Slow burn project- T1 Speeduino EFI

Bruce.m · Post by **Bruce.m** » Thu Mar 20, 2025 2:34 am

Still gathering parts for the type4 engine (!). My beehive spring order via Amazon was cancelled unfortunately so reordered via Summit. Yet to make the final decision on pistons / cylinders and whether to go turbo or not….

So making some improvements to the T1 engine ready for the end of winter (& heavily salted roads).

After a decent highway run (30mins or more) i would get a raised idle speed which is possibly due to some flex and air leak in the nylon manifolds. The manifolds also had some flex due to the nylon absorbing moisture from the air. They were very stiff initially after printing but nylon is hydroscopic.

So, making a few changes. Firstly there is better filament available now. Bambu PPA-CF has a higher temperature tolerance. Roughly another 50C and is more stable. It has a high Young’s modulus (stiffness) and it doesn’t absorb moisture, so stays that way. I also bulked out the lower end of the manifold design around the flange a it has a tendency to flex in that area.

I’m also looking at adding a channel in the mounting face for a O-ring seal. The space between the two ports on a type1 head is very tight so initially i went with an o-ring that would enclose both ports.

Bruce.m · Post by **Bruce.m** » Thu Mar 20, 2025 2:35 am

Bruce.m · Post by **Bruce.m** » Thu Mar 20, 2025 2:43 am

I printed a test piece so check the fit and function.

The seal to outside was excellent but even with a shore 50 o-ring (the softest i could easily source) it took a fair amount of pressure to compress the seal. The pressure is proportional to the length of the o-ring, so it needs to be the minimum for a 1 bar seal.

The leakage between the ports was also a lot. Potentially that could be fine since the vac port is already equalising but I wasn’t super happy.

Version 2 sunk the seal deeper, and added a channel between the ports so I could cut a piece of o-ring to divide the ports more effectively.

This seems to be a good design although the wall thickness at the tightest point resulted in a small gap. Hopefully this doesn’t risk extruding the o-ring into the gap.

Will be printing the updated manifolds in the next few weeks.

Post by **Piledriver** » Mon Mar 24, 2025 10:31 am

The common modern setup for automotive OEMS is bonded seals (not just automotive) these are molded in place, frequently reusable seals, essentially RTV or similar sometimes on thin metal gaskets. Head gaskets on water cooled cars also have a variant that's usually adhesive once hot. Example: VW ALH valve covers...

Another overlooked variation is a small machined groove designed to hold a thicker cross section of sealant to allow for far more flex than the ultra-thin section between bolted parts would allow.

Bruce.m · Post by **Bruce.m** » Thu Mar 27, 2025 1:41 am

Maybe not obvious from the photo but the seal is sitting in a channel. The channel is 3mm wide for the 2.4mm cross section seal so it can deform into the space and not be compressed (as per the Parker design book). The seal projects about 0.4mm beyond the surface and appears to seal fairly well. I might push it out by another 0.1mm in the final version.

I’ve printed a similar test piece in the new Bambu filament. So far its remained rock hard and hasn’t softened since printing last weekend. So optimistic that it is an improvement.

Post by **Piledriver** » Thu Mar 27, 2025 1:55 am

I totally get it, I typically change a few orings per day on various equipment...Sometimes big ziplock bags full of them.
Just mentioning some non-oring designs possibly worth playing with, as some may be easier and can take at least as much as if not more pressure.
I'm also a big fan of C rings.

Bruce.m · Post by **Bruce.m** » Sat Mar 29, 2025 2:49 am

Roughly 25hrs per manifold and 125grams of filament at 80% infill. Print bed at 100C and print nozzle at 300C (zero fan)

Bruce.m · Post by **Bruce.m** » Sun Mar 30, 2025 1:55 pm

Kafer_Mike · Post by **Kafer_Mike** » Mon Mar 31, 2025 9:26 am

Nice. What filament are you using?

Bruce.m · Post by **Bruce.m** » Mon Mar 31, 2025 9:30 am

Relatively new Bambu Labs filament. “PPA-CF”
I did need to upgrade my Ender3V2 with a creality Sprite direct drive hot end, to enable a 300C nozzle temp.

Kafer_Mike · Post by **Kafer_Mike** » Mon Mar 31, 2025 9:46 am

Bruce.m wrote: ↑Mon Mar 31, 2025 9:30 amRelatively new Bambu Labs filament. “PPA-CF”
I did need to upgrade my Ender3V2 with a creality Sprite direct drive hot end, to enable a 300C nozzle temp.

Thanks. I recently picked up a Bambu Labs P1S along with the hardened nozzle and extruder drive gear. Looking to print some CF parts for my car.

Bruce.m · Post by **Bruce.m** » Mon Mar 31, 2025 12:06 pm

Nice

My beehive springs from CompCams arrived today so I’m keen to get on with the type4 build. I am probably going to be designing/ printing manifolds for that. Either for 40-44mm Honda throttle bodies (exactly as above but larger bore), or a plenum style single throttle body intake.

Post by **Piledriver** » Mon Mar 31, 2025 1:24 pm

Slick!

Was looking at trying this myself, was looking at building a version of the high temperature Cerberus 3D printer, that can optionally run PEEK (or other media) in pellet form, as the raw material is a fraction of the cost of the filament.

https://www.hackster.io/news/cerberus-i ... ebf0b963f0

Several relatively cheap 3D printers can use jewlery wax pellets for lost wax casting, was also considering going that way, while PEEK is great stuff, aluminum is mo betta.

A small vacuum furnace for aluminum isn't horribly expensive or huge, most are big enough to melt plenty for 3D printer sized parts.

...I know, way too much time on my hands.

Bruce.m · Post by **Bruce.m** » Wed Apr 02, 2025 5:53 am

Quick test fit on a loose head. With a greased valve pushed in, i did a human “vacuum” test and the o-ring is sealing really well.

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