# Briggs vanguard conversions

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#### Hephaestus

##### Well-Known Member
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$. EFI, 12v electric start. Did have that ranger in mind - as it's a project I wouldn't mind right now. Some reading and googling tells me there's just about everything available to make these work as aircraft engines. Everything from Pistons, sleeved cylinders, billet/cnc/forged/cast rods and hundreds of cams to choose from, stoker kits, I did see mention of a dual sparkplug and larger valve head option over on a lawnmower racing page. There's actually some details on turbo (using that geo metro 3cyl turbo) and smog pump superchargers odd as that sounds. Spin on oil filter, says we've got some oil cooling options, on top of just air cooling. It's interesting how many options are out there, and it seems fitting to maybe start talking about what's needed to make one work for that the ranger design. #### Vigilant1 ##### Well-Known Member Lifetime Supporter Well let's do a thread rather than making the ranger thread even harder to follow I had grabbed a 23hp vanguard v-twin the other day at a garage sale. Attached to a siezed up trash pump for under 100$. 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.
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.

#### Hephaestus

##### Well-Known Member
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.

#### Vigilant1

##### Well-Known Member
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.

#### Hephaestus

##### Well-Known Member

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

#### Vigilant1

##### Well-Known Member
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.

#### Hephaestus

##### Well-Known Member
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.
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.

#### Vigilant1

##### Well-Known Member
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.
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.

#### Armilite

##### Well-Known Member
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/en_us/product-catalog/engines/big-block-vtwin-horizontal-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.

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#### mm4440

##### Well-Known Member
Stock cams need to be replaced to get power at higher than the typical 2400 rpm torque peak.

#### Hephaestus

##### Well-Known Member
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.

##### Well-Known Member
Wouldn't that reduce power though? You want cooler intake charge for power... Seems odd to me.
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.

#### Vigilant1

##### Well-Known Member
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.
Thanks. Here's a previous discussion on it, with some pictures.
Valley Engineering did a lot of good work on that kit--they made the changes that were well-suited for aircraft applications. And they claimed 32HP continuous for these 993cc engines, which is consistent with what everyone else with flying experience has found: For these types of engines it takes at least 30cc of displacement per reliable, continuous HP.
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.
Before anyone acts on this generalization (that an airplane engine will have more forced air flowing over the fins than a typical industrial engine installation): Squirrel cage blowers (as used on these engines, in your home furnace, in your car's heater/AC blower, etc) are used (among other reasons) because they excel at working against static pressure. The only thing that causes air to move where we want it to go is the pressure gradient from where the air enters the plenum to where it leaves. Due to fin spacing on these engines, as well as the realities of baffling (esp the need to turn the air numerous times, including a turn at the back of the cylinder head to cool the critical exhaust port area), there will be considerable "drag" in the airflow, and this results in increased static pressure at the entry point of the cooling air. A squirrel cage blower ("centrifugal blower") has a high "solidity" and can do a good job of continuing to pack air into the plenum as the pressure in the system builds--that's the main reason they are used in this application. A low-solidity axial fan (a propeller would be an example) or dynamic pressure available from increasing aircraft airspeed are relatively poor in this regard (at the ultralight speeds we are considering here). So, while there may be gobs of air available, getting it to flow through the fins and around the corners requires pressure that may not be available--the air will spill out around the plenum opening rather than go in. This is one reason that some aircraft builders have found that AC cores don't work for them as heat exchangers for their liquid-cooled aircraft engines. The fin spacing is too close. A car's HVAC blower can easily push air through them, but the dynamic pressure available even at 100 kts is not sufficient to do so.
So, it would be best to do some actual testing with a manometer panel and a candidate engine/baffling setup (maybe on top of a car or in a truck bed on a stand mounted high enough to be in the airflow) to see how well the air is really going through those fins. Compare the readings to what is achieved on a well-designed piece of professional lawn care/other industrial equipment before jumping to the conclusion that you'll have "more Forced Air going over the Engine."
http://www.ecotrons.com/products/small_engine_rhb31_vz21_turbocbeavailableharger/

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.
Okay. Keep us informed of how it goes. Track your pennies, too. An early investment should be made in a CHT gauge and deciding on good thermocouple placement (as near as practical to the exhaust valve-that's the vulnerable aluminum you care about) and some digging on how CHT in these engines affects expected longevity. Things vary a little based on alloys and configuration, but CHTs above 450 deg F are usually "trouble" in the VW engines, and 475 deg F are far worse (even for a short time). The aluminum loses strength at this temp (well below the "melting point") and the valve seats erode. The differential in temps across the head can also lead to cracking. The temperature readings can vary a lot depending on the location of the thermocouple--you'll care about how hot the head is at the exhaust valve. I wouldn't be surprised to find that an engine that can lead a happy, trouble-free 1000H TBO life at 350 deg F will need to have the heads off and worked on every 50 hours if it sees 475 deg F frequently.

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