For those of you with the all-metal Saab i/c...

IronMonkeyL255 · Post by **IronMonkeyL255** » Wed May 12, 2004 12:43 am

What is the deal with the black plug on it?

I unscrewed it with an adjustable wrench and found it was partially in both sides of the i/c.

It is also more than a plug. It appears to be a spring-loaded thingy that vents air from one side of the intercooler to the other without letting it get cooled.

What is the purpose of this?

BTW, it is part # 9386418.

vrg3 · Post by **vrg3** » Wed May 12, 2004 12:47 am

I think that's a bypass valve that's supposed to open at very low temperatures. It helps avoid moisture in the intake charge freezing inside the intercooler. Some portion of the springy thing is probably a bimetal device or something similar.

IronMonkeyL255 · Post by **IronMonkeyL255** » Wed May 12, 2004 12:58 am

Wow. That was a quick response.

I was also thinking: There is a plug in the lower-righthand corner of the i/c that you could screw a hose-barb into for the wastegate plumbing. That would eliminate the need for having a bung welded onto the turbo>intercooler pipe.

Another thing I was considering: You could use a piece of ABS pipe for the turbo>intercooler pipe. Unlike PVC, it wouldn't let off any gasses when heated.

I was also looking around Home Depot the other day and saw a good pipe connector that was rubber surrounded by aluminum. This should do the trick b/w the turbo>intercooler pipe and the intercooler.

Do these sound like good ideas?

vrg3 · Post by **vrg3** » Wed May 12, 2004 1:02 am

I presume you mean blowoff valve, rather than wastegate. It might be annoying to route the return hose from a blowoff valve on the far side of the intercooler, though, right?

I don't think ABS pipe is rated for these temperatures, and the pressure and oil probably exacerbate that situation... you could probably get away with it but I'd feel more comfortable using steel or aluminum.

IronMonkeyL255 · Post by **IronMonkeyL255** » Wed May 12, 2004 1:07 am

Wouldn't be too difficult to route it. My main concern is the intercooler>coolant reservoir clearance.

Also, I don't know where to get a piece of aluminum or steel tube that would work. Most people get this stuff done at a welding shop, but my area seems to be completely devoid of any.

vrg3 · Post by **vrg3** » Wed May 12, 2004 1:11 am

Auto parts stores carry "tailpipe extender" thingies that might be appropriate.

IronMonkeyL255 · Post by **IronMonkeyL255** » Wed May 12, 2004 1:14 am

I may have to look around for that.

I was just going to use one of the pipes from a V6 Mustang CAI, but it is about 3" or 3.5": WAY too big.

IronMonkeyL255 · Post by **IronMonkeyL255** » Wed May 12, 2004 1:20 am

Also, I was considering the ABS piping because I saw one of the 2.5 n/a Legacy owners was using some for a CAI and it seemed to work well.

vrg3 · Post by **vrg3** » Wed May 12, 2004 1:22 am

Yeah... the ABS might work, but realize that compressor outlet temperatures on our cars are significantly higher than intake air temperatures on a naturally aspirated car.

IronMonkeyL255 · Post by **IronMonkeyL255** » Wed May 12, 2004 1:30 am

I'll have to check on the temp. ratings of the ABS.........

I was also going to use a radiator hose to line up the compressor outlet and the i/c inlet, so the ABS wouldn't be getting the heat straight from the turbo.

vrg3 · Post by **vrg3** » Wed May 12, 2004 1:41 am

It wouldn't get the heat from the turbo's body, but the air's still hot just because it was compressed. That's the reason for the intercooler, right?

This page says it's good up to 180 degrees Fahrenheit:
http://www.ppfahome.org/abs/faqabs.html

So you might be able to get away with the somewhat higher temperatures...

IronMonkeyL255 · Post by **IronMonkeyL255** » Wed May 12, 2004 1:47 am

I doubt it would get up to 180 degrees, though.

Correct me if I'm wrong, but isn't the stock intake stuff made of ABS? Just specially molded, thinner ABS, but ABS none the less.

vrg3 · Post by **vrg3** » Wed May 12, 2004 2:26 am

Well, you can compute compressor outlet temperature when you're on boost from the characteristics of the engine and of the compressor, but on full boost I'm sure you'll be above 180 degrees.

The thing is, though, that you're almost never going to be on full boost for very long, so not that much of the heat will really be transferred into the pipe. And once you're off boost the passing intake air will actually cool the pipe.

I don't know what material the stock piping is. I guess it does seem a lot like ABS though.

IronMonkeyL255 · Post by **IronMonkeyL255** » Wed May 12, 2004 2:49 am

I could swear that I saw 'ABS' stamped somewhere on the intake. I'll have to look around.

Does it really get that hot? I could see if I were running more boost than stock, but is it really that hot?

BAC5.2 · Post by **BAC5.2** » Wed May 12, 2004 2:58 am

ABS is not pressure rated. Plus, there are different types of ABS, and some of it will crack from heat-cycling. Some ABS is really rigid, unlike our stock peices which, as some of you may know, is very pliable. PVC would never work, as it becomes brittle as it ages.

I was JUST thinking about the drain plug idea, and it seems logical. Just unscrew the drain plug and see if that would work.

The only problem with that idea is the small diameter of the hose-barb. The stock DV has a 3/4" hose, while the drain plug looks to be only 1/2". Would the reduction of flow be detrimental to the performance of the DV? I don't know, but I am willing to try it out. I'll go to Home Depot tomorrow or Thursday when I have the car back from the shop.

IronMonkeyL255 · Post by **IronMonkeyL255** » Wed May 12, 2004 3:05 am

Where did you get your piece of pipe for turbo>i/c?

I was thinking I may just get a piece of regular pipe and JB-Weld the fitting on.

BAC5.2 · Post by **BAC5.2** » Wed May 12, 2004 3:14 am

JB Welding wouldn't work I don't think. Worth a shot, but if it leaks you are SOL.

I had the pipe custom welded at a shop near me. $.80 for the fitting and $20 to weld it to a 6.5" section of 2" OD Mild Steel pipe.

I want to keep looking around for an alternate to the welding to drop the IC price for everyone.

vrg3 · Post by **vrg3** » Wed May 12, 2004 3:56 am

There are some types of ABS which are rated for pressures up to 100 psi. I remember because we were considering using it for the hull of our submarine.

I think JB-Weld has a good chance of working. You would need to make a nice fillet all around the base, and you'd have to roughen up the surfaces really well with a file and/or sandpaper. It's harder than it first seems to make a good epoxy joint.

I recommend brazing or soldering it though, if you can find steel pieces. You just need to make sure the pieces fit very well together.

Phil, if I had been in DC when you were doing the job, I would have brazed or soldered the fitting on for you.

BAC5.2 · Post by **BAC5.2** » Wed May 12, 2004 3:59 am

I might re-do it.

The more I look at it, the shittier of a job the shop did. It'll work, but I'd like to re-do it. Espically getting the correct size. I thought the pipe was a 2"ID, not 2"OD.

I'll JB Weld this pipe up so at least it's definately air tight, and use it until I can get a better solution.

IronMonkeyL255 · Post by **IronMonkeyL255** » Thu May 13, 2004 8:21 pm

Where can I get a piece of steel for the main tube?

What should I use for the fitting?

I just found out one of my friends has a mig welder, so if I can find the pipe and the fitting, he'll weld it up for free.

vrg3 · Post by **vrg3** » Thu May 13, 2004 8:39 pm

Like I said, a tailpipe extender might be good for the main tube. For the fitting, you might be able to just use a short 1/2" iron pipe nipple from the hardware store, since that'll have an outer diameter close to 19mm. If you put the hose clamp over the portion with the threads the threads will kind of cut into the hose a little and keep it from blowing off.

Or if you can find a metal 3/4" hose barb fitting you could use that....

IronMonkeyL255 · Post by **IronMonkeyL255** » Thu May 13, 2004 10:08 pm

About how long does it have to be?

I was going to use the Pep Boys rad hose like BAC2.5 for the post-turbo bend.

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For those of you with the all-metal Saab i/c...

For those of you with the all-metal Saab i/c...