Restrictor Ramblings

Joined
Oct 17, 2004
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Midwest, Illinois
I got this idea from a thread on an import board. The discussion was in regards to restricting oil to turbos.Might be old news to most of you, just sharing an idea. In my mind the restrictor should be on the output of the head, after the filter. YMMV, some folks restrict the input. I do not know if it's critical either way, just that the majority of bypass systems restrict the out flow of the filter. This could still work even if the filter has a built in restrictor and you wanted to throttle it back more. You'll have to figure out flow rate on your own, but I found it pretty easy to use a measuring cup, and count seconds to calculate quarts per minute/gallons an hour. Thread the end of the fitting internally and add a hex head plug with red loctite on it to seal. Just drill the size hole you want in the hex head. 1/32 drill bit is .0312 3/64 drill bit is .0468 1/16 drill bit is .0625

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beanoil

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In that thread, some import guys had switched turbos and needed less oiling for their selection. Different bearings and seals.
 

Astro14

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It's a new concept to me... I've owned several turbo cars, and never considered restricting the oil flow to the turbo(s). But then, my turbos have all remained stock. Even with a mild tune, I've not needed a different turbo... Hard to believe there is such a thing as "too much oil" to the turbo.
 
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Back in Arizona. Finally
Back in the Mazdaspeed 3 days a smoking turbo was an issue when you straight piped the exhaust system- no back pressure the theory went caused oil to get past the turbo seals and she'd smoke her a** off at idle. I ran both my Mazdaspeed 3s totally stock and never had a smoking turbo. No oil consumption either. Restricting the oil to the turbo was supposed to alleviate this.
 

beanoil

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Oct 17, 2004
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I only got the idea from a turbo thread. The restrictor idea seems solid to me, and would enable a generic filter head to be used with a bypass filter. Heads for specific bypass filters have a restrictor built in, but oil pressure and viscosity can effect flow, and someone may want to slow that down.
 

555

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Would you be kind enough to let us know what engine/vehicle/turbo you are modifying? At least for curiousity's sake since a lot of BITOG members like turbos. Thanks
 
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Dec 31, 2016
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Waco, TX
This is common practice. It keeps the seals from having to hold back a Tsunami of oil. A lot of factory installs have restrictors, you just don't realize it.
 
Joined
Oct 24, 2018
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Houston,TX
Same here, restricting the feed to the speed3. also kept the charge pipes much cleaner. (FMIC) turbo mainly need flow more so than pressure.
 
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