B6 I/C w CIS - BOV alternatives?

[bahnzai]

Hi guys,
Looking for some ideas from the voices of experience here. I am changing from a stock I/C and BOV manifold on a CIS motor to a Blown6 I/C. This set-up eliminates the stock BOV manifold.
If I use a 965 rubber intake boot with the 3/4" rubber boss and tie that to a 3/4" pipe at the outlet side of the B6 I/C (see the red cap in the pic) with some type BOV/Re-cir valve, does that move enough air to serve its function? When the throttle shuts, will that let the system re-cir enough to minimize lag as the original design is suppose to do?
If so is there an aftermarket BOV that fits that bill?
I have done some searches here, learned a lot, but did not see this same type set-up.
Thanks!

[oilonly]

Here is a video on what I did with a billet valve. (mounted it sideways)
1:12 in the video shows it clearly.

930 engine.3gp - YouTube

Plus here are two other photos on how it is done with a mode bov.



What is this valve?

To much VAC on BOV

[jsveb]

I bought a Forge VW type blow off valve. Think it serves the purpose.

[RarlyL8]

Doesn't the intercooler come with everything you need to mount it up?

[Ronnie's.930]

Originally Posted by RarlyL8

Doesn't the intercooler come with everything you need to mount it up?

Ha! Brian the comedian!

[JFairman]

"If I use a 965 rubber intake boot with the 3/4" rubber boss and tie that to a 3/4" pipe at the outlet side of the B6 I/C (see the red cap in the pic) with some type BOV/Re-cir valve, does that move enough air to serve its function? When the throttle shuts, will that let the system re-cir enough to minimize lag as the original design is suppose to do?
If so is there an aftermarket BOV that fits that bill?"

Porsche felt one 25mm or 1" blow off recirculation valve was enough for the 964 turbo so I guess it's big enough and flows enough boosted air to avoid compressor surge with stock CIS and a K27 running .7 or .8 bar.

The intercooler hose connection and C2 type blow off valve and elbow hose boss are 25mm or 1" and not 3/4" or 19mm like you said, and there are alot of them both name brand and asian copies of name brands available that will work. Quality control inspection on alot of the low cost asian ones does not exist so the customer becomes the quality control inspector if he buys it online... That said some of them work well.

A modified high horspower motor running higher than .8bar boost should have a larger blow off valve that can flow more air like a 32mm or 50 mm BOV.

You can also play around with running two of them with one recirculationg and one vented to atmosphere if they are piston type and the spring tension is adjustable with shims or a bolt so you can adjust and balance which one opens first and how far they both open.
If venting one to atmosphere it's good to put a small stainless steel mesh air filter on it so it doesn't suck in any dirt during long decelerations when the turbo spools down so much that positive air pressure inside the intercooler turns to vacuum.

[bahnzai]

Thanks everyone for the responses so far. This is breaking new ground for me, so the feed back and pictures/links/video are a tremendous help. I wanted to make sure I was on the right track.

On the Blownsix website the 930 full-width I/C says "This IC is NOT a bolt-on application and will require some modifications". I bought it from someone that did not want to tackle the mods, so I am learning.

JFairman- you are right on the 25mm sizing, I was eye-balling it. Thanks for the advice on the larger BOV. I may need to look at that down the road.

I also wondered if the 25mm I/C pipe was close enough to the throttle to have good response?

[Helmsy]

If you haven't bought the B6 yet - don't. I bought one years ago (half-bay) and it nowhere near fitted properly. I won't go into explaining the hours spent trying to make it fit.

To cut a long story short I ended up going to Chris at TK and they made an IC that fit out-of-the-box and looked 100% better than the B6 paper weight still sitting on my shelf.

Maybe just my experience and they may have improved but my advice would be to consider your other options first.

[bahnzai]

Ben, thanks for the heads-up, but I already have the IC. I bought it used but as new and unistalled.
I know I have some mods & mounting yet to go...

[Kraftday]

A really cool customer from Canada had the B6 IC which was made to work just fine on his engine package. This 3.3L, EFI engine made over 500hp on the dyno. Build photos and fab work at MODE a few years back. The 965 BPVs also work well and a are a bit quieter operation. MODE has been manufacturing the billet by-pass valves here in Scottsdale, AZ USA since around Y2K.




And here is another successful project that used the B6 IC and MODE BPV: Patrick Motorsports - 1978 930 Turbo Group B

Hope this helps you make it work!

[proffighter]

Here is my B6 with CIS some years ago with 965 elbow hose and billet BOV. Worked very well:

[WPOZZZ]

Originally Posted by proffighter

Here is my B6 with CIS some years ago with 965 elbow hose and billet BOV. Worked very well:

I have a similar setup on my 930. I used a Forge 007 diverter valve.

[bahnzai]

Thanks, that is the IC I will be running. The specifics on the BOV are a big help!

[Kraftday]

The new Tial QR BOV is a really cool part allowing recirculation but with the larger piston / body. I'm sure it would be up to the task for the higher boost 930s.

Check it out here..
TiAL Sport.com

[TurboKraft]

The Tial QR has a large 50mm valve, but the ID of the port is smaller than a stock Bosch valve (25mm OD / ~23mm ID). ALl that valve area, and no space to release it.
Fail, Tial. Fail.

[proffighter]

Originally Posted by TurboKraft

The Tial QR has a large 50mm valve, but the ID of the port is smaller than a stock Bosch valve (25mm OD / ~23mm ID). ALl that valve area, and no space to release it.
Fail, Tial. Fail.

Ouch!

[Kraftday]

Originally Posted by TurboKraft

The Tial QR has a large 50mm valve, but the ID of the port is smaller than a stock Bosch valve (25mm OD / ~23mm ID). ALl that valve area, and no space to release it.
Fail, Tial. Fail.

That’s the ultra critical German tuner I’ve come to know..

Guess if the vent port is too small, its mere scrap then..not a cheap mistake using one it seems!

Was there a car you saw in the shop that had one Chris?

[TurboKraft]

We got a Tial 50mm QR in to use on a big 4.0L Turbo engine, hoping to have enough flow from one valve to handle all the turbo's CFMs, but when the part arrived I was disappointed to find the outlet port had an ID of approx. 19mm -- smaller than a stock Bosch valve.
Sure, it had a nice smooth radius from the body of the valve to the outlet port to help the flow, but still not enough cross section IMO. If they made it with a 38mm / 1.5" outlet port, we'd use it.

Turbosmart and Forge both make high quality oversize valves. Time permitting, we would have ordered in some of those for evaluation.

Short on time, we ended up using 2x Bosch Sport diverter valves instead. Tried and true, no worries.

[Kraftday]

Nice you got to shake down that part..silly engineer at Tial. Looks fairly identical to the Q BOV so they must have tried to get smart by making a interchangeable re-circulation body configuration but then said "good enough"...agreed, weak!

Doubling up with those dual Bosch / factory type valves will saves some weigh and money and were good enough for 993TT / 996TTs.

Check this out..good old internet..
Tial Q Blow Off Valve- Whats in the Box? - YouTube