Drinaldis

I'm making a set of boost leak testers. A single for the intake that fits in the coupling the airbox connects to. Also, a set to block off the turbo and provide a fitting for the other side. What size in the airbox fitting (~3in)? What size are the turbo hoses (~1-5/8)?

Making them from scratch so exact numbers would be helpful.

Thanks in advance,
David

cbracerx

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DaveCarrera4

You are covering old ground, I believe it was the 3" PVC pipe end plugs that fit. Drill and tap for 1/4" NPT threads and screw in the fittings for an air hose connection. Use a hose clamp to secure it. If you search you'll find a few threads on this.

Drinaldis

I plan to machine mine from aluminum round stock so having actual dimensions would be helpful. 3" PVC schedule 40 pipe is something like 3.315" od. If I machine mine to be 3.315" and they're a little too big or a little too small I'd be bummed. just sayin'

James88

Have you considered these, they're very well priced.
http://turboboostleaktesters.com/new-category/

993GT

I built my own, test at turbo inlets, 2" 's

vogz

I don't know why people continue to boost test intake pipes PRE turbo. Those pipes never see any positive pressure. Another local 996 Turbo owner and I boost leak tested both of our cars with a "Home Depot" $15 setup tonight. All that was needed was a PVC end cap with a hole drilled and a air hose fitting screwed in. Then a 2 inch rubber pvc coupler and 2 in rubber end cap and three hose clamps.

We removed the small intake pipes just before the turbos and installed the pvc cap with the air fitting directly to the passenger side turbo (a little more room to work) and the rubber cap to the other turbo. Run about 15psi through and see if there's any hissing.

We ran mine all the way to 20psi and no leaks at all @ 71K miles! My car is stock with the exception of a Speedtech exhaust. We ran his to about 2 psi before we heard a ton of hissing. Turns out the bottom of his diverter valve hose is ripped.

Anyway, the only real way to pressure test every part that sees boost is to do it directly at the turbo inlets. That way you test the outlet, intercooler connections, y-pipe etc.

Kevin

Page 620-622 in the Porsche Service Manual gives a good description to test the full intake system..

I'd increase the test pressure to 16 to 18 PSI.. But you will find most leaks at 7 to 8 psi..

The MAF based Motronic has to have a sealed intake system (pre and post turbo) to operate correctly. Fueling trims and general engine performance will suffer if you have a loose hose PRE-Turbo.. The aluminum side intake plenum gaskets and hose connections are prone to leaks from clutch and tranny removals. The oil tank reservoir pressure relief hose ties into the side intake plenum (the hose leaks at the two connections).

vogz

Exposing pre turbo intake parts to positive pressure that they normally would never see could cause leaks that would not be there under the vacuum conditions that the intake piping normally sees. A smoke test is the proper way to check for vacuum leaks.

Olemiss540

Isnt the point of pressure testing to "cause" leaks?

vogz

Those pipes never see positive pressure, and aren't designed for it, so why expose them to it when you could do a smoke test instead?

You could break something that wasn't broken is what I'm trying to say.

Olemiss540

Gotcha, I just am not sure what items pre-turbo one could actually break with 10psi of air pressure unless it needing replacing anyways.

vogz

The small pipes right before the turbo are plastic and they slip onto the metal alien looking pipes. There is no rubber seal, it's basically just plastic clamped onto metal. I could see those leaking very easily if exposed to pressure no matter how old they are. There is a reason the boost side doesn't use any thin plastic parts attached like this.

Kevin

Testing the pre-turbo intake system is a must on 15 year old cars. To many hands have loosened and overtightened clamps>>including gaskets between the side intake plenum and aluminum downpipe.

In the perfect world, there would be no need to pressure test anything.

911mhawk

$1.18 + a hose fitting ~ $1