Thought on Blow Off Valves

mytmousemalibu

Cut your ride, sissy!
Apr 12, 2008
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IMO, for me anyhow, money well spent! .....Better to have some turbo protection and not need it than need it and sh!tcanning my turbo and possibly more! What if you shred your turbo and the engine starts breathing in motor oil and goes runaway! I can spit up all kinds of bad senarios;)

Besides snapped shafts, I have seen blades folded over from surge/stall/bark on a few gasser turbos. Now, dont take this wrong, but gasser VS diesels...some built up nasty diesels run rediculous stupid boost/drive pressures, far higher than any "gasser" i know of. Now with the turbo spinning at insane speeds with these pressures behind them and all this boost has nowhere to go but back out the front door...Im failing to see a hasher enviroment than that??? I'd just like to not subject my turbo to such extreme forces and fatigue. No doubt its not good on them nor can i see a BOV hurting. ;):rofl:
 
Jun 28, 2007
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Now, dont take this wrong, but gasser VS diesels...some built up nasty diesels run rediculous stupid boost/drive pressures, far higher than any "gasser" i know of. Now with the turbo spinning at insane speeds with these pressures behind them and all this boost has nowhere to go but back out the front door...Im failing to see a hasher enviroment than that???

I know several gassers that run 45 lbs of boost. But boost numbers aside, a diesel will NOT stall a turbo as hard as a gasser will. When a throttle body closes there is nowhere for the air to go but back into the turbo. When you let off on a diesel the air can still go through the motor.....how is that more harsh:confused:
 

MMLMM

Tunergeek
Mar 2, 2008
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So how about plumbing a n2o silinoind in to the system, with a window switch to the throttle. When you let off the silinoid opes up. You can even have a bypass switch for running around town and only use it racing or pulling....
 

FMOS

Hard Up
Nov 19, 2008
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Thats not a bad idea I think...???

It would work exactly the same as a BOV except not dependant on any pressure, it would just open regardless.

And would it not actually be somewhat beneficial for cruising the streets? If you let off completely the turbo would stay spinning higher rpm's and when you get back on it, it would have drive pressure again and when the solonoid closes you got boost again. ...just incase you wanted to street race the duramax with all the ricers.
 

super diesel

<<<< Under Pressure
So how about plumbing a n2o silinoind in to the system, with a window switch to the throttle. When you let off the silinoid opes up. You can even have a bypass switch for running around town and only use it racing or pulling....

N2O solenoid will get way to hot (found out one day a few years back). The spool valve from BD is cheaper and probably more reliable over the long haul and you would need the voltage switch anyway.

Tried the drive pressure thing on the Blowoff. We ran 2' of copper 1/4" OD line to the manifold and then to the top of the Blowoff. It didn't get to hot for the touch at the Blowoff (one concern of mine). However, it didn't work out as we planed unfortunately. I'm thinking that the pressure from it ideling down was still to much for it to overcome. It barked pretty good. For my tests, this myth is busted even though the idea is sound. Oh well. Still got it working good the other way (original set up).
 

MMLMM

Tunergeek
Mar 2, 2008
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N2O solenoid will get way to hot (found out one day a few years back). The spool valve from BD is cheaper and probably more reliable over the long haul and you would need the voltage switch anyway.

My boost gauge line dont get hot, unless you saying it would get hot from the many uses in a row, which is why I was saying it would be good for racing or pulling or burnouts.

why a voltage switch, you only need it to release when throttle is at zero percent, a window switch I think would be fine. how much is a voltage switch, worst case you could build a good one around 30 bucks....
 

super diesel

<<<< Under Pressure
My boost gauge line dont get hot, unless you saying it would get hot from the many uses in a row, which is why I was saying it would be good for racing or pulling or burnouts.

why a voltage switch, you only need it to release when throttle is at zero percent, a window switch I think would be fine. how much is a voltage switch, worst case you could build a good one around 30 bucks....

I was talking about the N2O solenoid. With it activated all the time (power flowing to the coil) it gets hotter than HE*L.

A voltage switch senses the rising throttle voltage as it's depressed and activates the spool valve to let pressure from the manifold hold the Blowoff closed untill you let off the thottle. Then it switches the power off to the spoolvalve so it releases the pressure on the top of the Blowoff (depressurization in the I/C and on the turbo).

UPDATE!!! The drive pressure setup is working like a champ. There is a change we had to make to get it to work though. This will be cheap to set up and get to function. Who's ready?
 

TrentNell

Finally underway !!!!!
Jul 7, 2008
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I was talking about the N2O solenoid. With it activated all the time (power flowing to the coil) it gets hotter than HE*L.

A voltage switch senses the rising throttle voltage as it's depressed and activates the spool valve to let pressure from the manifold hold the Blowoff closed untill you let off the thottle. Then it switches the power off to the spoolvalve so it releases the pressure on the top of the Blowoff (depressurization in the I/C and on the turbo).

UPDATE!!! The drive pressure setup is working like a champ. There is a change we had to make to get it to work though. This will be cheap to set up and get to function. Who's ready?

whats the cost ? and whats the peak boost pressure limmit ?
 

JoshH

Daggum farm truck
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Feb 14, 2007
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UPDATE!!! The drive pressure setup is working like a champ. There is a change we had to make to get it to work though. This will be cheap to set up and get to function. Who's ready?
What did you have to do? In this thread they say all that needs to be done to dial it in is maybe swap springs around until it works perfect.
 

MMLMM

Tunergeek
Mar 2, 2008
4,086
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Reno, NV
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I was talking about the N2O solenoid. With it activated all the time (power flowing to the coil) it gets hotter than HE*L.

A voltage switch senses the rising throttle voltage as it's depressed and activates the spool valve to let pressure from the manifold hold the Blowoff closed untill you let off the thottle. Then it switches the power off to the spoolvalve so it releases the pressure on the top of the Blowoff (depressurization in the I/C and on the turbo).

UPDATE!!! The drive pressure setup is working like a champ. There is a change we had to make to get it to work though. This will be cheap to set up and get to function. Who's ready?

I was thinking plumbing the solenoid to be open when power is applied. when no power to it, the solenoid would rest closed. the switch would send power when the throttle was at rest (idle or zero % tps). You would also have a switch that would shut off the solenoid when not needed then at idle you wouldn't even be sending power to it.

As for the voltage switch, I can make a switch on a circuit board that will read the tps voltage and switch when ever the tps voltage drops or raises fast or slow...

Think I am on track to a budget BOV? :D
 

super diesel

<<<< Under Pressure
whats the cost ? and whats the peak boost pressure limmit ?

The cost is that of the Blowoff valve and having it welded to the pre I/C pipe, 2' of 1/4 copper tube, brass fitting to crimplock it to the copper line and to screw into the manifold (1/8" or 1/4" NPT will be fine), 1/8 NPT brass fitting (screws into the top of the Blowoff valve) to a crimplock for the copper line. That's it.

What did you have to do? In this thread they say all that needs to be done to dial it in is maybe swap springs around until it works perfect.

HA HA HA! We removed the spring altogether. You could maybe cut most the coil off? I havent tried this yet. It blows off even at real low boost pressures now. Pretty cool.

I was thinking plumbing the solenoid to be open when power is applied. when no power to it, the solenoid would rest closed. the switch would send power when the throttle was at rest (idle or zero % tps). You would also have a switch that would shut off the solenoid when not needed then at idle you wouldn't even be sending power to it.

As for the voltage switch, I can make a switch on a circuit board that will read the tps voltage and switch when ever the tps voltage drops or raises fast or slow...

Think I am on track to a budget BOV? :D

Forget that stuff man. This is WAY simple and cheap and works like a charm. It's as simple as it gets, cheap as it gets, and is far more reliable at lower boost pressures. I would not go with a cheaper Blowoff than the Tial 50mm. This is the only ones I use and have tested. If you use something else, your on your own.

And there it is boys and girls and childeren of ALL ages!
 
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TrentNell

Finally underway !!!!!
Jul 7, 2008
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I figured you were selling kits ? thow i apriciate you working for free :p looking like 250-275 bucks to put together not bad , what spring is in your tial i see they offer 7,9 or 11 or is this the spring you ditched ?
 

mytmousemalibu

Cut your ride, sissy!
Apr 12, 2008
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Yes. Spring is ditched. The exhaust pressure even at idle is still pretty firm on it. No need for the spring. Ebay sells the Tial 50mm Blowoffs. Get it with the aluminum flange to weld it to your pipe.

Word of caution, lotta cheap copys of TiAL stuff on fleabay!!!! The fakes look very close to the real deal! They have a FAQ on TiAL's page of what to look for as to identify a clone! Just wanted you guys to be aware:hug:

I want there new BOV they came out with! Its on there site too. Had absolutly zero issues with mine, great product!
 

super diesel

<<<< Under Pressure
Word of caution, lotta cheap copys of TiAL stuff on fleabay!!!! The fakes look very close to the real deal! They have a FAQ on TiAL's page of what to look for as to identify a clone! Just wanted you guys to be aware:hug:

YES! WATCH OUT!!! It should say TIAL on the head if it's athentic.

I do have a $100 knock off here that were going to try for the folks that don't want to (or cant) go very deep here. The diaphram material looks and feels identicle though. I cant say for longevity if it will hold up though. However, were going to try one for gigles.
 

CurtisEmery

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Mar 21, 2008
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Engineered diesel has a real nice drive pressure activated blow off. The great thing about it is it uses a piston instead of a diaphram. So heat is a non issue. Its priced affordably too.
 

TrentNell

Finally underway !!!!!
Jul 7, 2008
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Engineered diesel has a real nice drive pressure activated blow off. The great thing about it is it uses a piston instead of a diaphram. So heat is a non issue. Its priced affordably too.

i saw wastgates on there site but no bov's . :confused: maybe i'm slow :rofl:
 

mytmousemalibu

Cut your ride, sissy!
Apr 12, 2008
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i saw wastgates on there site but no bov's . :confused: maybe i'm slow :rofl:

I have personally seen wastegates used a BOV's before! Now thats of course not there intended use. But for all inensive purpouses, wastegates and BOV's do the same thing but on diff respective circuts. The only real reason i see being an issue would be that the valve seating on a wastgate might not seal, depending on wastegate type where as BOV's tyipcally have a silicone sealing gasket. The instance i had see was a local promod racer has a massivlly turboed 69 camaro and uses the same HKS flap-type as his wastegate and as his BOV.