100HP Build

[Cajun_Ag]

I thought I would go ahead and start a thread on our project. I will say up front that it will be a slow process because both my buddy and I are building it for fun and neither of us have wives that are on board with the project. We picked up the engine last week and now have to get it running. The engine is currently in a Kawasaki 900ZXI jet ski. The engine generates 98HP @ 6750rpm and 81ft/lb of torque at 6000rpm. It does not classify as a true mini since we exceeded the 750cc for 3 cyl criteria, but for $200 I could not pass up the deal.

[chuckitt]

Go for it, I want tell anyone you cheated on cc. . Like to see you get it working.
Chuck

[Duane Scarborough]

Cajun_Ag,

Like Chuck said, go for it. We aren't too picky about the classifications. A 4A084 has 4 cylinders, and almost 1400 CC. But it doesn't have 100 HP

Good Luck with it, and please keep us posted.

Duane

[Bogger2]

Hey Cajun_ag,
I like your train of thought. 100 hp or so, should be pritty radical. I figure after I get board with my 503 rotax only 45 hp, I might have to try another two stoke like what your trying.
Are you going to make a reduction? At two stoke RPM iI figure it's a must.
You got me very jealous.
Definately keep us posted,
Bogger

[Cajun_Ag]

A reduction is mandatory. The engine makes peak HP at 6750 rpm and makes peak torque 81ft/lb @ 6000rpm. I'm kinda in uncharted territory here so I'm leaning toward a ~2.5:1 reduction & a 66-72" prop. Those are just ballpark figures so correct me if I wrong about the process below in picking teh correct redrive & prop.
Contact prop manufacturers obtain torque numbers required to turn the prop @ max rpms @ their most efficient pitch. I'm looking at IVO & Powerfin. I like the pitch adjustability of the composites and I have no experience with wood props.

[Stackem]

Powerfinn is out of business.

[Cajun_Ag]

Powerfinn is out of business.

You are correct. There are still some props in stock out there that will suit my needs. I really like the E series I have on my fan boat. I really hope someone buys the rights and starts making them again.

[Bogger2]

Hey Cajun_Ag,
I have a 62 inch 3 blade IVO on my 503 rotax with a 2.58 reduction. Max recomended RPM is 6800. I would of went with a 64 inch setup, but The cage size wouldn't allow it.
I will be going to get the electricly veriable assy. for it real soon.
It works quite well on my 116 hull form Airboat Pros from Chuck.
Keep designing
Bogger

[Cajun_Ag]

Well we tore into the engine because of bad compression readings of 43/120/95 and found that one piston broke a ring and scarred the cyl pretty bad. Then we went ahead and broke it down to the crank and the bearing are not in very good shape. Note to self "You usually get what you pay for & sometimes less!!" I found another motor from a shop that the guy is willing to give me $250 core credit for mine so I'm too bad upside down in this deal. I budgeted 2,500 for the entire build at this rate we might over shoot that just a bit.

[Duane Scarborough]

Cajun_Ag,

Funny thing about airboat budgets. From talking with people, budgets are always made on the optimistic side, so the end cost is always way over budget.

But the time required to complete the project seems to always be underestimated as well. So I guess it works out that way.

Good luck with it. Can't wait to see progress photos.

Thanks,

Duane

[Cajun_Ag]

On the plus side, I now know what a 2 stroke looks like inside and out.

[Cajun_Ag]

I took a little detour on the way to pick up our new motor.

In the end we got a limit of ducks and a newly rebuilt engine. I just talked to my buddy and he said that according to UPS the re-drive is on his doorstep. Once we figure how to mount it we'll begin the prop hunt.

[Duane Scarborough]

Powerfinn is out of business.

You are correct. There are still some props in stock out there that will suit my needs. I really like the E series I have on my fan boat. I really hope someone buys the rights and starts making them again.

Cajun_Ag,

You are in luck. Powerfin is back in business. (under new ownership) And they've relocated to Wharton, TX.

http://www.powerfin.com/

I just stumbled across this while looking for something else, and remembered your wish.

Duane

[Duane Scarborough]

I took a little detour on the way to pick up our new motor.

In the end we got a limit of ducks and a newly rebuilt engine. I just talked to my buddy and he said that according to UPS the re-drive is on his doorstep. Once we figure how to mount it we'll begin the prop hunt.

There must be something really interesting laying on the ground next to the boat. It sure seems to have all those Duck's attention.

Duane

[buster]

Hey,

Somebody check beside that boat, I think there is some duck food spilled on the ground there

Dave

P.S. Sorry, I just couldn't help myself

[Cajun_Ag]

HAHA They were all Texas Longhorn fans and ashamed an Texas Aggie got'em and took their picture.

[Duane Scarborough]

Naw, they just look like hungry ducks to me.

I said that Powerfin was back in business, under new ownership. I was only sorta' right about that. From what I've gathered, it's the founder's son who started it back up. That should add some continuity to the product.

Duane

[Cajun_Ag]

Thanks Duane
I dealt with his son Stuart Jr. a couple years back when I built my bowfishing fan. I think several others did as well which leads me to believe that he handled alot of the daily operations anyway. The only complaint I've ever heard was due to how long it took to receive a prop after order. If I recall mine only took about 4 weeks, which seemed fair to me, but I would think that should be shorter with the new facility.

[Duane Scarborough]

Cajun_Ag,

O.K., I can 'fess up now on why I was following / checking out Powerfin. I stumbled across an Ebay listing for an almost new 68" 3 blade Powerfin, and I had made a dirt cheap low bid on it.

Then I started investigating the Powerfin Prop. The more I looked, the better I liked it.

I did some ciphering, to see if it would work with my rigging, and decided that it would.

I've just "won" the bid. I ended up paying a good bit more than my initial bid, but still only about 1/3 the cost of a new one.

Shame, shame, shame on me.

So, when I get it together, I'll have 2 props to test.

Duane

[Duane Scarborough]

Naw, they just look like hungry ducks to me.

I said that Powerfin was back in business, under new ownership. I was only sorta' right about that. From what I've gathered, it's the founder's son who started it back up. That should add some continuity to the product.

Duane

Well, I was wrong again.

Powerfin IS under new ownership. But the old owners are still involved.

Here's what I ran across today on the Powerfin website:

"Please also note that Stuart Sr will continue to consult with us on new propeller projects, as his son leads our employee training program.

Regards,
Fredrick Scheffel, SFIE, CEO of SkyTrails LSA/POWERFIN"

That may have been on the website before, but I either missed it or miss-understood it. Sorry if I led anyone astray.

Duane