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More questions on boost controller plumbing
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ideola  



Joined: 01 Oct 2004
Posts: 15506
Location: Woodstock IL

PostPosted: Thu Aug 25, 2011 2:59 pm    Post subject: More questions on boost controller plumbing Reply with quote

Question 1
Will these two configurations accomplish the same thing? If not, which is the preferred configuration for providing counter pressure to the top port of our dual port wastegate? I've seen examples of both diagrams on various websites...

...........

Question 2
Does it matter how big the line is going to the boost controller? A lot of the kits I see have 1/8" silicone lines, which seems tiny compared to the OEM actuator line on our car. Should the boost controller plumbing use a line that is roughly the same size as the actuator line, or does it not make any difference?

Question 3

What is the ideal material for the boost controller line, cost vs. functionality taken into consideration? Silicone? Cloth Braided? Steel Braided? Simple rubber hose?
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Rasta Monsta  



Joined: 12 Jul 2006
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PostPosted: Thu Aug 25, 2011 3:44 pm    Post subject: Reply with quote

I like the setup on the right. . .failure mode (100% bleed) would result in factory boost level, while the one on the left could result in fragmentation grenade.

As for the line size, I think bigger is better for the 930 wastegate. . .it has a large volume diaphragm that requires a lot more airflow to fill up than the compact modern units that use small silicone line. I experienced the effects of this using a boost controller with tiny barbs/limited airflow. . .there was a boost spike as the wastegate "waited" to fill up.
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morghen  



Joined: 21 Jan 2005
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PostPosted: Thu Aug 25, 2011 5:16 pm    Post subject: Reply with quote

Rasta Monsta wrote:
I like the setup on the right. . .failure mode (100% bleed) would result in factory boost level, while the one on the left could result in fragmentation grenade.

As for the line size, I think bigger is better for the 930 wastegate. . .it has a large volume diaphragm that requires a lot more airflow to fill up than the compact modern units that use small silicone line. I experienced the effects of this using a boost controller with tiny barbs/limited airflow. . .there was a boost spike as the wastegate "waited" to fill up.


+1
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Dutch924-racer  



Joined: 23 Jul 2007
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PostPosted: Thu Aug 25, 2011 7:14 pm    Post subject: Reply with quote

See also this topic:

http://www.924board.org/viewtopic.php?t=32772&highlight=boost+intercooler
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stevekat  



Joined: 19 Jan 2008
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Location: Los Angeles, CA

PostPosted: Thu Aug 25, 2011 8:19 pm    Post subject: Reply with quote

The set up on the right, protects you from a line failure from the charge tube to the boost controller, or the boost controller to the top of the waste gate. If the signal line breaks on this set up you are screwed, as in almost any set up.

On the version on the left, your waste gate never opens. You are screwed 100% of the time. This set up can only limit pressure going to the waste gate actuation, but in all instances the counter pressure is greater than or equal to the signal pressure. The alternative set up you are thinking about should have the boost controller installed after the split coming off the line from the charge tube but to the top of the waste gate, not the signal side.

The third alternative is to have only one line, to the bottom (signal of the waste gate) with a boost controller installed in this line. If single line fails, you are screwed.

I like the braided cloth hose to keep it looking original, but have used braided silicon in the past and had good results. This cloth line is expensive and probably doesn't last as long as silicon. I'd probably go with a minimum of 1/4" ID or so. Steel braided is probably over done.
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flosho  



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PostPosted: Thu Aug 25, 2011 11:28 pm    Post subject: Reply with quote

I would definitely use some larger ID line than 1/8th. Make sure the boost controller you have has bigger ports as well.

I experienced the same thing Rasta did with a MBC, spiking boost because the MBC could not flow enough air to get to the WG before hitting ridiculous boost levels. I hogged the ports out and its fine.


If you are worried about fail safe mode, perhaps you could install some sort of fuel cut system like the stock system.
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ideola  



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PostPosted: Thu Aug 25, 2011 11:42 pm    Post subject: Reply with quote

Cool, thanks for all the replies! The one on the right is easier to plumb in too!

Interesting that the diagram on the left was taken from a well-known 944 performance shop's website...this is how they recommend setting up a dual port wastegate

I will plan to use 1/4" fittings and tubing. Now to find a source for good quality braided line. Open to suggestions...
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flosho  



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PostPosted: Fri Aug 26, 2011 12:14 am    Post subject: Reply with quote

ideola wrote:
Cool, thanks for all the replies! The one on the right is easier to plumb in too!

Interesting that the diagram on the left was taken from a well-known 944 performance shop's website...this is how they recommend setting up a dual port wastegate

I will plan to use 1/4" fittings and tubing. Now to find a source for good quality braided line. Open to suggestions...


You could always go with 1/4 EFI hose.. That is rated at a very high PSI and its still plenty flexible!
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ideola  



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PostPosted: Fri Aug 26, 2011 12:31 am    Post subject: Reply with quote

Ok, will see if i can find a wholesale source for that, thanks!
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stevekat  



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PostPosted: Fri Aug 26, 2011 2:54 am    Post subject: Reply with quote

I could be wrong with my assessment of the left diagram, however I believe the conclusion that it generally won't actuate is correct.

ideola wrote:

Interesting that the diagram on the left was taken from a well-known 944 performance shop's website...this is how they recommend setting up a dual port wastegate

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WEASEL149  



Joined: 19 Aug 2005
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PostPosted: Fri Aug 26, 2011 4:05 am    Post subject: Reply with quote

The manual for my Blitz boost controller basically has the same diagram as the one on the right.
This is how I plumbed mine in taking the line for the controller from the overboost protection switch side directly opposite the wastegate signal line.

I think generally you want to be using the same bore piping as the original Porsche line or slightly larger so counterpressure can reach the wastegate quickly enough otherwise you're gonna get wastegate creep, although really you should be able to dial the creep out with the controller by just opening it up more.

I used another spare wastegate signal line for the counterpressure side so it's identical, then used 2 short silicon hoses provided with the Blitz.

I think the harder the pipe, the better as this should ensure a fast signal.
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WEASEL149  



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PostPosted: Fri Aug 26, 2011 4:12 am    Post subject: Reply with quote

Actually, looking at the left one they've got it the wrong way round.

You need to situate the controller somewhere on the line that goes to the top 'vent' port on the wastegate.
You want an uninterrupted boost signal going to the standard port on the side otherwise I think you'll have spiking problems.
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stevekat  



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PostPosted: Fri Aug 26, 2011 4:23 am    Post subject: Reply with quote

Porsche sells braided cloth line. I think they used to sell it by the foot, now I think you have to buy a minimum or some fixed amount. It is quite expensive. I've seen some on ebay too, again expensive.

These guys have factory style coolant hose, perhaps they have smaller diameter as well. You'll probably end up with a metric equivalent.

http://www.carpartsdiscount.com/auto/parts/82/porsche/924/heater_hoses/coolant_hose.html?3593=120859

ideola wrote:
I will plan to use 1/4" fittings and tubing. Now to find a source for good quality braided line. Open to suggestions...

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ideola  



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PostPosted: Fri Aug 26, 2011 1:21 pm    Post subject: Reply with quote

Hmmm...least expensive braided option is stainless over teflon, believe it or not. I'm concerned about this being flexible enough to make the bends into the cockpit, plus having to worry about it causing abrasion damage on items along the way. The nylon braided stuff is almost twice the cost. Before I go plunk the money down on that, is there any reason that plain old 1/4" rubber heater hose stock wouldn't be sufficient???
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flosho  



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PostPosted: Fri Aug 26, 2011 1:37 pm    Post subject: Reply with quote

Personally, if there is no danger of excessive heat, rubber hose will work fine. No need to over engineer it.


The EFI hose is roughly $4 a foot but is a little more heavy duty than heater hose.
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