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2849 Views 10 Replies 4 Participants Last post by  shankun
What blow off valve should i use for a 1.8T?
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In vw speak; it is called a diverter valve. Current stock valve's are 710N's and made by Kayser.

Volkswagen part #: 06A 145 710N
Kayser part #:KYS 3.023.351

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There are many aftermarket versions out there; if you are running a tuned car and higher than stock boost levels, a performance DV might be a good upgrade.

Forge Motorsport, seems to be one of the top brands for the 1.8T; 007 was a high recommended model and now they have upgraded to the 008. You can get the closed system diverter valve and the splitter, that opens up to the atmosphere for the "blow off" sound.

Product-category: _34 and Volkswagen: Beetle 1.8t | Forge Motor Sport USA I High Quality Motor Sport Parts
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The VW 1.8T is not designed to use an atmospheric blow off valve "BOV" it has a diverter valve "DV".
If you remove the DV and install a BOV it will cause the ECU to put you Beetle into limp mode.
I won't get into why the DV is important and what it dose you can google that your self.
There is a DV splitter that is made by Forge it has a partial atmospheric but if you research it the results are not worth the trouble. The majority of the post I've seen result in a flutter in boost that is near impossible to get rid of.
If your looking for the whooshing sound replacing your factory air box with an open filter system like the Neuspeed P-flow intake is the stable way to go. This will not give you any gain in performance but it will give your car the whoosh sound when you let you foot off the fuel pedal.

Best of luck, feel free to ask lots of questions.
The great BOV-DV debate. All depends on what you are looking for. Do you want the "psssssshhhht" or "woooooooooosh" sound? People will say "BOV will cause your car to explode and send you straight into the 7th ring of hell, or just cause a CEL". With a BOV there is a "learning" period where the car will not "function" properly. I have tried a few, starting with the
Forge Splitter valve, I am currently on a HKS SSQV, no CEL, no issues. I had one on my MK4 GTI for 6 years also, not one issue. There are other ways to accomplish the sound, like a new DV and cold air intake.

These engines are designed on a closed loop system. That is a fact. Some people have had issues with installing a BOV, that is also a fact. I am only speaking on my behalf here, I have one and do not, nor have i had a CEL caused by a BOV. My CEL is currently on because of an oxygen sensor, because the flex pipe on the down pipe rotted off.
So, tell us about your experiences with various brands of dv's and bov's; plus, which you would recommend. It seems people recommend Forge the most but also tend to be the most expensive. I have been reading about their latest DV; the new (supposedly improved) # 008 and it gets good reviews.

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Forge makes a great product. The split-r is a great concept. BUT if we rely on the logic of the original design of the closed loop system, the loss of pressure due to atmospheric expulsion it will jazz up your ECU until it learns what is going on. I liked it, but it wasn't aggressive enough for me. The sound just wasn't there. Then I went 3 inch turbo back from APR with the stage 2 tune, FMIC and all silicone hoses with some other "goodies". The split-r just didn't make the cut.

On to the HKS. I was very hesitant on buying one. Reading the horror stories on the vortex, but then I remembered a great saying, "it's my car, if YOU don't like it that is YOUR problem".

I also had the APR R1 diverter valve.

Back to the HKS I went. Had it on the car for years. Sold the GTI. Got the beetle, knowing it would never stay stock one of the first things I bought was a new HKS because I missed the sound. There is just something about it.

The first few drive cycles, the car will stall out, yes I know, scary. Eventually the ECU will adapt and you will be fine for every day driving, beasting on the highway.

Some places sell some aluminum plugs for your intake pipe, I just went to my local Lowes and bought a PVC plug to shove in the hole.

She had been on the car 11 months now with out issue.

Any other questions feel free to ask!

Once again, this is my own personal experience, results may vary.
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So, which model HKS bov's are you using specifically; do you like the HKS because of the aggressive sound characteristics, the improved boost performance or both?

Also, what did you think of the APR DV R1; I have seen negative reviews about it.

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The last 2 I had by HKS SSQV. The revision on my first one, I don't remember. The one I have now is the 4. The R1 failed under high boost (25+psi). the car would buck when I smashed the gas on the highway and go into limp mode, did some data logging and determined the R1 was to blame. That is when I bought the first HKS. Aftet that it was smooth sailing.

Replying on the interwebz so if I missed a question I will respond in a new reply
I went with the HKS because it held up to the boost I was running on my GTI. Will my beetle see 25+ psi, only my bank account will tell! At the time when I was looking for a replacement for the R1, HKS was rated high in the reviews I read. Figured, well if these people like it I might as well try it. Not once has it failed on me. I really hope that this will help in the great BOV/DV debate.
Another option is offered by AWE Tuning; they use a stock Porsche DV from their Turbo engines but I haven't heard much feedback about it. Being from Porsche; you would assume it would be durable but who knows.

(SKU: 2010-11010)


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I have heard of this a while ago on the vortex. Never followed that thread.
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