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pro charged a/c boats

C

carte89

Active member
wondering if anyone can tell me how strong these setups are? I have a heavy 14x7'6 boat with an 0540 and was considering pro-charging mine but am considering going c/m and gearbox instead. thanks
 
here is a link to ingest some info on the subject: https://southernairboat.com/phpBB3/viewtopic.php?f=85&t=67860

maybe spooledup50 can add some real world knowledge!! (I'm still tinkering) :salute:
 
On a boat that size I have to say you are setting yourself up for a world of heartache. Can it be done? Sure. Will it last? Doubtful. And, you will spend a fortune in avgas keeping that beast fed. Keep in mind that with a supercharged air-cooled engine you have to throw a bunch of fuel at it to keep it cool. You should follow Swamp's advice and go CM with a gearbox. Just for reference, I'm running a heavy 15x8 DB with a supercharged LS engine that's been modified to make something in the neighborhood of 650-675 hp. I'm running a 2.55 OxBox with an 82" 4 blade NGR. I've put over 300 hours on this combination and it's a boat that goes anywhere I want it to. There's no 540 out there that will ever compete with it pushing that size boat, especially with the reliability. That is just too much boat for an aircraft engine.
 
digginfool said:
On a boat that size I have to say you are setting yourself up for a world of heartache. Can it be done? Sure. Will it last? Doubtful. And, you will spend a fortune in avgas keeping that beast fed. Keep in mind that with a supercharged air-cooled engine you have to throw a bunch of fuel at it to keep it cool.
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I am in complete agreement with diggin on the above, eventually you are gonna hate yourself for building the biggest fuel pig in the swamp.

I disagree on the solution.

digginfool said:
You should follow Swamp's advice and go CM with a gearbox.
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Swamp and diggin's pigs do run good, they just took years to get there :stirpot:

I say keep the engine, get a lighter boat, throw the Pro Charger at it if you still got the itch. Regardless that's a 1 year effort max.

Then think about a CM build on the existing hull, now you got time.
 
carte89 a few other less expensive suggestions:

1. add nitrous - use for butt-pucker situations
2. tweak hull, bottom, engine angle, jacks, etc
3. where is your 76" NGQ pitched now & whats your WOT?
4. Carb or FI?
5. Lightweight battery
6. Fuel capacity/fill - I had a 40 gal tank, but only filled to 30 most outings
7. Headers/Exhaust - possible 25hp gain! https://southernairboat.com/phpBB3/viewtopic.php?f=47&t=32748

just a few off the top of my head! :thumbleft:
 
Thanks for the info guys. I agree with what y'all are saying. I have considered nitrous, prob shouldn't go there haha. I have messed with engine angle, the bottom of the hull is pretty good, fairly new. Carbed engine and the 76" ngq is right under the 2 mark on the hub and turn it 2700 wot. I do have a lightweight battery 21lbs fuel tank is 20 or 25 gallons. Headers are norman clay unstack ram horn style headers. Honestly the boat does real good for what it is, nice thing is if i get hung up i can get it out myself.
 
carte89 said:
Another thought would be to put a gearbox on it
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A buddy of mine had a O-540 that had been geared. He was running a big 3 blade (78 or 80" I think). This was setup on a light 14' aluminum deck over. It pushed the hill like a tractor and was very good on fuel, it ran lower engine RPMS vs. the direct drives doing the same thing. But he couldn't keep jugs on it due to overheating. The bigger prop pulls air from further out, decreasing the amount of cooling air that the engine gets. He ran a low shroud and it still wasn't enough. Eventually sold the boat because he got tired of messing with it.

If you put a tall shroud (~12" exit) like the GSO guys run you might be able to keep it cool, but you are off on an experiment. Personally I would want a fuel injected engine to try that route, there is a huge difference in cylinder temps between the carb and injection.
 
That prop setting is typical for a 540.

You can make amazing power levels with a 540 cubic inch engine, the big journal crank engines in particular (That should be what you have??). But, to survive for longer than a short drag race, you have to deal with the heat. If you can keep cylinder temps in check, the engine will do it. Before you go down any of these power upgrade routes, I suggest installing a set of CHT probes and gauge on #3 and #4 cylinders and see what you have right now, cause it's gonna go up with more power unless you improve airflow. The goal is 300-350 F, Lycoming says 400 for maximum life, 500 max.

Here is one thread to read. Those air racers preheat their oil to over 200 F before they even crank the engine. They run tighter clearances so they can run hotter oil (less flow diversion for cooling, less engine wind-age, same reason NASCAR tapes up the grill). But they change the oil a lot more often...

https://southernairboat.com/phpBB3/viewtopic.php?f=47&t=71696&p=690046&hilit=race#p690046

Go for it, I'll throw my 2 cents in. :thumbleft: I guarantee I got no problem experimenting with your equipment :cherry:
 
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