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New to airboating

A

archermatt

Member
I just bought my first boat and wondered what kind of routine maintance I need to do on a 540 straight valve Lycoming. What kind of fuel should I run and where do I get parts near Palm Bay, FL. I appreciate any advice also as far as operation too!

Matt
 
no problem, This site is a good place to ask questions, lots of experienced boaters on here as well as those of us who are just starting out. do you get the airboat world magazine?
 
Not yet. I figured with the money I am spending in the boat, I need to save as much as I can to get it running in top shape and have it serviced. Plus the additional gas for learning to use it.

What grade fuel are you using. I have heard to use high octance aircraft fuels, but others have said to used normal 95 pump gas?
 
I run aviation gas 100LL, but there are lots around that run 93 octane in their Lycoming, both in the air and on the water.

Watch out for high temperatures with 93 octane - some say it can cause higher operation temperatures. Also watch for detonation issues with it. If you run that, don't try any tricks like advancing the timing for additional power.

There are several people in Florida that handle Lycoming parts for airboats. Jr. Jurnigan does rebuilds, several on "Airboat Trader" on the internet that have tons of parts from crashed, storm damaged, or prop strike grounded airplanes.

You are in trouble. It is like a addiction you will never shake. Welcome to the club.
 
To throw in my .02 if you have a pretty stock staight valve you could probably get away with running the 93. There is no question though the 100 Octane LL is the way to go. The lead really helps keep the motor cooler. The other option is to go with a shroud. Other than that keep the oil changed regularly. (I think there was a thread a couple of days ago about this) and enjoy.
 
Thanks guys! I'm excited to get out there, and even more excited about using the boat to get to my duck spots next year!

Matt
 
You want some lead in your fuel for the valves. I usually run about a 50/50 with 100LL & 93 pump.
Don't shut the engine down when very hot, let it idle down as the oil cooler is what keeps the top of your clyinders cool, as they are much hotter than the oil temp gauge states.
If you can afford one, put a shrowd on the engine. Jugs are $500 installed so one jug = the shrowd.
A subsciption to Airboat World will save you money in the long run. Same with joining a local airboat club. I suggest the Brevard County Airboat club. Contact 321-259-5156.
If you can afford an airboat, you can afford the above. If not, you may wake one day to find your boat worth about $10.00
PW
 
Thanks PW, I appreciate the info ! What is a shroud look like, who makes them? I've never seen one on an airboat? Where do you buy the 100LL fuel?
 
I finally got out on my boat this weekend and had a blast. Stayed down in the shallow marsh for a few hours before venturing out on the river. Was pretty cool and I have the bug. Spent about 5 hours this morning running up past the bee line and to 50 and everywhere in between. Thanks for the advice guys!@

Matthew

PS Where do you get the shrouds from and what do they look like? I haven't seen any on any boats yet.
 
Remember that Lycomings are aircooled. You are getting massive cooling compared to an aircraft, and typically you tempertures will be much lower at standard operation ranges. If you install a shroud and it is not correctly installed, your Cylinder Head Temperatures will skyrocket very fast, especially if you have to push the throttle hard for time. You can smoke a cylinder really fast. I know at least 20 0-540s around here in a 80 mile circle, all operated in different ways by different people and none have shrouds.

If you are concerned about CHTs, then you can set up a CHT gauge for around $150.00 for one cylinder. Change the probe from cylinder to cylinder, find you hottest one and leave the probe for the gauge attached there. Then you can monitor the Cylinder Head Temperature ranges as you operate. I found it educational.

Waterthunder suggested a temperature gun, type you point and get temperatures from. If you know someone you could borrow from, that would be cheaper than both.

Only saw one shroud on a Lycoming, and it was configured by a certified A&P mechanic to keep the temperatures within the Lycoming recommended ranges, around 180 is what they were shooting for. Worked great at cruise around the lake, but when they had to hit the throttle and maintained high RPMs, the temperatures skyrocketed. They changed the engine and rigging to a auto motor, due to the thinking there was something wrong with the motor. I got the shroud, the motor went cheap. Motor is still running fine and at the low end of the normal operation ranges. Wish I would have had the money at that time?

Look at small airports of 100LL fuel, that is where we get ours.

Enjoy that new boat.
 
Pat I hate to do it but i completely disagree with you about the cooling shroud on the 0540s.


I run CHTs and a shroud built by Marks Airboats, on adverage my CHTs are 100 to 150 degrees lower with the shroud on. That means alot when your CHTs are running at 550 degrees during the summer time without the shroud. Its not just my boat either, its a hand full of guys around this area that i run with that and get the same results.




If its designed right it will force air flow threw the cooling fins and not around them. Also at wide open throttle it cools even better because of the increase airflow across the fins.


Now i am not tring to start a pissing match here, but i have had first hand experiance with running shrouds on 0320s to 0540s and everything in between and they all recieved the same results, that was cooler running across the board.




Sorry Pat, Kevin
 
Kevin - Don't want a pissing match either and it is hard to hurt my feelings. I was not meaning to make it seem like I was disagreeing with you either, just warning people to make sure it is done properly. Somebody that really knows what they are doing could come up with something. Especially someone like Mark or some of the other airboat guys. But I would not want to build something myself. Probably not something just anyone should consider doing themselves, unless they got a money tree and a set of spare jugs or had a real good look at the real deal.

The shroud I spoke about is sitting in my shed. Somebody I know got the motor almost for free and the shroud came with it. When they ran the motor without it and had no temperature problems, they offered me the shroud. Would be glad to put a picture of it on the site for you cowboy, let me know.

It would seem that if the shroud acted like an air scoop of some sort, it would direct more air over the cooling fins. I will harass Mark about them.
 
I will post a pic tomorrow when there is daylight.


Mark has played with his design for 20+ years and it really works. There are many things to consider when building one and he has done a good job researching it.



Pat tell Mark i said hi tomorrow.




Kevin
 
Bobby and Patti from Powershift had a shroud on a continental a/c at the Broward show. Bobby says it makes a world of difference. But I also heard that you have to be careful not to let debris buildup under it and start a fire. I think that is why lake runners are using them more than glades runners. If you think about it, airplanes put them in a shroud, other wise the engine would be exposed on every Cesna.
 
Airboat Shrouds have interested me for years even though I don’t like aircraft motors too much. Airboats are harder on aircraft motors than people think for two main reasons. (1) An 0540 in an airboat has the ability to make more power than it ever could in an airplane. See the closer to sea level you are the more oxygen is present in the air thus you can run more fuel and make more horsepower. Here is the killer the more power a motor makes the more heat it generates so in an airboat a 540 generates more heat than it ever could in a plane unless you purposely lean it out. Second is the higher the altitude the cooler the air temp. So when these motors are in a plane the ambient air is much cooler so the heads run cooler plus they make less power so they generate less heat. Most airboats run at sea level with ambient temps over 90deg.
 
So why do so many people prefer aircraft engines over the car motors beside the weight difference?
 
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