Amagi82

Alright, I'm feeling CREATIVE today!

Since I have to buy some metal plate to fix my rear supension and some mandral bent pipe for my exhaust anyways, and since I pulled the stock intake manifold off and was repulsed by how poorly it was designed, I've decided to try my hand at intake manifold design. I figure All I need is a couple metal plates, I can cut them out to match the carb, and to match the intake ports, and some mandrel bent piping, that I can route to make intake pipes, and adjust size as best I can to match the shape of the intake ports.

Now this is probobly a bad idea.... but what the hell, why not! Is there anything special that needs to be attached to the intake manifold, or can it just be a nice free pipe from the carb to the ports? Do i just make a seperate pipe for that coolant pipe that runs between the holes for the coolant?

Give me some thoughts! As far as I'm concerned, it couldnt possibly flow as bad as stock, so why not?? And if it does suck, I still have my stock manifold anyways.

Keaponlaffen

I think you have a big enough job ahead of you fixing your rear suspension up, I'd worry about that first

Amagi82

lol, I have a habit of tackling 16 projects at once, hahaha


Its just that with this, if it even worked half as good as the professional designs, I'd be almost in the 13s with just this, exhaust, and weight reduction, hahaha

Jeff20B

iTrader: (13)

It could work. I too don't like the stock manifolds, unless they're from the '70s.

Just block off the coolant ports with a flat plate and it'll be good (probably). That's what aftermarket manifolds are like.

Rx7carl

Mazdatrix sells the plates on the engine port side already cut out. BTW, youll need a brake booster port. Oh and you can block the coolant ports on the motor with 20mm freeze plugs. Autozone carries them. Good Luck!

Amagi82

you can run with the coolant pipes blocked off??? Wont that sacrifice the cooling ability of the engine?

I bought some metal plate today for the flanges, now I gotta find some mandral bent pipe, anybody know where you can get some cheap mandral bent pipe in small sizes??

WackyRotary

I ALLWAYS block off the coolant passages into the intake so I don't have a mess of coolant everytime I take the weber sidedraft off. Don't have to add coolant either then. I only put them in while the engine is apart so I can get the aluminum crude out from tapping the holes.

Amagi82

Alrighty, sounds good, I dont have to worry about making coolant lines then, that saves time and money

Now i just gotta find that mandral bent pipe and weld it all together

Amagi82

ugh!! making custom flanges by hand SUCKS!!! I think I've half lost my hearing from this stupid router. The flange to the intake ports is nearing completion, its been cut to size, and 2/4 ports are done. PITA!! lol.

but I've started, I might as well finish.

Sammymatik

Man always use ear plugs when doing that kind of work!

But you should just make up some cardboard templates and go down to a machine shop and have them make up the plates for you! Shouldn't be too expensive and it will save a crap load of time and effort.

I guess if you plan on making another intake then you should go and have that part done at a shop!

And got any pictures?

RixRotary7

One thing I would make sure to do if you do make a new intake manifold is to get some tubing so you can connect the vaccum lines that go into the stock airbox to the new manifold. Also, make sure NO air is getting around your filter because you will risk getting debree into your carb., then into your engine. Just some food for thought.

RixRotary7

Keeping your stock airbox is a VERY good idea because if you run a cold air intake (snorkel), then you do not want it to suck up water if you are driving in the rain. Also, if it does not work, why then you could always go back to the stock one. Good luck man!!!!!

Amagi82

I'll take pics when i'm done, but i got a new idea! Theres some fiberglass stuff in the garage, I might be able to make the runners out of fiberglass! That would be sweet.

How would I make round tubes with fiberglass, what is a good center material to form the shape into that you would wrap the fiberglass around, then be able to get the center material out? Sorry for the lack of proper terms, I'm not all that familiar with fiberglass work.

Rx7carl

I dont think FG will last in the hot and fuel vapor environment man.

Amagi82

what if I made some heat shields then put some heat wrap over the fiberglass to insulate it?

Rx7carl

I still think they will get soft and melt. JMHO

Amagi82

dang... hmm... ideas? Mandral bent pipe in the proper diameter is proving hard to acquire.

Rx7carl

www.mcmastercarr.com

rotarygod

iTrader: (1)

Big companies such as Edlebrock, Holley, Weiand, etc, make mockups for their new intake manifold designs by fiberglass. They do test them this way too. Fiberglass dissipates its heat really quickly. It just doesn't stay hot compared to aluminum. the air/fuel mixture from the carb through these manifolds is typically cold enough that in some cases ice can form, even when it is warm out! Its very efficient. This is similar to the new composite manifolds for most modern cars. They don't hold heat in leaving the intake air colder and denser compared to the aluminum manifolds which helps make power. I have yet to see a composite manifold for carbs though. This isn't only due to the fact that cars don't come with them anymore (not in this country) but to their abilities to freeze up the suspended fuel traveling through them. It may work good here in Houston most of the time but you'll be taking the bus alot if you live in Minnesota. Intake temperatures never get so high that fiberglass will melt from it. If they do get this hot you've got other bigger more immediate problems such as detonation. The biggest concern I would have is in making sure that you have it thick enough that it doesn't collapse or leak. The flange wound have to be thick too so the heat difference between the engine housings and the manifold don't cause it to warp. It could potentially work very well though and if you have some fabricating skills and some time I say go for it. Be careful.

If you want to know how to form runners go find some parafin wax somewhere. Any crafts type of store will sell it in chunks. You can melt it and then put it inside of aluminum, pvc, or steel tubing and wait for it to harden. Then warm up the pipe to the point that the parafin is just starting to get soft on the outsides. This will allow it to slide out of the tube. Now take the wax, heat it a little where you want it to bend and slowly bend it how you want it. The cross section will change slightly but if you are patient you can get really nice curves. When you get the runners lined up where you want them, fiberglass over them being very careful to be consistent. Do several small thin layers being sure to use as little resin as neccesary to do the job. Take your time here. You can never make it too thick. After you have your product made dip it in boinig water and let it sit awhile. The wax will melt leaving you with a perfect shaped fiberglass runner. I've tried this before. It takes practice and alot of patience. I'm willing to bet you'll go back to your old one before your done.

Another option to form runners is to use the blue styrofoam that is used as outer insulation on houses when they are built. It is thick enough that you can sand it to shape. You can make runners very quickly this way. The down side is that fiberglass will eat it away. You can substitute fiberglass resin for certain epoxies while still using fiberglass mat. The same general application process remains the same. Instead of boiling out the finished product though you pour acetone through it. This eats it on contact leaving the runners intact. You'll have to research different epoxies though as many are toxic to contact with skin. They can also be very expensive.

The easiest route is to buy aluminum tubing from Burns Stainless or McMaster-Carr. Have a machine shop cut out your flanges for you and then weld the tubes where you want them. This is the method that I used on my custom manifolds. I don't have the patience right now to perfect the other methods but I'm not against them.

Have fun!

Rx7carl

I was thinking more of header heat radiating upwards when stopped in traffic and possibly melting it.

Sammymatik

I think fiberglass could work in this situation. I doubt that the intake runners will actualy get all that hot... the onlything really gonna heat them up would be the exahust manifold. Header wrap might remedy this problem. I guess if you could use a remote thermometer attached somewhere near the two mannifolds you could get a temp reading to give a more absolute idea of the temperatures you need to withstand. I know that epoxy resins', of the right type, can withstand some fairly high temps. If you found the right epoxy and used fiberglass, possibly CF, you could use this type of composite for an intake mannifold.

Of course with composites come the troubles of molding such a shape but, this can be dealt with for sure. Probably using foam and then removing the foam with acetone would be the easiest thing to do. And yes polyester resin will eat up foam however, epoxy resins are compatible with foam which would allow you to creat a foam plug then cover the plug with fiber then remove the plug with acetone.

I have worked with foam and I have to say I like it. It's very easy to shape, easy to clean up, and cheap. I'm not sure if you have a place near you that sells foam, you might wanna look around for a supplier. The wax method is viable but just sounds like a bitch from the explanations given above.

But if you did wanna go with metal piping then have you checked at a muffler shop? I know they often have tube benders which you might be able to get them to make the shape that you need.

Fiber might work but I guess it depends on exactly what type of purpose your gonna use the car for. I don't think that the strength of the fiber is really an issue, it would be the heat if anything. Composite materials are extremely strong, they can make drive shafts out them, boats, planes, whatever just about.

I'm interested in hearing what progress you make!

TheAuroch

Food for thought, just make sure that whatever technique you use, you callculate the thickness of the walls on the finished product. Otherwise the diameter of the intake will actually be less, therefore decreassing your airflow, even though it is a more efficient flow. This is not a major problem, just make sure you plan for it... My friend didn't, and now he's back to square one.

ex: straw v/s water hose, you get the picture...

Rx7carl

Sammy, what kind of foam would you reccomend? Oh and forget the muffler shops. The crimp benders they use would ruin your port shape.

Sammymatik

Rx7Carl: I think it's the open type pvc foam... I can't exactly remeber the name. I know that there is a closed type foam that is blue colored that can be used with polyester resins but this type of foam can't be washed away with acetone. I usualy use the white traditional type foam, maybe it's styrene? I can't remeber the names right now but I could find out. But near me is a shop that makes various decorative things out of foam and they sell a variety of types and densities of foam. I've got a rear spoiler just sitting that is made of foam and coated in a thin plastic... if I ever get round to finishing the surfaces I could make a mold for a spoiler. I'm thinkng hood sounds more fun though.
And what do you mean ruin the port shape? I would figure that a plate for the engine and one for the carb could be cut out of steel/aluminum plate and then have the bent pipe welded to it? And they don't have a mandril bender at muffler shops?

TheAuroch: If you use a plug and laminate over it, thickness would not be a problem.

On more question: What is the advantage to making a mannifold? I do have some extra foam laying round, but what is really the point to making my own mannifold? Is the work involved justified in the HP gains? Especialy when there are other after market mannifolds available, like the RB I've got. Or is it just that this is a fun project , and I know it's very feasable.

Rx7carl

Most muffler shops dont have a mandrel bender, they use a crimp bender so you get what looks like what you see in the autoparts store for exhaust bends . Actually JC Whitney sells mandrel bent tubing also.

Advantage is you can design a port size, shape,length thats more efficient than modding the stock manny.