# Briggs vanguard conversions

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

1. May 12, 2019

### Hephaestus

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Well let's do a thread rather than making the ranger thread even harder to follow

I had grabbed a 23hp vanguard v-twin the other day at a garage sale. Attached to a siezed up trash pump for under 100$. EFI, 12v electric start. Did have that ranger in mind - as it's a project I wouldn't mind right now. Some reading and googling tells me there's just about everything available to make these work as aircraft engines. Everything from Pistons, sleeved cylinders, billet/cnc/forged/cast rods and hundreds of cams to choose from, stoker kits, I did see mention of a dual sparkplug and larger valve head option over on a lawnmower racing page. There's actually some details on turbo (using that geo metro 3cyl turbo) and smog pump superchargers odd as that sounds. Spin on oil filter, says we've got some oil cooling options, on top of just air cooling. It's interesting how many options are out there, and it seems fitting to maybe start talking about what's needed to make one work for that the ranger design. 2. May 12, 2019 ### Vigilant1 ### Vigilant1 #### Well-Known Member Joined: Jan 24, 2011 Messages: 3,305 Likes Received: 1,414 Location: US So, just to clarify, you have a B&S Vanguard horizontal shaft engine of the 38XX series, 627cc, with EFI (something like this one). Is that right? It will be a good little engine t play around with, get weights, etc. We've had a few threads on similar engines, including this one from a guy who ran the h*ll out of his when using an Ace redrive and a lot of aftermarket parts (that thread got a bit heated, but there's good information if you can read around the flames). Direct drive would save weight, complexity (some TV issues) and possibly cost. I don't think you'll get 35 reliable continuous HP from this engine, whether run in direct drive or with a PSRU, just due to the heat rejection issues. Some folks believe there's some "padding" in the B&S HP numbers and that, with proper attention to airflow, they can be run at higher HP for a long time. I think that would need to be shown. 3. May 12, 2019 ### Hephaestus ### Hephaestus #### Well-Known Member Joined: Jun 25, 2014 Messages: 567 Likes Received: 122 Location: YMM That's the one I've got yes. Just researching right now as most of the Vtwin bits are mostly interchangeable (the 18-28hp, I think there's differences on the big block? 30+), so I should be able to bore it out, swap parts for basically a stroker build. (Basically the 28hp version). I don't think I've ever built an engine to make power down at a lower rpm. So could be fun... The direct vs redrive, and how to properly support the thrust bearing will be interesting. 4. May 12, 2019 ### Vigilant1 ### Vigilant1 #### Well-Known Member Joined: Jan 24, 2011 Messages: 3,305 Likes Received: 1,414 Location: US When you are looking for bits to build up this engine, you might find some useful things in the Vanguard 810cc engine. They only make it in the vertical shaft version (used for zero turn radius mowers). In complete form it tends to sell at a very good HP/$ ratio and has a good HP/weight ratio (as these engines go).
- The questions people grapple with on converting these engines:
-- Direct drive vs psru
-- Drive the prop from the PSRU end or the flywheel end? The crank is often beefier at the flywheel end, and if we keep the flywheel or a lightened version of same (it has the ignition components and teeth for the starter), then it is better from a crank stress perspective to put all the weight/inertial loads on one end of the crank.
-- Retain the stock flywheel or save weight? See above.
-- Retain the stock fan? They blow a lot of air and do a good job of keeping these engines alive in tough daily use. They also suck some power. It might boil down to whether this is a tractor or pusher installation.
-- The exhaust valves are on the PTO end of the engine. In a tractor installation, ideally you'd love keep them at the front to optimize cooling at this most critical part of the head. Having them tucked at the back side of the head is not great. But, see above point about the crank ends, desirability of driving the prop from the flywheel end. So, another decision/possible compromise.
Etc.

Last edited: May 12, 2019
5. May 12, 2019

### Little Scrapper

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My best friend is a executive for B&S. You wouldn't believe the testing they do on that engine. It's truly a great engine.

6. May 13, 2019

### Hephaestus

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I definitely would, there's landscrapers in the family who swear by them. I've spent my fair share of days on a riding mower throttle cranked mowing fields. Pretty much why I don't hate the idea of using one, as the failures are rare and abuse/maintenance related.

Think this is quite dedicated to a build for the ranger style design. Not to say that wouldn't cross to others.

Guess the first decision is PSRU or direct. As that'll change RPM needs. And if I go direct I'm guessing I should put a proper thrust bearing into the mix.

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7. May 13, 2019

### Vigilant1

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If you go direct drive, the experience of the MC-30 Luciole builders and the SD-1 folks might be a useful guide. From what I understand, M.Colomban did a lot of development work on the engine setup in the MC-30, so it would be worth finding out more about that. They have many builders and a lot of hours. If they aren't using a thrust bearing, you might not need one, either. Unfortunately, it's hard for an English speaker to learn much about the MC-30.

8. May 13, 2019

### Vigilant1

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IMO, B&S deserves a big attaboy for bring production of these Vanguard V-Twins to the US (from Japan) >and< (more importantly) for maintaining the quality of the engines while doing that. I hope they will do whatever they need to do to keep the quality high--it will be very shortsighted of them to save a few bucks or cut corners on these Vanguard engines (making them pricey Intec engines). The professional market will be hard to win and keep--the Kawasaki's in this HP range have a good reputation, and these folks need a motor that starts and runs reliably.

9. May 13, 2019

### Little Scrapper

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Personally, I wouldn't bet a bucket of piss on B&S's future. They are in serious trouble going forward. It's really sad, corporate greed is gonna slaughter them when this.marlet gets soft. I have solid reasons for saying this.

Regardless, that engine is a absolute gem.

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10. May 13, 2019

### pictsidhe

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The 23hp is the biggest of that block type. The 810 is a completely different engine. It is about 10lb heavier and has larger crankshaft journals. It doesn't have the same reputation as the 627 and is an older USA design, though doesn't appear to be made of glass. There is a new 810cc Vanguard, of which I know little. The 627 was initially designed and built by Daihatsu in Japan. Briggs wanted an engine to match Hondas and didn't mess around. It is now being built in the USA. Briggs does not seem prepared to sacrifice quality in that transition.
The direct drive Luciole conversion hangs the prop on the flywheel and the mods are only available to buyers of the Luciole plans. I believe that it has a claimed 35hp.
$100 is one hell of a price for that, would you take$200?

11. May 13, 2019

### Vigilant1

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Here's a picture of the SD-1 aircraft with their "SE 24" engine,which (I believe) is the same basic engine as you have. Direct drive. They claim 24 HP, it obviously uses a carburetor and the regular "magneteron" igniton coils driven by the flywheel magnets. I don't know, but it looks like the prop extension is bolted to the flywheel.

They also sell kits for 31 HP 4-stroke engines (Kohler-based?) and 33 HP 4-stroke engines (B&S or Vanguard?). Those have more displacement than your 627cc engine.

12. May 13, 2019

### Hephaestus

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Interesting I'm guessing that copper is used like carb heat?

13. May 13, 2019

### Vigilant1

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Yes, but it is "on" all the time. The Valley Engineering Big Twin uses the same setup. It helps keep the fuel warm and from condensing in the runners, so not the exact same purpose as carb heat.

14. May 13, 2019

### Hephaestus

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Wouldn't that reduce power though? You want cooler intake charge for power... Seems odd to me.

http://sergiolaviateur.unblog.fr/11-le-moteur/

Google translate is a wonderful thing. Also has a link for the ignition system they're using.

15. May 13, 2019

### Vigilant1

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Edited to add: The SD-1 "SE33" engine is based on the B&S "Commercial Series" (not the Vanguard version) 810cc vertical shaft engine. Like the others, the prop extension is mounted on the flywheel, so it doesn't use the engine PTO and the exhaust ports are at the opposite end as the prop.
I dunno about claiming 33HP from this engine that B&S only claims makes 27HP (28HP for the Vanguard version with EFI). 810cc/33HP = 25.5 cc/HP, which would be an "unusually high" continuous HP for an 810cc 4-stroke NA air cooled engine. 27 HP (continuous) from an 810cc engine would be consistent with other engines of this type.

16. May 13, 2019

### Armilite

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When looking at any of these Honda/Briggs/Clone Type Engines HP, you have to look at CC used, CR used, CAM Lift & Duration used, Intake & Exhaust Valve Size used, CARB Size used, and Max rpm it was Designed to be used at. All of these Industrial Engines are Designed for 3600rpm account that's what Generators, Water Pumps, Air Compressors, Saw Mills, Trash Pumps, etc., use. Most of these Engine Companies also offer a Hi Rev kit to run them up to around 4950rpm. Why 4950rpm, account the Stock Cast Iron Flywheels are only good up to 5500rpm, where they can explode if used in a Higher rpm.

The biggest Stock V Twin from Briggs is the 993 37hp EFI. So compare Spec's between your 627cc 23hp and the 993cc 37hp engine.
https://www.vanguardengines.com/na/...rizontal-shaft/vanguard-370-gross-hp-efi.html

Both Engines use Restrive Air Filters and Exhaust Mufflers for Noise, with Small Carbs for turning only 3600rpm in Industrial Applications.

Notice, Vegas Carts 625 (96mm x 86.5mm) 626.3cc Single is also rated 23hp@3600rpm! It can be Big Bored to 100mm. It's based off the Honda GX390.

627cc EFI V Twin making 23hp@3600rpm has a 85% Volumetric Efficiency. Uses 8.3cr. 627cc at 85% turned 5000rpm = 31hp.
627cc V Twin at 3600rpm is making 34 cfm. A 28mm Mikuni Flows 52.1cfm the smallest my chart shows and I bet these have Smaller 24mm Carbs.
627cc at 5000rpm is making 47 cfm. A 28mm Mikuni Flows 52.1cfm and so these Smaller 24mm Carbs don't cut it.

993cc EFI V Twin making 37hp@3600rpm has a 87% Volumetric Efficiency. Uses 8.2cr. 993cc at 87% turned 5000rpm = 51hp.
993cc at 3600rpm is making 55 cfm. A 29mm Mikuni Flows 55.9cfm and I bet these have Smaller 24mm Carbs.
993cc at 5000rpm is making 76 cfm. A 34mm Mikuni Flows 76.9cfm and these Smaller 24mm Carbs don't cut it.

Stock, these Engines can be turned Safely to 5500rpm Max with a proper Hi Rev kit! A Hi Rev kit consists of (HD Chrome Moly Push Rods, HD Valve Locks & Keepers, and Heavier LB Valve Springs). Why 5500rpm Max, that's the Max the Cast Iron Flywheel is good for. 6250rpm is the highest I have seen used even with the Upgrades of HD Billet parts. You have to decide what HP you really need and the Max RPM you want to use it at. The Rotax 912 80hp is rated at 5500rpm. All of these Engines need a Better K&N Type Air Filter, a Bigger Carb even for 3600rpm, and a better, Tuned Header Exhaust, Higher lb Valve Springs even for 3600rpm, a Billet Aluminum Rod, and better HD Rocker Arms. For Planes, Weight is a Big Issue, so most people use the HD Billet Aluminium Flywheel even if just using it at 3600rpm.

On these Honda/Clone GX390 Type Singles they can be Big Bored to 100mm. The Highest Stroke I have seen is 86.5mm.

Your 627 is 2.97" Bore and 2.76" Stroke. 2.97" = 75.438mm and 2.76" = 70.104mm.

The 993 is 3.37" Bore and 3.41" Stroke. 3.37' = 85.598mm x 3.41" = 86.614mm

The GX390 is (88mm X 64mm) 389cc or (3.5in x 2.5in) and can be big Bored to 100mm, so +12mm, so these V Twins can also probably be Big Bored +12mm.

What a Stationary Industrial Fan Cooled Engine can use at Continuous and one converted for Airplane use will be different. You have Oil Coolers, Ceramic Coatings, more Forced Air going over the Engine.

Last edited: May 13, 2019
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17. May 13, 2019

### mm4440

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Stock cams need to be replaced to get power at higher than the typical 2400 rpm torque peak.

18. May 13, 2019

### Hephaestus

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http://www.ecotrons.com/products/small_engine_rhb31_vz21_turbocharger/

Honestly this is what I'm leaning towards, upgrade the connecting rods, pistons, cam, sit down and find out if rv6ejguys system can work, add the turbo.

If I've done the Excel sheet right... Stock motor #s with 10psi (pretty conservative boost) leaving Ve at 85% - 84cfm & 53hp at 4500rpm.

If Ve increases - as the spreadsheet says it should that's 95cfm & 60hp at 4500rpm.

19. May 13, 2019

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The Valley Engineering carb heat system is quite innovative. It uses a small diameter steel tube between the exhaust pipe and the base of the carb. At low throttle settings when carb heat is needed the manifold vacuum is high and it draws in a large volume of hot exhaust to warm the intake charge. But, at high throttle settings when carb heat isn't needed, the vacuum in the carb is low and very little hot exhaust is drawn in, thereby keeping the intake charge cool.

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20. May 13, 2019

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