# Briggs vanguard conversions

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

1. Oct 4, 2019

### Hephaestus

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Lucas is evil... Patent on the short circuit and all.

Multiple triumph, minis, Landover, many MGBs...

The only good thing about Lucas was it ensured I was able to buy them all for pennies due to electrical issues

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2. Oct 5, 2019

### blane.c

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Has anyone taken the stock engine up to various elevations and tested it?

3. Oct 5, 2019

### blane.c

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810cc LP/NG

https://www.brandnewengines.com/49G575-0111.aspx

Vanguard 49G575-0111 parts list

https://www.vanguardpower.com/na/en...nginemanuals.html?searchrequested=49G575-0111

Price of tapered crankshaft? at B&S $238.50 and Replacement Parts .com$266.53

https://shop.briggsandstratton.com/apps/omega-search/?q=798737#q=798737
https://www.ereplacementparts.com/crankshaft-p-1735027.html

The crankshaft Icon in the B&S parts breakdown is not tapered but the part number is off the LP/NG tapered shaft model.

4. Oct 5, 2019

### blane.c

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Ooooh that is a nice looking tapered crankshaft.

5. Oct 5, 2019

### Hot Wings

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I live at over 5000 ft. Density altitude during the summer often is above 10,000. ALL of these industrial engines*, lawn mowers, string trimmers chain saws etc. need leaning to run properly at this altitude. Some come with alternate jets. Some don't even have a way to adjust the idle mixture - Thanks EPA.

* closed loop EFI excluded.

6. Oct 5, 2019

### blane.c

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7. Oct 5, 2019

### blane.c

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How do we find out if the tapered LP/NG is forged or cast?

8. Oct 5, 2019

### Vigilant1

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Yes, the tapered PTO shaft looks nice. That lack of a relatively sharp shoulder where the crank necks down to the PTO straight shaft would be a help.

If you buy that 49G series Professional Series engine propane/NG engine with the tapered crankshaft, you also get the chrome exhaust valves (which are normally only stock on the Vanguard engines).

I'm not sure how these "designed for gaseous fuels" engines come from the factory, maybe with no fuel pump? There's a page on the Vanguard site that indicates conversion of the Vanguard engines to run on propane/NG is now done by a third party.

Last edited: Oct 6, 2019
9. Oct 5, 2019

### Vigilant1

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What is "boat gas?" Do you mean unleaded gasoline (without ethanol)? In my experience, the fuel without ethanol is much more stable (and fuels without ethanol also have a lower vapor pressure, so have a lower tendency to get bubbles/cause vapor lock. That's sometimes important as altitudes increase and a temps under the cowl go up.) There are finally some places I can buy "real gasoline" near me, but it's not very convenient.

10. Oct 5, 2019

### blane.c

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11. Oct 5, 2019

### blane.c

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I want the EFI engine and put the taper crank into it. Rather than propane engine and put EFI on it. But may not be possible as Vanguard boasts "dynamically balanced engines". It depends on what "dynamically balanced engines" means to the propaganda people at B&S. It also depends on whether or not the taper shaft crankshaft is forged or cast, there are still a lot of questions on the best combination for this engine. Breaking the "code" somehow to get past the propaganda machine will be nice. How much does it cost to hire a professional "Hacker"?

12. Oct 5, 2019

### Vigilant1

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Did the same guy post this?
In its stock form, it is probably more weight than anyone would want to carry in a tiny airplane and 5 quarts of oil is a lot for these engines. That oil volume and the mega filter is designed to provide 500 hours of use-- that's 3 months of use for a lawn service, but over 10 years of use for a typical pilot. Nobody should leave old oil in an airplane that long--water, acids, other corrosive stuff--yech. I want it out of there on a regular basis, and I'll leave my fresh oil up on the shelf and add it in at oil change time.

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13. Oct 5, 2019

### pictsidhe

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Buy one and look at it...

14. Oct 5, 2019

### Vigilant1

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The Vanguard 810cc engine with EFI and a tapered PTO shaft is available as an option, according to their site. See the page here, go down to "options." I think the exact model might be a 49E875. I've got no idea what it will cost. The Vanguard site says all their 810 crankshafts are forged.
Observations (things you probably already have thought through):
- The lambda stock closed loop EFI will be killed by 100LL
- The degraded operation modes of the stock EFI would be a good to know. When any one of several sensors fails, what happens? "Limp home" suitable for a lawn tractor might not be enough to stay airborne
- The Vanguard EFI engines force you to buy a muffler (that's where the lambda sensor goes).
- EFI = required high-pressure fuel lines and fuel pump
- Their EFI also controls spark timing--so another flight-critical system (ignition) is also on that same circuit board.

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15. Oct 5, 2019

### blane.c

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At marina's you can get different brands but this is an add for 1.

16. Oct 6, 2019

### blane.c

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I am sure I have more examples of contradiction, many more.

17. Oct 6, 2019

### Vigilant1

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810cc engine in direct-drive pusher installation: Any examples? Any thoughts?
- Thrust bearing (or not) and wear: I suppose it's a non-issue since "pulling" on the flywheel end (SE-33) and "pulling" on the PTO end (TiPi's project) have both been used or at least strongly considered and not found wanting. In both instances, there are no dedicated bearings and the crankshaft can be expected to eventually wear a groove in the case (and then we can insert a shim).
- Cooling: This would seem to be the major difference with a tractor installation. The lack of "prop blast" in a pusher configuration changes the situation a bit. At first blush, configuring the engine with the prop on the flywheel end seems to have the advantage, since then the exhaust side of the heads will be forward, facing into the breeze. If we have a high-mounted engine (say, to get as much of the prop disk as practical in the clean air above a high wing) and a moderately clean aircraft with climb and cruise above 60 MPH, then the "eyebrow scoops" on "heads-up" engine might get good exposure to the incoming air, though it won't be the same volume (or, especially, static pressure) as we'd get from a nearby tractor prop, and it won't be very effective at all during ground ops. With heads down, side scoops might be more useful, and if placed in the high-pressure area under a high wing (and especially if in the prop blast of a separate forward engine) they could be fairly effective.
Fan?: Like many pusher installations, the rear engine of the Cessna 337 (aka USAF O-2) required some extra cooling help. An axial fan was mounted with the prop to help create a low pressure area in the rear to draw cooling air through the baffling and keep the engine temps in check. This is more "aggressive" than using the prop alone (as is done in the Vari-EZ, etc), and it seemed to improve cooling considerably. Or, I suppose we could use the fan that comes with the engine to push air through from the front (if the prop is on the PTO) and use much of the stock baffling (to include the "window" to push pressurized air through the oil cooler). I'd think that blower would take a significant toll in power available for the prop, but it might be possible to cut it down (or remove "blades" in the blower?) and it is also possible the fan "tax" will be reduced as airspeed increases and more air is forced into the central blower intake under dynamic pressure, reducing the pressure differential the fan would be working against.
Anyway, I'm not aware of anyone using these engines in pusher direct drive mode--any known examples? Opinions on issues that would be faced?

Last edited: Oct 6, 2019
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18. Oct 6, 2019

### BBerson

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My current project is a pusher. I think the stock fan is ideal in every way. Except it's on the wrong end.

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19. Oct 6, 2019

### pictsidhe

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There would only be a fan 'tax' if the fan was less efficient than the prop. The engine needs X volume of air at Y pressure to stay cool and froody. Whether the prop is moving that air, or a fan, the power to do so is still coming from the engine. On a 103, you could probably gain some speed from an engine fan, if you're legally limited and measured power did not include the fan power. Which would be extremely hard to measure properly
Alternative cooling could be from an ejector aka jet pump from the exhaust gases. This is nearly 'tax free' pumping power. I pondered an ejector pump on mine, but decided not to for several reasons. If the prop blast is inadequate, I'll fan it. Mine will have an annular air intake behind the spinner. The circumference is 120cm, so I won't need a large annulus. Fairly stealthy way to get air to my V12 water cooled Merlin engine.

Last edited: Oct 7, 2019
20. Oct 6, 2019

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