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2:1 vs 2.68 numbers

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Waterthunder

Waterthunder

Well-known member
Here are some 2to1 vs 2.68to1 gearbox results. End result the 2.68 swings 50 less RPM at WOT and swings more then twice the prop of a 2to1.


SBC zz4 350 355hp 2.09:1 ratio Stinger gearbox 78" wide blade Sensnich pitch setting 1.5
Engine rpm's
cruise:xxx
wot: 5050

SBC zz4 350 355hp 2.68:1 ratio Stinger gearbox 78" wide blade Sensnich pitch setting 3
Notice here that the motor is swinging twice the pitch mark now. With a 2.09 it swung 1.5 and with a 2.68 it swings 3
at more RPM's. This tells you it still needs more prop to get back to the same RPM's the 2.09 was swinging
Engine rpm's
cruise: 3800
wot: 5200

SBC zz4 350 355hp 2.68:1 ratio Stinger gearbox 78" Ultrawide blade Sensnich pitch setting 1
Engine rpm's
cruise: 3700
wot: 5500

SBC zz4 350 355hp 2.68:1 ratio Stinger gearbox 78" Ultrawide blade Sensnich pitch setting 2
Engine rpm's
cruise: 3500
wot: 5000

Note: cruise rpm's are at a GPS derived speed of +/- 25mph all rpms are with a single person & full tank of gas (40 gallons).

The last one is the one I've got it set at now, & man does that Ultrawide have some push! It is also so much quieter, due to the low prop signature. I think I'm going to like this setup a lot. Look forward to meeting you here in the near future.
 
Dave, I have a friend with the same set up on a 14 x 7.5 hammat.
SBC 330 hp, 2 blade prop. It runs really well, however, it will not run the hill well. It's a 4 seater. Perfect condition!!!

Will having the 2.68 box and the wide three blade make his boats run the hill. AND, will it get better fuel economy?

Their are a couple of set ups like that in the airboat trader at a fair price.
I think more people are wanting to go with the higher gear boxes and the wide props to get the most performance out of their boats.

Having looked at this info for over a year I still do not understand.
I see the tour boats running belt drives at 2 to 1 with the big blocks.

I saw your boat at Loughmans and it was the most impressive boat out there.

Explain it one more time!!! DSD
 
I have the zz4 and 80" 3-blade Power plus, w/2:1 belt drive.
Would like to try a setup like yours but can't get past the problem with
cold weather locking up the gear box. (grease gets too thick)
Hope they come up with a beltdrive soon.
I am in Minnesota, and I travel in sub 0 temps......................
 
I have about a 300 hp small block and had a 2.12 with a 6 blade turbo warp drive on a 14 by 7.5 hamant and the boat ran good but wanted a little more push so i got a sensenich 2 blade super wide q series and put it on and could swing it at 4700 wide open set on below 1 boat pushed good and now I put on a 2.68 and set the prop on 2 and on 3 boat has awsome push on 2 turning it at 5000 wide open and runs dry alot better if i run it on 3 runs good only able to run about 4300 wide open
as for fuel It seams to be burnning less with the 2:68 went for a long boat ride yesterday and I made it back with out running out from lk washington all the way to 528 and back
 
OK time to tick off a few more people. All the airboat manufactures but two dislike me already and a few actually try talking people out of buying my motors. Heck one refuses to build somebody a boat if they use one of my motors. Back to the point in the beginning when everybody thought higher ratios meant more RPM's all the boat manufactures loved 2to1 ratio's the weren't too concerned about performance they just wanted to control what RPM's a motor turned so they went with a 2to1 AND set the pitch to turn 5,000RPM's max. Heck I had two airboat manufactures ask me to quit pitching the 2.68's because they don't want to warranty motors turning more RPM's. I still think none of the big manufactures like running 2.68's on their boats but they will in another two or three years I'm sure because allot of people are catching on. Another reason for the belt drives on tour boats is who cares about performance or weight on a tour boat. The extra 100 or so pounds and the added torque roll is of no concern in a 20 foot boat. I have seen at least 15 cases where the same exact combo ran much better with a 2.68 then a 2to1. As for the gearbox oil freezing up isn't your motor oil also doing the same? You know you can run a gearbox oil with a much lower viscosity for colder climates there are simple fix's to that problem. Now I have two Caddy's running 2.68's and them things have insane push don't park your truck behind them because they might flip it over.
 
Well, I am interested in trying one and offering to my customer as an engine option. I am just waiting to hear back from you on a price. So I can run one asa demo for a while.
I am even willing to try the Gear again as you reccommend for the engine set up, although I have had lots of trouble with the Gear Boxes in the past.

I think you build one hell of an engine!
 
Well my turn to pissem off, LOL I run a stinger gear box, 3.12 ratio, I swing the 82" super wide triple at 1550 prop rpms, motor turning 4800, prop set at just past 3, problem with the marks is they are not good accurate on the sensenitch, I used a protractor and at the tip I got 20 degrees.
rotator .... stinger ... I prefer stinger, just my choice, they stand behind them 100% if you want one and don't have a dealer just call me with a pm and I will get you one I am a dealer for them.
 
i am confused on setting my prop now after country's post i make sure everything is level and use an angle finder that reads in degrees on the tips and i get 60degrees are there different types of the protracter and angle finders or do they do the same?
 
The marks are OK. Here is the best REDNECK way to set your wide blade prop. Find the mark it runs best at then track it by a piece of wire or metal. Make sure each blade is the same 95% of the time I have got rid of those pesky vibrations people complain about just by tracking their prop for them.
 
my prop was a pain to set they are whirlwind psr blades powersift hub and no reference marks i set them to my desired engine rpm and tried my angle finder and got that reading i was just worried.i did track each blade with the ruler clamped to the transom and measured where they track within 16th of an inch.
 
I should have been able to figure it out but... how do you use the wire to track the prop? I have used a tape measure and measured from the same point on the cage but I don't have real confidence in it. would you clamp the wire to something where it touches the trailing edge of the prop and turn it over and make sure it is the same on the other blade? I'd like an easy way to set the prop accurately without an expensive angle finder.
 
Dan I have never done the wire trick although it is used by many. You can get a protractor/angle finder from warp drive or classic airboats for about 35 bucks I think. It is made to clamp on a warp drive blade but you just use the other side which is flat to measure the pitch. You set one blade where you want it and then lock down the dial on the protractor and set the others the same. Pick a point on your cage to align the tips with so they all get set the same. You will not be measuring the actual pitch of the prop but you will be setting all blades the same. If you want to measure the actual pitch you need to contact the prop maker and ask where they measure it at along the blade. each one is different. The most important part is to get them all the same and then you can add more or take some out depending on the results when running. You at least have a benchmark to go by at that point even if it isn't the actual pitch. You also can tell the prop maker where and how you measured it and they can duplicate it and tell you the actual pitch for what it is worth, which is actually nothing, because it only matters how it works for you on your boat and engine setup. remember though that different applications/use require different settings so you need to decide what you want at the time of course you could be like me and carry the protractor with you along with the wrenches and if you need to change it for a particular reason it really doesn't take long once you have done it a few times and played with it you will be able to adjust easily for the current situation.
 
I just got thru tracking my prop last night I used a pice of Aluminum tubing and clamped to the transom after I set the prop on the marks where I thought it should be I rotated it to where the trailing edge of the prop was touching the middle of the end of the tubing then I rotated the prop around and checked the next blade the some way and it ran very smooth when I was done.
 
Ok guys, I had asked this months ago and never got a real answer.

How do you set the tracking on these new composite multiple blade props? Its one thing to measure it but still another to set it.

With my old woodem props I measured it by taking a machinests scale and finding the exact center of the prop tip. I'd take a little center punch and make a little ding right on the tip end. Did this to both ends. Then I'd take a set of vice grips and a piece of welgng rod with a point ground on it and clamp it to the cage. Bend the rod around so the point points to the center punched mark on one blade. Then rotate the blade forward to the other blade and check if its in the same exact point on that blade. It usually wasn't. I set the tracking by differential hub torque on the prop. I always rotated the engine both forward and then backward to double check my points. Took a few but it sure did eliminate any vibration.

Nother issue I see is balancing the prop blades weight with composites. Do ya add material or grind some away to balance them?

With my old wood props I made a balancing rig from a skateboard wheel and truck. Skateboard wheel fit nicely in the hole in the prop. Was easy to find the balance point and add weight by adding hard solder to rivet heads on the blade that was the lightest.

All these new composits just baffle me. I'm not questioning they are great, im just trying to figger em out.

Scotty :?: :?:
 
Had a whirlwind 1/4 inch off track...no way to fix....should have sent it back...in a bind had to run it...cost me a engine 100 hrs later...would be interested in the answer to tracking composit prop in billet alum hub.

grant
 
I don't know about tracking a composite prop, hav eno idea how you would change it if you found it out, guess send it back.

Now there is a problem out there with the composites, I am not picking on one manufacturer and no it is not WW. Sensenitch has had a real problem with blade weights. they say they tip weights are the same, however if you weigh the whole blades ther is sometimes several ounces difference in them. This has caused some vibration, anyone got any suggestions I know alot of them egt sent back to sensenitch.

Maybe others have the same problem, I don't know ... does anyone else know.
 
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