Search the Community
Showing results for tags 'I shall call him Gremlin!'.
Found 1 result
-
Reading through Monzter's intake manifold thread, I got the itch to do something similar. But I don't have access to a big CNC nor the 90+lb chunks of aluminum bar to get the thing done his way. I started out with some research, learning how dual-plenum intakes work, and the acoustic tuning done to match intake runner diameter, runner length, and port length together for a desired torque peak. This is the result: Manifold ID: 38mm Manifold length: 265mm Total intake runner length: 395mm This should produce peak torque at 5300RPM, and support enough airflow for 300 horsepower or more. Plenty for the task at hand. Started with the dual-plenum assmebly. Didn't get a lot of photos of this part, but I didn't really want to buy any 4.125" diameter tubing...so I scrounged some up from the scrap bin: Trued up, welded together, and most of the powdercoat stripped: Side lopped off, getting ready to cut the slot down the bottom of the primary plenum: This is the stock rack area...notice that wooden baseball-bat looking thing? That used to be a cheap table leg...turned it in the lathe from 2.5" diameter down to the smallest diameter I could comfortably turn using an offset tailstock. I would have liked to taper down smaller, but it would have made some of the other work more difficult, so no big deal. Here I've wrapped the table leg with flat sheet aluminum, and am working it into the finished conical shape...not quite there yet: The dual plenum assembly: This is the interior slot, it's 13mm wide here, and will finish up at 16mm wide after cleanup: Cutting up runner tubing...38mm ID, 41mm OD, runner tubes are 7.100" long. Layout: Holesawing the port openings...they're cut on a 15* angle, and stepped to provide a positive stop for the runner tubing.. Close up shot of the port openings...this is one of the errors I mentioned. That port is about 1.2mm too low in the flange. The goal was to lift the port up in the head, as it is now they are centered up. I'll probably weld up the lower edge of the port in the finished manifold, and lift the topside some. Here's the finished flange, with the full profile chopped out with a hacksaw and Thanatos, the Destroyer Of Worlds. (That'd be the name of my big electric die grinder...) Flange bolted to one of my cylinder head cores, with the front and back runner tubes welded up. This is the point at which I miss the opportunity to fix mistake #2. Runners 2 and 5 welded up, this is where mistake #2 becomes not-easily-fixable: Fitting runner #4 into place, #3 and 4 are angled, but are two-piece runners. The transistion will get blended inside the runner tube and if I need to, I'll weld the outside of the tubing to build up the wall thickness in areas before sanding it back, this will let me contour the inside of the runner correctly. See where I mentioned mistake #2? This is it. The center two runners are shorter than the outer four by 0.060". This happened because the welding distortion that occured when I welded runners 2 and 5 into place pulled the jigging plate into a bow, and I didn't check for flat before I started work on the center two runners. No worries, once the braces are in place then I'll have the manifold milled flat and it'll all work out fine. Here's a shot of the whole works: Some more angles: Another oops caused by mistake #2...can't get the bolts in because the flanges are too close...: Nothing a little time with a screwjack and a few wrenches couldn't fix. Had to be done anyway because the throttles didn't bolt up to the jig plate! Took four hours for me to straighten things up right... Had to slap together a custom Intake Manifold Straightener Widget to get everything lined up right. Anyway, that's it for this weekend. Current runner length is 9.5", which is 1" short of the target. Once the manifold is decked and I have a final runner length, I'll cut the air horns to hit the target runner length.
