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Turbo vacuum line diameter

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Old 08-18-2015, 02:08 PM
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Default Turbo vacuum line diameter

I'm running an s362 Borg Warner twin scroll on my k20z1, eg chassis. The clearance of the manifold, turbo and downpipe are real close to the firewall. So running vacuum lines is difficult without getting them too close to a heat source. So I ran the lines in copper tubing, same tubing that you'd run oil pressure or boost gauges off of. I'm afraid the lines are going to be too small and cause problems in higher boost levels. Anybody run lines like this and it be successful? If not, any suggestions for bigger diameter lines that can stand to be close to heat?
Old 08-19-2015, 12:00 AM
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Default Re: Turbo vacuum line diameter

A lot of people run hard lines for pressure signals, oil, coolant, etc. Just be sure to convert to braided or flexible line if your lines go from turbo/engine to firewall or turbo to engine. The vibration of the engine, along with movement of the engine, and the thermal expansion and contraction of the turbo manifold can easily crack or split lines that are 100% hard. Think of the braided sections like the flex joint in an exhaust system.

Howeer with copper being highly conductive in regards to heat I would run heat sleeves on the lines that are near a significant heat source just to be safe. You can do the same thing with stainless or aluminum hard line if you have a flare tool. With all 3 you can run a hard line to AN adapter if you aren't just running plain hose. If you are running those copper hard lines to plain hose though be sure to use silicone hoses as they are much more tolerant to heat and chemicals than generic rubber hose.

As long as the inner diameter of your lines is the same as the fitting inner diameter you'll be fine. I don't know how extensive your use of hard line is but blow off valves tend to like a slightly larger hose/fitting diameter with their own dedicated pressure source, the FPR also likes it's own signal as well. Signals for boost control are best located on a charge pipe before the throttle body as they never need to see vacuum, typically running off the compressor housing is too turbulent which can cause boost stability issues.
Old 08-19-2015, 06:41 AM
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Default Re: Turbo vacuum line diameter

The blow off valve line is run off its own pressure source and is run with a larger hose compared to the rest. it was one of the pieces i could get away with rubber hose since it was far from serious heat. I was mainly concerned that the copper was going to be too restrictive. If it doesn't show any signs of issues on the dyno, then i will make sure to heat wrap any spots that are close to heat sources. thanks for the reply
Old 08-19-2015, 07:46 AM
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Default Re: Turbo vacuum line diameter

Basically, whatever the inner diameter of the fitting on your wastegate is, that's the minimum size line you should strive to run, without bottle necks anywhere along that path.
Old 08-19-2015, 11:19 AM
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Default Re: Turbo vacuum line diameter

Bottle necks?
Old 08-19-2015, 12:42 PM
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Default Re: Turbo vacuum line diameter

Originally Posted by Psychoteen101
Bottle necks?
A place of restriction.
Old 08-19-2015, 04:32 PM
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Default Re: Turbo vacuum line diameter

The lines attach the fittings with crush sleeves, wouldn't that cause restriction?
Old 08-19-2015, 04:36 PM
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Default Re: Turbo vacuum line diameter

The crush sleeves don't alter the inner diameter of the line when used properly. They simply grip the outer diameter of the tube and seal the line against the fitting. You could use a flare tool and flare fittings if it bothers you that much.

I've made my own hard lines using both crush sleeves and flare fittings without issue.
Old 08-19-2015, 06:54 PM
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Default Re: Turbo vacuum line diameter

Excellent. I'm hoping it won't cause any problems. Thanks for the info
Old 08-20-2015, 09:11 AM
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Default Re: Turbo vacuum line diameter

Originally Posted by Psychoteen101
crush sleeves
compression fittings

actually, the little ferrule is called an olive, lol






damn..turbo K EG. badass
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