Jump to content
SAU Community

no bov low boost .5 stock bov .7 bar boost?

1400r

By 1400r,
in Engines & Forced Induction

 Share

Recommended Posts

1400r Veteran

1400r

Posted
Posted

bypassed my stock bov on my 32 the other day and it made the nice flutter noise but would only hit .5 bar not the normal .7 bar with it hooked up to bypass I stuck a bolt in the vac line leading to the top of the bov. Also when I tried to run the bov as non plumb back it would open and close at idle? once replumbed it was fine again. Any idea did I bypass the stock bov wrong I could make up a plate if that what I need to do my mate cefiro runs no bov at all and it boosts easily to .7

RB30-POWER Mentor

RB30-POWER

Posted
Posted

If you remove the vacuum/boost feed line from the top of the BOV it will leak under boost.

You need that connected to equalize the pressure on both sides of the bov diaphragm.

If not you have boost/positive pressure pushing on the bov piston inside the crossover and no pressure on the other side to eqalize the pressure and keep it closed. Without that it will open and let boost out.

Hence you getting less boost.

Not to sure why your messing with it anyway.

Messing with it will only cost performance at the end of the day.

1400r Veteran

1400r

Posted
  • Author
Posted

the vac line seemed to suck when I took it of not blow as it would need to hold the bov closed? however this was only at idle so it may change under load. Im messing with as it seems to be leaking (opening and closing at idle) when I took the plumb back hose off.

R33vit Experienced

R33vit

Posted
Posted
the vac line seemed to suck when I took it of not blow as it would need to hold the bov closed? however this was only at idle so it may change under load. Im messing with as it seems to be leaking (opening and closing at idle) when I took the plumb back hose off.

Under boost there will be positive pressure not vacuum

RB30-POWER Mentor

RB30-POWER

Posted
Posted

They do open under idle as one side has vacuum on it from the plenum (the hose your talking about). This is normal.

The system is designed to do this. Almost all OEM bov fitted cars are designed to recirculate on idle.

When you 0 vacuum or boost, the boost from the plenum line will push on top of the bov and keep it closed because the pressure on top of the bov and in the crossover are equal.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Murray_Calavera
      R33 GTR running -9 with no tune

      By Murray_Calavera · Posted

      I don't understand how this hasn't boiled down to - Upgrade the turbo when you have everything required. ECU, injectors, fuel pump, turbo, etc. Do it all at once.  If you don't have everything required, just enjoy the car as it is and keep saving up your pennies. 
    • Duncan
      R33 GTR running -9 with no tune

      By Duncan · Posted

      Sounds like you've got an interesting adventure ahead here with local support if you have trouble! My guess is that, unboosted, you will be OK with a small upgrade like -9. What will happen is that once the stock ECU sees more airflow than it expects it will add a heap of fuel and pull a heap of timing to be safe because it can't understand how it could get that much air without there being an issue. You will see clouds of black smoke and it won't pull hard through the midrange and top end. So, overall it will be a bit frustrating but should be OK. If you are still nervous set the base timing back 2o through the CAS, but it will be even more sluggish everywhere. As said above through...this is not my guarantee your engine won't be blown into a million pieces, leaving you looking for very hard to find parts A better idea is get a computer with logging ASAP, wire in a wide band O2 sensor and a use remote tuner. I've done multiple cars this way and while it is not as good as a specific tune on a dyno they can get it 90% right. I'd suggest if you can afford an R33 GTR these days you can afford an ECU and tune. And if you can't afford that you sure won't be able to afford the rebuild if it goes bad in the meantime,.  
    • Duncan
      New kid on the block

      By Duncan · Posted

      Yeah it would be nice if someone took the time to put that sort of information together, but there are a lot of variations in looms. I think you are making this way hard for yourself if you just want to get it running....sourcing an SR20 with the right wiring will be a billion times easier than matching the RB loom to an S15 chassis. If you do end up going this way, you just need to trace every wire in the loom with a multimeter, 95% of them will go to a location you can confirm at the ECU.....and then post it up for the next person who needs it  
    • Duncan
      Coolant leak?

      By Duncan · Posted

      Just top it up with water, and keep a general idea of how much you added. It is normal for water to be pushed into and pulled out of the reservoir through the cap, and it should not be more than half full or it will be likely to overflow when hot. Any decent mechanic can do a pressure test of the cooling system to confirm if you have a leak. Keep in mind if it is only leaking a little and when hot it may well evaporate before you see it hit the ground
    • GTSBoy
      Coolant leak?

      By GTSBoy · Posted

      I'd ask the shop what they used and use that. Mixing coolants is sometimes OK, sometimes not, and you have know the details of each coolant to know whether it's a good idea or not.
×
×
  • Create New...