# Van Guard 23hp V Twin 627cc?

### Help Support HomeBuiltAirplanes.com:

#### Armilite

Anybody had any dealings with the Van Guard 23hp V Twin (Small Block) 627cc? The GX390 Singles can be Big Bored to Max 100mm. I have a chance to buy one for $75 that says it just needs a Rod, No Head, or Cylinder Damage. If a 460 Single upgraded can make 37hp@5000rpm, a 460 458cc/37hp= 12.4cc to make 1hp. A 627cc/12.4cc = 50.5hp. A Big Bore 794cc/12.4cc = 64hp. What is Stock Cam lift? What is the Max they can be Big Bored? Any Stroker Cranks for them? SPECIFICATIONS 23.0 Gross HP* Model 3864 HP (gross) *23hp@3600rpm Engine Displacement (627 cc) Engine Configuration Horizontal Bore (in) 2.97 = 75.438mm ===> Maybe a Big Bore (85mm x 70mm) 794.7cc Stroke (in) 2.76 = 70.104mm Weight (77 lbs) =====> Stripped down for Airplane use it should be lighter. Oil Capacity (oz) 48 Compression Ratio 8.4:1 #### Victor Bravo ##### Well-Known Member HBA Supporter I do know that the Para-Zoom company in Germany uses this engine as the base for their paramotor and ultralight engines. They claim to bump the power up to 33 or 34 HP without losing any of the engine's reliability. I believe that their modifications do NOT include increasing the bore or stroke. I understand there are Kart or Mini-Tractor racing classes that use the small block Briggs V-twin engines, and they are reported to be able to make 50-60HP when set up for racing. But the reliability will go to hell pretty quickly of course. #### Vigilant1 ##### Well-Known Member Lifetime Supporter Kevin Armstrong (HBA username "Factory Fit' or similar). Has a lot of experience with them powering a trike with an Ace redrive. Also, they are the base engine that is modified and used on many Luciolles (Colomban MC30s). This engine may be good for up to about 25 continuous HP in aircraft use, anyone planning on more may be disappointed. Last edited: #### Armilite ##### Well-Known Member I do know that the Para-Zoom company in Germany uses this engine as the base for their paramotor and ultralight engines. They claim to bump the power up to 33 or 34 HP without losing any of the engine's reliability. I believe that their modifications do NOT include increasing the bore or stroke. I understand there are Kart or Mini-Tractor racing classes that use the small block Briggs V-twin engines, and they are reported to be able to make 50-60HP when set up for racing. But the reliability will go to hell pretty quickly of course. ============================ These Honda/Clone Engines are turned 7000 to 10,000rpm in Racing and last a Whole Season. They're very durable Engines if Maintained and Built right with the HD Racing Parts. So running them up to 5000-5500rpm for 2-3 Minutes for takeoff and then throttling them back for Cruise, isn't working them hard. My 10hp Single Cylinder on my 5000w Generator runs 9 hrs Continuous till it needs to be refueled. I just ran it for 28hrs just 4 weeks ago after a bad storm till we got Electricity back, then loaned it to a friend in another town who then ran it for about 36 hrs more till he got his Electric back on. #### Armilite ##### Well-Known Member Darn, they Sold it, I was 4th inline. #### Protech Racing ##### Well-Known Member SPECIFICATIONS 23.0 Gross HP* Model 3864 HP (gross) *23hp@3600rpm Engine Displacement (627 cc) Engine Configuration Horizontal Bore (in) 2.97 = 75.438mm ===> Maybe a Big Bore (85mm x 70mm) 794.7cc Stroke (in) 2.76 = 70.104mm Weight (77 lbs) =====> Stripped down for Airplane use it should be lighter. Oil Capacity (oz) 48 Compression Ratio 8.4:1 Like Quote Reply Report The weight is for the single cyl . The specs are V twin . #### n3puppy ##### Well-Known Member A little off topic but .... I see Briggs Stating 23.0 "Gross" hp per SAE J1995. That's what they got sued for. Overstated HP in a configuration not seen in real life. From Briggs - Gross Power is rated in accordance with SAE J1995. Net power values are taken with exhaust and air cleaner installed whereas gross power values are collected without these attachments. On the other hand - Honda uses "Net" per SAE J1349 since it is what happens in real life. From Honda - The SAE J1349 standard measures net horsepower with the manufacturer’s production muffler and air cleaner in place My Aeronca C-65 flew with simple stacks - no muffler. The Global engine (1/2 VW) in my N3 Pup also came with open pipes - but the noise was so much sharper than the C-65 that the airpark made me add mufflers. When folks are flying these industrial engines - are they using mufflers ? Last edited: #### TFF ##### Well-Known Member The V engine has a noise advantage. Not flying behind one, but our hangar tug is a Craftsman with a Kohler 20 hp V twin. It’s been fed 100LL mostly in the last 20 years. The muffler is finally too bad to patch anymore. It does feed 2 into one. It sounds mostly Harley like. There is a gate to the sound. A lot of times a Harley sounds like a two cylinder radial. To me, 1/2 VWs crackle more like two singles. Single pipes. I bet if the pipes were brought together it would mellow the sound or make it more aviation like. Much more complicated exhaust in bends than a can on a short stack. #### Armilite ##### Well-Known Member SPECIFICATIONS 23.0 Gross HP* Model 3864 HP (gross) *23hp@3600rpm Engine Displacement (627 cc) Engine Configuration Horizontal Bore (in) 2.97 = 75.438mm ===> Maybe a Big Bore (85mm x 70mm) 794.7cc Stroke (in) 2.76 = 70.104mm Weight (77 lbs) =====> Stripped down for Airplane use it should be lighter. Oil Capacity (oz) 48 Compression Ratio 8.4:1 Like Quote Reply Report The weight is for the single cyl . The specs are V twin . ======================================== The specs are correct, taken right off Van Guards website. There are Small Block V Twins and Big Block V Twins. This 627 is a Small Block and says 77 lbs. The 470cc V Twin is the Smallest I have seen. A Rotax 277UL Fan Cooled complete with Gear Drive was 65 lbs. If I had gotten that 627 23hp cheap, I was going to see How much Weight I could cut off it when I rebuilt it. I'm sure I could get it below 65 lbs! Today Small Block Briggs Van Guards come in: 479 13hp & 16hp = 72 lbs. 570 18hp = 74 lbs. 627 21hp & 23hp = 77 lbs. 627 23hp EFI = 77 lbs. The Honda GX390 Single Case Can be Big Bored to 100mm! Stock Bore x Stroke (88mm X 64mm) (3.5 in x 2.5 in) 389cc The largest Stroke I have seen used is 86.5mm. +12mm Over Bore! A Single (100mm x 86.5mm) 679.6cc! A Vegas 625 (96mm x 86.5mm) 626.3cc 23hp@3600rpm Single is around$825.
-------------------------------------------------------
+12mm = 0.4724395 in. So these V Twins can also be Big Bored 10-12mm!

A 627 V Twin 23hp@3600rpm. 8.3cr 626.9cc. A +12mm = 842.2cc!
Bore (2.97 in) = 75.438 mm.
Stroke (2.76 in) = 70.104 mm.

A 570 V Twin 18hp@3600rpm 8.2cr 569.2cc. A +12mm = 775.1cc!
Bore (2.83 in) = 71.882 mm.
Stroke (2.76 in) = 70.104 mm.

A 479 V Twin 16hp@3600rpm 8.2cr 480.8cc
Bore (2.68 in) = 68.072 mm. A +12mm = 665.3cc!
Stroke (2.60 in) = 66.040 mm.

A 460 Single (92mm x 69mm) 458.8cc with 40mm/32mm Valves, 34mm Carb, 11.0cr, .307 CAM, Tuned Header Exhaust, K&N Air Filter, Dynoed 37.37hp@5000rpm.
459cc/37 = 12.4cc to make 1hp! If these V twins are built similar they should make similar hp@5000rpm.

V Twin 627 626.9cc/12.4cc = 50.5hp@5000rpm! 77 lbs!

V Twin 570 569.2cc/12.4cc = 45.9hp@5000rpm! 74 lbs!

V Twin 479 480.8cc/12.4cc = 38.7hp@5000rpm! 72 lbs! With just a better CAM this could make 40-42hp!

Most USA Part 103 & Small Kitplanes fall between 540 lbs - 660 lbs for there MTOW.

An MTOW of 660 lbs needs 40.1hp!

An MTOW of 600 lbs needs 36.5hp!

An MTOW of 540 lbs needs 32.8hp!

Van Guard V Twin Small Block Spec's.

#### Protech Racing

##### Well-Known Member
The Pretty little small block twin would be perfect at 75# FWF and 32+HP. Would be around 2000$done with a drive . Issue is that there are very few UL pilots and plane combinations that would fly well at 32HP . I think the big single can do 28HP continual at 65#FWF maybe . and cost around 1300$ with the redrive .
Same issue s. Tiny airplane .

#### Armilite

##### Well-Known Member
The Pretty little small block twin would be perfect at 75# FWF and 32+HP. Would be around 2000$done with a drive . Issue is that there are very few UL pilots and plane combinations that would fly well at 32HP . I think the big single can do 28HP continual at 65#FWF maybe . and cost around 1300$ with the redrive .
Same issue s. Tiny airplane .
====================================

A Honda/Clone 460 (82mm x 69mm) 458.8cc Single with mods Dynoed 37.37hp@5000rpm. 458.8cc/37hp = 12.4cc to make 1hp. So a 627 Small Block V Twin if built the same way 627cc/12.4cc = 50.5hp@5000rpm! ACE Aviations Belt Drive for the 623 cc = 3.9 Kg / 8.6lbs. The 627 21hp & 23hp = 77 lbs. Once you strip off the Cooling, Mufflers, Cast Iron Flywheel, Balance Shaft, etc., probably about 15 lbs. 77 lbs - 15 lbs = 62 lbs + 8.6 lbs for Redrive = 70.6 lbs, maybe less! My T-Bird I just makes Part 103 with a 65 lb Rotax 277UL Fanner with a Gear Drive and Exhaust. ACEs Belt Drive for the GX 390/420 is 2.85 kg / 6.3 lbs and could be adapted to the 277UL. I could probably cut off 10-12 lbs off the Airframe. The T-Bird I MTOW of 660 lbs only needs 40.1hp. You could run it Direct Drive at 4000rpm for 40hp and Save 8.6 lbs.

5000rpm = 50hp
4750rpm = 47hp
4500rpm = 45hp
4250rpm = 42hp
4000rpm = 40hp
3750rpm = 37hp 75% Power.
3500rpm = 35hp

#### Attachments

• 45.6 KB Views: 3

#### Protech Racing

##### Well-Known Member
That shows 11/1 compression. That seems high for a high duty cycle engine. 10/1 and 100 av gas might work tho.
I have found that if you buy fuel at the airport, more peeps will tolerate your using it.

#### Armilite

##### Well-Known Member
That shows 11/1 compression. That seems high for a high duty cycle engine. 10/1 and 100 av gas might work tho.
I have found that if you buy fuel at the airport, more peeps will tolerate your using it.
=========================

A Rotax 277UL uses 11.8cr, All Water Cooled Rotax's use 11.5cr. Polini Thor 250 uses 11.5cr.

Stock there a 1000 hr Duty Cycle Industrial Engine at 3600rpm Continuous. With the HD Racing parts and running Mobil Oil there better Engines, and are turned on Carts up to 10,000rpm. Yes, I would probably use 100LL or a blend if just flying locally. A Simple blend to remember of 50/50 100LL/91 makes 95.5 Octane. But Fresh 91 is all you need.

#### Vigilant1

##### Well-Known Member
Protect,
Unless you really need the lead, it is best to avoid it IMO. Also, unless things have changed, it doesn't play well with the synthetic lubes you've said you prefer.
I have used straight 100LL in my VW aero engine, and I plan to start using real gasoline (zero ethanol) instead when I get the heads put back on. There was lots of lead buildup in there, and more than once buildups stopped my exhaust valves from sealing correctly. I may mix in a small amount of 100LL, but I don't plan to run it straight anymore on a regular basis.

Last edited:

#### Protech Racing

##### Well-Known Member
The 100LL has less lead than your VW engine was designed for. Maybe you have some loose valve guides? My guess is over rich mixture and some oi l burning . No lead or additives will keep the chambers clean of course . Gapless rings should help the VW with the loose PTW values. Just like racing Harleys. Do all of your holes have the same build up?
I have run it for years in Race cars without issue. Always with synthetic oil, almost always with Total Seal gapless second rings. Maybe due to running them WOT more and rebuilding the head at 40 hrs makes it easier/cleaner. Now all that I run is 110 Octane LL Sunoco . Due to fuel testing.
100LL Mixed with E 0 -89 will of course work as long as I watch detonation.

2 stroke compression is figured without blow down. The dynamic compression wont come up until the pipe and port timing get synced up and make some serious torque . Thats why they can use lower octane fuel.

Last edited:

#### n3puppy

##### Well-Known Member
The Pretty little small block twin would be perfect at 75# FWF and 32+HP.
Protech - Are you suggesting a 627 build of
32hp full power and 24hp @ 75% cruise
Or
42hp full power and 32hp @75% cruise power

Last edited:

#### Protech Racing

##### Well-Known Member
42 sounds better. I hope to build either the big single or the Twin and see how it flies my plane after the Hirth 30HP.
Vigilant, I made a statement regarding lead count without looking up the numbers. Sorry.

#### Armilite

##### Well-Known Member
Protect,
Unless you really need the lead, it is best to avoid it IMO. Also, unless things have changed, it doesn't play well with the synthetic lubes you've said you prefer.
I have used straight 100LL in my VW aero engine, and I plan to start using real gasoline (zero ethanol) instead when I get the heads put back on. There was lots of lead buildup in there, and more than once buildups stopped my exhaust valves from sealing correctly. I may mix in a small amount of 100LL, but I don't plan to run it straight anymore on a regular basis.
============================

Did you run only 100LL or did you use one of the Anti-Lead Additive also?

AVGAS burning engine No Addative 25 hrs

#### Armilite

##### Well-Known Member
AVGAS treated with the TCP additive 30 hrs