Blow off valve turbo boost control
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Blow off valve turbo boost control

  1. #1
    Highaboosta Unchained's Avatar
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    Default Blow off valve turbo boost control

    In following with what Ron and Hass have been experimenting with I installed two Ebay 50mm blow off valves,

    They were only a piss ant $ 35. each. I've spent more than that on lunch before. I dismantled them and they are a good quaility unit with a solid brass piston with 2 o-rings on each piston. A V band flange with a stainless vband clamp.

    I have it piped so I can vent to atmosphere and just let the boost blow the valve open for a low boost # or close a 1/8" ball valve and it will operate just like a normal blow off valve that is open with manifold vaccuum and closed with boost to get a high boost number.

    It came with 2 springs in it and I removed the heavier one to test it with. It was just vented to atmosphere. It made 6.5 # boost and held that number steady. What's surprising is that the wastegates were set for 15# boost so they never opened. The compressor tube boost control did the whole job. It worked real well. I added back in the 2nd spring to test again with next time.
    Some interesting things to learn here. With the normal boost which is at 23# since I relocated the wastegates the header backpressure was at 18# which is real efficient.
    With the wastegates not opening and just relying on the blow off valves it showed 11# header backpressure. For operating at the lower boost I should back the wastegates down to about 5#.

    Now that I have tested it I am going to get one of those cheap solenoids like Hass found on Ebay and that will let me control it on the fly and have total boost control.
    For a racer this could use a timer to switch between the high boost number and the low boost number just like they do with nitrous. A flick of the switch could bring on 800 hp that doesn't cost squat.

    Here's my datalog,

    The added control over this monster is excellent. I could run the bitch on pump gas if I wanted to.

    I was pretty amazed that it still pulled those 60% gears to 5800 rpm with only 6.5# boost and the rpm was still climbing on the datalog. I'm curious to see what it would top out at with such low boost.
    It was certainly less of a thrill ride to me at low boost but someone who hadnt' ridden in it at high boost would probably still be impressed.
    Last edited by Unchained; 07-03-2012 at 05:39 AM.

    Twin Turbo 1800 HP V-Drive lake boat

    http://s621.photobucket.com/albums/t...t=MAH05771.mp4

    Quote Originally Posted by Trigger View Post
    No one cares about your buddies old antiquated garden hose technology.
    Quote Originally Posted by MAXIMUS View Post
    I think I could run more boost but it's a real hand full right now

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  3. #2
    Senior Member Hass828's Avatar
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    Quote Originally Posted by Unchained View Post
    In following with what Ron and Hass have been experimenting with I installed two Ebay 50mm blow off valves,

    They were only a piss ant $ 35. each. I've spent more than that on lunch before. I dismantled them and they are a good quaility unit with a solid brass piston with 2 o-rings on each piston. A V band flange with a stainless vband clamp.

    I have it piped so I can vent to atmosphere and just let the boost blow the valve open for a low boost # or close a 1/8" ball valve and it will operate just like a normal blow off valve that is open with manifold vaccuum and closed with boost to get a high boost number.

    It came with 2 springs in it and I removed the heavier one to test it with. It was just vented to atmosphere. It made 6.5 # boost and held that number steady. What's surprising is that the wastegates were set for 15# boost so they never opened. The compressor tube boost control did the whole job. It worked real well. I added back in the 2nd spring to test again with next time.
    Some interesting things to learn here. With the normal boost which is at 23# since I relocated the wastegates the header backpressure was at 18# which is real efficient.
    With the wastegates not opening and just relying on the blow off valves it showed 11# header backpressure. For operating at the lower boost I should back the wastegates down to about 5#.

    Now that I have tested it I am going to get one of those cheap solenoids like Hass found on Ebay and that will let me control it on the fly and have total boost control.
    For a racer this could use a timer to switch between the high boost number and the low boost number just like they do with nitrous. A flick of the switch could bring on 800 hp that doesn't cost squat.

    Here's my datalog,

    The added control over this monster is excellent. I could run the bitch on pump gas if I wanted to.

    I was pretty amazed that it still pulled those 60% gears to 5800 rpm with only 6.5# boost and the rpm was still climbing on the datalog. I'm curious to see what it would top out at with such low boost.
    It was certainly less of a thrill ride to me at low boost but someone who hadnt' ridden in it at high boost would probably still be impressed.
    Thats Great Mark! 6psi makes me wonder you have the capability with your efi that you could run around all day on pump gas and then switch over to pure Methonal and have that button on the wheel bring you to 30psi+ if you desired. I bet that if you could get that thing launched with a lower boost # say 12+/-, then bring in full power , you would be able to run a real impressive time for a 21' boat. Have any clocks locally?
    Last edited by Hass828; 07-03-2012 at 06:43 AM.
    "if we keep doing it the same way we always do..we will always get the same results"
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    LP-25.com Infomaniac's Avatar
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    It'll never work........

    AND PUMP GAS !!!
    If For Some Reason I Do Something Worthy Of Recognition. God Provided The Ability And Deserves The Credit.


    QE 439 Twin Turbo

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    Highaboosta Unchained's Avatar
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    Quote Originally Posted by Hass828 View Post
    switch over to pure Methonal and have that button on the wheel bring you to 30psi+ if you desired. :
    When I think about running it at 30 psi on methanol again like last year it makes my balls schrivel up.
    That was WAY WAY too much for a lake boat.

    I'm thinking if I can flatfoot the throttle at 6# boost +- and then hit the button to bring in 22# boost once it's planed out, that should be a great plenty and not be stressing the motor as much as the previous nightmare.

    Ron and Dillon's program only running 11# or 12# boost to run the 8.0 class with only a .620 cam is not stressing the assy. much at all.

    This has turned into a great cooperative effort by the few of us in the serious turbo camp.

    Twin Turbo 1800 HP V-Drive lake boat

    http://s621.photobucket.com/albums/t...t=MAH05771.mp4

    Quote Originally Posted by Trigger View Post
    No one cares about your buddies old antiquated garden hose technology.
    Quote Originally Posted by MAXIMUS View Post
    I think I could run more boost but it's a real hand full right now

  7. #5
    Senior Member earlbrown's Avatar
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    With the wastegates closed and less load on the compressor wheel aren't you worried about overspeeding the turbos?
    Seems like an odd way to control power levels unless you're looking for the instantaneous hit when the BOV's shut

  8. #6
    Senior Member Hass828's Avatar
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    Quote Originally Posted by earlbrown View Post
    With the wastegates closed and less load on the compressor wheel aren't you worried about overspeeding the turbos?
    Seems like an odd way to control power levels unless you're looking for the instantaneous hit when the BOV's shut
    When the pressure ratio drops off the turbos will actually slow down, not speed up. Very much like a vacuum cleaner motor. When you stop up the hose what does the motor do? when its wide open whats it do? Very simular situation with the turbos.
    "if we keep doing it the same way we always do..we will always get the same results"
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    Highaboosta Unchained's Avatar
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    Quote Originally Posted by earlbrown View Post
    With the wastegates closed and less load on the compressor wheel aren't you worried about overspeeding the turbos?
    Seems like an odd way to control power levels unless you're looking for the instantaneous hit when the BOV's shut
    There's a lot of factors to consider Earl. I'm still trying to figure them all out but it's a step in the right direction IMO. Putting in less boost is putting out less exhaust too so that would keep the turbo speed down as compared to full boost. Also there's less volume to vent on the intake side than on the exhaust side.
    It would make better sense to have the wastegates open at a point below where the BOV opens.
    I'm wondering if just having a light spring on the wastegate with no connection to the manifold and just letting back pressure open it would be a viable option too. Ron and I were discussing that.

    Hass made a good point about this experiment, "It's best to ignore whatever you heard about how this won't work right" because it does.
    Last edited by Unchained; 07-04-2012 at 05:22 AM.

    Twin Turbo 1800 HP V-Drive lake boat

    http://s621.photobucket.com/albums/t...t=MAH05771.mp4

    Quote Originally Posted by Trigger View Post
    No one cares about your buddies old antiquated garden hose technology.
    Quote Originally Posted by MAXIMUS View Post
    I think I could run more boost but it's a real hand full right now

  10. #8
    Senior Member Hass828's Avatar
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    I believe this thing is designed to control the boost on centri. setups by manipulation of the BOV.
    https://www.easyperformance.com/prod...ost-controller
    "if we keep doing it the same way we always do..we will always get the same results"
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  11. #9
    Senior Member earlbrown's Avatar
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    What is that dip in RPM from when you went WOT. Does you boat have a transmission or some sort of torque converter?

    Hass, my vacuum revvs to the moon when I cavitate it. That's how I know the water needs to be drained


    I see that venting the intake charge makes for some rock solid boost. I'm still trying to wrap my head around dumping pressure that you've already "paid for". I did consider the fact that after dumping, the exhaust energy should drop proportionally as well. It still just seems weird to me.

    On my turbo engine I've got a tee on the line from the compressor to the wastegate. The tee has a metered orifice that runs to an electric solenoid. The wastegate is set to my lowest desired boost level and the solenoid has the option to raise it. It vents wastegate signal until right before detonation. Since it holds the gate completely shut until it needs to open, spoolup is greatly increased (not to mention the computer can retard boost if I get some crappy gas or there's a problem with fueling).

    Have you already tried that kind of boost control and moved on to the BOVs? I wouldn't be the first time I've showed up late to the party!



    On the other hand.... Mark, are your turbos so big that you can't get them into the max efficiency island at your high boost levels? I could see where speeding up the shaft speed and venting with a BOV might be more efficient that way.

  12. #10
    Senior Member Hass828's Avatar
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    Quote Originally Posted by earlbrown View Post
    What is that dip in RPM from when you went WOT. Does you boat have a transmission or some sort of torque converter?

    Hass, my vacuum revvs to the moon when I cavitate it. That's how I know the water needs to be drained


    I see that venting the intake charge makes for some rock solid boost. I'm still trying to wrap my head around dumping pressure that you've already "paid for". I did consider the fact that after dumping, the exhaust energy should drop proportionally as well. It still just seems weird to me.

    On my turbo engine I've got a tee on the line from the compressor to the wastegate. The tee has a metered orifice that runs to an electric solenoid. The wastegate is set to my lowest desired boost level and the solenoid has the option to raise it. It vents wastegate signal until right before detonation. Since it holds the gate completely shut until it needs to open, spoolup is greatly increased (not to mention the computer can retard boost if I get some crappy gas or there's a problem with fueling).

    Have you already tried that kind of boost control and moved on to the BOVs? I wouldn't be the first time I've showed up late to the party!



    On the other hand.... Mark, are your turbos so big that you can't get them into the max efficiency island at your high boost levels? I could see where speeding up the shaft speed and venting with a BOV might be more efficient that way.
    Whewwwwwww! We are done trying to decide/or have a discussion about whether it works or not, that has been determined. It works and works perfectly. Does exactly what we need it to do.
    That "dip" in boost was because I blew the pump out a tiny little bit(got a bit anxious with the boost button) and touched the rev limiter so I let up on the button that controls my boost solenoid, then got back in it. Spool up is not hampered because the BOV as well as the wastegates stay closed till the boost is at max, whatever it may be at the time.
    If you cant/wont understand the vacuum metaphor then maybe someone else can reword it so you can understand it. But it DOES work. As for me, at this point the only thing that the wastegates are any good for is to eliminate backpressure. And The wastegates should be set so that they open just before the BOV. JMHO.
    Good Luck, Hass
    "if we keep doing it the same way we always do..we will always get the same results"
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    LP-25.com Infomaniac's Avatar
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    Earl wastegate control does not work for us.
    If For Some Reason I Do Something Worthy Of Recognition. God Provided The Ability And Deserves The Credit.


    QE 439 Twin Turbo

  14. #12
    Senior Member Hass828's Avatar
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    So hows this workin for ya Mark?
    "if we keep doing it the same way we always do..we will always get the same results"
    H8-2-W8
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    Highaboosta Unchained's Avatar
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    It worked real well. One of the cheapest improvements ever.
    I put those bigger springs in the BOVs and it leveled off at 10#.
    I still need to add the button on the steering wheel for high boost.

    On Jacks big turbo setup I question how good his boost control is going to be even with better wastegate placement.
    He really needs to add this setup.

    Twin Turbo 1800 HP V-Drive lake boat

    http://s621.photobucket.com/albums/t...t=MAH05771.mp4

    Quote Originally Posted by Trigger View Post
    No one cares about your buddies old antiquated garden hose technology.
    Quote Originally Posted by MAXIMUS View Post
    I think I could run more boost but it's a real hand full right now

  16. #14
    Senior Member Hass828's Avatar
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    Quote Originally Posted by Unchained View Post
    It worked real well. One of the cheapest improvements ever.
    I put those bigger springs in the BOVs and it leveled off at 10#.
    I still need to add the button on the steering wheel for high boost.

    On Jacks big turbo setup I question how good his boost control is going to be even with better wastegate placement.
    He really needs to add this setup.
    He thinks that he will have total control with the C02 /Boost Leash & 60mm gates. When it doesnt happen I'll enlighten him on the path to total control.
    Another thing that I was trying to explain to him is the troubles that one will encounter while trying to actually tune one of these deals. Even with datalogging capabilities. You will need to hold WFO long enough for the tune to level off to see where your at, wether that is 3-4 sec or maybe more. In a boat like he has that is going to have him going rediculously fast. Very dangerous. So tuning is sketchy and very dangerous to do.
    "if we keep doing it the same way we always do..we will always get the same results"
    H8-2-W8
    [email protected] first pass

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