borristhboxer

Hi there i was just wondering about a porject i have been working on
i Hvae installed a .21 os max rg-m engine into a 1:12 proboat hydroplane, Llumar with the original flex cable and setup, just a motor swap really and running 30% nitro.
It's running a .21 max pipe and well it goes okay. I have played with the y535 prop and the m435 prop and seems to run nice so i uploaded it to youtube and was happy with it.
The other day i purchased another boat, (Elam) stock standard and running the .15 engine in it. I put the y435 prop onElam and run it in, then ran it againstthe LLumar running the .21 and the y535 prop. Well i tell you what, LLumar run like **** and totally not nice, Elam was not far behind at all!!!
Not happy with everything i swapped the props over on both boats and put em back on the pond against each other.
Man it was all backwards! Elam was kickin LLumars arse!! i was thinking to myself what the [email protected]# until it was like the last minute of the run and then LLumar just took off like it hit another gear. There was no stopping her and she just pulled awayby over a good straight by the time she ran out of fuel compared to Elam.
Atfer looking at the video and trying to work out what was going on i noticed that the bum of LLumar was dragging in the water until the last minute, which is where it flew!!.
Since doing this i have cleaned out the fuel tank, enlarged the fuel line, and drilled out the fuel tank by 1 drill size bigger, also replaced the breather pipe from the exhust to the fuel tank with the same size as the fuel line which is 1 size bigger.I leaned it off a little and swpped the props back over so LLumar has the Y535 prop on it again and run it by it's self. It looks okay but the sound from the exhust just isn't the same and it dont look to be as quick or as light in the bum anymore. I glued on an extra wing on the front conard to force air into the air trap under the boat and a litte extra on the rear with to help with uplift. It seemed to help but not really. The high pitch scream of the motor just isn't there and well i can't tellif speed has changed. It sounds a better but not really.
I have just ordered a p735 prop and a 40mm prop, cant remember the exact one but i was hoping for some help and advice.
I dont know if i should change my drive setup to a bigger 1 and start looking into an adjustable skeg or what to do.
I would like to get LLumar up to speed it's meant tobe running. Today i had it on the water and with full throttle you can tell it's trying to get up and go like itdid the other day but just can't seem to go all theway for some reason no matter how long i hold it in a straight line.It does change sound going from 1/2 throttle to full throttle, but a bad thing today was a little windwas around and it gave some flight which was good.I heard that same pitch from the exhust and itwas running really loose and fast until i hitthe corner and blew it over.
It's all good motor is fine and the electrics are just drying out.
Thanks for your help


first run against each other www.youtube.com/watch?v=de1SI4IIx9U

last run of the day. http://www.youtube.com/watch?v=FoZF6xJeTNM

TCHedOff

When I was breaking in my rigger last yr, the same thing happned to me - thing hit another gear for a lap of so just before it ran out of fuel. The more experienced boater w/me explained to me that the engine gets leaner when your engine is about to run out of fuel.... if your rihc on the needle you'll get a burst of speed, if you are already real lean, it'll die on you as it gets too lean... if you are right on the needle it'll run the same speed til it runs out of fuel. (I have a video of this if you want to see it happen).

So lean the needle out more (if you arent breaking in your engine).

Engine temp will also act the same way.... many a boat will (relatively) chug along for 1/2 a lap to a couple laps until the engine gets hottter, and then pick up an extra gear of speed.... Try a hotter plug in that case.

Last comment: To allow the boat to run freer on the water, you may want to consider laminating some 1/16" or 1/32" ply strips to your sponsons bottoms to create sharper edges/flatter surfaces on the areas that contact the water. If you havent seen/read about what I'm speaking of, do some research first.

misshydro

My boat can only drive mine at 3/4 or less throtle.. It can be a had full to handle..My Oberto.21 RS Redhead.. They do suck down in some turns.had troubles in one turn.Like to jump and skip to much accross the water.[link]http://www.youtube.com/watch?v=5rcjIdPo0GA[/link]. On this run I'm running a 40mm prop... plus I have the miss vegas adjustable strut and rudder setup on my Oberto..couldve ran my boat in a longer distance but a kid thew in a big stick in the water for his dog to catch and it was in my road..Heres a thread I done on my Oberto. might help you out..[link]http://www.rcuniverse.com/forum/m_7053339/mpage_1/key_/tm.htm[/link]

Ron Olson

My Feedback: (1)

One more thing, you're tuned pipe may be too long. What may be happening is that it's finally getting on the pipe after it has run for a while and gotting up to the RPM point where the pipe is starting to do its job.
Just for the helluvit, measure your pipe from the glow plug following the path of the exhaust to the widest part of the pipe. I'm guessing that it's more than 8-1/2". The header and/or the pipe will probably need shortening.

misshydro

No mine is at 8 1/2"

Ron Olson

My Feedback: (1)

I wasn't typing about yours but his.

borristhboxer

okay did a few measurments and from the widest part of the pipe to the glow plug is 11.5 inch's.
What would be the difference in cutting it down make and making it too short?
Still onthe area of change, the vegas strut set up orchanging from the proboatskeg whatchanges do i needto make and whats involved? i want to know before i embark and a driveline changejust so i get it right first time.
alsowhat drive shaft size is better and whyi think the standard is 1/8? why should i upgrade to a 3/16?

Ron Olson

My Feedback: (1)

Yeah, you need to whack off 3" there and it should run much better. You can remove it from both the pipe and header to get the length right. A tubing cutter does a nice job.
If you ever find that you went too short then you can add length with a tuned pipe coupler. You want a little gap between the pipe and header anyway so that they don't make contact.

TCHedOff

I think one question you had was about what happens when you get too short on pipe length?? One symptom is that when you back off the throttle, and then floor it, it'll take a number of yds to get back on pipe (in my case like 20 yds). So you'll notice you've lost "throttleability". Is that a word?

As for flexcable, the Lumar orginally had a smaller engine, that's why the flexcable/propshaft is small; 3/16" flexshaft/propshaft seems to the norm for .21 size boats. The 3/16" is stronger and gives you more prop choices to run. But chaning up to a bigger flexshaft will involve replacing you brass tubing.... may be a bigger job than you want to tackle (or not).

misshydro

I'd ment his should be close to mine 8 1/2..should start off at 9" and cut 1/4 off at a time to find that sweet spot..I'm still running the miss vegas flex cable .150 without any proublems..

borristhboxer

Alrightly just a little update for you, after taking off the extra wing on the conard and cutting down the exhust to just over 9 inch's from the original 11.5 (thought it was somewhere nice to start). I was keen to bash it around on the lake. 2 days of waiting since the blow over and for the wind to drop down i go it onto the lake man what a difference! At 1/2 throttle it was running like the other day a full noise! i gave it a few hits at full and it started to lift the nose  now this was what i liked to see and the noise was heaps better plus the speed!!!
I'm running the Y535 prop for the testing and 30% nitro.
I got 5 - 8 laps out of it before her before i headed to the shore for a check on how it was all going. Added some more fuel, about 1/2 a tank leaned it out 2 more clicks started it up and set her going for another few laps. It's getting to be more touchy under throttle responce but still taking about 5 - 15 yards at full throttle before you hear it at full noise. At least it's getting there, before cutting the exhust it took 12 - 14 laps before you heard it.
Anyway it was about 4 laps into a high speed run when the battery's started to die on the boat a little. Thanks to the fail safe it slowed to idle  and I steered it to the shore line. Should of recharged the battery's before i ran it []
Anyway I think I might cut off another 1/4 inch from the exhust  and give it a crack! Hopefully i can get a few laps in tomorrow and against the standard elam running the same y535 prop again to see the difference. I'll try to record it and upload it. I find it's better to replay your work and see the difference improvements have made since the last run.
I'll keep you posted

lipdaddy

can't wait for the video.

Ron Olson

My Feedback: (1)

I'm glad that it ran better! With the .21 in it, you should be able to turn a larger prop. I'd try a 40mm next but just take one thing at a time right now.

misshydro

You need to didtch that y535 prop,its to small for a .21... I'm running a 40mm prop..I got a 440/3 that I'm going to try out.Plus running 33% nitro too.

borristhboxer

Well guy's just a little update for you.
Ive been waiting for a nice day for a few laps and it was now!!
After doing about 6 laps of full noise with the Y535 i'm happy with the exhust length and tune of the boat, so  i changed props to a 440 prop. Okay its totally different boat speed wise and starting to be a real weapon on the water!!
I couldn't corner for **** at speed until i backed off but then once in a straight line again the power went on and really got it cracking!!!
found the exhust sweet spot to be 8.75 inch from the glow pug thank for everyones help with that.
I have upgraded the turn/skid fin to the high performance proboat one just to see how it goes.
A new rudder and drive setup have been ordered as what i am running will not handle much more, standard proboat crap just adapted a new shaft to suit a 3/16 props.
Once the new rudder comes i'll beef up the back so it can handle the extra strain and finally setup a 3/16 adjustable skeg and shaft.
Didn't run it against my other boat for a speed check but hey you can see and hear the difference at the moment.
Hopefully if the weather holds i'll put both boats on the water soon.
I'll keep everyone posted on the next few changes

malicent

good to hear its running nice for you, but i don't think you will ever be totally pleased with a .21 in that small of a hull.

borristhboxer

Hey there guys sorry for taking so long.
I have taken the boat to a boat building friend of mine. He cut off the rear wings and has taken out the servo box. At the moment we have moved the engine and re-set it up in the boat, about an inch back and a lot lower than before. I have a new driveline setup that will also be put into place as we are doing this.
The servo box will be repositioned once a few hull mods have been carried out but all work is going ahead really well.
I saw it for the first time last night and there is ample room to get to the fuel tank, which i had an issue with. I have a new strut and rudder so when i get it back it's going to need a few laps to start setting it up again.
Another main thing is we are changing the engine cover and going to make a new and smaller version to suit the boat, kind of change it from an unlimitied into a grand prix hydroplane look
ill try an upload some photos soon

borristhboxer

Hydro Junkie

Why would he move the engine back? Unless the radio box is going in the front, he's not helped in the boat's balance. When it's all back together, put the boat on two fingers and see where it balances. If it's more than an inch behind the sponsons, it's going to be tail heavy.

joseywales

moving that motor back will make it alittle tail heavy. We keeped the motor were it was at. HJ ,I bet he moved the motor back because of his header. Bet he didnt want to cutup the cowl to make the header work. That's why we had misshydro's oberto header customized to make it fit under the cowl without moving the motor back.

Hydro Junkie

JW, you know as well as I do that a 21 is too powerful for the Pro Boat hydros. All you have to do is watch Misshydro's Oberto on the water to know that any time it gets to a certain speed range, it gets unstable and it has to be either slowed or it will blow over. Moving the engine back in Borristhboxer's boat can make his boat even more suseptible to blowing over than Misshydros. In this case, I was asking if the radio box was moved forward to compensate for the weight of the engine being moved back and the larger tuned pipe. If the radio is staying in the back, the boat may be highly unstable.

borristhboxer

Hey there guys sorry for taking so long. I went and had a good look over the boat last night to see the differences between it and a standard proboat.
My engine that i had put into the boat is not actaully moving back at all. What we have done is dropped the engine so it's now lower in the boat. I thought we had moved it back but after talking last night with the boat builder, he told me that no that was a dumby set up while he was building the new engine mounts so thats cool, sorry for the mistake! The fuel container has been taken out and the bracket that held it in has been changed to lock the fuel cell in the boat better, mine was broken
The engine bay has been extended to allow for a new collet on the rear of the engine becuase i am replacing the drive shaft with a bigger and stronger set up, so thats why the control box has been moved all of about 15- 20mm back from the original position. To allow for the new collet, but we are not going to put the rear wing setup back on the boat as i am changing the look of it and turning it into a Gp Hydroplane.
Also i am adding in some floation into the hull, once we cut it open i found that there was nothing inside of it!
The proboat people i will say made the hull really well, the boat builder was impressed with the lay up of fibre glass

ill keep everyone updated on how things go, attached is 3 pictures. 1 is the shaft just sitting in place, the other 2 is the boat that we are going to make mine look like

misshydro

JW, you know as well as I do that a 21 is too powerful for the Pro Boat hydros. All you have to do is watch Misshydro's Oberto on the water to know that any time it gets to a certain speed range, it gets unstable and it has to be either slowed or it will blow over. Moving the engine back in Borristhboxer's boat can make his boat even more suseptible to blowing over than Misshydros. In this case, I was asking if the radio box was moved forward to compensate for the weight of the engine being moved back and the larger tuned pipe. If the radio is staying in the back, the boat may be highly unstable.


Ok Hj, moving the engine back?? come on.. with the back end being tail heavy that will make to front end lighter=more chance of a blow over... need your weight tord the front to keep the front end planted down from less chance of a blow over. Proboat have a horrible CG=center of gravity. Might be breaking out the oberto and place a weight in the nose of the boat,that might keep it from blowing over. JW is the one who made it blow over.

borristhboxer

hey there guys and girls just wanted to give you an update on the way hydro is going at the moment.
The new engine mounts are installed and setup, the shaft has been installed and setup with the new skeg on the back of the boat
we are going to glue the deck back together soon, and start the engine over in the next week or 2... then it's up for a re-spray and testing
i have attached a few pictures of the way the boat is coming for everyone to see. The control box was just sitting on the back, not in position when i took the picture. It will be moving forward, also we put foam into the hull to help it float incase of a blow over

borristhboxer

Hey there guy's sorry to take so long about giving an update to the rebuild...
the hydro got put on the shelf while the hydro season has been going in Australia, but since I'm on holidays a little bit of wrk has been done.
The radio box has been cut down and made a little thinner, then we reglued the deck and control box back into the boat.
Once this was done a new radio box cover was made out of carbon fibre with clear plastic sections in it to see inside. The engine cover has been extended just under an inch to refit onto the boat and now its starting to be glued together. Tomorrow i might start the shaping of a new engine cover, keeping in with low profile and fit-out of the boat.
Its been primed & sealed where any mod's have been done until we test it on the water. Once I'm happy it will be repainted into the proper racing colours
The engine was setup into the boat, being a few mm's off the bottom of the hull and moved closer to the fuel tank to get the center of gravity correct for balance.
well I'll keep you posted on how it comes out
Oh i also ran my stock standard proboat nitro elam against the stock standard electric elam and kicked its butt!! both boats have not mod's and are as they came from proboat nothing changed.... just shows a little nitro is better than any battery hydro