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Lycoming 150 and RPMs..

eddy

eddy

Well-known member
I cant seem to get more that ~2600 RPM at full throttle. Should I mess with the prop pitch? I turn a Sensenich two blade carbon prop which is currently set to 2.

Should I mess with the prop pitch or leave it alone?

Looking for a little more torque without loosing top end speed.

What do you all think?

Eddy

:?:
 
you could always try the adjustment and if you don't like the results you could change it back . to me I would rather have the low end torque to push me then the top end speed I'm sure someone else will chime in
 
I will agree with you...

I assume I can push the 150 up to 2900-3000 rpm without hurting the engine, but I just dont know.... Im sure that if I adjust the pitch a little, i will get 300 or so additional rpms..

I just want to do no harm to the engine..

Basically, what should be the idle rpm range...

Thanks for your reply.
 
Sounds like you have your prop set pretty well. The idle RPM should be about 500. The max RPM is 2700 and you could go a little more but I wouldn't. At 2600 max you should get more longevity out of that engine. If you run it higher be sure to keep an eye on the cylinder head temps, oil pressure, etc.
 
Eddy,
That prop looks big for a 320. If it will only rev to 2400 and it probably does slowly, I'm thinking that prop should be on a 360. But I'd like to know what you have, I have a 320 I'm looking to put a prop on and would like the input.
 
I tell you what, I can run 3 dudes at 40mph... @2600 RPM.

I had a little trouble on a dry island over by macks on my first run a month or so ago, but I plan on visiting the island again as soon as I get the boat back. Im hoping the SteelFlex application will get me to the point Im looking for without touching the engine nor pitch on prop....
 
eddy, try taking out just 2 degrees at a time till you get to about 2800 to 2850 max rpm. If you are on the # 2 mark bump it back to a hair under 2 if you don't have a protractor to use. You can always put it back to where it is now if you don't like the way it performs at a higher rpm.
 
eddy,

You got an adjustable prop......adjust the damn thing.....that's the only way you are going to get the right setup for your boat and operating style!

Just be thankfull you don't have to buy a half a dozen wood props to get where you need to be :)

Grant
 
Looks like my prop eddy...mine's 70", on a o-320(160 hp) and is set on the full side of the second mark. I'm turning around 2800 right now, but I have to be honest, my boat feels better to me when I get the rpm's up around 2950.

Grant's right...just fool with it. With an extra set of hands helping, it don't take but a few minutes to change the pitch. Just don't go over 3000 rpm's per Sensenich recommendation's:
Sensenich's New Composite Adjustable Airboat Propeller FAQ ":21tt9ztb said:
Q) Is there an RPM limitation on these propellers?
A) Testing has shown that narrow and medium blade propellers can be safely spun up to 3000 RPM, and wide
blade propellers to 2800 RPM. However, optimum performance on a direct drive engine will be achieved at
approximately 2750 RPM,...
Click to expand...
http://www.sensenichprop.com/sen_html/airboat/carbon-faq-5.pdf

2600 ain't enough IMO. Even if you just take it up to 2750, there should be a noticeable difference in performance.

Rick
 
blackpowderscout":3tx4ldjo said:
Watch out for the 'yackers!!!!!
:P

Adam
Click to expand...


yackers at Macks Fish Camp here in western Miami-Dade county :shock: Havent seen any...



Thanks guys for all your posts... Cant wait to get my boat back and take it out for a spin....
 
Eddy, I'm with Grant on adjusting the prop for your best setting. Make the adjustments and turn up the RPM's to get what you want. It sure doesn't hurt to run that engine at 2750 for a short while but I wouldn't keep it there all day. The higher RPMs means more heat which means less engine life. Even though a prop can safely turn 3000 RPM's doesn't mean you want your motor to run that fast. The only time I would turn an O-320 up to 3000 RPM's is if it's not my engine.
 
I also ran the same prop on my 125. With my pop-up pistons and a few other things it was right around 140 H.P. I could turn that prop 2900-3000 at right between 1 3/4- 2 on the pitch setting. My prop was a 68 in. If your 150 is right then you ought to be able to turn that prop up more on the number 2 setting. Unless it is a 70 in. You need to turn it at least 2750-2850 for that prop to push efficiently. At least that is what Sensenich told me.
 
I'd say drop the pitch until you get it up to at least 2850rpm. What you need to do is like Grant says and adjust the prop to where you feel your getting the best push. Most people go by what the performance they get from a prop on the hill running.
 
Good lookin boat Eddy.
Prop1.jpg

Did you put those mufflers on there?
If so, did they drop your rpms?

Listening to Ricks post makes me wonder.
Perhaps your motor aint giving all it's got.

Got a buddy that was'nt happy with his motor,
Pulled the spark arrestor off the carb. Problem went away.

The wrong mufflers, or aircleaner can choke you down.
They could also cause your engine to run way hotter than it should.
You might try removing the mufflers, and spin it up to see how high it will turn.
Won't take long, and then you'll know.

If all else fails, back down on the pitch and get it turning up to at least 2900.
Let it eat!
I would.
If it can't take 3000, it don't belong in the woods!
 
Thanks Cowboy...

I put the mufflers on myself. I did test it without mufflers. No RPM/Engine performance difference.

I just get the boat back tomorrow, and I will return home from a business trip here in Orlando on Saturday..I plan on running it after the airboat show on Sunday... or I may end up calling sick on Monday :lol: gotta go hit the marsh..

More in a couple of days...


Thanks for all the posts..
 
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