Cast Aluminum Intake Manifolds

It just occoured to me that cast aluminum intake manifolds ought to be simple enough to make in the backyard.

Years ago I played around with green sand casting. I uses the Gingery books on how to buld your own metal workshop tools from scratch and built a small furnace. I got aluminum pots and pans from yard sales and thrift stores and mads molds and mostly cast, don't laugh, D&D battle figures. Yea I was one of *those* geeks. lol

Anyway I was thinking aluminum cast intake manifolds shouldn't be all that hard. Cut off the top vacuum nipples, make a sold cast, drill and tap the tops for vacuum fittings and use a piece of rubber tubing to mate the carbs to the manifolds.

Or it might be possible to neck down the manifold and use an o-ring and set screws to get a good seal. That might be more work tha it is worth though. Probably better to make the OD of the back of the manifold match that of the carbs and go wit rubber tubing and a set of clamps. Plus that would be easier for the average bear to install.

Just think. Manifolds that never tear and last forever...

Comments? Suggestions? Am I nuts? I think it would work. Wonder what I ever did with my crucible and tongs...

As a side thought - anyone else here ever built any of the Gingery tools?

 

Ciberratt

I did some alloy casting years ago at college, it wasn't that hard but for all the setting up, pattern making, etc. wouldn't it be easier to cnc them out of billet? cnc time is pretty cheap these days and you can even get a 3D scan done of the original, add whatever mods in software and presto, you have the finished items, all nice and shiny without that rough cast finish that would take forever to polish. Just my thoughts, cheers, Ian

 

Sounds like a good idea to me, not sure of any reason it would not work as a replacement for the rubber ones. Thats something I have always wanted to do (cast something that is just never took the time to do it unless you count fishing weights) if you decide to do it take some pics or shoot a video.

 

I thought of that but I was looking for a solution that could be accomplished in my backyard using scrap materials. Turning scrap into useable stuff is a hobby of mine

I have cad software and a milling machine. Unfortunatly to convert the one I have to CNC is a pain. It has been done and there are forums for that...

I have not looked into farming out CNC work before. I would think it would cost more than new rubber boots? Part of the point was to make useable manifolds for less than the cost of new ones. I'd rather spend time than money... I will check around though and see what something like that costs. I might be able to get it done in the shop at the college... student project....

 

I also considered making them in a 3D printer I was looking at buying for making small robot parts but I doubt the materials would hold up to the heat of the head...

 

Well yea if I set it up I'll shoot vid and take pix... if it works I could probably cast a batch of them and make then available to others here who didn't mind doing the final polishing themselvs

Got to find my Ginger books. I think all that stuff is in storage. Havent seen it in years.

I'm with ya. Only thing I've cast in years is bullets for reloading .45's for my Colt.

 

Sounds interesting. I would like to see the finished product and might be interested in some since I noticed a damp seal on mine the other day :cry: Benn looking ocassionally on fleabay for some but haven't found any yet. I know chacal (Len) has them but don't have the funds for all of them right now. Thats why I was looking for some on fleabay. Anybody got a set laying around collecting dust that would want to unload them???

 

I foolishly bought the Ginger book on how to rewind my electrical motors, should have bought the casting book instead. I'd love to try something like that out, the shop I work at chucks LOTS of billet scrap.

 

Personally I would think that between the added vibration transmitted, and the heat transfer, the carburetors wouldn't be in a very happy place. Part of the rubber intake manifold's job is to absorb the vibration, and to isolate from heat.

 

*ding*ding*ding* Bob, tell that man what he's won!

BINGO!!!

My Norton, with its 7000rpm redline and only two cylinders/carbs has cast intake manifolds holding its stone-age slide valve Amal carbs. The carbs gradually wear out, internally, from the shaking. But they're only two lumps of cast pot metal and a couple of jets; with soldered brass floats.

But even though it's a '74, that bike is firmly rooted in '50s tech. Now let's talk about the XJ series' carbs, which were cutting edge in their day.

The CV carbs on the XJs are truly precision instuments. (Every one of us should know that by now, or you haven't been paying attention.) They need to be isolated from the much higher frequency vibrations of a high-revving inline four or they would probably disintegrate. You think your CVs are hard to keep in tune now; attach them SOLIDLY to the head and see what happens. I shudder to think.

And we haven't even touched on thermal transfer. (The Norton incorporates a couple of 3/8" bakelite spacers to address that issue.)

But on an XJ? Bad idea. Honest. Rubber manifolds really are the better mousetrap.

Don't hold it against them for some cracks after 30 years' solid service.

One other thought: Think about the potential damage when your home-cast manifolds fracture at their mounting points (or the carbs') and you suddenly start running horribly lean or the bank shifts position and your throttle sticks...

Some things are best left to the Yamaha engineers. They did a pretty good job; just fix their handiwork.

 

google the word "sintered"... just sayin
as to farming out the cnc work, it will be tremendously cheaper if you
A) can be very clear about what dimensions are in no way critical and be pretty loose (=/- .015?) on the few that are even remotely critical (ie spacing and size of intake ports)
B) get 20 other guys that all want one to pony up a commitment so you can sign a purchase order for a larger batch at the jobshop you get 'em cut at.

on any given job a fast and loose rule of thumb is that ten of something will cost about twice as much as if you only want one of it.

 

Every so often, someone's Brainstorm finds it way to the Forum.
An idea gets expressed.
Debate begins.

With as much as they love to design and make parts from Cast or Machined Bright Alloy; why are the Manifolds made from Rubber?

If Aluminum Manifolds were better than Rubber, ... why are they already NOT a popular aftermarket available part?

There's got to be at least ONE good reason why Aluminum Cut or Cast Manifolds aren't:

a) On the bike.
b) Available.

It's likely to be a Mechanical Engineering design to control Heat and Vibrations, as Fitz points-out.

Also consider:
Protected under Patent.
They don't want you to make them.
They want you to buy them!

 

I hate to break it to ya, if you had read his entire post you would see
his idea was to mate the cast part to the carbs via a rubber boot.
The boot would be as good a dampener as the original set up or better.

SEE BOLD TYPE BELOW

 

Here's my non-rubber manifold.

It's copper and brass, and the only insulation is the cork/rubber gaskets at the head.

It actually doesn't get too hot when running - I guess because the air flow and fuel evaporation help cool it. It can heat soak a bit after parking, but that hasn't been a problem so far. Of course, it's only got about 250 miles on it so far... I'll let you know how it holds up over the longer term.

Cheers,
Paul

 

Thats quite the operation. How is the mileage on it?

 

With the previous manifold (which wasn't as good as this one), I was getting about 40 around town and 52 during a mountain, high-ish speed, highway trip.

So far I haven't put a full tank of gas through this one without spending a decent amount of time during street dyno pulls and no load tuning in the garage. Despite that, I got about 35 in town on the last tank.

 

SQLGuy, Do I understand you right that you are getting less milege with the fuel injection system vs. carburetors???? Also, what's this about aluminum manifolds? Now that sounds like a winner depending on the carb to manifold connection? Getting away from the boots between the carbs and the cylinders makes sense to me. Wonder why Yamaha didn't do that in the first place. Seems like in the long haul they would have been a more permanent solution. I listen and try to learn but it never seices to amaze me just how available the Yamaha Seca is to change and modification. I have wondered if in it's hay day anyone ever went to higher compression pistions and variations in the cams??? grunt007, 81'XJ 750R. Personally I think that the XJ 750 would be an ideal engine to put in one of these little electric cars for milege and more reliability than the electric concept and all of the battery's. Here in Michigan battery concepts with the winters and snow don't always work so well.

 

Just a thought on that note: Would painting it bright aluminum help dissipate heat better than black and alleviate the condition?

The finished system looks very nice, by the way. Anxiously awaiting ongoing evaluation results.

 

I look-upon that Fuel Injection Mod with envy.

I hope it runs better than these Carbs do.

Although, that's not saying much.

Performance-wise, I guess.

I hope its fast and efficient.

 

I have no idea. Are you running a carbureted XJ750? If so, what mileage are you getting? And what altitude are you at? The 52 MPG was on a 300 mile trip up and down mountain roads at elevations from 6000 to 10000 feet. I don't know what mileage I would have gotten with carbs on that trip... although I know they wouldn't have liked the elevation changes.

My in-town commuting is at 6000 feet.

Googling, here's what I found from Cycle World's tests back when (altitude unknown):

"Happily, the Seca 750 gets great mileage—54.9 mpg on the Cycle World mileage loop, a mixture of city, country and highway riding—so encounters with the hyperactive low-fuel-level warning system are punctuated by long miles of warning-free riding. Test bikes are ridden at close-to-legal speeds on two laps of the 50-mi. mileage test loop, but even at extralegal speeds the Seca gets good mileage. Mixes of 85-mph blitzing and 65-70 mph cruising on open-country roads typically yielded 39-41 mpg, and the tank that included 85 miles at full throttle on a road racing track out of a total of 107 mi. still gave an average of 27 mpg."

 

My XJ750 Seca is presently not running and there lies the problem. I knew how much milege Yamaha said they could get but when you mentioned the cast aluminum intakes you caught my attention. These boots between the carbs and the cylinders seems to sort of SUCK! Are you casting a manifold for these engines out of aluminum? If so are you selling them? You have struck my interest. On the subject of fuel injection, what kind of money does the parts to do that cost? Mine is not at this time to the point of where I can still judge just how much money I want to put into it. The first time it fired it sounded to me like it was only firing on one coil. Presently I am searching for some carbureters since the previous owner thought it was cool to hit on the float bowls with a ballpeen hammer when the float valves stuck, consequently cracking two of the float bowls-amature mechanic? grunt 007, 81'Yamaha 750 SecaR, Mi.

 

No to either. I converted my bike to port fuel injection with some junkyard parts, Microsquirt, and home-made parts. The manifold is one of the home-made parts - it's made out of copper pipe fittings, brass pipe fittings, copper plate, and brass plate, cut with a band saw, angle grinder, and Dremel, and soldered with a torch and silver-content plumber's solder.

 

You might give this product a test and see if it will repair the cracked bowl.

http://durafix.com/

 

Wow RicCoMatic!! nice!!Great link - lots of possibilities

 

Has anyone tried the durafix?

 

Haven't actually tried it, but several years ago saw a demo at an antique car market in Dunkirk NY. fella joined pop cans and repaired a few damaged parts for the crowd. He explained it was just technique and after a little practice it was easy.

 

RickOmatic, I have tried a product in the past which is I think the same product you are talking about. It did work but I do remember that it did take a bit of time to get the hang of how to get it to tack on to the product. I am still thinking of whether to try it on my float bowls. White metal keeps making me think that it might disolve before I would get it to tack on. Like I said, it's a possibility but just in case I feel that I should pick up a spare float bowl before trying it. If the float bowl was made out of aluminum I would be more encouraged to try the product on it but don't mis-understand me, I know the product does work. I purchased mine years ago at a motorcycle swap meet but for the life of me I can't remember just what I repaired with it but I do remember that the repair did work! At that time it was a real life saver for sure and that is why I keep it on hand. grunt007, Mi. XJ750R Seca, still in primary stage! Now I have to re-pair two riding mowers, and one New Holland Diesel tractor which today decided to stop operating the front end loader bucket totally! This is always the time of year here where the mechanicle work really piles up around my place and naturally my bike has to wait until the rest is back to working order since I mow 6 acres of lawn with hills and trees and 5 acres pf [pasture)-brush hogging.

 

Black sheds heat a touch better. Reflective surfaces work both into and out of an object so while light shiny on something of bright aluminum will cause it to heat up slower it also cools down slower from a given temperature.
Unless I misunderstood your proposition, which is entirely possible.

 

Black sheds heat at roughly ten times the rate of polished aluminium.

The property describing the ability of a material surface to "get rid of" heat is known as emissivity.

http://en.wikipedia.org/wiki/Emissivity

Highly polished aluminium has a total emissivity value of 0.09, black paint 0.92, roughly ten times the relative value, hence ten times the heat rejection capability under identical circumstances. Surface roughness also improves the rate of heat rejection because it upsets static boundary layers which insulate the material and impede heat transfer. Flat black is the go.

http://www.monarchserver.com/TableofEmissivity.pdf

 

The "surface roughness" bit is right on. As a pilot, we love a good surface boundary layer and the smoother the better! Interrupting the boundary layer, in aviation, creates drag. Thats a no-no...

 

and yet in cooling you need all the turbulence. Same goes for the interior surfaces in the hot zones of a water cooled.

wow, been a long time since high school physics (which I actually paid attention to) I didn't realize the difference was that significant. Then again I couldn't even remember the word for "propensity toward emitting-y-ness"
I also recall somewhere that pristine aluminum is the most reflective. It's what they use over silver in some enormous optical telescope mirrors. It's just that KEEPING it pristine is a chore as it corrodes much more readily than others. (one of silvers better qualities)