I am new to the diesel arena, only owning my Ram for 3 weeks now. I have been into building performance gas engines for quite a while, so it has taken some relearning to the philosophies of diesel performance. One thing I haven't seen anyone use yet is a Blow Off Valve (BOV). Especially making over 20lbs of boost, it would seem to me to be beneficial to have one in order to maintain turbo RPM's in between shifts. Almost all the turbo ricer guys have one. It virtually elimates turbo lag. I am look for some expertise from some you diesel building veterans...Any reasons for not using one? I found a company that makes one for diesels. Let me know what ya'll think...

HKS BOV

-Muzzy

 

We have no throttle body, which I am sure you have figured out? Thats why you don't see blowoff valves "common".

 

BD power offers a blow-off valve for our trucks.
Usually the ricer stuff is a little too low volume and light duty for our boost and volume applications.
I would like to get one someday, no one likes to bark expensive aftermarket turbos.

Are they necessary, not really.

--Justin

 

I'm runnung a BOV and it does help. FYI stay away from the HKS it can be bad news, especially with N2O.

 

Thanks for the feedback. Due to the expense, it definitely wouldn't be my first mod for the money.

Crawler-

How much difference did it make? Did you notice less lag on on the turbo spooling up? Thanks.


-Muzzy

 

A little faster "re-spool" after shifts. But, the main goal for my blow-off was to keep the turbo in one piece.

 

Crawler,
What psi are you push'n?

 

Just 4?psi :

I'm not sure. My 60psi guage died and I'm just using a 35psi AutoMeter and I occasionally tap to "0" peg.

 

Muzzy..good question...This has been discussed in detail on another web site, including what one Vendor is selling and my homemade system I'm currently using and very sucessfully I might add.

http://www.turbodieselregister.com/f...blowoff+valves

Steve

I'm only linking you to this site, as it has not been discussed in detail on DTR as far as I know...We can continue this discussion on this site, if the moderators agree.

 

http://www.bd-power.com/ram/product....ard&tt=ram

Notice it says TIAL on the top!

The non ricer imports... Guys who make power not room for more stickers..... run Tial blow off valves and external waste gates.



BD buys a tial BOV (blow off valve) and builds and program their own PIC microcontroller board to monitor throttle position and MAP. It controls the valve via PWM (pulse width modulating) a vaccum solinoid. BD really only makes the controls that makes it work on a diesel due to it not having a throttle body.

Yes vaccum solenoids can switch pressure too. Its the same as what controls EGR and VPC systems in cars. My car has the same solinoid for factory boost control as the EGR system.

That is a cool product and all but a cheap an effective version would be to just use a std TIAL bov. Don't get an HKS or anything else the TIAL is the only one that can dump massive amounts of air easily.

You will also need a relay and a vaccum solinoid. Since there is no throttle there is no major pressure differential between the turbine outlet and the intake manifold. On a gas car the throttle is closed, manifold pressure drops. Manifold pressure goes in one port of the valve holds it shut. When the throttle body closed the pressure on the back of the BOV drops so the valve just fights a spring (which is adjustable too).

Now wire the clutch pedal to the relay and the relay to the solinoid. Connect the relay to the solenoid. Run vaccum line from the mani thru the solenoid then to the valve.

You really need a three port valve. In the off position the common port (BOV side) should be connected to the manifold. When on the BOV port should connect to an unconnected completely open port on the solenoid. This will allow the valve to open easiest when its time to shift yet hold nearly any boost pressure when you want it too. Trust me it's made by tial.

That will cure shifting bark and maintain spool more between shifts.

The off throttle bark.. like if you stomp on it and let off and you arent shifting. You could just tap the clutch pedal just enough to trip the switch. Depending on clutch system endplay and your foot work the clutch wont move but the switch contacts will.

The BD power controller really just cycles a solenoid off and on much like a fuel injector cycles. So it can come up with pressures at the BOV reference port inbetween manifold and atmospheric pressures. So in other words it can greatly vary many aspects of the valves opening.

If you consider that just a naked tial BOV runs about $250 the extra control of the BD electronics is probably worth it especially those who who don't tinker with enough stuff to make their own system.

If the BD guys are reading along..... good thinking behind the product however....

pssst...

try monitoring the signal to the injectors and base the PWM for the valve off that. Less fuel, more BOV opening... More fuel... less bov opening. Monitoring just the TPS is'nt enough for the auto trans trucks. Monitor the PCMs operation of the injectors (maybe pump pressure instead?) and when the PCM defuels during shifts the turbo guard will follow its lead and blow off. It will also do it in direct relation to just how far the PCM is backing things off.

 

Don't most people call them wastegates, they should be one in the same. They both control manifold boost pressure, and booth are air pressure operated. I use to run a long wheel base dragster, and the terms were always intermixed, they both relieve overboost. We can run with or without a "wastegate" our engines can saftly run up to 50 psi. Were the gas engines are usualy limited to 15-20 psi. They also have a much more "sensitive" fuel management system, they must maintain a strict air/fuel ratio, where diesels do not. They are always taking in a maximum amount of air, we just add more fuel. And also gassers are very sensitive to "pre-ignition", which rises as the boost rises, which causes another concern of intake air temperature. We run at a very low rpm range, most don't see 2500. Where gasers are in the 7000 and up range, formula one cars are running 15-17K rpm. I use to be at 7500, which ment my turbo was turning 162,000 rpm! On a 80 degree day, my intake air charge temp at 20 psi was 389 degrees, very different from the trucks. I can run down the highway on an 80 degree day and my intake air temperature will be 110-130, much cooler, and much lower boost pressure.

 

Y-Knot

A wastegate controls boost by bypassing exhaust gas past the turbine housing.

A Blow Off Valve is between the compressor housing and the manifold.
A BOV can be used to either control max boost (similar effect as a wastegate however the turbo can also overspeed) or the BOV can be used to dump the excess pressure builup when there is little exhaust flow to keep the turbo pumpin. We we lift off the throttle or shift we lose drive pressure and the boost in the intake tract tries stop the turbo in motion, following that boost actually slips past the turbo and makes a loud WOOF noise (turbo bark). The sudden deceleration of the turbo is hard on the shaft as well as the thrust bearings it rides on. This was the main killers of the original stock HX-40s people used to run. A BOV in this type of set-up vents the excess boost into the atmosphere. By venting this pressure the compressor(turbo) maintains it's speed, providing better re-spool following a shift(manual) or on trottle lift and re-aply. If you suddenly lift off of the throttle it opens the BOV and relieves the extra pressure keeping you from barking the turbo. I've been running the Turboguard since it was first available and did some beta testing on the advanced sytem with adjustable timeing, tps response, perscentage of tps signal drop, pulsing, etc...



Sorrry for the long post and I know I just skimmed through it, but I'm running on 2 hours of sleep in the last 60 hours and it's catching up to me.

Later,
Wes
(903)520-3582
(480)229-9765

 

Ok thanks Now I know, I have seen those installed it the intake manifolds.

 

Wastegates and blowoff valves are similar in function and design but serve two very different purposes.

A wastegate controls boost pressure by limiting the amount of enery that the turbine wheel is exposed to. if you don't drive the turbine you don't get boost.

wastegates also allow an exhaust housing to have a somewhat adjustable 'size'. this is done by varying the pressure(boost or drive) at which the gate opens.

A blow of valve is used to stop an overpressure condition in the intake stream. This is usually to prevent the compressor from stalling. when the throttle is released the drive pressure drops and the copressor is using kinetic energy to compress the charge. if the pressure difference from one side of the compressor to the other is too great the flow reverses causing the compressor to stall and the air flow to reverse throgh the compresssor. this makes the 'bark'. when the turbo 'barks' the compressor usually decelerates very rapidly. if the deceleration is violent enough you get catastophic failure. most of the time it is neglegable or causes a cumulative wear condidtion.

then there are the 70+psi grab on the binder moments that are a bit scary.

the blowoff valve is used to short circuit the compressor and drastically reduce flow resistance causing a lack of 'bark' and hopefully saving some of the kinetic energy to make it easier to spool back up.

FWIW,
Mark