Turbosmart Dual Port BOV - Full VTA

Hey guys, out of curiosity today I decided to try run the Turbosmart Dual Port BOV on full VTA on the Mazda 6 MPS, it was 50/50.

I blocked the recirculation hose of with a bottle cap and clamped it down.

I blocked off the recirculation exit on the BOV with a supplied "blocker" that came with the BOV.

To my amazement, it sounds SO MUCH better. It was really unexpected, and since I went back to the stock TIP the BOV has sounded like a pos on 50/50.

Even though it sounds so much better, I have read that running full VTA is not good for our cars, but WHY?

The car seems to run fine, idle fine, boost fine, no backfire.

it will run rich on throttle release since the MAF is expecting to see a bunch of air come back when it recirculates, that extra fuel risks detonation, or runs through the exhaust and burns through the cat causing it to backfire. thats a very basic summary but basically, VTA = no good unless tuned to fuel cut on throttle release.

I second RAYD's comments. If you plan to use full VTA then you need to program your ECU so that on throttle lift-off it initiates a fuel cut so you don't send fuel to the engine that is unmatched to its required air and thereby rinse the lube off your cylinder walls with unburnt fuel, get backfires and soot up your cats. I'm sure I covered this one before. If you don't have an ECU that permits such programming, then stay out of 100% VTA territory.

That bottle cap arrangement sounds very risky too, if some part of your contrived blanking plug lets go then

(1) - you will suck unfiltered air that is not measured by the MAF and therefore run dangerously lean and/or
(2) - the bits will head straight down your bypass hose to the TIP and into your turbo.

RULE 1: If you don't really understand what is happening, or likely to happen and why, then don't do it UNTIL you have researched it.

As an afterthought, the possibility exists that you may not be getting backfires because your bypass blanking plug is already sucking air and thereby compensating for the richness. This does not mean that all is well.

The other thing you need to remember is that Mr Plod will give you a sticker straight off the bat for an atmo-venting bov...

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Originally Posted by Doug_MPS6

I second RAYD's comments. If you plan to use full VTA then you need to program your ECU so that on throttle lift-off it initiates a fuel cut so you don't send fuel to the engine that is unmatched to its required air and thereby rinse the lube off your cylinder walls with unburnt fuel, get backfires and soot up your cats. I'm sure I covered this one before. If you don't have an ECU that permits such programming, then stay out of 100% VTA territory.

That bottle cap arrangement sounds very risky too, if some part of your contrived blanking plug lets go then

(1) - you will suck unfiltered air that is not measured by the MAF and therefore run dangerously lean and/or
(2) - the bits will head straight down your bypass hose to the TIP and into your turbo.

RULE 1: If you don't really understand what is happening, or likely to happen and why, then don't do it UNTIL you have researched it.

As an afterthought, the possibility exists that you may not be getting backfires because your bypass blanking plug is already sucking air and thereby compensating for the richness. This does not mean that all is well.

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Thanks for that, I haven't been backfiring at all though, and the bottle cap I'm sure it won't come off, but I'll be changing back to 50/50 now anyway.

Quote:

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Originally Posted by MadAussie

The other thing you need to remember is that Mr Plod will give you a sticker straight off the bat for an atmo-venting bov...

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50/50 Will get the sticker anyway

Nope - I've run 50:50 for ages, although I've changed to 100% Bypass now because I need to divert the maximum amount of air to the turbo. I never had a comment from Plod, despite being parked or in traffic next to them on many occasions. At high boost there can be a lot of air letting go even at 50:50 and you will get noticed, but you are judicious about not blowing-off too loudly when Plod is around then they'll ignore it. That means not putting your boot into it which is generally not smart when Plod is on the horizon. Situational awareness required!

I think the car smells like burning oil now, could it be the full VTA spitting it out? Changing back to 50/50 today.

Could the burning oil smell be present because the car was just serviced and new oils put in?