Fg Xr6T Manual Lots Of Lag And More Flutter Than Bov

[tfc]

My ute 2009 FG is running 330rwkw and when I am changing gear I am noticing much more lag than I used to. Now I am not sure whether this is just due to having more power or what?

I am also noticing a bit of turbo flutter rather than the BOV 'Pssshhht' noise, although both noises are there.

I have a pod filter and a Herrod intake and the standard Bosch BOV.

Wondering if there is any way to reduce my lag and also whether this flutter may be too damaging to my turbo?

I don't think its too bad but certainly more than it used to be.

Any wise advice or tips?

Cheers

[XRSEXT]

lol f*ck of the blow of valve altogether if you want and run maximum flutter.. no it doesnt do any damage to your turbo.. have fluttered since new and have recently changed to a bigger turbo and my standard one had zero shaft play when checked out.. dont listen to anybody but the sweet sound of ZUTUUTUUUTUUUU.. also maybe check for boost leak if exessive lag

[tfc]

Thanks mate. How does no BOV reduce lag? Seems to me it would keep the turbo spinning rather than stop it when you shut the throttle?

[luke187]

The turbo is spinning at 150,000+ rpm, a bit of back pressure isnt going to overcome the inertia of that. Im sure there is some extra load put on the thrust bearings, but how much and what is the real world effect? It could mean it lasts 200,000km instead of 220,0000. As ive said before, the biggest advocates are the ones who sell the solution. The rest is just regurgitated as truth by people, they tell their mates and so on and all of a sudden its a scientifically proven fact with billions of busted turbos reported worldwide. The other part is people mixing up a mismatched turbo which is surging under load, which im sure is very bad as it has 2 forces acting in opposite directions on opposite ends of the shaft - its not hard to imagine damage from this.

With the lag argument:

A) Car has NO blow off valve. Lets say that back pressure on the compressor really does overcome the inertia of the compressor, turbine, and chra and causes it so spin slower than if there was no additional back pressure (ie when you use a bov). How much EXTRA time does it take to spin the turbo back up?

B) Car HAS a blow off valve. Imagine your whole charge pipe system - from the outlet of the turbo, all the pipe work, intercooler etc. How long does it take for the turbo to pressurise this before its able to pressurise the inlet manifold. When you run a bov it vents the all the pressurised air which then need to be re-pressurised again before the the inlet manifold can. How much longer does this take than when there was NO blow off valve?

For me every BOV ive heard sounds crap, in addition to that the sound no bov makes is awesome, care a lot how the car sounds so that's that. it I ran one of my old cars on the street for a couple of years, 27psi every day - no bov. Turbo is still around and still good to go.

[gaz097]

I actually done abit of testing on this by plugging my boost gauge directly to my cold side piping. Without a bov boost would drop to about 4 psi from 16 almost instantly and come back to 10 when I got back on the throttle during a gear change. With a bov boost goes to 0 but came back to 12 when opened throttle again.

[Wenier]

That would kind of make sense to. As with using the BOV the turbo is still spinning quickly as you've given the air somewhere to go hence starting at 12psi once opening the throttle. Whereas the 10psi is because the compressor surge caused by no BOV has actually slowed the compressor down slightly.

But in the end from what you found is 2psi really going to be at all noticeable.

[luke187]

Interesting. I wouldnt mind doing some back to back tests with a proper data logger taking reference off manifold pressure so you can overlay no bov vs bov or slowing down turbo vs repressurising charge pipes. In the end I think you'll find its splitting hairs, which at low boost levels I think any wear would be negligible therefore go with the best sounding one. CHOOOO TOOO TU TU TU TU

[gaz097]

Yeah it's all peanuts worth of boost really but I do think the standard bov plumbed back (put front wheel under slight pressure not vacuum) would be best if u were 1/4 racing. Also why the boost drops so quick without the bov is because of the initial spike. I originally had the boost hose hooked to the cold side without the tee restrictor and kept spiking the gauge of the scale the instant I shut the throttle. The gauge was exactly how it sounded as well. Big Tuu first then tututut would cause the needle to bounce.