Monzter-inspired Intake Manifold

[Xnke]

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.

[madkaw]

I admire your fabbing skills-and BIG tools to get it done. I am taking the easier route by using a Cannon intake and a single TB. I'm also going to order a plenum extrusion instead trying to make one. I'm going to attempt the aluminum baseball bat for my primary plenum.

The project looks good! If I ever get down that way, would like to see it in person.

[Xnke]

Really, the only big tool I used was the lathe, and I only used that for turning the form for the cone. the TIG welder you aren't really going to get around needing if your are going to fab aluminum sheet, though.

Edited December 3, 2012 by Xnke

[Snailed]

A lot of people would argue that Oxy/Fuel welding is superior to TIG for welding sheet aluminum. It's a bit harder to do though.

[Xnke]

Yes, a lot of people would argue that. I have the equipment and the skill to weld aluminum with an oxyfuel torch, I did it for a few years till I bought my TIG. It sucks. Gotta use a sodium based flux, which flares BRIGHT yellow, masking the puddle, so you wear an extra dark cobalt or gold shade. The good cobalt shades are very hard to find and the one I have is cracked...so it's no good anymore. The gold shades that can block the sodium flare are exhorbantly expensive. The only benefit to using the oxyfuel setup for aluminum is if you are going to be working the sheet over a wheel or with a hammer; for doing bodywork. The weld deposit is much softer, and the heat affected zone is much larger, meaning that when you start working the weld bead it doesn't crack or split, but rather spreads into the surrounding soft metal, causing a much more gradual change in thickness. It's very often used in aluminum-skinned aircraft repair.

 

In this case, you'd be hard pressed to find a method superior to TIG for welding .500" thick plate to .065" wall thickness tubing. Even a master of the oxyfuel torch is going to have a seriously difficult time controlling the puddle on that joint...

Edited December 3, 2012 by Xnke

[340ZXTTAZ]

Hey I've got one of those Cannon Intakes for sale over @ Z31 Performance. It is drill out for injector bungs already, all it needs is the plenum made and throttle body flange.

 

Sorry for the sameless plug, but at least you can get an idea of what he was talking about.

 

 

http://www.z31performance.com/forum/viewtopic.php?f=9&t=36404

[Xnke]

I belive we have rules about posting for sale ads outside if the classifieds...let's not.

Tonight's task is to figure out the order of operations for the velocity stacks. they are machined from 2.25" solid, because I scored some at the local recycler for far less than I could buy smaller material. I may also attempt to spin some horns from flat sheet, I have been wanting to try that for a while now.

 

EDIT: why is "Tonite", when spelled correctly, censored?

Edited December 5, 2012 by Xnke

[redzedturbo]

That is beautiful jake! And the flange a++

[Snailed]

Yes, a lot of people would argue that. I have the equipment and the skill to weld aluminum with an oxyfuel torch, I did it for a few years till I bought my TIG. It sucks. Gotta use a sodium based flux, which flares BRIGHT yellow, masking the puddle, so you wear an extra dark cobalt or gold shade. The good cobalt shades are very hard to find and the one I have is cracked...so it's no good anymore. The gold shades that can block the sodium flare are exhorbantly expensive. The only benefit to using the oxyfuel setup for aluminum is if you are going to be working the sheet over a wheel or with a hammer; for doing bodywork. The weld deposit is much softer, and the heat affected zone is much larger, meaning that when you start working the weld bead it doesn't crack or split, but rather spreads into the surrounding soft metal, causing a much more gradual change in thickness. It's very often used in aluminum-skinned aircraft repair.

 

In this case, you'd be hard pressed to find a method superior to TIG for welding .500" thick plate to .065" wall thickness tubing. Even a master of the oxyfuel torch is going to have a seriously difficult time controlling the puddle on that joint...

Haha! yes, it does suck. I have very little experience with it, but I know I like TIG better as well. Just thought I would point it out becasue it's an interesting welding process.

[Xnke]

Argh. I'm really not digging the air horn turnings. The one in the photo below took me four hours to get completed, when machining from solid. I really should try to find some 2.25" OD .250" thick tubing to machine these from...would take about fifteen minutes each, then. (But then I'd have to buy some more material...and I've got a 14" bar of 2.25" solid drilled through already...)

 

 

The next issue is vacuum management. I did not provide any method for drawing manifold vacuum in the actual runner assembly...the wall thickness and the planned throttle arrangement didn't leave much room for it, and I wanted a good clean look.

 

The FWD Maxima throttle bodies I'm using have a pair of ported vacuum ports on the front, which I don't like and don't think I can use effectively with Megasquirt. At off-idle, they would read very high vacuum, but as soon as the throttle was cracked the vacuum signal would go away, and with ITB's that's already a major issue. The steel, pressed-in tubes were drilled out of the aluminum casting, and the holes plugged with driven in aluminum slugs. These throttle assemblies ALSO have a water jacket on the bottom that comes out into a pair of 8mm hose barbs. The jacket runs under both bores, behind the throttle plates...and I am not going to be running hot water through my throttle assemblies. If I could run chilled water, or if the passeges were drilled and tapped I could run cold refrigerant from the A/C system, but that's a lot of work. And I still need a vacuum log!

 

 

Instead, I've carefully plugged the original vacuum ports, and drilled through the water passage into the throttle bores with a .220" drill. The passages get all the chips blown out as best as possible, and the outer holes welded back solid. The individual throttle assemblies will have the water jackets joined together and the front of the log will get routed back to the megasquirt, and the rear of the log will be routed to the brake booster via a check valve.

[Xnke]

Worked out a new order of operations while I was goofing around at work, and tried it tonight. MUCH MUCH FASTER! I was able to complete these four velocity stacks in two hours, they are (I had to recalculate this) 1.3" in length, and the center two stacks are supposed to be 1.0" in length. I will machine them tomarrow evening, and get them pressed into the baseplate and welded in place. After the stacks are welded into place, I'll bolt the whole manifold minus the plenum together for documentation purposes, and to make sure that everything will seal up.



Close up of how the air horns actually touch, I would have liked to have a longer radius, but this will have to work. It's all I can fit in there.



Soon....Soon I will be assembling the plenum and will start measuring for the following:

Throttle Linkage
Injector bungs
Fuel rail mounts
Heat shield mounts
PCV vacuum port
TPS clearance. It's gonna be DAMN tight to get a stock Nissan TPS in place. I might have to switch to a Subaru TPS, they sit on the throttle backwards from the Nissan unit, and I think they still rotate the same direction. That would be an elegant solution.

Idle control will share the vacuum log with the brake booster, and I'll tap into the vacuum log for the MAP sensor. The PCV vent on top the valve cover will be rotated to the passenger side, and will be plumbed into a port on the side of the inlet of the supercharger. Any blowby mist will get dumped into the supercharger inlet, and will form a coating on the supercharger rotor assembly, keeping the rotor-to-rotor and rotor-to-case tolerances tighter. Yeah, that's it.

[Leon]

This is probably irrelevant at this point, but just for general knowledge, the more radius your air horn has, the better it'll perform. There is a point of diminishing returns, but your air horns, although beautifully crafted, could use a tighter radius on the lip.

With that said, this is looking good!

[cockerstar]

As a solution to touching air horns a pair of complementary flats seems to do pretty well. 

 

http://www.zcar.com/forum/10-70-83-tech-discussion-forum/115952-customers-6-itb-intake-progress-pictures.html

 

Edit:  What the hell is this new software's problem with BBcode? 

Edited December 6, 2012 by cockerstar

[Xnke]

I did flare the ends of them a little more, they got mushed between the bores some. A little work with some cartridge rolls (these air horns are SERIOUSLY thin) blended the radius in better. These horns are 52mm at the base, OD, and 54mm OD at the top, and the internal bore is 48mm, tapering to 50.5mm, then the 1" radius starts. Like I said, this is the best *I* can fit ito the plenum.

 

More photos of the assembled plenum this evening, including Mistake #4. This time, things are getting ugly.

[Snailed]

Neat vac idea. Can you run a hybrid TPS & MAP based load scale with megasquirt or just one or the other? I have never tuned MS but some systems have that avalible for ITBs. It works well.

 

I made a couple velocity stacks out of thin tube with a solid 5/16" ring that I rolled and welded to the end of the tube. With just a tiny bit of clean up, they looked really aerodynamic for what they were.

[Xnke]

Yes, you can use Hybrid Alpha-N with MS1extra, and MSII extra actually has a naturally-aspirated ITB mode. The ITB mode, however, does not support boosted applications. I'll be running Hybrid Alpha-N, assuming that I don't make enough vacuum to run straight Alpha-N.

 

Here's the assembled plenum, from the top:

 

 

And Mistake #4. The fire-extinguisher-turned-plenum pulled enormously during the welding of the secondary plenum, and I didn't catch it in time. A little filler rod and some sheet cut to fit the gap fixed it, but it'll always be ugly. Good thing it's on the bottom side and won't be seen!

 

 

The manifold is still at the machine shop, and I dropped off the plenum assembly today to get flattened. Hopefully I'll get them back next week.

[Meph]

Post up some pictures when its gets back from the shop.  I love seeing custom work!

[yellowoctupus]

Been there on mistake #2. Had to fly cut my whole S/C mounting surface flat again. Nice work, I love the repourposed extinguishers. Been trying to figure out how to use two as 'gas tanks' or propane bottle holders on a motorcycle for years. The extinguishers are still sitting in my scrap bin though....

[Xnke]

Got the manifold back from the machine shop today, but the plenum assembly was not ready yet. I'll have to run studs in the plenum, which I haven't made yet, since they are about 70mm long M8x1.25. No big deal. I will probably fit studs in every location, just because I feel like doing it that way. And I have a whole box (100) of M8x1.25 nuts.

[Xnke]

Got the plenum assembly back from the machine shop, and have it mocked up. Not bad!







And this will be irritating.



Argh. Anyone got any ideas for a more compact potentiometer type TPS that will fit the nissan shaft? Or even one that has the connector body flipped 180* or so?