E21 Intake Runner FAQ
By Karl Koenig, Bill Barrett and Art (in California)
Edited By Peter Florance
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I first heard about replacing 528i intake
manifold runners with the corresponding parts from 320i from
Metric Mechanic. They advise it when larger displacement engine
is swapped in. Then Grassroots Motorsports tried it on their
project 528, and got some dyno numbers. Its one of those
things where you say "It cant be that simple."
But it is, and it works. Those bigger runners made a noticeable
differencethe butt-force dynamometer registered the
difference within a half block of the driveway, the first time I
pulled around a street corner in second. This kicksdo it.
OK, now for how to do it. Naturally you need 1 ½ donors to get six runners. Local BMW guru found some for me and put them in a box, so I cant say what came from where on the donor engines, but I ended up with three runners with no studs for hanging stuff, two with short studs, and one with long studs. I also got intake manifold gaskets for 528i at the top and 535i (Karl has E34 3.5L, so the head is a little different - ed.) at the bottom. I used the runner with long studs on cylinder #1 to support the fuel pressure regulator, with left over sway bar bushings to isolate the bracket from the manifold. I used the two with short studs on cylinder #2 and #4 to support the fuel return line and the wire harness on the left side of the engine. (Peter's note: The threaded bosses on the sides of the intake runners are open to the inside of the intake runners. You must install 6mm bolts whether you use them for mounting or not, to avoid a serious vacuum leak. I sealed the bolt threads with sensor-safe Ultra-Red silicone sealer but a teflon sealer or tape will work as well. ) Brackets are home made. The one supporting the pressure regulator started by fiddling with a piece of cardboard to make a template. I also had to reposition the original fuel regulator support to meet the bracket I made. The picture shows how it all ended up. Actually the appearance is kind of subtle.
Have fun with it.
Here's Bill Barrett's installation on a 79 528i (w/ 3.3L) including an adjustable fuel pressure regulator and fuel pressure gauge:
Bill writes: "After installing 320i runners, I wanted to add an adjustable fuel pressure regulator and gauge. To make the mounting rail, I used 1" aluminum and 2" right angle brackets. The brackets attach to the studs in the runners and are through bolted into the aluminum. All parts were purchased at Home Depot for less than $10."
|320i intake installation|
(one on the left from 320i, rest are from 5 series)
(one in middle not cleaned)
||the cross brace you
need to cut
|things you need:
- good ratchet set with at least two different length extensions (some of those bolts are hard to get to..)
- bolts are 12mm
- mounting hrdwr bolts are 10mm
- one hacksaw (I'll explain below)
- scewdriver to get hoses out of the way
- Berryman Chem-dip (this stuff rocks!)
- and of course intakes from up to 79 320i (plenty at your local pick n' pull)
- if you want, 320i intake gaskets (but 528i gaskets work fine and are same size)
parts #s for 320i gaskets:
Okay.. hope this might helps someone
-art in CA
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