cast your own EA81 inlet manifold ?

steptoe · Post by **steptoe** » Thu Aug 21, 2014 8:47 am

What is wrong with all the genius with the Subaru world with not having come up with casting our own aluminium alloy inlet manifold ?

Its been done before in race circles

Cannot be that difficult surely ?? Gotta be more rudimentary than carbon fibre, 3D printing and stuff

Arn't the insides made hollow by making sandy clay shapes set up within another sandy clay mould and just

pour in your molten alloy, let it set cold, machine up necessary mating ends.Drill and tap holes for booster and other vac connections and temp switches ...

Surely peoples would pay what ? $200 or more for a custom made run of manifolds to take a weber carb without adaptors, two webers if you feel the need.

Start saving beer cans boys !!

autospeed has a three part story ...must have been done here

http://www.matildafoundry.com.au/

Part 1 of the story http://www.autospeed.com/cms/article.html?&A=112614

Part 2 http://www.autospeed.com/cms/article.html?&A=112615

part 3 http://www.autospeed.com.au/cms/article.html?&A=112616

Willy Fisterbottom · Post by **Willy Fisterbottom** » Thu Aug 21, 2014 10:04 am

Wow that was a good read. Wouldnt hurt to give Matilda a call to see how much it would cost? The hardest part would be getting the part seems to be getting a good pattern box made.

steptoe · Post by **steptoe** » Thu Aug 21, 2014 6:54 pm

Enquiry would sound best coming from an engineering related business than just a forum member. A few options come to mind for manifolds and that would be create one half that doubles as both left and right with air and water transfer outlets - similar to the cylinder heads being ambidextrous for twins .And a weber receptive would sell better, in a package deal with the 'Bottom unequal length Y pipe ?

Silverbullet · Post by **Silverbullet** » Thu Aug 21, 2014 8:58 pm

The hard and skilled part is making a pattern to begin with. Whatever part you want you need to make a perfect replica in wood first, to press the casting sand around which makes the mold. Then for the internal cavities like you said Jonno you need to make a plug in the shape you want the internals to be, made out of a different sand and placed neatly inside the mold.

For the EA81 manifolds you would need 2 internal plugs since you need a coolant passage separate from the air passage. That Matilda foundry looks promising for a possible place to make them since they say they can do one off's.

Would probably cost alot more than $200 per manifold though...well depending on how many you make in a run.

Post by **TOONGA** » Thu Aug 21, 2014 9:22 pm

RSR was quoted $28,000 for a mold alone from a company here in W.A. He had to supply and original manifold to be cut in half and modified for the mold process as well.

I know how to do foundry work and many other types of casting and large work doesn't come cheap.

TOONGA

steptoe · Post by **steptoe** » Thu Aug 21, 2014 9:48 pm

looks like Jules is the man !

tony · Post by **tony** » Fri Aug 22, 2014 2:43 am

hotroddisorder.com/p/casting-at-home-making -flower-pot and
cyphertext.net/~gfish/forge and
rotblattsculpture.com/Articles/building a bronzec

for some ideas.

YouTube · Post by **El_Freddo** » Sat Aug 30, 2014 1:10 am

^ That is awesome!

Then I looked at an EA81 manifold and said bugger that for a joke!

You'd want to be very good at your moulding skills to get it right! Then you need machining work done to finish it off... Might be worth the effort if you were doing simple castings...

Cheers

Bennie

tambox · Post by **tambox** » Sat Aug 30, 2014 4:48 pm

A friend of mine used to cast alloy manifolds in his barn to adapt 3 webbers to a holden 6, that he then sold on.
It can be done, just need to be set up.

steptoe · Post by **steptoe** » Sat Aug 30, 2014 8:35 pm

Well, don't have him waste time doing an EA81 - make it EA82 style to appeal to the masses and can be made to fit EA81

Subydoug · Post by **Subydoug** » Sat Aug 30, 2014 9:35 pm

When I was a kid, my dad built a small forge out of a gas bottle and a manky old vacuum cleaner, and we used it to meld down beer cans. About 50 or 60 cans was enough to cast a cylinder of aluminium about 80x80cm. We then machined it to what we needed.

Made things like this,

Making things like carby adaptors would be easy, but something like the ea81 manifold? For low volume you probably better off fabbing it out of tube and plate steel.

Regards

Doug

Silverbullet · Post by **Silverbullet** » Sat Aug 30, 2014 10:33 pm

Nice one Doug, was that a homebrew CNC or was it machined manually? If the latter there's a bit of skill in that thing

Subydoug · Post by **Subydoug** » Sun Aug 31, 2014 9:25 am

All manual with a index wheel. Only got into cnc these last few years.

Doug

steptoe · Post by **steptoe** » Sun Aug 31, 2014 10:54 am

what is it ? curious to see thinner at base of each fin, so would be not power transfer like a cog ... 360 / 21

I would have gone lazier way and made it 20 fins

Silverbullet · Post by **Silverbullet** » Sun Aug 31, 2014 11:05 am

Subydoug wrote:All manual with a index wheel. Only got into cnc these last few years.

Doug

So you must have had the indexing head geared to the feed handle at the other end? To get the helix?

Sorry if I'm hi-jacking here, I just love seeing this kind of stuff

steptoe · Post by **steptoe** » Sun Aug 31, 2014 11:19 am

hi-jack away - ladder climber

Subydoug · Post by **Subydoug** » Sun Aug 31, 2014 3:17 pm

Very observant of you Jonno, yes the fins are thinner at the bottom. Ideally a V shaped cutter would be the way to go. Me and my dad were trying to build a small axial turbine. The ali shroud was also beer cans melted down.

SilverBullet, picture tell a thousand words?

I cant find my favorite thing we built out of beer cans. It was a valve head for a pulse jet. Looked a lot like a reed valve for a 2 stroke. lots of math

.

Regards

Doug

Silverbullet · Post by **Silverbullet** » Sun Aug 31, 2014 3:34 pm

Mmmmm lovely

Wish I had the money and space to have such tools in my shed

one day...one day

YouTube · Post by **El_Freddo** » Tue Sep 02, 2014 9:26 am

steptoe wrote:hi-jack away - ladder climber

Hey, hey, steady on with that term! If you're going to use it in this context "respectful" should be used.

Ladder climber out my way isn't a good thing...

I too am happy for silverbullet Sam to hijack away - it's all interesting and I love seeing what others can do. The use of a lathe fascinates me!

Cheers

Bennie

Dean.nabbe · Post by **Dean.nabbe** » Tue Sep 02, 2014 3:21 pm

i have to say, i'm impressed.. i wish i could do half the stuff you guys talk about...
the Brumby upgrade is my first ever semi complicated DIY task... building the hardtop tonneau is my first ever go at design and build of anything..