that I could electronically control it somehow. Hmm....
 
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