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DV+ diverter valve on GQV

In the intercooler thread I mentioned that I have fitted an aftermarket diverter/blow-off valve on my QV.

Since I can't find anything on this topic here, I thought it might be interesting for you guys if I shared a bit of my experience.

The reason I started looking into aftermarket diverter valves was that some internet reading suggested me that the stock valve might not be all that happy with increased boost pressure following remapping. Also, the original valve is of the membrane type which is prone to deterioration over time and boost leaks even at stock boost levels.

BUT in a modern car such as the Giulietta, the diverter valve is actuated by the ECU which is much faster than the external aftermarket valves which are actuated in pressure differences. Also, the valve has to recirculate the air in order to avoid screwing up the air/fuel ratio when going back on power.

So, enter the DV+ valve from Go fast bits. It retains the ECU control over the diverter valve, fits as a straight replacement of the stock one, reformulated vented air and is able to hold far more boost. In addition an additional spring in the assembly retains some residual boost pressure in the intercooler, allowing going on boost quicker as the turbo doesn't have to start "from zero" on upshift.

The unit that fits the QV (at least the ones with the 940A1000 engine that I have) is the T9354. When I contacted them about it they first said that they had no clue. After a few emails back and forth with them we concluded that it should probably fit. I ordered it form the German site with the thought of returning it should it not fit. Fortunately this didn't happen.

So, what is the result? More power early in the rev range, quicker boost and much better throttle response, especially in N mode. In D the retained boost is visible in the dynamic display as the boost graph never goes empty on upshift or liftoff. I also get the (subjective) impression that it holds boost better towards the redline.

One caveat to my impressions is that I fired a larger intercooler at the same time as the valve, so I cannot swear what effect is attributable to which mod.

I liked to this article In the other thread where they describe the turbo lag reducing function of the valve.


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I have the dv+ in my MiTo QV and have to say that the change was noticeable, although slightly. I think you mainly notice the larger intercooler.
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Where did you guys get the part from; and where did you get it installed?

Any idea which model is compatible with my 2016 1.4MA w/150HP?

I really want to join thios DV+ club
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I'm going to try and buy this for my 2010 Giulietta QV! Hope it fits that engine as well. My car is mapped and have a larger intercooler fitted. I always thought it would be nice if the boost would hold a bit better between shifts. The DV+ sounds like it might do just that! :-)
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Where did you guys get the part from; and where did you get it installed?

Any idea which model is compatible with my 2016 1.4MA w/150HP?

I really want to join thios DV+ club
Just bought it from ebay. Installed it myself, for my diverter valve type a good installation booklet has been delivered.
Not sure if this is the case for the T9354.
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Originally Posted by mru View Post
Where did you guys get the part from; and where did you get it installed?



Any idea which model is compatible with my 2016 1.4MA w/150HP?



I really want to join thios DV+ club


I don't know which one fits the 1.4 MA but I bought mine from the German Go fast bits site.


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Originally Posted by Esser View Post
I'm going to try and buy this for my 2010 Giulietta QV! Hope it fits that engine as well. My car is mapped and have a larger intercooler fitted. I always thought it would be nice if the boost would hold a bit better between shifts. The DV+ sounds like it might do just that! :-)


It should be the same engine as mine, so it should definitely work. For the newer QVs with engine code 940B2000 I don't know, but I think that the turbo is exactly the same.


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I have the dv+ in my MiTo QV and have to say that the change was noticeable, although slightly. I think you mainly notice the larger intercooler.


I actually think that there is a synergy. The valve allows some pressure to be retained and the larger intercooler stores a larger volume of compressed air at a given pressure.


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DV+ diverter valve on GQV

As I was faffing about under the hood for another project (thread to come soon) I also tried to take some pics of the valve in place. After a lot of scraped hands, dropping the phone and general swearing I managed to take one half decent photo.



As you can see the third bolt is in a rather cumbersome place which makes the fitting a bit complex. Could very well be that access is much easier in the 1.4.


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As I was faffing about under the hood for another project (thread to come soon) I also tried to take some pics of the valve in place. After a lot of scraped hands, dropping the phone and general swearing I managed to take one half decent photo.



As you can see the third bolt is in a rather cumbersome place which makes the fitting a bit complex. Could very well be that access is much easier in the 1.4.


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Oh dear... It looks like you need tiny hands to reach anything down there! Where exactly is the valve located, compared to the turbo?
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Originally Posted by Rundberg View Post
I don't know which one fits the 1.4 MA but I bought mine from the German Go fast bits site.


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Many thanks! Now if I could only find out the correct part for my car....
I'll just ask via their contact form.
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For those of you interested in GFB Diverter valve, below is a Youtubey of Brett from GFB explaining how it all works!

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Oh dear... It looks like you need tiny hands to reach anything down there! Where exactly is the valve located, compared to the turbo?

I have marked the location of the blow-off valve in these two pictures, one of the turbo itself and one of the whole engine. In these pictures it looks rather easily accessible, but as you could see from my picture when auxiliary stuff gets thrown into the mix things get more complicated. I would not attempt this as a diy project, but then I'm not much of a mechanic either...





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I have marked the location of the blow-off valve in these two pictures, one of the turbo itself and one of the whole engine. In these pictures it looks rather easily accessible, but as you could see from my picture when auxiliary stuff gets thrown into the mix things get more complicated. I would not attempt this as a diy project, but then I'm not much of a mechanic either...





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Great pictures - Thank you very much! I am going to attempt this as a DIY project :-)
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Great pictures - Thank you very much! I am going to attempt this as a DIY project :-)


Awesome, my hat off to you! Please take a lot of pictures and tell us how it went!


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I'd also be interested in this and which part number would fit a 2016 GQV as I'm shortly getting it remapped and would like to retain the additional boost, rather than rely on the stock diaphragm valve.

Keep us posted.
Andy


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Awesome, my hat off to you! Please take a lot of pictures and tell us how it went!


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I'd also be interested in this and which part number would fit a 2016 GQV as I'm shortly getting it remapped and would like to retain the additional boost, rather than rely on the stock diaphragm valve.



Keep us posted.

Andy


I would say with 99% confidence that it is the same one since the newer models also have a Borg Warner turbo, but since I have spent zero digging on the specific differences between the 940A1000 and 940B2000 engines I cannot say for sure.


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Good to see some Aussie engineering and manufacturing assisting in improving performance in our Alfas.

I was always concerned that the factory DV wasn't up to scratch especially when the QV engine is pushing close to 22psi stock.

Turbosmart also make one but I think the GFB unit is a better package.

Also consider replacing the factory Wastegate actuator if you are running higher boost. The factory spring is barely rated at 22psi as most people who have open filters will attest to when they hear the wastegate flutter at peak boost during acceleration.

with higher boost, a higher rated DV, wastegate and intercooler are always recommended. with the exhaust, intake and bespoke map, there is no reason the QV motor shouldn't be nearing the 300bhp mark.
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Quote:
Originally Posted by Rundberg View Post
In the intercooler thread I mentioned that I have fitted an aftermarket diverter/blow-off valve on my QV.

Since I can't find anything on this topic here, I thought it might be interesting for you guys if I shared a bit of my experience.

The reason I started looking into aftermarket diverter valves was that some internet reading suggested me that the stock valve might not be all that happy with increased boost pressure following remapping. Also, the original valve is of the membrane type which is prone to deterioration over time and boost leaks even at stock boost levels.

BUT in a modern car such as the Giulietta, the diverter valve is actuated by the ECU which is much faster than the external aftermarket valves which are actuated in pressure differences. Also, the valve has to recirculate the air in order to avoid screwing up the air/fuel ratio when going back on power.

So, enter the DV+ valve from Go fast bits. It retains the ECU control over the diverter valve, fits as a straight replacement of the stock one, reformulated vented air and is able to hold far more boost. In addition an additional spring in the assembly retains some residual boost pressure in the intercooler, allowing going on boost quicker as the turbo doesn't have to start "from zero" on upshift.

The unit that fits the QV (at least the ones with the 940A1000 engine that I have) is the T9354. When I contacted them about it they first said that they had no clue. After a few emails back and forth with them we concluded that it should probably fit. I ordered it form the German site with the thought of returning it should it not fit. Fortunately this didn't happen.

So, what is the result? More power early in the rev range, quicker boost and much better throttle response, especially in N mode. In D the retained boost is visible in the dynamic display as the boost graph never goes empty on upshift or liftoff. I also get the (subjective) impression that it holds boost better towards the redline.

One caveat to my impressions is that I fired a larger intercooler at the same time as the valve, so I cannot swear what effect is attributable to which mod.

I liked to this article In the other thread where they describe the turbo lag reducing function of the valve.


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Hi Rundberg,

Thanks for the detail descriptions. Just a quick question. Does it make the blow off sound? Cufff Cufff? I hate that sound unless it is a Suburu STI...

BR,

Can
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Hi Rundberg,



Thanks for the detail descriptions. Just a quick question. Does it make the blow off sound? Cufff Cufff? I hate that sound unless it is a Suburu STI...



BR,



Can


No, this mod is only about performance and zero about show off. It is completely silent as it recirculates the vented air, just like the stock valve.

I'm planning on doing quite a few mods on my QV but I have no intention of turning it into a ricer




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What can happen if you turn the pressure spring way up is that you get compressor surge (wah wah wah noise) that means that it is overly tight and is an incorrect setting.


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Originally Posted by Rundberg View Post
No, this mod is only about performance and zero about show off. It is completely silent as it recirculates the vented air, just like the stock valve.

I'm planning on doing quite a few mods on my QV but I have no intention of turning it into a ricer




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Thanks buddy. I'll try to find this upgrade... Check my signature for mods
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Originally Posted by Pokinacha View Post
Good to see some Aussie engineering and manufacturing assisting in improving performance in our Alfas.



I was always concerned that the factory DV wasn't up to scratch especially when the QV engine is pushing close to 22psi stock.



Turbosmart also make one but I think the GFB unit is a better package.



Also consider replacing the factory Wastegate actuator if you are running higher boost. The factory spring is barely rated at 22psi as most people who have open filters will attest to when they hear the wastegate flutter at peak boost during acceleration.



with higher boost, a higher rated DV, wastegate and intercooler are always recommended. with the exhaust, intake and bespoke map, there is no reason the QV motor shouldn't be nearing the 300bhp mark.


Yeah, I can only say that I am very happy with both Aussie engineering and customer service. It is obvious these guys care and are enthusiasts themselves.

Thanks for the tip on the wastegate.

Yes, 300 HP is the magic limit I'm going for


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Quote:
Originally Posted by kalzoon View Post
Hi Rundberg,

Thanks for the detail descriptions. Just a quick question. Does it make the blow off sound? Cufff Cufff? I hate that sound unless it is a Suburu STI...

BR,

Can
With an open air filter replacing the OEM airbox(that feeds hot air from the engine bay) you will hear the dump back through the intake. It's not a STI chuff as such. If you listen to a McLaren P1, Noble M600 or the Formula Ford that Chris Harris drove a couple of years ago, you will hear the organic dump that the DV creates. The HKS sequential or Forge BOV are all manufactured to sound that way. You will also hear when the turbo experiences compressor stall and surge which is useful in making sure your car is running optimally.
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Okay... So I might have been a bit too sure of myself, when I stated that I was going to try this as a DIY project.
I just went out to my car, removed the engine cover and unscrewed the turbo heat shield.
Where the hell is that diverter valve located at?? I simply couldn't find it at all! Are you supposed to change it from underneath the car?

I attached a few pictures of my engine bay with the heatshield off. Perhaps a friendly person could advise me as to where I might locate the diverter valve? :-) The pictures that Rundberg posted made great sense, untill I actually made it out to the car... Then they made no sense at all!
Luckily I haven't bought the new one yet!
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