Posts by Dave Berenholtz

Finally  it is time to install the engine mount for good.

Since it was painted, the mount had developed a few scratches but as yet no rust had formed. I thought about respraying it but sanity took over and I just touched up a few spots with a brush. The paint should come off easily so that if it develops any cracks over time they will be easy to spot. A super hard paint job with baked on colour is just going to make early detection difficult.  That’s my story and I’m sticking with it.

The mount fits pretty well. I had had issues as it seemed super tight. My friendly local sheet metal craftsman worked a little of his bendy magic and its all good.

The slight deviation from plans are those special pipe washers that I sort out years ago.

It is just great to finally have those washers finally in place.

I went to a lot of trouble to use the correct length bolts and number of thick or thin washers. Upper and lower were of course difference AN dash sizes. I finished off with rechecking the torque and adding some torque seal. Not show in the photos however. I bet you might spot it when I get the engine back on. For now just imagine blue blobs on the nuts.

This is my method for knowing something is done up. When the plane is ready for first engine start and taxi, I want to know what remains to be tightened, and not have to check EVERY nut on the whole build, except visually.

This sump has been a saga. I wanted the induction facing forwards to meet the RAM air duct, not backwards where I would have to turn the air 180 degrees and use up a lot of under the cowl space.

Initially it was to be the Skydynamics cold air induction sump. The engine builders tried hard but it just couldn’t be made to fit. I had sent detailed dimensions of my ‘space’ but this was not enough.

Next up they arranged for a helicopter sump and modified it to fit. Again communications over the Pacific failed despite my best efforts. What arrived was huge and I couldn’t even put the lower cowls on. It was facing forwards but there was zero space for the air filter and no room for the radiators either.

A Superior rear facing cold air induction sump was later sent. This fits a treat but the air intake is pointing the wrong way. Did I mention it fits?

In case you missed other posts, here it is. The sump is just held on with four bolts for now. I have dealt with the rear facing, but at the cost of turning the air and eating up the space I wanted for the oil heat exchanger. The 180 turn has been OK’ed by a fluid dynamics expert as not a big issue given I have already slowed the air in a plenum.

To do oil changes, I’d have to remove the induction! As a fix I have ordered a quick drain fitting that will go in the side hole you see above. It will get most of the old oil out, maybe all of it if I raise one wing. I can do the main plug at each 100 hourly which might be a time to find out how much is really left that the quick drain misses. If its none… I will remove the bottom fitting and just put a plug in.

I spent a while doing the usual clean up, but it was pretty good, I just had some gasket residual to deal with. The engine has only done 25.2 hours on the test stand.

I sourced longer bolts than were supplied. These are the standard Lycoming/Superior spec. A smear of 515 went on both sides of the gasket.

Torque was 95 inch pounds, the standard for 1/4″ bolts. I used thin washers to ensure I had some thread showing. I could have used one thin and one thick except at the rear center. Am I getting too fussy? There is threat all the way with these bolts so they are impossible to ‘shank’.

I’ve put the runners on too. Again a smear of 515 on the gaskets. This is the ‘final’ fit up for the sump story, I hope. The throttle body however is just bolted up loosely as this will come off and on again as I sort out the throttle cable.

This seemed a small thing but it took a LOT of time and effort. I need to replace this fuel line pipe because the original one was in the way of the exhaust pipes.

This is my second pipe attempt. Working on the first I realised that I couldn’t get the really sharp bend I wanted and still fit the AN-6 fitting into that 45 degree port. I ended up using the extra 90 degree black fitting you see above,

After a LOT of effort I got the pipes to line up. Frankly after tightening it still wasn’t right and I spent a long time tweaking and fiddling my nice initial bends. The result is definitely is not perfect showroom quality, just safe and serviceable.

Do the right thing and bead roll the end right? So I had to research that. Buy a bead roller, then realise it was the wrong size and get another one. All for this one pipe. Then it wasn’t the deepest bead roll anyway.

It really was overkill. I keep trying to keep the standards up and I seem to be pushing my boundaries and learning new things. Even when they are a little job like this. It took a while to figure out how to use the thing! Yes no instructions came with it of course.

Eventually a pipe was born with a bead rolled end.

Here’s where it goes. It really does fit.

Note the tight clearances. This whole thing was also about moving that temperature sensor from the rear left to the front right cylinder. Both have suitable ports. The rear one would have interfered with the radiator placement, so it had to be moved here.

It is a very exact fit for the clearances required but it works. Lets move on.

We are getting near to putting everything together so I can start tweaking the details. First up that lid needs fasteners.

I had a couple of goes getting the holes for the screws and subsequent nutplates done. As you might have read earlier, I should have made the top lip deeper. Anyway, as always, I got it happening.

The six nutplates are all done with soft rivets. Did I mention earlier that I added some plies to the inner top section of the plenum box? This was so after countersinking I wasn’t dealing with sides that were too thin.

The monster is finally built. It wouldn’t look out of place in Lock Ness.

May I indulge in a few overall pics?

There is an issue with the sniffer valve clearance that has been bugging me. I might just get away with this. I may put a cable tie with some rubber use that tube as a fixing point to help support the plenum weight.

Its a bit of a monster with the 3″ pipe diameter, However I need to add a few millimeters to the angle at the firewall to have everything sit just right. Then I will be reducing the plenum face plate and fixing it to the firewall. There is still some transition work to do from the RAM air chute.

I’m pretty happy with the fact that I have gotten this far with quite a major part of the engine install.

My carbon pipes need to be secured with hose clamps. Given they are only three ply they would be subject to breakage from even a hint of over tightening. Another consideration is keeping the 3″ diameter consistent for the fittings at the throttle body and the air filter.

Here I have already added an aluminium ring here to the U pipe on the inside. Now it is prepped for a couple of plies on the outside.

A much easier join is just a 50mm wide piece of aluminium tube. This will take a hose clamp at the silicone joiner and then the air filter. I have made slopes at all the edges. Otherwise it is pretty hard to get the rubber joiners and the filter to fit.

Back to the U pipe and the outside join is now cured ready for the cleanup.

The long carbon pipe also needs an aluminium end piece. It first needs to be cut to length and is yet to be joined where the cut was made to get it off the mold.

The lengths are starting to make sense. I did a lot of checking for angles and if the bottom of the cowl was clear.

I decided the other end of the U pipe, where it was going to join the longer pipe needed an aluminium ring. This made the pipe transition perfect as the long pipe was the exact fitting diameter. Here I did the 2 ply inside join.

Now with the outside carbon work done it is looking good. Although I had to add a little weight, the rings have allowed really clean smooth fits.

Next I was ready to add the long pipe with its aluminium joiner ring and the freshly cured U pipe ring.

As usual a bit of preparation time and a think about the best way to approach this layup. I went with 3 ply joining strips for each end and two ply for the long pipe.

An interesting layup and then the usual peel ply to help transition the edges.

After the cure and a good clean up I have added a little weight but I really do have a robust pipe of the correct size.

This plenum needs a lid to both hold the air filter and allow access to get it out for cleaning.

The blue foam on the plenum has been contact glued, ready to make the lid. The other parts still need quite a bit of work.

I wanted to make a lid with curved edges so the carbon would sit well. On reflection a longer lid lip would have made the nutplates easier later. I’m not known for making anything easy.

After cure and separation I have a tight fitting lid.

An hour or so got all the blue mold foam out and a clean hole in the top.

The air-filter is that tight fit to the lid I wanted. With a hose clamp goes on the outside it doesn’t need to be RTV’ed in place and I’ll be able to completely remove the filter for cleaning.

Looking through the still rough ‘firewall opening’ you can see the model airplane spinner I have on top of the filter. The idea here is to cleanly separate the incoming air that is then sucked into the sides of the filter. Just using the flat filter top is a bit of a sudden handbrake even for the slowing and expanding air.

The U shaped pipe still has to be joined to the long piece but I have enough for some trial lining up now.

It looks like this is going to work out. I’ll need some aluminum pipe pieces where hose clamps will go. I will use two of those silicone rubber joiners which I hope will be enough of a buffer between the fixed firewall plenum and the movement of the engine.

This is where the plenum will sit. (Now a week or so later I will have to adjust this by about 3mm or so. Such are the very tight tolerances.)

How was I going to make this work? I went for a 5 ply layup with some reinforcing strips. The odd shapes, oddly worked.

Ahhh so pretty. This was a challenging job under the plane that took all day if you include the prep work. I think just this part was around 7 hours.

After the cure and a bit of a clean up, we have a plenum fitted and angled. As I said earlier, it will need a tiny adjustment to juggle the angles.

Having first made the U pipe now it is time for the long section.

I wish everything was as ‘easy’ as this. I first covered my 3″ diameter aluminium pipe with duct tape.

Then after sizing the required carbon, I simply laid up three separate pieces and then covered it in peel ply. Later I cut a line with the dremel and carefully separated the piece from my pipe mold. It worked a treat. Another very strong and lightweight part.

Back to my plenum mold. Some careful refining took place.

Clearances here are critical. What am I going to bump into? Will all the bits line up? Can I still put the cowl on or will I hit the bottom? So cowl off and on and the gaffer tape sling happened quite a bit here.

This is how it looks from the firewall entry. I am thinking about how the air will expand slowly and cleanly into the plenum space that holds the air filter.

You might notice a couple of dents in the bottom left of the picture? These are where the sump plug and a plug hole blank fitting just happen to be in the way. I want to ensure I won’t get any rubbing as the engine moves on its mount, particularly at startup.

It took a while to get all the duct tape on. I first used some modeling clay to fill a few of the larger defects in my foam blank. Again, not a show piece, I just want this functional. I used a weighted plastic cup as a base and hot glued the mold base to it.

After quite a long three ply layup and a little peel ply we have a plenum.

This is the end that now needs a lid.

Time to bite the bullet and make that hole where the 750mm long RAM air tube meets the firewall.

Yes I am still firewall planning too. Those bits of cardboard keep moving around.

You might see a problem here in in the hell hole. The full diameter of the chute opening looses about a third of its width as it make the transition. I was well aware of this when positioning the RAM duct as a greater angle than I wanted was needed to get to the firewall. The other way would have been to make the whole cowl lower or have a middle lump.

My thinking was that once I had expanded the air from opening to firewall I needed to expand it and slow it further with a plenum. Yet here I was doing the opposite, contracting the duct before opening it again at the plenum air filter stage. Well I decided that the small losses here were worth the overall gain of a longer pipe and not increasing the profile of the cowl and hence more airframe drag. We will never know if my choices here were good or not.

Here’s my ugly hole in the wall. I wanted a better transition than what I might do with a file.

Out came the micro to improve this area.

I used the RAM air duct to help line it up and make a match. Of yes I have been working on the transition forward of this entry hole.

I grabbed a bit of foam I will probably never use again. You can see that nice big exit needs a ramp.

Once my block was in place for the ramp all it needed was some 5mt epoxy. There is no need for anything stronger than the foam here or waiting for an overnight cure.

You can see this looks like a smooth transition for the air to go to the firewall.

I have since glassed the end with a flox corner.

I have to say this went on and on.  It has had two fills to make the transition as smooth as I can. It still needs more refining a couple of weeks later. I did another little fill between the plenum and the duct too.

I’ll need even more fiddling after I finalise the plenum angle as I need to move that about 3mm. I didn’t even bother with photos. This is typical of the sort of thing that takes far too long because I want to get it right.  Not perfect, I think I know where that line is now, just right. I am thinking about happy molecules of air, not show plane awards.