g741.org

Engineer's dream = mechanic's nightmare.

I do hope you post a video of this beast when you finish, Josh. I want to hear that monster run!

oh, there will definitely be videos!

If that engine starts up and runs sweet first time I will be very impressed indeed !!!

Keep up the interesting work Josh!

Stu

so, I promised Id spill the beans, and, I actually put this (mostly) together a LOT faster than I thought I would. As you all can tell from the model, that is one hellaciously complicated hunk of modern art/intake plenum. As such, I know anything I try to weld up will look terrible


so.....



I'm going to cast them.






First step is to make a positive mold. After a bit of debating, I decided to do a wood mold, as I have a decent array of wood tools (another one of my hobbies) and A wood mold is infinately reusable, so long as I am gentle with it. This way, if I dont get the gating or risers right, I simple cast another plaster mold around my wooden model and keep pouring till I get it right.

So, I started out by ripping a 2X4 dow to 14" long chunks squared off at 1.5"X2.75".

I glued 6 of these together, then another 6 to form two 14"X6"X2.75" blocks. The seam in between them is not glued, and that is intentional, you'll see why in a bit.

I then traced the respective patterns on each end using dimensions from teh computer model. Unfortunately, I dont have a printer, otehrwise I would have just printed each end view, cut it out, and glued it on. For Throttle Bodies, I'm going to use a pair of ford 65mm Mustang 4.6L bodies I got at my local you pull it yard for $10 each. 65mm is 2.55 inches, perforct for the 2.5: discharge out of the Holset turbos.

TB end:




Opposite end:



And, in this picture, you can see the reason for the seam in the middle:



Next step was to trace and cut the taper on the Lehman Chamber:



Then, deck the sides:



then, go wild with the table saw, and remove as much material as possible:









then, after making all these:



And some sanding (I got smart and put an 80 grit flapper wheel on my 4 1/2" grinder... made on heck of a mess, bet it cleaned it up fast, especially those pesky knots!)
you get this:





I like the candy stripe of the pine mixed with the red doug fir. I didnt do it on pupose, I just used what wood I had lying around





Then, ripped some 1/8" thick end plates oout of plywood on the tablesaw, and cut the profile on the scroll saw:









And, I'm going to make a slight tweak to the original design. In the original design, I had a slot taken out between the runners. Im going to try to avoid doing that, and, instead, make a steel backing plate that will gasket joint to the face of the plenum. Then, steel runners down to teh heads. This is for two reasons: 1. servicability. I can disassemble the entire unit then. And 2. vibration. Long curvy cast aluminum runners would be a pain to make, and would most likely crack from theweight of such a large plenum hanging off the end.

to do that, I of course need a gasket surface, and that is what this is for:



I'll drill and tap that for bolts, and bolt the steel end plate to it. That 3/4" thick plywood, which will give me a good thick gasket surface I can machine flat and then drill and tap.

Josh,

Impressive design and wood working.... I know that you already have the motor shoehorned into the engine compartment and that your twin turbos had to be position so that the hood would still close....how will this new addition affect the hood on the truck? Have you set it on the motor and closed the hood?

The pattern making is looking really good.... that is a lot of work so far.. I just wanted to add that just making the part you want out of wood and making something that will come out of a rammed sand cope and drag is a different thing... the pattern needs draft ( a slight taper ) to be able to remove it without disturbing the remaining sand...
I have done some backyard casting before and I found that fairing out my wood patterns with cheap bondo was the easiest.
For a part as complex as you are designing... you might be better off carving it from foam and doing a lost foam casting.

thanks for the comments guys

As far as height goes, thats the reason for the computer model. if you notice in the model, they are below the turbocharger height. Turbos clear the hood by about an inch, so I should be alright.

I plan on sealing the wood model with fiberglass resin, the using it to cast plaster molds. I originally considered lost foam, but, without CNC equipment to make perfect replicas, I was worried about getting the chamber volumes the same, same curvature, etc. I plan on cutting the top and bottom plates to match the seam in the actual part, this way I can pour a plaster core, and remove it, and pour a olaster exterior shell, and remove the mold, then set the plaster core in the shell.

I plan on standing it vertical, just as in tle pictures, only feeding it from the throttlebody end, and putting a large riser on it there to ensure I get fillout of the TB plate cavity.

Jeez, I feel like I'm on another planet when I hear you guys speaking technically about casting etc.............

Your some guy Josh!


Stu

Time for an update!

Thanks for the kind words Stu. I take life the same way that Thomas Edison did... Worst that happens is you fail and have to try something else!

So, I finished the pattern... and, it works!

I also did a 3D model of the runners and gates. I talked with a friend of mine at work, Jeremy, that works in our casting quality area, and he helped me develop the gates, runners, and gas tubes shown in the model.





the long thin tube is a gas tube to allow the air to escape from the pattern as the metal is poured.

then, here is the pattern all glued together:













I didnt take any pictures of it, but, I went through and radiused a lot of the sharp edges with body filler, sanded out high spots, and filled low ones, then coated the whole thing in fiberglass resin to give it a smooth surface. I then sanded it out with fine sandpaper, and buffed it, so it was like glass to get the plaster to release.

Speaking of, my 1st attempt:



not so good... not enough water.

So, second attempt:



better, but, if you leave it hollow, the wals are too thin to support themselves trying to pry the mold off, and you end up breaking them, like this:



so, as they say, 3rd time is the charm!



about 30 lbs of plaster scrap... good thing the stuff is cheap!



4th attempt was pretty good as well:



I need to fill a few spots where there were air bubbles, but overall, I am satisfied:



on to the outside... I had some scrap wood, so a whipped up this little box that will hold 1/2 the mold at a time. I made it kind of big... I might go back and fill some of it with foam blocks just to take up room so I need less plaster:



It won't get cored like this, this is both halves in at one time, but, it gives you an idea.. and yes, I'm going to attach the power wagon logo to the mold so that it will cast in the letters into the plenums

Very interesting read. Looking forward to seeing how it comes out.

Why?


Because I can! that's why!

Ah HAHAHAHAHAHAHAHAHAHA!!!!

So the turbo's are out then in favor of the screw chargers?

Or are the Twins gonna' feed the huffer's?

I feel giddy....

with those castings it should be fairly easily to go into limited production, right? Very cool

Ray:

snails feeding the blowers... twincharged. Should make it, uh, interesting.

First and only extensive use of twincharging was WWII bombers. The aircraft engine companies figured out that combined together, you could make more power than with just a single type. Reason being is the turbos raise the overall efficiency of the system, while the blowers raise the intake tract to the highest pressure point in the system, so you dont get a backup of exhaust gasses like you do with just a turbo. Force those gasses out, they take the heat with them, and you can raise teh boost up even further.

Josh wrote: snails feeding the blowers... twincharged. Should make it, uh, interesting.

I think that "interesting" is rather understating it a little....

I would figure that a twin turbo BBD should more than satisfy the need to replace broken parts daily. When does the rest of the driveline get the required strength upgrades? 4Wheeler right now has a decent article on the New AAM 11.5" rear axles. They stand up to hotrod diesel abuse so it should be good for your appliction as well.

Josh have you crunched any numbers through a desk-top dyno to see what type of HP and torque you'll attain with this monster yet. Even if its close to reality it should be more than enough to scare the b'jesus out of granny at the grocery store....