Hello all and thanks for reading. I want a blowoff valve but don,t have 600 dollars for the good one. So I was going to pick up a valve for gas application and use a cruise control switch from work and utilize the wabco vac pump currently on the engine. Has anyone done this or can think of a reason not to ?

 

Might I ask what for?

 

They have pop off valves for when your running high boost with twins and what not. But I don't think you need a blow off valve, but you could look into pop off valves.

 

I am sure that i need a blow off valve but I dont have 600 dollars for the electric version.

 

those things are annoying on those little "rice rocket" cars,

“2 cylce weed whacker sound”....phhhhissssstttt..…next gear…...”two cycle weed whacker sound”.....phhhhiiisssssttt....


the muscle car guys that I hang out with every once in a while call it there "blow me" valve....


it may not be needed on our trucks until you hit a certain point but it may be cool to have, and it may sound a heck of a lot better without the weed whacker noise...

 

I definately agree, keep it sounding like a Cummins, for a ricer.

 

I always get the ricers that don't know squat about cars and trucks, you know the kind that payed someone to throw an intake and a HUGE muffler on there half primered honda...they want to know "where I got the turbo for my truck", "how much did it cost to turbo that", "think if I turboed my civic it would sound like that"...etc....

I have a BHAF and a straight pipe...it's a little loud when I let it whine...so they all don't know what to think when they hear a truck sound like that...

 

I dont want one for the noise!!! I need it so I dont damage my very exspensive turbo upon boost back up. Thats what happens when you let out of the throttle and your turbo makes a barking sound. It does not happen too much on a stock turbo but it is very easy to do with over 30 psi of boost and an aftermarket turbo.
I am currently running 45-50 psi of boost and if I am not careful it will "bark" every time I shift. So I am pretty sure I need one , but dont have 600 dollars for one.

Is anyone else doing anything about blow off valves???

P.s. I think they sound cool because I am a fan of horse power and statistically speaking , if you can hear a blow off or any other turbo parafineliea, it means horse power...or Iam just turbo crazy...

 

Jim,

A BOV will not help you to prevent barking the turbo. Gassers have them because when the throttle plate snaps closed, it can cause a HUGE spike in intake pressure as all that boost now has has nowhere to go! This can actually break a throttle plate or cause other problems.

On a diesel, you have no throttle, thus no risk of this kind of damage.

In order to have an effective anti-barking setup, you'd have to have it linked to your fuel pedal somehow. You want to have a valve that "knows" when boost is good and when it's bad. Normally, boost is good, except when you suddenly lift the pedal and the turbo barks as the drive pressure collapses.

Perhaps you could wire in a pop-off to the APPS somehow so when you lifted at a high-boost condition, the popoff could open and alleviate the bark-causing pressure.

Note that the newer trucks come with an electronic wastegate. This gives the ECM more control over boost and helps to prevent barking.

Another option might be a pedal-mounted microswitch that is wired the "opposite" way to a pressure relief valve. When the pedal's on the floor, the valve is closed and allows full boost, when you lift, the valve opens to bleed off boost below a certain point, say the stock boost figure of 21--24psi or so.

With THIS setup, could have have the big boost when you needed it (WOT), and still have enough boost (up to 21 psi) for driving around town. Obviously, this give you a driveability problem when you want less than WOT but still more than XX boost.

Just something to think about. A BOV will NOT help to reduce barking on a CTD unless it is linked to some kind of device that lets it "know" when to open based on pedal position.


Justin

 

have you checked out the turbo saver?? i am not sure where too get one but heard a guy at our local shop talking about one. It is just setup like a relif valve, set the pressure for it to relive. EG> you run 32 psi boost, and are getting a bark. You set this valve up at 34 psi. This turbo saver is supposed too be setup for diesel engines.

 

Hohn, you are absolutely correct. I was going to use a cruise switch that opens a vac port uppon closed throttle. they are used to release vac when the brake or clutch is depressed.
What I was going to do is hook it up to the vac pump so when throttle is closed the vac can open the valve. Also I am going to install the valve inches away from the turbo. I just hate the turbo bark...

 

I hate the turbo bark also and get it frequently, whenever someone pulls out in front of me when pulling, or Sometimes on a hard shift when pulling a hill. That being said, I would doubt that a vacuum power valve would be near fast enough to kill the pressure on a shift or fast decel.

If you do it and it works, keep us posted. I for one would be interested int he mod. I have 130 pounds air pressure on the truck, that might be more effective.

 

Question, would a 16 or 18 exhaust housing help or hinder the bark effect?

 

IMHO, a 16 or 18 housing WOULD reduce barking quite a bit. The larger housing will reduce the drive pressure and "loosens" the connection between the exhaust stream and the turbine. Just as a larger housing causes more spoolup lag, it will also cause more "lag" when letting off the pedal.

if you can sacrifice the spoolup, a 16 housing will reduce peak EGT and barking.

Justin

 

Thanks for the reply. I had thought that was the scenerio but was not sure. In my case the spoolup is secondary to pulling with freight. As a matter of fact, it would probably be a lot easier on my drive train. I have no immediate plans, but will one day go to a larger housing and full four inch exhaust into five inch stacks. MIghty just keep four inch stacks. I have been watching my boost and I get into bypass very quickly so could use the larger housing.