Cataraman

[gasfreak]

Hey I have a team strike catamaran hull from offshore models with a cc racing pro mod 26 zenoah in it it will run 44 mph with a speedometer I have been told this boat will run about 60 mph by several people on other forums now what I am wondering if it is possible would it hurt the performance of the boat if I moved the rudder behind the prop instead of being offset what kind of speed should I expect from this setup what prop to run if there is anyone with info please let me know I have been messing with this boat for a month and just cant get it the way I want it

 

[Scott Schneider]

You want better feedback on what / when & how to get 60 from your gas model?

Go to: http://www.jrcbd.com/index.shtml

 

[gil sonsino]

I've been playing with a similar equipment a Sprint cat 42"with my own modified Zen G26 and speeds are around 55mph.Check the Cg of your hull(30%) seems your boat is running wet and DO NOT replace the rudder behind the prop keep it alone (off set).

What pipe,pipe lenght ,and prop are you using.We are playing with different pipes but the better one is the .84 parabolic(drilled stinger) set at 34cms from the center of the plug(include the header),props are Prather 275(back cut & barr cut),H50 cupped 6,9 ,H31 cupped 6,5.

Hope this help

Gill

 

[Preston_Hall]

I know thet say 60 but believe 50-55. I have the same engine in a Sprint, 2" band pipe, Uctura 670 with tips cut off and it runs about 52. Should go a little faster but the engine is too far back for now and the boat is loose.

You should easily run in the upper 40's. Do you have the "S" bend header or just a 90 degree job? The "S" header gets cut almost as short as possible. Pick a prop to start with, set the strut level, and raise it about 1/4" above the bottom of the boat. Never put negative in it.

Also, in your opinion, how accurate is the speedometer.

Pictures might help out.

 

[gasfreak]

I know thet say 60 but believe 50-55. I have the same engine in a Sprint, 2" band pipe, Uctura 670 with tips cut off and it runs about 52. Should go a little faster but the engine is too far back for now and the boat is loose.

You should easily run in the upper 40's. Do you have the "S" bend header or just a 90 degree job? The "S" header gets cut almost as short as possible. Pick a prop to start with, set the strut level, and raise it about 1/4" above the bottom of the boat. Never put negative in it.

Also, in your opinion, how accurate is the speedometer.

Pictures might help out.

Hey thanks for the help so far here are some pictures of the hull and pipe and hardware if you see anything wrong let me know thanks again

I know thet say 60 but believe 50-55. I have the same engine in a Sprint, 2" band pipe, Uctura 670 with tips cut off and it runs about 52. Should go a little faster but the engine is too far back for now and the boat is loose.

You should easily run in the upper 40's. Do you have the "S" bend header or just a 90 degree job? The "S" header gets cut almost as short as possible. Pick a prop to start with, set the strut level, and raise it about 1/4" above the bottom of the boat. Never put negative in it.

Also, in your opinion, how accurate is the speedometer.

Pictures might help out.

Hey thanks for the help so far here are some pictures of the hull and pipe and hardware if you see anything wrong let me know thanks again

 

[Mike T.]

Can't tell much about your CG from the pictures so I'll just say the Supercat has to be run on a fine line between too wet and blowing over. That balance comes from having the right CG, thrust angle and prop. Accurate racing used to have a good write-up on setting up a Supercat. So did Eddie Barnes, the guy who made them. Some of the guys on Jims e-mailed me some of their best advice once and may do the same for you.

From the pics - first of all, get rid of the tygon water lines and use XL size silicone tubing. Tygon is too small inside to deliver the needed flow and gets soft when hot - It can therefore slip off easily when hot and cook your motor. Also, use wire ties as clamps on the water lines to make sure they stay on. Not pretty to overheat a Zenoah for want of a 2-cent wire tie.

Back to the speed problem - make sure the exhaust manifold is not leaking water into the exhaust system. Water will cool the gasses and kill the tune. Block one line and blow into the other to test. If the pipe is forced to lie to one side, that can cause leaks. Also, how long is the pipe fron the exhaust port face of the engine, around the bends, to the seam center of the chamber (beginning of the rear cone)? Just because it's welded doesn't mean it's the best length. Should be around 12.5 or 13 inches. Make sure you have the right prop and it is sharp and balanced. Prop Shop 6717 3-blade is good for most cats and might do yours some good.

Which carb model # is that? What needle settings are you using?

My experience working with a Supercat and racing against them is that they are about as fast as anything else but can be a real handful to drive around the oval when the lake is chopped up. Some of the guys who run them would disagree with my assessment.

 

[Mike G]

Dom (aka ACLazer) has the sweetest running SuperCat I have ever seen. He would be able to steer you in the right direction but he likes to know who he is talking to too!

 

[gasfreak]

Here are some more pictures of the hull and hardware the boat is 44 inches to transom not the other part sticking out on the back the motor is 16 inches from sparkplug to the transom the pipe from the plug to the seam in the pipe is 9 1/2 inches can I cut the pipe and add the silicone hose in the splice or adding to the pipe would be better but still put in the hose so I can adjust it if needed thanks agian for all the info so far I will get this thing right with you guys help and I know it

ok here are the pictures sorry

 

[gil sonsino]

I agree with getting rid of tygon to cool your engine.I Have experienced the same problem using it so go with large silicone tubing as said . Silicone hose coupler won't hold these temps for more than two or three laps so forget to use them with a gas engine .Teflon couplers have being used with relative sucess,though.

If your carb is the 257 you must set your needles at 1 turn the high and two and a half the low.

Good luck

Gill

 

[gasfreak]

It is a 257 carb I dont think I can make it idle at 2 1/2 turns out that sounds like a lot but Im sure you know more than me about it my high side is about 1 1/4 out and low side is about 1 1/2 now so if I back the low side out to 2 1/2 and turn the high side in to 1 turn you think it will run ok are these base settings for this carb because zenoahs web site said something like I have them now just wondering

 

[gil sonsino]

yesterday night I went to the boat to check out my needles and CORRECT the high is set at 1 ,1/8 turn and the low at 2,1/2 turns...you can't go wrong with this set up on the 257 Walbro. Also remember that my engine is modified and runs with a different pipe.Let me know how is your progress and good luck

Gill

 

[Mike T.]

With Walbro carbs there is some "bleed over" from low to high, so too rich or lean on low messes up the high end as well. The general rule is a total of 3 turns, and most Walbro models work with 1-1/2 on each needle to start out, then lean the high from there. For some reason the 257 is different and works best with low 2-1/2, high 1 to begin. Mine is running 7/8 on high right now. If it won't idle because 2-1/2 is too rich, open the throttle more. If you set your low needle lean enough to have a nice clean idle like your chain saw has, it will falter when you gun it. Next problem is the 257's low needle likes to fall out from vibration when set at 2-1/2. One solution is to use short bits of tygon tubing on each needle so they interfere with each other and can't turn as easily. By the way, save all that tygon for use as fuel line becasue it's worth about $1 per foot at the hobby shop.