ok thanks in advance for any suggestions I receive. I have recently bout my uncles airboat he built. It is a lycoming 320 on a diamondback 12' hull. It has a wood prop on it currently. I'd like to be able to run on dry ground and currently it will break free if I'm not in it. I'd like to get a composite prop and hope that change will help. My uncle has another prop (wood) that he says will let it run dry but it can over rev the engine, but u just use it to break free and back off. My current prop will run at 2700 rpms, im still trying to learn and understand everything before I take it out, so I've been reading the manual but honestly I'm not sure exactly what the engine should peak at. I have been reading all yalls conversation and they are all pretty close but just looking for experienced advice since I'm new to owning my own boat. I've been on the river a bunch growing up on this boat but its different when I have to make the decisions lol. I would also like to see what options are best ,if any, to get more hp from this engine. I have looked at the razor and another prop from whirlwind, I have called them to see what the recommend and need to call them back Monday. Also l try to post pics of the boat and the numbers on the prop.
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Lycoming 320 power and prop
- Thread starter Rafterjm
- Start date
lewisdj1971
Well-known member
I just purchased a Sensenich JM 67” for my lycoming 0360. It improved my performance a lot from my wooden 66/36. To me it was worth the money to get the adjustability needed to fine tune it to the desired performance. Rule of thumb is do not exceed 3000 rpms on that engine. I set mine to max at 2850. That’s a nice little boat! Mine is 11’ and wish it was longer.
Striker543
Well-known member
I don’t think you can buy a better prop for that engine than a sensenich NGQ. More expensive but it would be worth it to me. Also don’t put that other wood prop on and spin it over 3000. That can cause it to blow up and when wood props blow up they do a ton of damage to the boat and potentially to people nearby.
the carb you have is an MA-4-5....if there is a tag on it there will be a part number stamped on the tag 10-????...if ya give me that number i can tell ya exactly what you have...it looks like a nice setup with the filter assembly.....gear nosed engines have a gear reduction unit bolted to the crankshaft on the prop end they are found on the larger engines 0-435 0-480 0-540....the whirlwind blade sounds right but i would also talk to sensenich before i pull the trigger on a new prop and stay with a 2 blade no matter which one ya choose imo
kwanjangnihm
Moderator
here is a photo of a gearnose engine :thumbleft:
Slidin Gator
Well-known member
Rafterjm said:
Rafter,
From my perspective the first thing the boat needs to do is move on ground while I'm still seated at the controls, even if it only runs 10 mph flat out on water. It's embarrassing to have to run the hill via remote control. Barely on a plane, just being careful. :dontknow:
What is your hull width, or more specifically, what is the maximum prop diameter the setup can safely turn?
Rafterjm said:
That is not necessarily a bad prop recommendation as it will spin up quick and run faster while still giving you ground push. That prop was made for all around performance on that engine and is probably their default recommendation, just like the F150 is the default at the Ford dealer, until you show an interest in the 250. It is a sliding scale, more push on ground = less top end and vice versa.
Th O-320 should make around 150 Hp depending on details. We run a 72" whisper tip (previous generation of the carbon max) regular width blade on a 180 Hp O-360. My first thought is a 72" carbon max narrow 2 blade would be more in line with what you describe as a goal. Talk to them again and make sure they understand you are looking for maximum low end push and let them know how much diameter you can run. You should also talk with Sensenich and Water Walker with the same thoughts in mind. You will get a range of recommendations and reasons, consider them.
GMAC 76 said:
GMAC is right that you want a 2 blade, he is thinking about harmonics and engine damage while I am thinking about maximum push. Either way, don't bother thinking about 3 blades or more unless you are looking for max speed.
I have a av320 with a 72" whisper tip and it pushes like a tractor. No snap and not very fast but will run the hill loaded. More diameter, more push. My buddy had a sled with a 320 with a 66" cypress and it hauled ass but got hung up all the time. Also don't know what you run for a bottom but when my slick is shot I can barely run dry by myself. Some Jack's in the hull can help dry running a lot too. Don't just look at the prop, its a complete package that has to work together to do what you want.
Hendog458
Active member
SeatCover What rpm are you turning that prop and what degree pitch?
Just curious as I recently switched from a 63 inch 5 blade warp to a 68 carbon max with the same motor as you. I wanted to go longer, but can only fit a 68 in my cage. But I can barely get to 2600 on the trailer with the new prop.
It's certainly a huge upgrade over the warp. With the warp any dry running I had to floor it before I got to the dry and hoped momentum would carry me to the next patch of water before I got stuck. With the whirlwind it'll take off on dry ground no problem now.
Just curious as I recently switched from a 63 inch 5 blade warp to a 68 carbon max with the same motor as you. I wanted to go longer, but can only fit a 68 in my cage. But I can barely get to 2600 on the trailer with the new prop.
It's certainly a huge upgrade over the warp. With the warp any dry running I had to floor it before I got to the dry and hoped momentum would carry me to the next patch of water before I got stuck. With the whirlwind it'll take off on dry ground no problem now.
kwanjangnihm
Moderator
Hendog458 what was your max WOT with the warp? Remove a few degrees of pitch with the carbon max.
Hendog458
Active member
kwanjangnihm, with the warp I could hit 3000 on the water. I'm around 2800-2850 on the water with the whirlwind now with the prop set right between the 5 and 7.5 mark. So I guess it's not really that bad.
I'm going to play with the pitch a bit more to see how it affects performance. I'm happy with how it's running as it is. But as with how everything goes with airboating, I want to feel like I'm getting the best performance I can out of a decades old a/c motor. haha
I'm going to play with the pitch a bit more to see how it affects performance. I'm happy with how it's running as it is. But as with how everything goes with airboating, I want to feel like I'm getting the best performance I can out of a decades old a/c motor. haha