Wood Bar Dyno Run

[leshoman]

Just uploaded a new you tube showing Wood Bar Dyno Run.   I believe this finally answers the question about accuracy  of my TTO tach. Two digital tachs, the TruTach in Steve's Wood Bar Dyno kit and a Globe, an RC tach, all agreed within 20 rpm and the TTO was only one that reads less than steps of 10.  I still have one thing to do but it appears i am getting about 42 hp.

[Hugh Sistrunk]

Hello Les,
What is your engine setup - piston and crank sizes?  Thanks

NightEagle

[leshoman]

Its a 94 x 86 with dual mikuni 34 carbs. A scott cassler engine. Just got to the 40 hr mark so not completely broke in yet. Been running a 58 x 20 tennessee prop with my new Franks Performance prop due here tomorrow. It is a 60 x 20

[Hugh Sistrunk]

Thanks for the info.  Will come in handy

NightEagle

[Dan_]

Les,
Thank you sir for the flick...
I took the liberty of modifying your post by putting the YouTube link on a separate line at the end of your message so it will show up in your post.

Keep up the good work with the go-pro.  Awesome videos... Thanks for sharing..!

[Steve]

What were the EGT's showing on that 42 hp run...

[Sam Buchanan]

Excellent data point, Les. Field history is beginning to gel concerning the "45 hp" 1/2 VW.

With a single Zenith carb the engine delivers ~38hp at 3000rpm, and with dual carbs dialed in properly can deliver close to rated power at ~3600rpm. The Zenith just doesn't flow enough to allow the engine to develop rated power but it does make a nice engine if the builder wants to operate at a lower rpm than is customary for the 1/2 VWs with a big cruise prop.

I suspect the power of the single carb and the dual carb versions would be similar at 3000rpm, but the single carb runs out of breath north of 3000rpm.

[leshoman]

During this test EGT at 1400 and CHT at 375. Oat about 55 degreesF

[rockiedog2]

Hi Les and thx
mine turned 43 hp with the 28s and 1350 EGT.  That was with a fresh top from Scott so not broken either. I expect it will make an honest 45 when it gets more time on it and go to Mobil One. Kiblinger's dyno seems correct to me. I had a lot of performance data from my earlier 37 horse and my 45 with the zenith performed near exactly the same. The dyno showed 38 hp with the zenith.
I ran a 6020 from Frank for a while and I thought it was a good utility prop but I was trying to turn 3600 rpm in the 45 climb so started clipping and  Frank adjusted the pitch and tip thickness several x. Finally concluded that it wasn't possible for my motor to turn 3600/45 with a prop as long as 58 so stopped there and am running a 5820 and a 5820 clipped to a 57. We could have gotten the rpm up but expected we might lose thrust by reducing the diameter anymore. 

Joe

[Sam Buchanan]

Hi Les and thx
mine turned 43 hp with the 28s and 1350 EGT.  That was with a fresh top from Scott so not broken either. I expect it will make an honest 45 when it gets more time on it and go to Mobil One. Kiblinger's dyno seems correct to me. I had a lot of performance data from my earlier 37 horse and my 45 with the zenith performed near exactly the same. The dyno showed 38 hp with the zenith.
I ran a 6020 from Frank for a while and I thought it was a good utility prop but I was trying to turn 3600 rpm in the 45 climb so started clipping and  Frank adjusted the pitch and tip thickness several x. Finally concluded that it wasn't possible for my motor to turn 3600/45 with a prop as long as 58 so stopped there and am running a 5820 and a 5820 clipped to a 57. We could have gotten the rpm up but expected we might lose thrust by reducing the diameter anymore.

Joe

It's interesting that your prop experiments track pretty closely what the prop calculators predicted many months ago.  

No substitute for actual field history, however. Builders these days have a lot more data than us early adopters did three years ago.

[leshoman]

Some more input regards the Wood Bar Dyno, Received my new Performance prop from Frank and did a pull test with both the Tenn. 58x20, 3230 RPM static, best it would do, and the Performance 60x20, 2850 RPM best it would do.  Have one more test to do this weekend. 

[Sam Buchanan]

Some more input regards the Wood Bar Dyno, Received my new Performance prop from Frank and did a pull test with both the Tenn. 58x20, 3230 RPM static, best it would do, and the Performance 60x20, 2850 RPM best it would do.  Have one more test to do this weekend.

Les, good to see some more analytics with the 45 engine.

The racket we hear with the 60x20 is most likely the prop tips cavitating and a large amount of thrust being lost to tip drag. In other words, the prop is generating noise instead of thrust as demonstrated by the low number.

The Tenn Props 58x20 tracks very closely to what I pulled with my 45 when testing a Tenn Props 58x22. It was good for 180 lbs, you got four more lbs due to being able to pull 180 more rpm because of the flatter pitch. Very much as expected.

60" is just too much diameter for these engines. You might want to consider having Frank tweak the prop to something close to what Joe is running, but that may end up being a climb rather than cruise prop.

Anyway, great info, and we look forward to more tests. This is interesting stuff!

[Hugh Sistrunk]

Hey Les, good demonstration - will be interesting to see what the engine rpm comes up to in flight when it has time to unload..

[PropMan]

Nice video Les!
Well I had hoped for more static rpm, I'm still tweaking the props for the 45hp.  With each new bit of information they get better.
Sam,I don't think 60" is too much diameter for the 45, just need to find the right combo for pitch. with these small engines there is a lot more than Diameter, pitch, and surface area to play with. Funny how smaller props can be more challenging to get right than the large ones.
Of course the mission will dictate prop size and shape to a point.
Yes, it may need an adjustment to dial it in, looking forward to further info.

[Steve]

Nice video Les!
Well I had hoped for more static rpm, I'm still tweaking the props for the 45hp.  With each new bit of information they get better.
Sam,I don't think 60" is too much diameter for the 45, just need to find the right combo for pitch. with these small engines there is a lot more than Diameter, pitch, and surface area to play with. Funny how smaller props can be more challenging to get right than the large ones.
Of course the mission will dictate prop size and shape to a point.
Yes, it may need an adjustment to dial it in, looking forward to further info.

Frank:
If Les can work with you and find the final 3 HP of 45 the 60" prop will be turning over 3000 rpm... 3 Hp as a percentage of 45 is a huge loss... There also is a cam thing from the writings of Bob Hoover regarding swinging a long prop on the Vw (lowering the peak torque band with retarding the cam timing by 4-7 degrees)...
Steve