blow off valve - Diesel Forum

na4now · 12-24-2005, 11:17 PM

I was just wondering, can you add a blow off valve to our trucks?

Jordan

kfjensen · 12-24-2005, 11:46 PM

[ QUOTE ]
I was just wondering, can you add a blow off valve to our trucks?

Jordan

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..And sound like the ricers [img]/ubbthreads/images/graemlins/vomit.gif[/img] [img]/ubbthreads/images/graemlins/vomit.gif[/img] Just drop some coin on a bunch of power enhancments then when you blow by the blow off valves you can give them a little black soot [img]/ubbthreads/images/graemlins/smokin.gif[/img]

na4now · 12-24-2005, 11:48 PM

Does that mean I can put one?

johndeerebones · 12-25-2005, 01:10 AM

You don't need one. The reason the ricers have one is they have a throttle plate. They are running along at full boost and you let off the gas, throttle closes, you shift, problem is while you shifted the turbo just about dead stopped from upwards of 100k rpm in a very short time. Not very much of this and you'll be replacing a turbo.

We don't have throttle plates though so when we let off the engine just pumps the extra air through and the turbo can spin down naturally. They are for ricers and bad drag cars, not diesels. If you gut the ebpv, put a 3" down pipe on and straight exhaust you get some sweet turbine spin down noises from the exhaust that is much cooler than a blow off valve if thats what you're looking for.

na4now · 12-25-2005, 01:39 AM

Well that makes sense.

I just got a 3" DP, just need to put it on, and get my muffler and cat deleted. Then Im putting 5" from the axle back....that should sound good.

Jordan

Nit · 12-25-2005, 02:16 AM

now when you get up to higher HP levels you wil find that you can and will stall teh compressor, and it does sound like a blow off valve, I am waitign for the turbo to explode soon if I do it too much. it not only stalls it studders between shifts adn rpm changes, quite badly in one settign.

johndeerebones · 12-25-2005, 04:52 AM

Nit is right, to fix this you need a wastegate, to releive drive pressure, not boost like a blow off valve. You would need a blow off valve from &*(& to let off the kind of cfms our turbo will flow at peak boost, let alone a bigger turbo like the h2e

gtspowerstroke · 12-25-2005, 03:30 PM

[ QUOTE ]
Nit is right, to fix this you need a wastegate, to releive drive pressure, not boost like a blow off valve. You would need a blow off valve from &*(& to let off the kind of cfms our turbo will flow at peak boost, let alone a bigger turbo like the h2e

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A waste gate doesn't fix the stall NIT is talking about. A waste gate just bypasses the turine housing controlling overall boost. When you have stall when you back out of the throttle real fast or when it shifts you would need a blow off valve to cure it. But it's not an issue on our trucks with a stock turbo. I have never heard of anyone blowing up a turbo from this. The H2Es have a very robust shaft and don't have a problem with it either. However on some of the big twin turbo set ups the small turbo doesn't have that large of a shaft and depending on what turbo you have you can and will snap the shaft if you are building a ton of boost and back out of the throttle real fast. In this case you would need a blow off valve. They are hooked up electronicly to the throttle positition sensor so they sense when you back out of it real fast. They aren't the typical type that you would see on a gasser that blow off at a certin pressure.

Nit · 12-27-2005, 04:21 PM

that is exactly what I need now, I know we can't use teh std blow off valve as what pressure do you set it too?? 35psi. tehn it would never work, somethign electronic would be great but the setup tiem of that would be huge too, if you loose too much boost between shifts then you jsut as screwed,and what about full throttle auto shifts? can't deal with that, mine studders really bad, but after each shift, the boost rockets back up, Tony has one settign done jsut nasty to street drving. [img]/ubbthreads/images/graemlins/grin.gif[/img]

John_G · 12-27-2005, 04:40 PM

Nit,

You don't have a throttle plate between the turbo and the intake (or at all).

No need for any BOV w/o a throttle plate as you CANNOT get a pressure spike without one.

gtspowerstroke · 12-27-2005, 04:41 PM

Craig, BD has them available now. I know of a couple guys running them on twin turboed Dodges. I haven't seen a stock turbo blow of from this so I doubt it's really that big of an issue for you right now. But I guess it can never hurt. I belive they are in the $500-$550 US range.

Nit · 12-27-2005, 06:42 PM

John , I know I don't have a plate but it still stalls quite badly, as teh motor jsut can not use that much air at one tiem, teh biuld up in teh intercooler pushes back enough to stall it out. I am runnign between 10-35 psi in teh matter of less than a sec of time.

gtspowerstroke · 12-27-2005, 09:44 PM

[ QUOTE ]
Nit,

You don't have a throttle plate between the turbo and the intake (or at all).

No need for any BOV w/o a throttle plate as you CANNOT get a pressure spike without one.

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You are right that it won't spike from a throttle plate closeing but when you are building a ton of boost and back out of the throttle real fast it gives the same effect as the engine can't use all the air stored in the intake tract. This is further pronounced with an intercooler where you have a much larger volume of compressed air. This volume of compressed air forces it's way back through the turbo causing a stall condition. This can bring a turbo spinning at/near/or over 100K rpm to a stop and possibly reverse it in VERY short order. This is very hard on the shaft as you might imagine. At the levels that our stock turbos are at it doesn't seem to be a problem. However start running a set of twins up in the 50+ psi range and watch out! It could cause catastrophic failures!