Restrictor Design...

Alright....so it's probably a black art, but someone has to know something.

Most would design a restrictor with a "velocity" stack that leads INTO it.

however.. the attached photos kind of show the inverse thinking.

it seems that instead of speeding the air up, they are trying to slow it down.

Is the idea to not cram as much air INTO the restrictor as possible, but instead have a "mass" of air sitting at the restrictor inlet, so it can easily suck in whatever it needs?

I sit here and work with Solidworks, and can model and analyse to my hearts content. Maybe i'm doing it wrong, but i'm taking the average velocity at the "outlet" of the restrictor, and times by the area at the outlet. This gives me CFM.

The design in both pictures does flow considerably less air..but that makes sense as the speeds are MUCH lower.

is this an effort to keep the flow from going supersonic and potentially bouncing back through the restrictor?

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Chris

other picture works best as a link

http://www.subaru-sti.co.jp/e/GRN/tec_info/img/tecinfo_3e.jpg

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Chris

Slow air is high pressure air.

That was the explanation given to me for some weird intake tubes made by one company... they were smaller at the air filter end and huge at the throttle body end, and the TB end had a big half-donut there. They're supposed to work really well.

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.

random: the guy in the pic is Shawn Jacobs...Sr. Tech on Blocks car at VTSC....i went to highschool with him and his older brother in VT. too funny.

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Jon Burke - KI6LSW
Blog: http://psgrallywrx.blogspot.com/

And that restrictor comes from prodrive. For $700 you too can have your own. If you would have asked this question a few weeks ago I could have taken pics and measurements of a 34mm and a 40mm from prodrive. But now they're gone.

Why didn't you just do it anyway? That's a terrible thing to tell the guy now.

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Michael LeCompte

what turbo is that? looks big...

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Jon Burke - KI6LSW
Blog: http://psgrallywrx.blogspot.com/

about the same size turbo i've got.

I think it's the IHI twin scroller...VF36 or somethin?

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Chris

Chris, my prodrive restrictor should be here shortly. I think you're best to just have that copied. BTW my motor started last night!!!!!

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Gone fishing

I found this one on ebay today, it's a Ford motorsport one

http://cgi.ebay.co.uk/cosworth-rally-34mm-turbo-restrictor_W0QQitemZ360098186720QQcmdZViewItem?hash=item360098186720&_trkparms=72%3A1301%7C39%3A1%7C66%3A2%7C65%3A12%7C240%3A1318&_trksid=p3911.c0.m14

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Michael LeCompte

pikespeakgtx Wrote:
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> I found this one on ebay today, it's a Ford
> motorsport one


ATM Sport, aka Ass To Mouth Andrew Thompson who will fuck you badly, quadruple his prices once he has your credit card number, who charges an average of 4-5 times what the actual postage is, who adds VAT to his inflated prices AND postage on EXPORT, and who simply does not deliver stuff and blames the Post is a criminal.

His outright criminal behaviour which I personally have a THICK file on, has gotten him banned on the various British Cossie forums so he resorts to several false names such as "Eddie Pain" and a couple of others and fucks people further.

The British Fair Trading Standards people are powerless to stop him as he simply changes the name of the business and then says 'That was a different company."

To which I siad "Lesse, same 2 phone, same mobile number, same fax, same address, same email, same principle Andrew Thompson, but different company?"
His answer "Yes differnt company, that was ATM, this is ATM Sport."

The fucker got me for 500-600 bucks for JUNK which he claims is "mint".


I have one of those, gotten for maybe 15 Pounds, fits Garrett TB3403 compressor housings which of course are machined up to accept them.
>
>
>
> Michael LeCompte

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Yeah he seemed sketchy with dealings I had with him before and I never went through with the deal because of it. Just didn't trust him. Prices went up like you said, like magically, randomly.

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Michael LeCompte

Do It Sidewayz Wrote:
-------------------------------------------------------
> Alright....so it's probably a black art, but
> someone has to know something.

>
> it seems that instead of speeding the air up, they
> are trying to slow it down.
>
> Is the idea to not cram as much air INTO the
> restrictor as possible, but instead have a "mass"
> of air sitting at the restrictor inlet, so it can
> easily suck in whatever it needs?
>
> I sit here and work with Solidworks, and can model
> and analyse to my hearts content. Maybe i'm doing
> it wrong, but i'm taking the average velocity at
> the "outlet" of the restrictor, and times by the
> area at the outlet. This gives me CFM.
>
> The design in both pictures does flow considerably
> less air..but that makes sense as the speeds are
> MUCH lower.
>
> is this an effort to keep the flow from going
> supersonic and potentially bouncing back through
> the restrictor?
>
> Chris

Just for perspective, though it might not be exactly the same: I was designing a moderate speed, moderate flow muffin fan setup to drive air through a restrictive (rectangular) opening into the middle of a 1 kW power supply heat exchanger, mounting into a tight electonics enclosure. The air needed to turn 90 degrees from the fan outlet into the exchanger fins. Since cooling and power supply reliability were critical in the application, I bothered to set up a flow meter, and played around with the arrangements of the fan versus heat exchanger air entry. It turned out that an approx 1/4" spacer between the fan and the heat exchanger entry was best, and produced an approx 50% airflow increase over the fan being directly mounted on the exchanger, and airflow was better at 1/4" spacing than at 1/2" spacing or greater.

There appeared to be a optimimum spacing between the fan blades and the exchanger opening; the fan imparted a partially circular motion to the air flowing out of it; it was not just straight flow out of the fan when you were close to the blades, and it appeared that the optimum spacing produced the best 'coupling' of this partially circular airflow to help the air make the 90 degree turn into the heat exchange fins.

Looking at a turbo, the air has to make a 90 degree direction change from entry to exit, all in a very shirt distance. Based on the muffin fan situation, it seems reasonable to suppose that the funny shape you showed on the restrictor might be there the help the air start to make it's turn through the turbo, thus helping the overall flow. (Imagine the shape of a funnel or toilet bowl and the spiral flow in those .....)

My ideas may be totally wrong in detail for this restrictor, but you should get the idea:
1- when air turns at any velocity, anything you can do to help that turn will increase airflow
2- the strange coupling effects in airflow cannot easily be visualized, are not necessarily intuitive, and odd shaped, experimentally derived shapes can produce unexepcted results
3- standard modeling does not apply in these restricted, air-turning situations


Very interesting; thanks for sharing the photo!
Mark B.