# Briggs vanguard conversions

Discussion in 'Firewall Forward / Props / Fuel system' started by Hephaestus, May 12, 2019.

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1. May 23, 2019

### Tiger Tim

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I wonder if it would be worthwhile for someone to make up the patterns and just cast new cases for these? Sort of like the old Long Harlequin engines: use as much as possible from other existing engines but stick it all on/in a crankcase specifically for airplanes.

2. May 23, 2019

### BBerson

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None of these engines are quite big enough for a typical American. Apparently the Europeans are smaller.
Americans want 40-50hp or more.
That's why I am mostly focused on conjoining two. (or even three of the singles in a three inline)

3. May 23, 2019

### pictsidhe

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The oil pump location is of little importance compared to the oil pickup location. The oil pickup is a pipe. If you can't change that, you should be looking at ready to run engines.
Oil pump on the 810s is on the end of the camshaft. Pretty close to the centre of the engine however you turn it.
Small block vanguards have a gear driven pump below the crank.

Last edited: May 23, 2019
4. May 23, 2019

### BBerson

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Sure. But it works better and lasts longer if the oil is always primed with no air in the line.

5. May 23, 2019

### Vigilant1

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That would be quite a project. Obviously It would cut costs a lot if inexpensive OTS parts (crankshafts, camshaft, etc) could be found to go along with any custom cases/welded-up cases.
An advantage of building something for the the 40-55 HP market is that it isn't already being served by other inexpensive 4-stroke aero-adapted engines (industrials and 1/2 VW top out at about 42, small displacement 4-cyl VWs start at 55HP). If the gap can be filled at under 150 lbs and/or $5000 (with starter and alternator), then it might be a popular product. IIRC, one SD-1 builder described an oil-pump priming system or a pre-oiler that comes stock with their SE33 engine kit. I think you've identified the reason. 6. May 23, 2019 ### BBerson ### BBerson #### Well-Known Member Joined: Dec 16, 2007 Messages: 11,199 Likes Received: 2,029 Location: Port Townsend WA I think two joined 810 V-twins could be around 52hp, 140 pounds and around$2000-3000.
Any four cylinder is smoother than two. All of my airplanes have been four or the one six cylinder.
Not sure I want to mess with a two cylinder at my age. I can afford a bit of luxury.
A 140 pound 1600cc VW would be an option, but would cost more in the end with all the needed accessories.

7. May 24, 2019

### Vigilant1

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It will be interesting to see what you are thinking about. The weight and price would be fine (I'm wondering how you'll hit that price target, though). So, you'd set it up as a V-4 to use the same crank and camshaft geometry? Simplicity and reduced cost at the price of more vibration than a horizontally opposed 4? Anyway, keep the info coming, in here or a separate thread.

8. May 24, 2019

### BBerson

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The simplest is just bolt two engines in tandem. I watched a bunch of videos of drag racers and tractor pullers that connect two engines direct. No problem. Both flywheels would be discarded and a light plate made to hold the rotating ignition magnet, to drive all four ignition coils (180° apart).There is a weight penalty with four mains, but I can't see an easy way to change that to three. I don't see that configuration vibration is an issue. Lots of v-4 motorcycles. All engines run smooth on the bench. Put a prop on it that loads it to max and they all start to shake from torque pulses. The more cylinders the better, with double the pulses at half the torque.

It might be easier to make a light VW. Also looking at cutting weight off a VW. I only want about 30-40 hp at around 2700 rpm with four cylinders. I think I might get a 1600-1835 cc VW to around 120 pounds with some effort.

Last edited: May 24, 2019
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9. May 24, 2019

### pictsidhe

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I have done a lot of miles in cars with ohv engines with oil pump on the end of the cam. Losing prime was not an issue. If your engine has sat 6 months, just crank till you do have oil pressure. An engine that has sat a while would always need some cranking for the mechanical pump to get fuel to the carb. A pressure switch and light is all it needs.

10. May 24, 2019

### blane.c

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Having flown behind Radials that have multiple cylinders hanging upside down there are two distinct differences that come to mind between them and opposed engines that stand out for a inverted industrial engine application.
(1) The upside down pistons had a oil control ring in the skirt. Here is a parts breakdown drawing of an 810cc, there is no room for an extra oil control ring.

Here is a picture of A Pratt and Whitney piston with the oil control ring at the bottom of the piston skirt clearly evident.

(2) The Pratt's had scavenge pumps that moved the oil out of the bottom of the engine to a oil tank/air separator, the oil in the tank fed the pressure oil pump.

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11. May 24, 2019

### BBerson

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I won't worry about that then. The older Briggs had no oil pump at all!
500 hours between overhaul is still double the old Cont. A40. (250 hrs.)

12. May 24, 2019

### pictsidhe

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I've seen right way up engines with an extra oil ring below the pin (one of those OHVs). You could have new pistons made for the 810. Even if the standard skirt was long enough, it wouldn't be thick enough.

13. May 25, 2019

### blane.c

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Do you intend to lighten this ? and drill & tap it to accept the propeller? or?

14. May 25, 2019

### blane.c

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A aftermarket 16 to 20 amp alternator weighs between four and five lbs (some of it windings) and requires brackets and pulleys to operate. The starter ring and support is always going to weigh something as well.
So what is a realistic goal to pair down this approx. 15lb flywheel to? Considering the alternator windings and timing pickups are attached to the engine block.

Last edited: May 25, 2019
15. May 25, 2019

### BBerson

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I bolted my prop to the flywheel for testing. The intent is to make something lighter with aluminum sheet or something. Milling the existing flywheel is not ideal or easy. It has many alternator magnets bonded inside. The outer starter ring is pressed on and can usually be knocked off with a hammer and brass punch.

16. May 25, 2019

### ncmc47

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Very nice, I wish I could afford.

17. May 25, 2019

### Vigilant1

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If we want to maintain the existing starter, alternator, and ignition setup (low cost, proven), then we wouldn't really be saving 15
Fuselage? If I get your point--if we want a starter, an ignition system, and electricity, then the 16 lb flywheel is not all dead weight (though some of it is). Going with replacements is going to weigh something, will cost more, and will be untested and (likely) less reliable. That's why I'd hoped to go halfway and just use the existing flywheel and drill out lightening holes if practical. 1/2" bit in a drill press, make a jig to assure every hole had a mate exactly opposite, remove burs/other stress risers when done. Bolt a short prop extension with a prop hub to that flywheel. But, I'm sure it would be more complicated than that.
I wonder if any of the lightened flywheels made for the horizontal B&S twins would happen to fit the 810cc?

I'm not crazy about the idea of using a prop extension (as the SD-1 and Luciole builders do)--it obviously adds stress to a crank and bearings. Without an extension, though, we'll have a very blunt cowling and need a big spinner to reduce drag. The 810cc engine is 18" across the outside corners of the cylinder heads, and about 14" from the bottom of the engine to the top of the heads.

Last edited: May 25, 2019
18. May 25, 2019

### BBerson

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The mower racers still need a flywheel, so they want a lighter and safer higher rpm one with aluminum. But I don't want a flywheel at all. These engines are really heavy with the stock full electric system, flywheel and starter and battery. My Honda can flip start. I don't know if Briggs Magnetron can hand start.

19. May 25, 2019

### blane.c

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corrected fuselage to engine block

20. May 25, 2019

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