Naive intake manifold porting question by a novice

[ptuomov]

I have some complex intake tract components cast from various aluminum and magnesium allows. They are assembled in a complex way and have various shafts and bearings and bores etc. If I want to port certain turns to be much wider, I’ll run out of casting and strike air or at minimum fail to keep minimum wall thickness. If I have an experienced person to weld more material to the casting, the casting warps enough that there are a large number of expensive machining operations that need to be repeated.

I have an idea that may or may not work and would like some feedback on it. How about using epoxy to build out the manifold runner thickness on the outside? Would this work, either just to strengthen the wall for cases where the original casting isn’t ported thru the wall or in a more extreme scenario porting straight thru the casting and into the added epoxy?

[MadBill]

It depends on the load, pressure, temperature and vibration the parts will experience, but there are some very tough epoxies out there. I've built 'structural' parts out of Devcon. Surface prep is important in achieving a good bond.

[PackardV8]

Yes, No, Maybe. You have large thinwall castings with differing expansion rates and are hoping an external bond will hold. No advice here is going to give you the confidence to invest hundreds of units of currency in professional porting and flow bench work. Share your process, materials and results. We'll all learn something.

If I want to port certain turns to be much wider, I’ll run out of casting and strike air or at minimum fail to keep minimum wall thickness.

Just a random thought - if there is so much improvement to be had, why did all the OEM engineers leave it on the table when it wouldn't have cost them anything to optimize the cross-sections prior to production?

[MadBill]

..Just a random thought - if there is so much improvement to be had, why did all the OEM engineers leave it on the table when it wouldn't have cost them anything to optimize the cross-sections prior to production?

Isn't that puzzle what keeps all us gear-heads in business?

[ptuomov]

It’s a science experiment of approximately tripling the stock power with as many stock or modified stock components as possible. The starting point is about 320hp normally aspirated 5.0L engine which had a design spec of working both with automatic and manual transmissions (which led to conservative cams and too-clever-by-half intake manifold). So we’re just tinkering with it and John’s turbo system to see what happens if you try things. It’s not a commercially feasible effort and it’s not being raced, at least not outside my test track (I-95).

[ptuomov]

It depends on the load, pressure, temperature and vibration the parts will experience, but there are some very tough epoxies out there. I've built 'structural' parts out of Devcon. Surface prep is important in achieving a good bond.

http://www.itwadhesives.com/userfiles/f ... ds_107.pdf

This spec sheet looks like a good match for the intake castings that I’m dealing with. Reading this, I’m actually quite confident that it’ll work well if it’s just used to provide strength on the outside and if we don’t completely grind thru the original metal.

[cgarb]

I would have more faith in welded material, as long as you weld it before it becomes paper thin. That's just me. I would use epoxy if I had a crack to fix while the engine was assembled. If I had the chance to fill with weld beforehand I would take it. I also have access to a Tig and someone to run it. I can, but haven't welded aluminum as much as steel.

[englertracing]

What you need is a certified badass aluminum welder.

[user-17438]

I wouldn't port magnesium and aluminum in the same place. . Sounds like bad.

[cgarb]

I did miss the magnesium part...my bad. Don't want to light that bad boy off. I would guess epoxy of some sort would be the best approach. If you grind a hole big, so you can put material on the inside and outside of the intake so the epoxy captures itself in the part. That would be better than just a layer on the outside.

[jcisworthy]

If expect to make a hole and intend to use epoxy, for better rusults, you can reinforce it with a tight mesh metal screen similar to rebar in concrete.

[kimosabi]

..Just a random thought - if there is so much improvement to be had, why did all the OEM engineers leave it on the table when it wouldn't have cost them anything to optimize the cross-sections prior to production?

Isn't that puzzle what keeps all us gear-heads in business?

Or how about keeping all the aftermarket companies in business...

[ptuomov]

The magnesium alloy that we're dealing with welds just fine with aluminum filler rod. We had a magnesium alloy oil filler neck done and there were no issues. I also have another magnesium intake manifold casting that is similar magnesium alloy to the filler neck and someone else has had it professionally welded on it and it looks very good. Finally, we had an aluminum throttle body housing welded for added material and that also welded well. These were all done by people whose day job is welding, of course.

So there's no issue with welding these components, other than everything warps a little bit and that means that a lot of machining operations on these parts have to be repeated. This adds to the cost on parts that have all sorts of complex features machined to them by the factory after casting. I'm seriously considering trying the epoxy route for parts that only need reinforcement on the outside because of wall thickness.

We've already done small amounts of epoxy filling on much hotter magnesium parts like the valve covers for purely cosmetic reasons -- many of these factory magnesium castings are really rough in terms of finish. They have lasted well despite seeing bigger heat cycles. The factory also has some sort of coating on the later model intake manifold inside surfaces that appears to be epoxy based, it seems to hold up pretty well after a quarter century. The intake manifold heat cycle isn't too extreme by my understanding and measurement (there's a factory sensor/switch in the intake manifold measuring the casting temperature to operate some fans).

[mag2555]

When I have massively reworked a Manifold to the point of needing Epoxy I have found that it's best to just port right the heck thru the thin areas where you likely to blow thru and then just rework the Epoxy with your finger wetted with soapy water, you can make a finish that is ready to go like this !

I start off with a two tube type Epoxy and then once sealed back up use the clay type for big fill area's.

Trying to rework a area that is half Aluminum and half expoxy always results in the faster and too great a removal of the Epoxy as compared to the Alimunum no matter how hard the Epoxy is!

Sanding with a roll for small shape changes is a different story as I can control the removal better!

Anit it great how once you light off Magnesium it just keeps burning under water!?

[ptuomov]

I wouldn't port magnesium and aluminum in the same place. . Sounds like bad.

It's a magnesium alloy that has a bunch of aluminum as well. It's not particularly flammable, but will of course burn if ground to fine dust.