Scott Reed
Junior Member
Does anyone know the reduction ratio for M-40/5432 engine /w Hurth HBW-100 transmission. I ordered a new three bladed prop awhile back, and I think I'm slightly overpitched as I can't get tach beyond 2150-2200 rpm. Below is an exchange I had with the prop folks. I guess most succinctly, is the ratio 1.80:1 or 2:1? I'm hauling for some extensive work, and it'd be a good time to pitch the prop correctly. Many thanks.
Scott Reed
Querencia, E38-200
scott.reed@att.net
ps I suppose I could release compression on engine, engage the transmission, crawl into aft cabin, snake into the small space and manually turn the engine shaft exactly one revolution whilst measuring the transmission shaft response. But that's way too hard for a big fella to do all by himself. Far better to ask you Oracles.
--------------------------------------------------------------------------------------------------------------------------
Sorry for the back and forth. I've conflicting information for reliable sources regarding the specs on the Hurth HBW-100 transmission.
The Universal Engine Manual that came with the Ericson says I have engine model #5432 aka #M-40. Further this manual says I have a Hurth transmission, model # HBW-100, and that the reduction ratio is 2:1.
In checking with two engine, transmission shops affiliated with Universal they both say the reduction ratio is 1.8:1 for this engine (5432), transmission HBW-100.
My inclination is to divide the difference and say the reduction is 1.9:1, which'll bring me within 5% on either side. Can you pitch the new prop based on this compromised 1.9:1 ratio? If I'm not dead on, I'll at least be closer to increasing or decreasing pitch if required.
Scott Reed
Querencia, E38-200
scott.reed@att.net
ps I suppose I could release compression on engine, engage the transmission, crawl into aft cabin, snake into the small space and manually turn the engine shaft exactly one revolution whilst measuring the transmission shaft response. But that's way too hard for a big fella to do all by himself. Far better to ask you Oracles.
--------------------------------------------------------------------------------------------------------------------------
Sorry for the back and forth. I've conflicting information for reliable sources regarding the specs on the Hurth HBW-100 transmission.
The Universal Engine Manual that came with the Ericson says I have engine model #5432 aka #M-40. Further this manual says I have a Hurth transmission, model # HBW-100, and that the reduction ratio is 2:1.
In checking with two engine, transmission shops affiliated with Universal they both say the reduction ratio is 1.8:1 for this engine (5432), transmission HBW-100.
My inclination is to divide the difference and say the reduction is 1.9:1, which'll bring me within 5% on either side. Can you pitch the new prop based on this compromised 1.9:1 ratio? If I'm not dead on, I'll at least be closer to increasing or decreasing pitch if required.