[drtye]

I would 100% of the time er on the side of caution and use the inserts. With that thin of a flange it wouldn't be worth the risk even if the material was up to the load/stresses. The fasteners not being torqued enough would be moreof a concern and potentially backing out into the manifold. Even with chemical thread locker.

 

[Scider]

Would this fit the bill?
Ultrasint PA6 FR (Flame Retardant) 3D Printing Material
Looks like it's melting point is 201C and flame retardant. Limited by printer bed size.

We use a fair amount of rapid prototype intake manifolds on our prototype engines these days, I know we ran through a lot of iterations on the 18MY 5.0L. They're commonplace in FSAE / Formula Student as well. I'll see if I can find out what material we print in. Here's a photo though. Note the brass inserts epoxied in for threaded fasteners, and the steel inserts for the fastening to the head. This is for a turbo motor as well. I've boosted the snot out of this manifold.

 

[Scider]

I haven't figured out specifically what the manifolds are printed in yet, but I did find this:
Higher melt nylons: PA12 → PA6/66 → PA6
High T engineering plastics for engine and tooling: Ultem → PEEK → PPSU

Edit:
PA12, followed by a sealing process called "Imprex"

 

[mrluke]

I haven't figured out specifically what the manifolds are printed in yet, but I did find this:
Higher melt nylons: PA12 → PA6/66 → PA6
High T engineering plastics for engine and tooling: Ultem → PEEK → PPSU

Edit:
PA12, followed by a sealing process called "Imprex"

Wow i'm shocked that PA12 is holding up to that sort of abuse! Ultem, Peek etc i've been looking at.

I'd be interested in where the steel inserts come from, are they bespoke made for each project?

The Imprex seems to improve porosity so something to keep an eye on.

Interested in any other info you have Thanks for the contribution!

 

[Scider]

From what I recall, they look like standard slotted, unthreaded spacers to me (McMaster-Carr). Anything bespoke would only up the cost. The brass inserts are probably standard off the shelf bits too, likely something with a knurled OD to take an epoxy set.

Unfortunately I don't have any information on what design changes we make for RP manifolds vs. their standard black plastic production cousins.

When I was in college, we didn't treat our formula car intake at all, but it has a short life expectancy. For reference, temperature wise we control intake charge to 100 degF and coolant temps to 200 degF as best we can, they'll generally see a bit more charge temp at peak power and if the controllers are messed up (which isn't uncommon).

 

[mrluke]

So slight update to my "studio" now using a box painted with black 3.0 rather than a piece of wood. Idea being that its easier for the software to tell what is the part and what is background.

Which appeared to work quite well, i'm getting better at this now.

First two pictures are in the software:

And this is the exported textured mesh in Blender.

Really impressed with the quality, there's a couple of small holes to fill in where I didn't get good enough photo coverage but generally the whole piece is much crisper.

The runners have about the first 50mm which is accurately modelled then after that they go solid. I dont really see this being a major issue and was actually expecting the runners to be solid pretty much the whole way.

Now I have to remake this as a simplified and tidied up model, the actual generated mesh is too dense to work with as is.

 

[LotusElise]

@mrluke amazing work. I am looking forward to the digital version. Are you going to add a wall to the surface?

 

[mrluke]

Small update.

This is by far the most complex part I have modeled and its taking a little while.

I'm not particularly interested in the outside features as this is only really for CFD.

Modelling to do list/WIP
- Runners are a constant radius
- Flanges to be squared up
- Overlength runners to be trimmed
- Plenum interior is only a mock up, needs tidying

This is the current state of play:

Combined

Just the model

Combined

Model

And a bit of a catch up.

You've probably spotted it in the model but I have chopped up the flange on the manifold to fit my k20a2:

I've also spent far too long cutting up little brass spacers for the bolt holes:

That'll be okay for these prototypes but definitely something I need to find a better solution for going forward. Ideally i'll find some similar sized unthreaded spacers and then adjust the flange thicknesses to suit.

Printing is mounted up and i've added some temp strips that will show the maximum temperature they have reached.

One on the bottom closest to the printed parts and likely to get hotest

And one on the runner because it will be easier to see when the manifold is installed

Printing should be okay up to about 150c. These strips measure from 70c to 110c. In reality I don't think I will even get a reading on this top mounted one.

I'll add hotter strips if need be.

Manifold should be going on the car this week to start durability test while I finalise the CFD model.

Once the plenum model is up and running i'm going to work on improving flow distribution between the runners by trialing slightly angled trumpets. Once I have a few that work well they'll be printed for back to back testing.

@mrluke amazing work. I am looking forward to the digital version. Are you going to add a wall to the surface?

I'm not sure what you mean by adding a wall to the surface?

 

[LotusElise]

This is by far the most complex part I have modeled and its taking a little while.

Very nice. Thanks for sharing, looks like an amazing work you have done there!

I'm not sure what you mean by adding a wall to the surface?

Just giving it a wall thickness over the surface model.

 

[mrluke]

Oh I see.

Unfortunately it isn't that easy, the scan has a very high number of points, in the region of 1 million. This makes it very difficult to work with. It's like working on photoshop with a 1 pixel brush.

I have to create a new model that effectively traces the scan but has more sensible geometry.

Sent from my Pixel 3 XL using Tapatalk

 

[LotusElise]

Unfortunately it isn't that easy, the scan has a very high number of points, in the region of 1 million. This makes it very difficult to work with. It's like working on photoshop with a 1 pixel brush.

That's a huge number of data points.

BTW, how did you solve the bolt clearance thing?

 

[mrluke]

Bolt clearance was tight but okay, until I put the the bronze spacers in which made it more difficult so I opened the holes up with the soldering iron.

Going forward I'll order cap head bolts to minimise the impact on the trumpets. They'll also be 5mm shorter so they don't have to go through the trumpets to put them in the holes.

Sent from my Pixel 3 XL using Tapatalk

 

[LotusElise]

Going forward I'll order cap head bolts to minimise the impact on the trumpets. They'll also be 5mm shorter so they don't have to go through the trumpets to put them in the holes.

Sounds like a solution. I like your idea of using a temperature indicator. Would be nice to know which surface temperature mine has. BTW, the Testo company is just a one and a half hour away from my place. I've used many emission and temperature measurement tools of them, they stand for higher quality equipment for a more fair price. Many of the service guys of my former engine company I worked for use them to tune the emissions correctly during service of the gas engines. Anyway, a good idea to use such an indicator.

Which process did you use to place the bronze spacers? Looks like a thermal heating process, but I am curious about the details .

 

[mrluke]

Sounds like a solution. I like your idea of using a temperature indicator. Would be nice to know which surface temperature mine has. BTW, the Testo company is just a one and a half hour away from my place. I've used many emission and temperature measurement tools of them, they stand for higher quality equipment for a more fair price. Many of the service guys of my former engine company I worked for use them to tune the emissions correctly during service of the gas engines. Anyway, a good idea to use such an indicator.

Which process did you use to place the bronze spacers? Looks like a thermal heating process, but I am curious about the details .

Thanks.

Place the spacers in location, put a soldering iron through them and wait until they get to ~200c at which point they melt through the nylon. Take the heat off when there is about 1mm left to go and press it on a flat metal surface for the last part. Helps to make it flat.

Easy peasy 👍

 

[LotusElise]

Place the spacers in location, put a soldering iron through them and wait until they get to ~200c at which point they melt through the nylon. Take the heat off when there is about 1mm left to go and press it on a flat metal surface for the last part. Helps to make it flat.

Thanks for the process explanation 🆙.

 

[mrluke]

Its been slow work but the manifold is pretty much modelled, i'm going to add a throttle plate and I have some small areas of geometry to tidy up but its pretty much there.

The runners now have more of a conical shape to align with the port shapes and I have pretty much done the internal face of the plenum.

Plenum

Original trumpets added

Printed trumpets and backplate

I've had a bit of delay getting the manifold fitted so next post could be results or it could be CFD watch this space.

 

[drtye]

Really impressive.

 

[mrluke]

So small update.

RSP Manifold is fitted (k20 conversion uses TTS mounts).

Has the printed trumpets and back panel installed

Also added thermal stickers so I can see what temps it is experiencing, which has hit low 70s during sustained spirited driving on the hot 25c days we have been having recently

I also had to make up a spacer to relocate the throttle body for clearance against the firewall. This has also replaced the adapter required to fit the RSP manifold anyway as it originally had an electronic throttle.

Initial thoughts are that its made a decent difference vs the previous PRB manifold. To the extent that the mapping is now off and its a bit lumpy / hesitant to drive around, especially under low throttle openings and at low/mid rpm.

It has also changed the sound of the engine a little with people describing it as sounding like a bike engine, no idea what that means but will take some videos soon i'm assuming there is more induction noise to it.


Initial thoughts are that the robustness of the parts isn't going to be an issue and i'm moving now towards recording and demonstrating the performance improvement that has been achieved.

Once the new exhaust has been sorted out in early August and the car remapped, i'll be arranging a dyno session to trial the PRB, Stock RSP and modified RSP back to back.

 

[LotusElise]

Initial thoughts are that its made a decent difference vs the previous PRB manifold. To the extent that the mapping is now off and its a bit lumpy / hesitant to drive around, especially under low throttle openings and at low/mid rpm.

Very nice, sounds like the engine has now not only at WOT more VE.

It has also changed the sound of the engine a little with people describing it as sounding like a bike engine, no idea what that means but will take some videos soon i'm assuming there is more induction noise to it.

Those two wheeler engines have a more salient induction noise. It's obvious, the more the induction is efficient the higher the likeliness it is more loud. The higher efficiency comes to a greater portion from the bigger amplitudes of the pressure waves. This is for the RSP the area beyond 5000 rpm compared to the PRB.

Once the new exhaust has been sorted out in early August and the car remapped, i'll be arranging a dyno session to trial the PRB, Stock RSP and modified RSP back to back.

I am looking forward to it.

 

[mrluke]

Progress has been a little slow but continues!

IATs have reached 50c (30c ambient) and the inlet manifold itself has seen 80c but no signs of any distortion to the printed parts.

Quite happy with the intake noise it makes now as well.

Still to do:

Fixing wiring for:
EGTs
Wideband
VSS

Then a remap before back to back dyno runs.