Cheap Modified UIM Runner Project (with PICS) - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


Performance, Brainstorming & Tuning Talk about modifications, or anything else associated with performance enhancements. Have a new idea for performance/reliability? Post it here. No idea is stupid! (please use Detailing and Appearance for cosmetic ideas)

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Old 03-13-2007, 01:04 AM   #11
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Looks interesting. I'm curious to hear about the results!
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Old 03-13-2007, 01:22 AM   #12
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Try a dual 45. 45 from left to right, and front to back, with the main opening toward the intake. Know what I mean?
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Old 03-13-2007, 11:52 AM   #13
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Quote:
Originally Posted by TrueWildMan
Try a dual 45. 45 from left to right, and front to back, with the main opening toward the intake. Know what I mean?
That much precision is more than I want to get into with this thing. Here'* what I did...

There was no easy way to secure these "horns" into my miter box, so I improvised. First I made pencil marks 5/8" from the inside edge as represented by the green arrows/line:




Then I clamped the piece down to a scrap bit of 2x4 on my bench, marking the top and bottom edges with a pencil:



I then cut at a 45 degree angle, following my pencil marks, lopping off as so:


After a bit more with the Mouse sander, here is the finished item:


And here are the marks left on my scrap 2x4, to serve as a guide to help me do them all the same:


Here they all are, fitted into the UIM. They are just as secure as before:


Looking into the TB opening, I judge that these horn openings better "face" the incoming airstream:



This was maybe another 30 minutes' work.
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Old 03-13-2007, 01:54 PM   #14
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I would be a little worried about cylinder #6 running lean since it'* in the direct path of the inlet.
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Old 03-13-2007, 02:01 PM   #15
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And if it does, you'll never know it until you smoke a plug. Your O2 sensor is going to balance your AFR based on all 6 cylinders. So if 6 runs lean, the others will run rich.


Cutting the back side of 5 and 6 may have been better, but in the long run, you're going to need 6 O2 sensors to tune that thing in (assuming Mike'* theory is right).
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Old 03-13-2007, 05:16 PM   #16
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Inside that huge plenum, in order for that #6 cylinder to draw more air than the others due to being directly in the path of the TB airflow, I assume we've got to believe there'* going to be some "ram air" effect.

By my calculations, at 6000rpm, assuming a generous 100% VE, the 231ci L36 will require 200 cfm through the TB to keep itself fully fed with air. Assuming a 70mm (2.75 inch) diameter TB inlet, that works out to an average flow velocity of about 81fps maximum. That'* under 60 mph, and well under the velocity we'd need to see any true "ram air." I know there will be regions in the cross sectional flow where the velocity through the TB is higher (and lower) than that, but I'm still not worried.

Of course, all that being said, in retrospect the whole 45 degree angle thing is probably more window-dressing than anything else. I guess I just wanted to be sure there were no restrictions to the runner inlets. Also, I believe that, if anything, the angled cut should improve flow to the rearward runners by removing impediments.

Once on the car, I will monitor and report on the spark plugs to see if any cylinders show signs of leanness or richness. Also, if it requires a Powrtuner fuel skew to bring 'em in line (similar to what you need to do with a Powerlog), I will report that.

I would say the whole rear bank is more in-line with the airflow than the front bank. Hey, if the front bank goes rich, maybe we can solve the '95 with Powerlog fuel skew issue right here
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Old 03-13-2007, 05:39 PM   #17
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that my insert in my dorman intake i think it differend its only 1 1/2 inches high http://i178.photobucket.com/albums/w...ick/insert.jpg
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Old 03-13-2007, 06:00 PM   #18
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I'm not real sure what you mean when you say it would need some sort of ram air effect to make that happen.
All you have is atmospheric pressure pushing through the air box, TB, and into the UIM at an angle pointed torward that #6 runner.
I would agree that cutting the 45 improved flow to the p/* and that the entire rear bank now probably can take in more air. But that #6 just seems like it'* at an advantage.
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Old 03-13-2007, 06:15 PM   #19
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CORRECTION: Oops, error in my calcs, double the numbers to 400cfm for the intake needs, thus we are approaching about 120 mph for intake air velocity through the TB (at least under idealized conditions).
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Old 03-13-2007, 06:19 PM   #20
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Quote:
Originally Posted by 95naSTA
I'm not real sure what you mean when you say it would need some sort of ram air effect to make that happen.
All you have is atmospheric pressure pushing through the air box, TB, and into the UIM at an angle pointed torward that #6 runner.
I would agree that cutting the 45 improved flow to the p/* and that the entire rear bank now probably can take in more air. But that #6 just seems like it'* at an advantage.
All the runners have the same cross-section, and all are drawing from the same "tank" of air (the plenum), so what advantage could it have, if not a ram air effect?
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