Quantcast

Briggs vanguard conversions

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

TiPi

Well-Known Member
Log Member
Joined
Aug 25, 2019
Messages
314
Location
Mackay (AUS)
This is no different than any other engine hanging on a fixed pitch prop. My Rotax 912 ULS is pitched for about 5,250 - 5,300 static, will run 5,300-5,350 in slow climb (65kts) and get to 5,650 WOT at sea level. Redline is 5,800. So I don't have a 100hp engine anymore☹
 

Hephaestus

Well-Known Member
Joined
Jun 25, 2014
Messages
1,775
Location
YMM
Well here's where mine stands.

I'll see what the builder says about YouTube hosting the video of it's first dyno run.

38hp at 3800rpm, 46lbft at 2600. Running 3psi of boost. 10minute run on the dyno static load, 3800rpm - required ~250cfm per head to maintain 280° CHT.

Now, porting work, connecting rods, high volume oil pump, new custom cam and installing a proper oil feed for the turbo.

Hopefully next run early December.
 

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
8,103
Location
North Carolina
Well here's where mine stands.

I'll see what the builder says about YouTube hosting the video of it's first dyno run.

38hp at 3800rpm, 46lbft at 2600. Running 3psi of boost. 10minute run on the dyno static load, 3800rpm - required ~250cfm per head to maintain 280° CHT.

Now, porting work, connecting rods, high volume oil pump, new custom cam and installing a proper oil feed for the turbo.

Hopefully next run early December.
Whoah, hang on, 52 ftlb, from 627cc? With 3psi boost and no porting?
 

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
5,060
Location
US
Commercial dyno? Supervised by the guy who did the mods?:cool:

The PSRUs do let em spin fast and still turn a decent size prop.
 

Hephaestus

Well-Known Member
Joined
Jun 25, 2014
Messages
1,775
Location
YMM
Whoah, hang on, 52 ftlb, from 627cc? With 3psi boost and no porting?
That's what his computer says, it's a lot lower than I'd have expected too.

Of course now you can begin the argument as to whether his Dyno is accurate. To me it's a relative # same with the HP. Since I don't think any department of weights and measures actually verifies data.

The torque peak was way below where the calculators said it should be too.
 

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
8,103
Location
North Carolina
If that 500cfm is dissipating the entire heat of the engine, it would have a delta of around 120C.
I am more than a little sceptical of the dyno.
 

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
8,103
Location
North Carolina
That's what his computer says, it's a lot lower than I'd have expected too.

Of course now you can begin the argument as to whether his Dyno is accurate. To me it's a relative # same with the HP. Since I don't think any department of weights and measures actually verifies data.

The torque peak was way below where the calculators said it should be too.
Lower? It seems awfully optimistic to me. Allowing for the boost, it's still a 28% increase in torque over standard.
 

Hephaestus

Well-Known Member
Joined
Jun 25, 2014
Messages
1,775
Location
YMM
Commercial dyno? Supervised by the guy who did the mods?:cool:
He is a true bayou redneck who builds motors for a living (mostly swamp/airboats). So yes it's his own personal dyno and when it comes back we can do club props.

Mods at this point really don't exist other than intake and exhaust manifolds.
 

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
8,103
Location
North Carolina
with 3psi boost (~20% over NA) and no other mods, he has somehow boosted torque by 56% over the stock torque at 3600rpm.

Sorry, seen claims like this far too many times...
 

mcrae0104

Well-Known Member
HBA Supporter
Log Member
Joined
Oct 27, 2009
Messages
3,391
I have been reading through old issues of Experimenter lately more than I've been keeping tabs on HBA.com, but how could the following article not make me think of this thread? Perhaps not much has changed in the intervening 71 years...

image.png image.png
 

BBerson

Light Plane Philosopher
HBA Supporter
Joined
Dec 16, 2007
Messages
13,584
Location
Port Townsend WA
This is no different than any other engine hanging on a fixed pitch prop. My Rotax 912 ULS is pitched for about 5,250 - 5,300 static, will run 5,300-5,350 in slow climb (65kts) and get to 5,650 WOT at sea level. Redline is 5,800. So I don't have a 100hp engine anymore☹
So if your engine is rated at 100hp at 5800 rpm, and you only get 5650rpm at wide open throttle in level cruise, then you have a cruise prop and you never see 100hp in normal flight.
The important number for the airplane designer to know (using this engine) is what hp is available for climb at 5350 rpm. The 100hp at 5800 rpm is not relavent.
Now if you install an extreme climb prop then you can cruise at 100hp with 5800rpm.
 

TiPi

Well-Known Member
Log Member
Joined
Aug 25, 2019
Messages
314
Location
Mackay (AUS)
These numbers are plausible:
The original engine has a ve of 70% and a torque of 43.5Nm.
Going to 100% ve is already an increase to 62Nm
Add the 3psi boost (+20% ve) takes the torque to 74Nm (54.5lbf.ft)
Torque on a turbo engine will increase with rpm as the turbo kicks in so "peak torque @ 2,600 rpm" is not peak, seems to have ben recorded at that rpm as this is the default "peak torque rpm" for industrial engines.
 
Top