To produce the same horsepower, or to produce the same thrust?

Thrust is the sum of available power output and the design of the prop.

I know this is an older thread but still along the same lines...

From what I’ve gathered from various threads is:
O540J1A5D - lower rpm, longer prop option, not auto fuel compatable.
O540J3A5 - same as above.
O540B4B5- higher rpm, autofuel compatable, but no long prop option.

Do most people find the reliability between the 3 pretty consistant?
To choose one over the other is a matter of personal preference?

Reliability is about the same.
With higher rpm comes lower compression ratio to produce same horsepower
Preference may be a factor for some, but availability of whichever engine is in the airplane one is looking at is more the deciding factor.
A minor consideration is that for every hour run, the bits of metal slide by each other less times for lower rpm engines thus longevity should be more, however most engines wear out more from sitting idle.
The B4B5 at 2575 rpm could take a longer prop but no one has certified one yet though if springing for an MT, possibly a one time approval could be got for their 83"
The injected engines are IO540 W1A5(D) 2400 rpm and V4A5 2700rpm 260hp

Andy Young wrote:

TomD wrote: If engine X produces 235hp at 2400 rpm and engine Y needs 2550 to produce the same HP, then the question would be if they both ran at 2100 would they produce the same or different HP. My guess is, no.

Assuming engine Y has lower compression, then I'm with you. At 2100 the high-compression engine (X) will produce more power than the low compression engine (Y). The whole reason Y has to spin faster to produce the same horsepower is the lower compression ratio.

Okay, so on that note, what is the real (component) difference between Lycoming's 235 and 260hp engines? I'm not referring to carbureted vs. injected, but the 2400rpm redline established by the prop governor. What are the differences other than the prop & governor?

maules.com wrote:Reliability is about the same.
With higher rpm comes lower compression ratio to produce same horsepower
Preference may be a factor for some, but availability of whichever engine is in the airplane one is looking at is more the deciding factor.
A minor consideration is that for every hour run, the bits of metal slide by each other less times for lower rpm engines thus longevity should be more, however most engines wear out more from sitting idle.
The B4B5 at 2575 rpm could take a longer prop but no one has certified one yet though if springing for an MT, possibly a one time approval could be got for their 83"
The injected engines are IO540 W1A5(D) 2400 rpm and V4A5 2700rpm 260hp

It seems I missed the above post in my early reading & responding above. Half-asleep, I guess.

I have the W1A5D in my M-7-235. What is the component difference between this engine and the V4A5 260hp engine? I would assume it would be more than just the governor and prop.

A lot. If you rake around the net you can find parts manuals for both engines. Perhaps the vintage of the two manuals were somewhat different but found very few components with the same part numbers. Yep, been thinking about that ever since I flew a friends 260 over a year ago. Sure did sound and feel good.

Jeremy,

Curious as to what your opinion is as to the difference in operations between the J1A5D and B4B5. I get the difference in RPM thus propellor options.

Wondering if there is much difference in smoothness, noise, power or fuel efficiency. Do they use the same mounts, airbox and cowling?

While we are at it, what is your all time favorite engine/prop combo?

Kirk

Weight differences from the Lycoming Operators Manual:

O-540-J1A5D, -J2A5D, -J1B5D, -J2B5......................................................387.00

O-540-J3A5D, -J3C5D ..............................388.00

O-540-B1B5, -B2B5, -B4B5, -J3A5.......................................................395.00

IO-540-W1A5, -W1A5D ............................400.00

IO-540-V4A5 ...........................................414.00

Kirk, each engine has its pros and cons and thus it is an individual call re preferred engine.
O540 J1A5D dual mag 2400 rpm 8.5:1 no mogas 78, 80, 81, 86" props
O540 B4B5 two mags, 2575 rpm 7.5:1 mogas 78, 80" 81" prop, higher gph
IO540 W1A5(D) two (dual) mags 2400rpm 8.5:1 78, 80, 81, 83, 86" props, no mogas smoother and more fuel efficient than carb versions but not easy to prop start except first cold start of the day. slightly higher o'haul cost.
IO540 V4A5 260hp two mags 2700rpm 8.2:1 no morass, 78, 80, 81" props higher gph higher o'haul cost heavier.
I find the IO540 W1A5 best suits my needs
Speaking of smoothness, vibrations affect the engine of course but also the airframe rivets and welds, electric connections, cabin sealing etc plus the humans aboard, thus the 80" three blade prop, but under certain conditions the 86" two blade though much noisier and less smooth and less clearance competes in thrust and is lighter

B4B5 uses pretty much the same components as the JiA5D but uses more fuel so not as efficient and is heavier
The quoted engine weights do not account for the weight difference of two versus dual mags. The earlier J and W engines were lighter than later ones as some parts have been changed for heavier and some for lighter components.

There you go Scott. 14 pounds of heavier guts.

Is there a difference in icing tendency in the carborated versions?

My B4B5 carb ices easier than any other plane I have ever flown...best $ spent are in the way of carb temp gauge.

maules.com wrote:Kirk, each engine has its pros and cons and thus it is an individual call re preferred engine.
O540 J1A5D dual mag 2400 rpm 8.5:1 no mogas 78, 80, 81, 86" props
O540 B4B5 two mags, 2575 rpm 7.5:1 mogas 78, 80" 81" prop, higher gph
IO540 W1A5(D) two (dual) mags 2400rpm 8.5:1 78, 80, 81, 83, 86" props, no mogas smoother and more fuel efficient than carb versions but not easy to prop start except first cold start of the day. slightly higher o'haul cost.
IO540 V4A5 260hp two mags 2700rpm 8.2:1 no morass, 78, 80, 81" props higher gph higher o'haul cost heavier.
I find the IO540 W1A5 best suits my needs
Speaking of smoothness, vibrations affect the engine of course but also the airframe rivets and welds, electric connections, cabin sealing etc plus the humans aboard, thus the 80" three blade prop, but under certain conditions the 86" two blade though much noisier and less smooth and less clearance competes in thrust and is lighter

B4B5 uses pretty much the same components as the JiA5D but uses more fuel so not as efficient and is heavier
The quoted engine weights do not account for the weight difference of two versus dual mags. The earlier J and W engines were lighter than later ones as some parts have been changed for heavier and some for lighter components.

Thank you so much for this comparison, Jeremy (& Gary). Like I said before , I have the W1A5D. Would it be possible to change it over to single mags at overhaul just by swapping out the accessory case? I think it's crazy to think I'm looking forward to spending far, far more to upgrade my airplane than I paid for it. Engine, prop, Panel, Tires, Wheels, brakes, floats...Where does it end?

When the money runs out
When the wife __________( you fill in the blank)
When life runs out

no, different back cover.