Damper Tube for boost gauge

[Buzzbomb]

My searches has yeilded nothing so I'm trying the noob forum first.

I need to buy what Subaru calls a damper tube for the aftermarket boost gauge I bought. I need to know what to buy, where I can find it, or the OEM part number so I can order it. Any help would be appreciated

[zoinks]

I could be wrong but the reason that it is there is because the line that comes with the factory boost gauge is a bit larger than what is needed. This restrictor corrects that. However, I would suggest buying some 1/8" vacuum line and running that the entire way. Here is a picture of what the damper tube looks like and where it is located....

[GilliganLQ]

I always thought the damper tube was there to act as a restriction in the line to help give a more smooth needle movement on the guage (i.e. eliminate jerkyness or vibration).

[zoinks]

I always thought the damper tube was there to act as a restriction in the line to help give a more smooth needle movement on the guage (i.e. eliminate jerkyness or vibration).

That's right.....because the rest of the tubing is too large. With 1/8" vacuum line, you get instantaneous response with absolutely NO vibration.

[Buzzbomb]

Thanks for the replies, here’s what’s going on.

We just got our WRX wagon about a month about and it did not come with a factory optioned boost gauge. I bought an aftermarket one and it didn’t come with anything to hook it up. I downloaded the instructions for the factory gauge and bought supplies to hook it up like per the Subaru instructions. I did purchase 1/8th inch vacuum hose for the install. After hooking everything up, the gauge rattles a bit when it’s in a full vacuum load, like sitting in gear with the brake applied (4EAT). Also when letting completely off the gas after accelerating. I didn’t think I was going to need it, but I guess I do.

Here’s something I did come up with last night. I came up with the idea of stuffing a small wad of foam in the tube right in the end of the hose before it hooks up to the gauge. I thought the porous foam would buffer the airflow without causing restriction. I tried it out in the garage last night and it seemed to work. I put the car in gear and held the brake and there wasn’t any audible rattle. I haven’t had a chance to drive with it yet because I’m working on a corner pod for it.

Thanks for the replies and once I drive with it to test it out, I’ll give an update.

[zoinks]

What brand of gauge is it? You also could have a tiny leak somewhere. Are you using brass fittings with teflon tape? Also, I would stay away from crush fittings, I prefer barbed ones. It could also be something with the 4eat, however I doubt it. Personally I wouldn't put the foam in there. I would be worried that under vacuum it would get sucked back into the system.

[Buzzbomb]

The gauge is a spearco gauge. I just tested it and there are no leaks there. The tee at the BOV is plastic with barbed ends. It's a 3/16 - 3/16 - 1/8. Then 1/8 ID vacuum hose goes from there to the gauge. Is the 1/8 hose you were refering to 1/8 OD?

I understand your concern about the foam getting pulled into the system, I thought of that myself, however I doubt it will move since very little actual airflow is going through the tube. Taking the gauge off the tube with the car running would most likley pull suck it in.

I'm starting to think my hose is too large. I don't want to buy new hose and re-run it. I may just try to find the stock restrictor.

[zoinks]

The tubing is 1/8" ID. However, I just went and measured it and it was actually 3/32" but it was labeled 1/8" at the store. Also the tee that I built was 1/4" - 1/4" - 1/8" IIRC.