tohastsu 50 hp needs to go faster

[itrjoel]

Hey iv got a 50hp mxd2 2013 .tohatsu. on a 14ft zapcat .
Iv got it going 45mph. But still far from what I want for speed
Iv got a D1 exausts
And a 10.2 x 15 ss prop
My reves 5100 wide open
Q: what els can I do for speed

Thanks joel babin

[Under the Thumb]

The list is practically endless, but to start with, you can look at proper setup in terms of

Cheap and easy

Engine height - centre line of the propeller needs to be in line with the hijacker inflation valves or a tiny bit higher.
Trim
Is 5100 on the rev limiter? or are you not getting full revs

Then on to the expensive bits - new prop, engine mods, prop modifications

Huge information resource here - Australian Thundercat Forums
The Setup Thread - Thundercat Inflatables Forum

You also need to work out how often you're going to be doing 45+ and whether acceleration and handling is more important than straight line speed on a mirror flat day.

[itrjoel]

Hey no thats not the revlimitor
It just wont rev past 5100 with 2 guys on board ill check the engine hight tonight
Dose this motor need jets and reeds and send this ss prop Away....
prop sending away ....

What I dont understand about sending the prop away.... how woluld they know how much to remove with out being able to test ever boat and motor r differnt...if to much is removed it will be f'd if not enough is removed ill be paying money and left with the same problem ...

[itrjoel]

My prop is
Pro Tech 10.25 X 15 REB3R15P.

[spartacus]

You might want to read this... http://www.rib.net/forum/f50/my-thundercat-61912.htm

[Roflhat]

Originally Posted by Under the Thumb

Then on to the expensive bits - new prop, engine mods, prop modifications

Huge information resource here - Australian Thundercat Forums
The Setup Thread - Thundercat Inflatables Forum

Originally Posted by spartacus

You might want to read this... http://www.rib.net/forum/f50/my-thundercat-61912.htm

These are both good things to read (I started both of them ). http://www.rib.net/forum/f50/my-thundercat-61912.html
45mph is about right for a 15p bunny prop. Maybe a bit slow, I was getting 49mph with my 15p prop, although it was cupped.
Once you start going for speed you really want a surface piercing propeller, chopper or cleaver.
The best starting point is trying to get max rpm with the prop you've got.

You should be getting more revs, the limiter is set at 5850. To get more rpm raise the engine up. If you're prop is cavitating you want to get it cupped for more grip.

Most of your performance gains are done by propeller selection. If you still can't get the speed you're after then start engine modifications.
Saying that, a set of boyesen carbon reeds is good on any engine. If you want more noise as well as speed you could do the exhaust mod - a 1" hole in the gearbox so the exhaust gases don't exit through the prop. Lighting coils can be removed from beneath the flywheel, frees up some hp.

Try and get some photos up of your propeller, engine set up, trim etc.

You can see here I ran a bit of orange string across the bottom of the hijackers to give an idea of prop height. This was with an 18p chopper, a 15p bunny should be lower.

[itrjoel]

So ... I checked my engine hight .. and the nut that holds the prop on is in line with the high jacker inflation valve
Are you saying keep raising the motor tell it
Cavatates then back down a lil so its not ...???
Im so lost with this stuff normally a car guy ..
Thanks joel

[Roflhat]

That sounds about right, your engine might already be too high.
Sounds like you're down on power, is it firing on all 3 cylinders?

[itrjoel]

hey guys/girls.
iv got a 14 ft zapcat with a 10.25 x15 prop on my 50 hp . and can only get 50 mph top speed and it seems most of my friends are doing 60 mph .. id like to bye a new prop somthing like a cleaver 10.25 x 18 ...or somthing im not 100% what i should get .. alls im looking for is speed nothing els.
thanks

[spartacus]

Checkout posts by Roflhat. He's mangled to get to warp speed by rebuilding his Tohatsu, Yammie carbs, different prop, etc.

[itrjoel]

ya dont want to mess with the engine just would like to change the prop .. so i get full speed and loose tork .... but i dono how far to go with it .....and dont have the money to just go bye a few props
stock 50hp everrun.

[henners115]

Have a look on boat mad, always props for sale or someone who can help

[itrjoel]

hey roflhat back on the net been awile back at looking at making this boat faster ... the motor is new and working fine but just not fast enough do u think a cleaver prop would help for speed like maybe a 10.25 x18 ..

[lukewhiting]

Have you had the propeller worked? Only costs about £60 amd will make a world of difference. Sharpen and thin the blades and get the edges cupped to stop cavitation in the bends.

[Roflhat]

If you're after good numbers with a stock engine you want to find yourself a decent Mercury 11x18p cleaver or 10 3/8 x 18p chopper. The choppers were originally for 10 spline 25hp but most have been resplined to take 13.
Both of them should give you about 56mph when set up correctly.
Yamaha make some good props too, 19 and 21G cleavers, which are also very good, although slightly tall for a standard 50.
If you're after even top speed (you will be ) then you could go for a 20p cleaver, still 11" diameter. The acceleration will suffer but you'll be going close to if not 60mph then.

Genuine merc props will always work well out of the box, although you can fine tune them to your application. You may have heard of Ron Hill, he makes all sorts of props but they're a bit of a gamble. Some are stinkers and some are beauties. Upto you, but I'd always go genuine merc props unless you buy a used prop that you know is balanced and works.

Unless your crew weight is very light 10.25" diameter is not ideal for a cleaver. It works on the chopper because it has over hub exhaust, so more blade area.

If you just want a bit more bite and slightly better top speed then do as Luke says. Money spent tuning propellers is always better than money spent tuning the engine.

[Roflhat]

Post some photos of your setup here if you can, have a looksee.

I sent tohatsu and email about the MX50D2 when it came out, but they keep their cards close to their chest...
Says it more durable, maybe they addressed the weak engines mounts and crank? Would make an ideal thundercat engine then

couple choppers for sale on boatracingfacts just now -
http://www.boatracingfacts.com/forum...silver-chopper
http://www.boatracingfacts.com/forum...er-II-for-sale

The first one doesn't say if its 10 or 13 spline, youd need to check that

[itrjoel]

ok sounds good will get a prop soon as i can find one. and pic wount be able to get the boat outa the basement tell the snow is gone but soon as it is will be back on here to post pic. had 1 more question my exause is through my prop now so when i do get a new prop dose it have to be a through the center as well. .. prob a stupid question

[Roflhat]

Doesn't have to be, if you get a cleaver it'll most likely be through hub (same as standard props). Choppers are over-hub (exhaust exits over the blades) giving you slip, so your acceleration will improve if you release the exhaust above the prop, i.e. above the cav plate.

It is a lot louder with above prop exhaust, so you could just leave it standard. Or if you drill 1" holes you can get rubber plugs to put it them when you want a quiet drive

[itrjoel]

some pic from last year

[itrjoel]

good summer it was