Evo/GSR men - VTA or Recirc?

[Jimbo]

What are you currently running and state why

[obeiron]

Recirculated because it came with the car
Will eventually switch to the metal version from the 8mr/9.

[De Dragon]

VTA, as it came with the car, but I'ma gonna try recirc soon as I've read its better for your MAF/ECU.

[janfar]

Recirc for now as vented affects the MAF readings and stalls out my car... once i go SD i will switch to VTA.

[crazybalhead]

recirc. VTA is for Vin diesel and paul walker.

[MISHI]

Recirc. If you want the lil sound the MR metal diverter vale gives off a little sound. Once you have a MAF as most said then leave as is cause it causes stalling...

[Jimbo]

I feel all the BOV VTA men hiding from this thread because they afraid to get called out for RICE

I made this thread/poll for a reason though; I've come to realise that most WRX/STi men run VTA and was just wondering how things compared on the Evo side...

[janfar]

VTA has its purposes at higher boost levels with low RPM spooling turbos. Its not all rice...

My recirc is quite loud though... i hate it...

[TRDGUY]

I believe running higher levels of boost will be limited with the Recirculating valve .... could be wrong to an extent

[Jimbo]

January & TRDGUY, you do know that there are aftermarket recirculating valves that hold higher boost levels right? I never said it had to be the stock valve

[BLUE_CP9A]

On the Evo I use the Forge Type RS -


On my other project 'm using the Tial Alpha Q -



I love the Tial as it holds 25 psi easily and flows well to avoid surge, no complaints. It also looks like a bong

I just upgraded the OEM evo piece to the Forged and my only complaint is the high pitch whistle type sound it gives depending on when you lift. The forge can also be adjusted easily.

I always preferred Recirculating valves as I rather put the air back in the system, I worked hard enough to produce it!

[janfar]

January & TRDGUY, you do know that there are aftermarket recirculating valves that hold higher boost levels right? I never said it had to be the stock valve

Yeeeeeaaaahhhhh...... that wasnt my point rory... Higher boost means more air suddenly blasting past the valve and toward your turbo causing a sudden shock on the rotating assembly of the turbine shaft... or venting back thru the maf and filter causing a vacuum effect against the turbo rapidly slowing it down...

[BLUE_CP9A]

January & TRDGUY, you do know that there are aftermarket recirculating valves that hold higher boost levels right? I never said it had to be the stock valve

Yeeeeeaaaahhhhh...... that wasnt my point rory... Higher boost means more air suddenly blasting past the valve and toward your turbo causing a sudden shock on the rotating assembly of the turbine shaft... or venting back thru the maf and filter causing a vacuum effect against the turbo rapidly slowing it down...

Huh??

[Jimbo]

January & TRDGUY, you do know that there are aftermarket recirculating valves that hold higher boost levels right? I never said it had to be the stock valve

Yeeeeeaaaahhhhh...... that wasnt my point rory... Higher boost means more air suddenly blasting past the valve and toward your turbo causing a sudden shock on the rotating assembly of the turbine shaft... or venting back thru the maf and filter causing a vacuum effect against the turbo rapidly slowing it down...

Huh??

Your guess is as good as mine bro...

[janfar]

Google it guys...

[Jimbo]

Google it guys...

Hmmm janfar, although what you wrote sounded severely misguided and misinformed, I decided to give you the benefit of the doubt anyway and do some googling.
Unfortunately I can't find anything remotely similar to what you have described.

From what I understand (my very miniscule .02c), the recirculating valve is dumping the air into the piping between the turbo inlet and the MAF which is in a state of intense vacuum (because boost is being built). Therefore it's simply sucked back into the turbo and pushed back into the charge pipe.

What you described sounds a lot like compressor surge...

But hey I've been known to be wrong and I'm def here to learn so please share some links that supports your theory. Thanks

[crazybalhead]

Janfar mussbe running fortypongaboose.

[Dave]

recirc on stock
i only vta on one thing lol

[MISHI]

What janfar is saying is that with much higher levels of boost the pressure would be too great for a recirculation valve no matter the brand and some air will still bypass the valve and cause compressor surge.

So to keep that from happening just VTA. I assume that is what is meant


My car is stock turbo and 21psi... and when it was bought it had a Tial knockoff VTA. The car idled like it had 272 cams and often shut off. When shifting in boost and letting off the gas, it would stutter badly. Good thing the previous owner left the OEM recirc valve. Used this till I bought the MR valve thanks to Dave.

So unless IMHO you really are running anything under 25psi, VTA isn't needed.

[Jimbo]

What janfar is saying is that with much higher levels of boost the pressure would be too great for a recirculation valve no matter the brand and some air will still bypass the valve and cause compressor surge.

So to keep that from happening just VTA. I assume that is what is meant

Nah Mish, he wrote

Higher boost means more air suddenly blasting past the valve and toward your turbo causing a sudden shock on the rotating assembly of the turbine shaft

By saying "past the valve," I believe his concern is one of pressurised air being sent back to the turbo and damaging it because of its overwhelming energy.

Regarding your theory of a boost level that is too high for any recirculation valve to effectively vent and VTA being a better option; well what makes a VTA so effective at flowing air? I think it's safe to assume that if the boost level is too high for any brand of recirc valve, then it would also be too high for any brand of VTA.
But this is why some people run dual BPV/BOV setups right?

Lastly, at those kind of boost/power levels, I think most setups would be SD and not MAF in which case... VTA all the way

[Dave]

From the Evo community, the consenus appears to be for the normal ppl is that once a MAF is present you go recirc and when speed density is employed you can go vented cause you would now employ the map to meter the incoming air.

[janfar]

Google it guys...

From what I understand (my very miniscule .02c), the recirculating valve is dumping the air into the piping between the turbo inlet and the MAF which is in a state of intense vacuum (because boost is being built). Therefore it's simply sucked back into the turbo and pushed back into the charge pipe.

What you described sounds a lot like compressor surge...

But hey I've been known to be wrong and I'm def here to learn so please share some links that supports your theory. Thanks

Bear in mind that when the recirc valve is activated boost is no longer being built hence the reason for venting excess presure from the intake piping to either atmo or turbo.

Here are some of the intense debates from a few years back...

http://www.evo123.net/showthread.php?t=2770

[honda hoe]

What janfar is saying is that with much higher levels of boost the pressure would be too great for a recirculation valve no matter the brand and some air will still bypass the valve and cause compressor surge.

So to keep that from happening just VTA. I assume that is what is meant


My car is stock turbo and 21psi... and when it was bought it had a Tial knockoff VTA. The car idled like it had 272 cams and often shut off. When shifting in boost and letting off the gas, it would stutter badly. Good thing the previous owner left the OEM recirc valve. Used this till I bought the MR valve thanks to Dave.

So unless IMHO you really are running anything under 25psi, VTA isn't needed.

Shouldn't that be over 25 psi?

[xtech]

Using a vta in the VR4 should be a recirculated. But I could get away with this cause I using a autobox.

[Jimbo]

Google it guys...

From what I understand (my very miniscule .02c), the recirculating valve is dumping the air into the piping between the turbo inlet and the MAF which is in a state of intense vacuum (because boost is being built). Therefore it's simply sucked back into the turbo and pushed back into the charge pipe.

What you described sounds a lot like compressor surge...

But hey I've been known to be wrong and I'm def here to learn so please share some links that supports your theory. Thanks

Bear in mind that when the recirc valve is activated boost is no longer being built hence the reason for venting excess presure from the intake piping to either atmo or turbo.

Here are some of the intense debates from a few years back...

http://www.evo123.net/showthread.php?t=2770

Thanks for the link; as you rightfully said, it was a debate but at the end there were no definitive conclusions about negative effects of recirculating in high boost applications. It seemed like a lot of hypothesising and "logic science" being employed to back up theories, the one guy trying to calculate the volumetric flow was hilarious lol!

You say

Bear in mind that when the recirc valve is activated boost is no longer being built hence the reason for venting excess presure from the intake piping to either atmo or turbo

I agree that boost is not being built if you mean that intake manifold pressure is no longer positive however you have to bear in mind that if you have a BOV or BPV, when shut that throttle plate by lifting off the accelerator, the turbo is still spinning at hundreds of thousands of RPMs therefore air is still being pumped.

Now note that I said pumped and not compressed; reason being because the existence of a BPV/BOV means that the air has a place to escape so that compression does not take place and as a result, no compressor surge.

Now in the case of a BPV the air escaping goes right back into the turbo, creating a "closed loop" of metered air if you will.
With a VTA BOV, the loop is open as the air escaping goes byebye

[Dave]

Psssh is for wimps, Dumps is for the big boys!

[BLUE_CP9A]

I just found what Janfar described as a crazy and a highly unlikely assumption, as Jimbo said misinformed and misguided.

I don't see any problem using a recirculating valve at much higher levels of boost and flow, there are valves capable of releasing such high pressures and volumes without causing surge. I.E. they are built to withstand such and flow enough. The TIAL Alpha Q is one such valve.

Surge is not caused by air being re-introduced into the turbo inlet, its caused by not being able to flow enough air when you are trying to release boost pressure in the piping after closing the throttle or an INCORRECTLY Sized TURBO.

80psi being released into the intake or atmosphere will no longer be 80psi....the pressure will drop back to near atmospheric pressure quite quickly, and the turbo which is still spinning will happily accept and compress that air when you get back on the throttle

The discussion link posted netted nothing sensible and the person who took charge of the debate made points that weren't sensible and he was simply trying to fight the point VTA is possible on Early Evos.

Also I can see a MAF !POSSIBLY! being affected by air being reintroduced in the intake having a vacuum effect and going the opposite direction (towards the filter), however I would put this down to poor positioning...ie to close to the MAF. Again highly unlikely.

Now high power apps won't see the need to run re-circulating as they most likely run MAP and it would be simpler to plumb a VTA. Why Bother?? They don't care about noise and they just want the air out to avoid surge.

[Jimbo]

^^ this

[MISHI]

What janfar is saying is that with much higher levels of boost the pressure would be too great for a recirculation valve no matter the brand and some air will still bypass the valve and cause compressor surge.

So to keep that from happening just VTA. I assume that is what is meant


My car is stock turbo and 21psi... and when it was bought it had a Tial knockoff VTA. The car idled like it had 272 cams and often shut off. When shifting in boost and letting off the gas, it would stutter badly. Good thing the previous owner left the OEM recirc valve. Used this till I bought the MR valve thanks to Dave.

So unless IMHO you really are running anything under 25psi, VTA isn't needed.

Shouldn't that be over 25 psi?

correct. My bad.


And Jimbo, as i stated, what i wrote was what I believe Janfar wanted to mean...

[roshan01]

Very interesting read for noob evo owner! This has changed my mind from changing to vented bov.