Hydro51

Well, i finally got my new prop and prop nut installed and tested it today and i'm happy with the results!! It gets on plane faster and carries it's speed through and out of turns to the top end better than it did with the old prop. The prop is billet machined aluminum and is 37MM in diameter with a 1.4 pitch.

Hydro51

Also, i'll finally burn the last tank tomorrow of  the 33% traxxas fuel the boat came with when i got it.  I know traxxas fuel isn't the best. 

What do you guys that run a .18 nitro motor run for fuel?  I'm wanting to stay with at least a 30% nitro content.  I'm also running an O.S. #7 plug.

Jerry Dunlap

It is not uncommon to run 50% nitro fuel in .18 size marine engines.

JD

Hydro51

Really, i didn't know it was safe to run that high of nitro in such a small engine. Thanks for the response!

Hydro Junkie

50% isn't that high when you consider that some use 70% in their .21 and smaller engines to squeeze every last ounce of power out of them. I run 50% in all my boats since it's plenty powerful. Something you also need to remember is that as you go higher in nitro, the MPG goes down. While nitro is an oxidant that helps give more power, the alcohol is actually the fuel. As you increase nitro, you need to increase tank size to make sure you have enough fuel to finish your heats if you're racing

Hydro51

Seeing as i'm not racing, i think gonna stick with a nitro content of 30% to get my bang for my buck. I'm considering O'donnell fuel, what you guys think about that brand? I run O'Donnell plugs in my buggy and they perform great, so i would think there fuel would be just as satisfing.

Ron Olson

My Feedback: (1)

O'Donnell or GrimRacer fuels are two brands that are easy to get and are both good.
What scares me in that picture is the streamlined prop nut. They're not known for staying on very well.
BTW, that appears to be a flex cable setup on your hydro. You may want to consider leaving a 3/16" gap between the drive dog and the stuffing tube.

Hydro51

Thanks for the advise! When i installed the prop nut, i put a little blue thread lock on the threads to help keep it in place. I also left enough play in the shaft so it's not putting any pressure on the strut and universal joint at the motor when i tightened the prop nut.

Also, the last time i had the motor out, i pulled the drive line to inspect it and found that it doesn't have a flex cable setup like most others i've researched. It's a direct drive setup with a solid shaft.

Hydro51

[quote]ORIGINAL: Ron Olson

O'Donnell or GrimRacer fuels are two brands that are easy to get and are both good.
What scares me in that picture is the streamlined prop nut. They're not known for staying on very well.
BTW, that appears to be a flex cable setup on your hydro. You may want to consider leaving a 3/16" gap between the drive dog and the stuffing tube.
[/quote€

Oh, the brand of my boat is a Vantex and it's 700MM in length with a Vertex .18 motor and the shaft is 4MM.

Hydro Junkie

I take it that boat is one of the Pro Boat Bud hulls, just looking at the picture of the transom

Hydro51

After about a week of researching on the web, i finally found the manufacturer of my boat. Either they stopped the paint scheme i have or somebody repainted it somewhere down the road. I know finding parts for it inside the U.S. has been a pain. That's why i joined this forum, to try and get more information about what parts will work with this boat that i can purchase inside the U.S. and not have to wait for them to come from over seas.

The first stainless steel prop i order was from Horizion Hobby and an upgrade for the Pro Boat 1/12th scale Miss Budwiser, but once i received it the shaft bore was too small for my setup so i bored it out to fit and installed the prop. It was to small in diameter and the boat barely moved. I believe this Hydro is a little bigger than the 1/12th scale Pro Boat Miss Budwiser.

I put my old Ofna buggy radio system in it, a sullivan tiger drive and an air fiter to keep from getting water in the motor as it splashes through the hole the cowling. It's been working great me so far.

http://www.fuyuanrc.com/detail.asp?id=14074

Hydro Junkie

Okay, it's a Pro Boat knock off. It's based on the 1/12 Bud hull but has just enough "tweaking" to make it sellable without running into legal issues

Hydro51

So are you telling me I got a lemon on my hands? Lol!  Either way it's still fun and besides, I only paid 40 bucks for it.

Hydro Junkie

I wouldn't call it a lemon but it won't be a speed demon either. You will probably get into the 30s but beyond that, who knows

Hydro51

That's the speed i estimated i've been getting from it the couple of times i've had it on the water.  Somewhere between 30 & 40MPH.  Which is good enough for me, i'm not looking to start racing with it. 

amax

I had one of those not exactly the same paint scheme but very close. The Hull is the same dimensions as the Bud\Pro Boat but Heavier built\laid up and will take a bit more abuse but less top speed due to weight. The biggest issue is the Exhaust System. MACS sells a Wrap to Center header that will fit (designed for the Pro Boat) but will need to be cut down as close to the last bend as possible while leaving enough to get a coupler on, and a MACS 2.5 Pipe Cut down to work best for your APP. (test then Trim and Test Again) will give you quite a bit more Top End. Other than that and the CY\Vortex Engine most of the other aspects of the set up are superior to the Pro Boat.

Hydro51

Finally, somebody with a little experience with the brand of boat i have. How about props, what size diameter and pitch did you get the best performance with? I was thinking of trying this one next. It's 40MM in diameter and has a pitch of 1.8.




I recently put a pro boat brand high performance turn fin on and tested it yesterday. I have to say it helped, cause it really cuts a right hand turn sharper and flatter than it did before.


About the exhaust, i've looked at the MAC setups, but recently found this on ebay, what do you think about it?

amax

a 40mm prop is WAY To Much for the CY\Vortex .18 a 35mm to 36mm is much more suitable. the Octura M435\3 is my prop of choice on a Stock Engine but the Y535 (2 blade) is also a popular choice. You want a prop that will let the engine turn up into the High RPM Range easily because these small displacement engines don't have a lot of torque to turn big dia. or high pitch props.
Also Never use an Unbalanced or Unsharpened Prop it will rattle the drive train apart and leave your drive shaft and prop at the bottom of the pond. Not to mention the performance it's Robbing you of.

That exhaust system SUCKS.
You don't want any more connections than absolutely necessary, each Connection is a disruption in flow and a potential Leak when the coupler burns out. Also having a coupler That Close to the exhaust port is a very bad idea when you get the fuel mixture dialed in the heat\Fire will eat that coupler in a matter of minutes.

Header Length is a Critical part of Tuning as well as Pipe Length Longer is Higher Torque\Lower RPM's shorter is Higher RPM's\Lower Torque, and Each Boat\Set Up\Driving Style is different. Even with the MACS Wrap to Center(WTC) Header it difficult to get the header short enough to achieve the RPM range the .18 engines are capable of. I had to Cut and Modify the MACS WTC header so it came Up and back then angled the pipe across so the tip of the pipe ended at the rear center of the hull to get it short enough to reach the range I wanted. BUT I'm a Speed Junky.

Hydro51

Thanks for the tips amax!

I'll also just save up and buy the MACS WTC header and 2.5 pipe and play with it a little and see how it does.

advanced builder

Yes look for a different pipe. http://www3.towerhobbies.com/cgi-bin...?&I=LXZ557&P=7
http://www3.towerhobbies.com/cgi-bin...?&I=LXZ660&P=0

Hydro51

amax, when you put the wrap to center header on your old vertex .18, did it clear the high speed needle without having to rotate the carb?

Hydro51

Thanks for the links. How would i get that pressure fitting installed in the pipe? I know it goes in from the inside and the nut holds it, but is there a trick to getting it inside the pipe to where i want it mounted.

Hydro51

Scratch that last question advanced builder. 

I pulled the threaded pressure fitting out of my old 1/8th scale buggy fuel tank.  It's 1/8th inch in diameter, when i get the MACS pipe i'll drill an 1/8th inch hole just before the fattest part of the pipe and put some high temp RTV silicone on the threads of the fitting to ensure a good seal when i install it.