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The next conversion: Toyan FS-V800 V-8

Old 08-26-2022, 11:34 AM
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Default The next conversion: Toyan FS-V800 V-8

Arrived at my home yesterday:

Cylinder block, exhaust headers/"mufflers

"Crankshaft, pistons&rods, intake manifold, airfilter and starter

Flywheel and startergear, pulleys, water pump, bearings, timing belt

Rockers and shafts, valve caps, main bearings and caps, camshafts, small parts

Carbs, nuts and bolts

Heads and oil pan

Rocker covers, piston ring compressor

Size comparison crankshaft

Size comparison pistons

Combustion chambers

Details of rockerbox.

Intention is, of course, to get it to run on spark&gas.

The quality of machining is marvellous. It really is. Everything is milled, and two of my friends (both specialized machinists) were amazed that for example the logo on the rockercover was milled out very finely, but without any visible tracing of the router on the base plane. Also for example the landing faces of the head and cylinderblocks were machined to mirrorlike surface without any machining marks. Basically nowhere machining marks are visible, only on the cams, and that is so conspicuous that I am more inclined that that is on purpose because of the factory envisioning grease lubrication there (better adherence of the grease).

The kit comes with tools that are completely unusable (the 1,5 mm Allen key held exactly 3 bolts before it rounded), and a bit of a downer is that despite really beautiful machining, deburring and cleaning is less thorough: I saw metal cuttings in the plugthreads of one head, the other head the combustion side of the plugholes were not deburred at all.

The pistons look nice, and what is remarkable: unlike ANY other engine I have seen of this scale, the piston pins are a pressfit, almost like on "big" engines. No pads or clips to keep them in place, they are pressed in. The bigends are bushed ("shelled"would be the better word) and the bigend caps are marked against reverse fitting. There is an oiler hole in the bigend, unidirectional which means that the pistons have to be installed with the oiler hole facing the right way or the bigend will fail.

The carbs are, to my amazement, pumped but not regulated, but it is a bit of a mystery to me how the pumps are powered, it looks like the pumps are operated on intake vacuum but that port closes above a certain throttle position, so that does not make much sense to me. The membranes appear to be Mylar or something like that. No idea if they will be gasoline resistant or not. Carbs are twin needle, with the conventional lateral movement of the throttle barrel.

Intake manifold has very small bores and passages, no idea how that will hold up.

The engine is mixture lubricated like any glow engine, and initially I wondered how the intermediate crankbearings were supposed to receive oil, but the bearing bulkheads have been placed such that part of the oil passing the ring will flow along those bulkheads, so I guess that is how, but if you ask me, it is a bit "iffy".

The plug holes are remarkably deep, when fully seated even a long reach plug would still be almost 1/4" recessed. Somehow that does not entirely look right to me, but hey, it is what it is.

The cooling water jacket is beautifully made, but the water in and outlets are extremely small, and I really wonder if these passages will allow sfficient waterflow. I would have to do some calculations on that.
The coolingwater pump is geared, and looks extremely tiny to me, if I had to estimate it probably does maybe a pint per minute. I really don't know.

The starter is a fairly bulky brushed thing, which means it has to be bigger than what would be possible with a brushless starter, but at least it saves using an ESC.

Unfortunately the flywheel is steel, so I have to attach a timing disc for the ignition on the belt-end of the crank, which is a bit of a bummer, because that makes consistent timing a bit harder to achieve (but easier to adjust, OK... )

The camshafts run unsupported over their entire length, and I have my doubts how that will work out, but it should be possible to install up to 5 intermediate bearings, but that will most definitely take qite a bit of precision machining. I'll try first without, since I have seen vids of these engines with allready quite a bit of runtime (all unloaded, admittedly, BUT at pretty high RPM) so it appears to hold up allright.

What I don't like is that I cannot see whether the valves have proper seats or are landing straight on the aluminium of the head. That really is going to be a matter of "wait and see", but for glow engines it is not unusual to have a valve guide and seat out of one single insert, possibly that has been done here as well. Too tiny for me to see properly.
(EDIT: took out the magnifying glass and there indeed appear to be seat/guide inserts).

Some test fits showed a huge amount of drag on the piston rings and the cam bearings, which I hope will reduce with break in. Going to be very, VERY careful with that.
Given that the engine is an 8 cylinder (an ignition every 90 degrees of crankrotation) it should theoretically be able to run very low RPM despite internal drag because there are no real periods where inerrtia has to carry the engine through powerless moments)

My plans for the engine are to at least figure out a way to bring the waste oil of the crankcase to the rockerboxes, but because of the crossplane crank, I think there is no breathing action in the crankcase, so I have no clear idea yet of how to do that.

As designed, the cooling circuit is as follows: Pump draws from lefthand bank, and delivers to righthand bank, which means that the lefthand bank is under negative pressure and receiving cold water, dearating naturally (inlet lower than outlet), but the right hand bank is not only receiving pre-warmed water but also not dearating natrurally (inlet higher than outlet). That is going to be the first modification, parallel flow through both banks, and from bottom to top.

If and when this thing will run, I plan to install it in a boat, with a closed loop temperature controlled cooling system and heat exchanger.

I have no idea what performance will be, but in stock form modified to gas, I'd be surprised if I would reach 1 hp, to be honest.

Going to be a challenge, but that is OK, I like challenges.
Old 09-18-2022, 08:24 AM
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I had the intention of making a build log here, but...

Before I knew it, the engine was assembled, and there was not that much to tell anyway, other than that the quality of this thing is fairly dissapointing.


It runs!

It took two days of messing about, in which it gave an occasional pop or rumble. Then it struck me: During the messing about I got the feeling that both carbs did something different, and nothing I did WRT needle settings made any difference. So I checked the carbs and sure enough found one pumper membrane fitted different than the other.
The correct position of these membranes is ambiguous (long story) and there is no exploded view of the carbs availlable. So I figured, one way the pump won't work, the other way the pump valves won't work, I don't like fuel pumps anyway, so screw it, as long as both membranes are positioned the same, SOMETHING should improve.

And it did, although like crap, it fired right up, more or less.

Here is one of those first starts:

It has all appearance that it runs better by the minute almost, but time will tell if that remains true.
Old 09-18-2022, 11:23 AM
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OK... It runs, and it is gradually freeing up, but as design goes, this engine really is a MESS...
When new it turns over so heavy that you will probably burn out the starter in frantic and frustrating attempts at getting it to run.
Now that it has about 1 hour of runtime on it, it frees up fairly nicely, and it has gained about 1000 RPM from that alone. And not only that, it wants to idle a lot lower as well.
Initially it would barely get below 3K, now I have seen it run at 1500 (but very unreliable) and it will stay running fairly reliable at around 1700~1800 RPM
The intake manifold is total crap (cylinders are connected to the carbs spacially, which means that one moment p to 3 cylinders are pulling in mixture within 270 degrees of crankrotation, then for a while nothing happens, then the 4th cylinder of the set draws its mixture.
This means that mixture needs to be set quite rich in order to ensure every cylinder gets "at least" an ignitable mixture.

I am most likely going to make new manifolds that will even things out a bit, but that is going to be a bit of a spaghetti manifold, since cylinders 1, 4, 6 and 7 are going to be on one carb, and 2, 3, 5 and 8 on the other. Going to need a bit of that pliable aluminium tubing from KN materials....

Now there's a challenge...

Oh... and it really GUZZLES even gasoline.
Old 09-19-2022, 10:40 AM
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Rings appear to be seating, when I turn the engine over by hand, I am starting to notice the individual compression strokes, and that is a good sign,
Have been able to lean out the idle mixture a tremendous amount. Fuel consumption yesterday was ridiculous, today quite a bit better.

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