Whose running Blow Off Valves, why and which ones?

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Volcano cruiser

Volcano cruiser

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This is to all the turbo diesel guys out there, oh wait I´m soon to be one:D. It being Sunday here and all I was trolling around the web in my never ending quest to keep from being confused about stuff. As I am in the middle of my turbo/intercooler build project (Yes scored the PWR 4x10 last night:bounce:) I got to noodling around BOV, my CT26 and the usefulness of a BOV in a 4x4 diesel application. I decided that , for now, I´m not going to run one. I want to get everything in and bolted on good, run it for a while get it fine tuned to where I want it. I f I don´t have problems I THINK that I´ll be good, we´ll see. :meh:

Just in case I´d like to know who among you is running a blow off valve in their turbo architecture. Why, with no throttle body to worry about are you running it? What type are you running in a 4x4 application, i.e. piston type, diaphragm type or recirculating type. This particularly intrigues me as the engine bay of my rig can either fill with water during a crossing, get covered completely in mud or thick dust. I would worry incessantly about anything that vented to the atmosphere and could possibly permit contamination to enter my engine air intake track. If you are running a BOV what PSI range is yours set at? What brand BOV are you running and how was it for ease of installation?

Search has been my friend in this endeavour, I even found a short thread about BOV and their usefulness with a Mitsi turbo on a 1HZ. The thread ended inconclusively so here I am. Thanks in advance.
John
 
You need low pressure and high pressure to actuate the bov
as 90% of diesels dont have a throttle body there is never any vacuum(low pressure)

1 its very hard to do and involves using brake vacuum

2 as there is little to no turbulence created as there is no throttle body its not worth it

but thats just me i run 24psi with no problems
 
do you have emissions where you live?

If so the bov has to be recirculated back into the engine in order to pass a visual inspection.

That might help you choose what kind of BOV you want to use.

Many aftermarket BOV manufacturers like Greddy, Tial, HKS will have models that have an attachment for a reciruculation tube or just a flange to let the pressure out into the atmosphere.

as rufus said, route your vac line from the top of the bov to the back side of the butterfly on your tb or intake manifold.

if your running an intercooler i like the bov mounted on the charge side of the intercooler rather than the TB side as it seems to help the turbo spool quicker. Most choose to run it a foot or so from the intake manifold because of ease of install.
 
dohcdelsol93 said:
do you have emissions where you live?

If so the bov has to be recirculated back into the engine in order to pass a visual inspection.

That might help you choose what kind of BOV you want to use.

Many aftermarket BOV manufacturers like Greddy, Tial, HKS will have models that have an attachment for a reciruculation tube or just a flange to let the pressure out into the atmosphere.

as rufus said, route your vac line from the top of the bov to the back side of the butterfly on your tb or intake manifold.

if your running an intercooler i like the bov mounted on the charge side of the intercooler rather than the TB side as it seems to help the turbo spool quicker. Most choose to run it a foot or so from the intake manifold because of ease of install.
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Good point. No emmissions control at all where I live now in Central America but yes back in the States when I get home. Regarding location of the BOV. As I understand it, in gasser applications and I just learned in diesel 3B and 2H applications, i.e. where a throttle body is involved, the BOV should be mounted between the turbo and the throttle body. Again as I understand it, this would allow the BOV to vent in the event that the throttle body was closed while boost was still being applied. As such, in a diesel non intercooled application I get mounting it between the turbo and the intake manifold. In my case I will be running an intercooler, so placing the BOV between the intercooler and the intake manifold also makes sense except for the longer vacum hose, if there is a benefit to running it there. Thus, in order to fully understand the benefits, why do you say that the turbo seems to spool better if the BOV is mounted on the intake manifold side of the intercooler rather than the throttle body side?


Thanks,
John
 
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RufusTheDufus said:
Do you mean the wastegate on an internally gated turbo?

Edited to add: or are you thinking that "TB" in the posts above is short for 'turbo'? I think it's short for throttle body.
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Rufus,
Thanks.I did indeed mis-take "TB" for "turbo" instead of "throttle body". :doh: Now it makes sense. Will edit out the non-conforming brain fart from the above post so that is makes some sense. Again, nice catch and thanks for clearing that up.
John
 
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I run a Turbo 3B with 17 psi boost
i ran a Greddy Blow off valve for the first while but found i really didnt need it
there is very little manifold vacuum even under the throttle plate and 9.9 times out of ten I couldnt hear the blow off valve open
i think there is enough places for the air to go around the throttle plate that it isnt needed
 
pressure differential is needed
but i think more pressure differential is needed then the 3B makes
I had mine on the throttle body side of the air to air so mabey there would be more pressure differential if i had mounted it on the turbo side
I dont think its necessary because these engines arnt like a gasser where the throttle plate pretty much totally blocks off the air passage
 
RufusTheDufus said:
Why are you considering a BOV? I don't see their usefulness in a typical diesel application, especially with an intercooler to buffer the pressure wave that reflects back to the turbo when the throttle plate closes.
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Rufus,
As I mentioned in my first post, I actually decided not to run one in my application, CT26 on a 1HZ with an intercooler. I didn't see how my setup would benefit from it. That being said I kept reading here that some diesel folks were running them and I didn't see why. As I looked around for the necessary parts to put my system together I kept seeing BOV for diesels being offered, and again I couldn't see what the usefulness would be in a diesel application. Hence I thought that I'd pose the question to see who is running BOVs in their setups and, most importantly, why.

The secondary point, yet addressed, has to do with BOVs in 4x4 off road applications. Basically stuff under my hood gets soaking wet, or covered in mud or dust after a day of wheeling. For the BOVs that vent to the atmosphere is there any possible chance of contaminants, read mud, dust or water, entering your air intake system through them as they vent? If not, is there a risk that these conditions could damage the BOV. If so what do people who have them do when they wheel, throw a sandwich bag over them rubberband it closed and hope for the best, I don't know but I thought that I'd ask.
John
 
1. you need a BOV in our applications to keep under control your turbo spike if you have one .. sure.

2. you can't run a BOV in 1HD-T or 1HZ coz you don't have there a butterfly to close and create the vaccum under it .. so you will end with no way to activate ( to tell ) the BOV ..

3. I do run a BOV in Tencha coz I was having around 5PSI turbo spike .. when I push she hard ..
 
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