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  • Member
  • Member For: 17y 7m 15d
  • Gender: Male
  • Location: Mount Isa

I have a rapid cooler kit and 10psi flash tune, on the dyno the car was making 265kw on 10psi cutting back to about 9. that's with the bov inline but with the vac line not pluged in. but I have since pluged the vac line into the bov and it over boosts like crazy. So I was just reading and had a thought. With the vac line not hooked up would the bov be opening under boost and regulating it to about 10psi and when the vac line is hooked up the bov stays shut and the comp cant handle the bigger cooler and piping so the car over boost? with the pod its hard to tell if the bov is leaking boost back to the inlet, theres is heaps of woosh either way. I suspect the bov is leaking because with the vac line hooked up the car boosts up harder.

but now I got a cat back exhaust and no bov hooked up and it spikes to about 13 then cuts back to 12 and jumps a bit up and down on the gauge as the wastegate opens and closes.....

once the dump goes on its gona get a custom tune so it doesnt matter, but just something interesting to ponder about.

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https://www.fordxr6turbo.com/forum/topic/43317-over-boost-with-bov/
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  • Member
  • Member For: 17y 7m 15d
  • Gender: Male
  • Location: Mount Isa

Just had a play and realised that all along the ute had been making 10psi only by the fact that the bov was opening and letting just enough out to make 10psi. so with the flash map and bigger intercooler it cant hold boost. put the stock map back in and it holds 6psi perfect. so dont pull the vac line off to get flutter remove the bov althogether. Im sure everyone knows this already.....I feel stupid now. explains why there was heaps more woosh from the pod then I expected and why it felt laggy, thought it was just the huge cooler....oh well we live and learn.

  • Dr. Speed
  • Member
  • Member For: 17y 9m 17d
  • Gender: Male
  • Location: The land of Politicians, Public Servants, Porno & Pyrotechnics

I'm guessing here - but I would think the cat back exhaust combined with the standard actuator would be causing the problems...

Anyone think different?

  • Member
  • Donating Members
  • Member For: 18y 11m 28d
  • Gender: Male
  • Location: Sydney NSW

Hey Josh,

Looks like you sorted it out... the bov needs air pressure from the vac line to hold it closed, when you lift off the throttle, there's no longer pressure through the vac line holding the bov closed, so it pops open and vents.

If you dont have the vac line conected, as you found out, the boost presure in the IC piping will eventually open the bov ( this will depend on how strong the bov is ) but usually 8 psi or so will open the bov.

It's not uncommon for poeple to use a bov rather than a wastegate to regulate boost pressure, though this isnt the best idea and can be very tricky to set up... usually done by tightarses that wont buy an external gate... some super charger set ups use this method too, it can bleed off boost and stop over boosting.

You know this could be an easy way for poeple that have just installed a bigger, highflow IC system and want to drive to a tuner without it overboosting... sure its not the best and Im not recomending it, but it does work and your pretty much not going to go over 10psi.

Cheers

Chris

  • Member
  • Member For: 17y 7m 15d
  • Gender: Male
  • Location: Mount Isa

so what was happing was the bov was venting back into the inlet at about 10psi, it was a bit laggy but still made a heap of power. think the turbo was probably working over time though makes heaps more air then needed. so now I have to bov hooked up with vac line venting to atmo. 8psi map its boosting to about 14psi. with the stock map in stays at 6psi. its all pointless anyways cos stupid arse tramps like a bitch with any amount of right foot....you can open the bov with ya finger and I think I had it the wrong way around so it would open it easier so only gettin 10psi....

so generic map with bigger cooler is a no go, so went back to stock for now untill a proper tune. how slow is 5psi like a atmo car.....

  • Member
  • Member For: 17y 7m 15d
  • Gender: Male
  • Location: Mount Isa
  Sasha said:
Hey I just saw you are in Mt Isa.. should meet up and go for a boost cruise this weekend mate. :spit:

yeah that would be cool, so we can drive around town 50 times in 10 mins trying to miss all the pot holes....lol, yeah send me a msg im goin to cairns/brisbane next week so this is my last weekend in town for a while.

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