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Thread: Intake Manifold Hose Connections

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Posts: 31-35 of 35
2008-10-15 12:12:23
Originally Posted by Wolf_SER
It's not weird, this has been for a long time you just didn't know . When taken directly from the manifold, a boost controler is not affected at all when it sees vac, however, the response to control boost and spiking would be noticeable more if taken from the manifold that taken directly from the turbo.

I've been using the good old "grainger valve" boost controllers since about 10 yrs now and never had a complaint about. This was Tomas Gus Mahon legacy to the turbo world.

I took these pics and explanation from the site of my good friend Dawes

This is a Hybrid Boost Controller, cheap and very very effective.

"Locate a boost source using the diagrams as a guideline. Now run a piece vacuum hose between the boost source and the straight end of the controller. A drop of oil on the brass tip will aid in adjusting the hose later. Do not use the original wastegate line as your boost source. The best place to use is a nipple on the turbocharger output, if you have one. If there is already a line attached, install a vacuum tee (as close to the nipple as possible). Alternate sources include the intake manifold, or the pipe between the turbo and throttle. Do not tie wrap this hose yet. You will need to rotate the hose about the nipples later. "

Diagram A

Diagram B

Very nice, I like that second diagram, especially since I got this outlet:
2008-10-15 12:38:38
One of the many gifts from the turbo Dodge community.
2008-10-15 13:03:16
Can I run the Diagram B setup, without a boost controller, or is it not going to be as accurate as if it was on the cold side of the pipe?

Actually I think my BOV has a nipple that goes to the waste gage, I just don't want to run a long hose haha...
2008-10-15 14:19:26
Originally Posted by Vadim
Can I run the Diagram B setup, without a boost controller

Originally Posted by Vadim
is it not going to be as accurate as if it was on the cold side of the pipe?
It depends what you mean by accurate. The source of pressure by the turbo is the highest you will find (being the hottest air) so your wastegate will see relatively high pressure air, usually a couple psi higher than what you'll see in the manifold. This means the wastegate will see 9 psi (or what ever it's set to) way before the manifold does, and your wastegate will open. This means you'll be seeing about 6 psi at the manifold. It's all a trade-off.

Some people like the signal coming from the hot side because the wastegate is quicker to re-act, causing less spikes and they just compensate for the early opening by "turning up" the boost a couple psi more.

Others like the wastegate to get a signal from the cold side (post intercooler) because it more closely represents the actual pressure the engine sees. These people typically put the boost gauge signal, BOV signal, and everything else on the cold side because they want all of their signals to be equal in pressure making it less taxing to think about different pressure sources.

Still others make sure their signal comes from after the throttle plate. The theory behind this is to keep the wastegate shut during shifts to keep the turbo spooled a bit more. When the throttle is closed and the wastegate signal comes before the throttle plate, the wastegate stays open until the BOV can bleed off enough pressure. When the throttle is closed and the wastegate signal comes from after the throttle plate, the wastegate closes immediately allowing what small amount of exhaust there is to keep the turbo spooled. This has a downside of increasing compressor surge or overboosting at partial throttle for large turbos or very high boost pressures. At partial throttle there can be a large pressure difference across the throttle plate causing the wastegate to see much less pressure than what the turbo is actually producing. Not only are you over shooting your boost target (and won't be able to tell with a boost gauge or MAP sensor sourced at the manifold), but the engine consumes much less air, this is where you get compressor surge. It's a pretty eye opening thing to hear compressor surge while you're accelerating hard with 20 psi at partial throttle when you're only used to hearing it on poorly setup cars at throttle closing.

For your setup (and most low boost set-ups) I would recommend the wastegate signal from the manifold after the throttle plate, but you'd really be fine either way. If you're not going to run a boost controller and want max pressure, I'd keep the signal post intercooler.
2008-10-15 14:29:19
Sweet, yeah for stock boost I don't really want too much either haha. Thanks for clarifying that
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