outdrive ratio
 

Are there any know negatives to running a 1:35 vs the 1:5 on the 28?

i remember reading on here somewhere about this. it has to do with your prop. they talked about the desired prop being in the 23-24 pitch range being optimal for bow lift. if your there already with a 1.50 i wouldnt change. dont quote me on this tho. griff would have a good idea. he is pretty sharp with this stuff

I'm good with the theory and all I just didn't know if anyone was running the 1:35 and if there was any draw back in the performance on the 28 . I believe the prop shaft spins faster than the 1:5 therefore allowing a smaller prop. I don't believe I was going to have a problem running out of prop on my set up with the 1:5. I am a little concerned about diverting from the proven norm though.

If your concerned about diverting from the norm, it's to late for that one dude.. :bunnydance:

If you are below a 32" prop, then I would probably stay with the 1.50.
A 32" should be about a 90mph prop with a 1.50

LOL. You got me:silenced:

I was told by Imco that with all top speeds the same between the two ratio drives.( assume props were obviously changed to match equal top speed) that the 1:5 had a better "rolling torque". Basically the 1:5 would have slightly better acceleration.

Not sure why they say "rolling" when we are talking boats. It also seems slightly puzzling when you think about the gears and prop ratios as just a math formula and why there would be a difference in acceleration. I know with cars the rear end gear and the tire size can be changed to achieve the same results. I guess the prop speed and hydro action make the difference in slip or something. weird.:bong:

Any thoughts?

bblades would probably know the answer

I have 1.33 on number III's with 425hp and 15 3/8 x 26, I can only turn them to 4200 rpm. I am hoping for some more rpm with nickersons carb work? I was told that if I switched them to 1.50 my rpm would probably be about right but I don't know.

Good idea

If Torque is your friend then go 1.5. Generally I/O boats are always faster with 1.5 vs 1.35 or 1.33 if props are available and they are now up to 36" or more. Remember a smaller pitch prop spinning faster mandates each blade to travel through more water per mile therefore more hydrodynamic drag per mile will be less efficient as far as top speed goes. Endurance would be the only reason( other than true back to back test results) to use a lower ratio as that will not multiply the engine torque as much so there is less theoretical propshaft and bearing loading at the (output) propshaft. This seems to be why diesels (high torque) use 1.3 or lower ratios and 2 strokes(low torque) usually need roughly 2.0 ratios. So much for my 2 cents:daz:

Hey Ironman! Do you want to participate in this years Lake George Performance Weekend Offshore Demonstration? Last year we had 3 Pantera's. If so, shoot me a pm.

when is that? how many pantera boats you got coming so far this year?

what happens at an offshore demonstration? Name of a pokerrun or something.....

I think Chris (Ironman) has a valid point in what he was saying about more hydrodynamic drag as it does have to push more blades through the water in a given distance..
I would also imagine part of the reason a 28 single with the average drive height will usually run faster on top end with a proper set up 4 blade than say a 5 or even 6 blade.. There's ofcourse always exceptions due to many variables such as the drive height, weight, & the amount of tourqe the particular rig makes..

I'll add that just having that little bit of extra tourqe multiplication availible to the prop with a 1.5 over a 1.32 at "say" 800 ft lbs. comes out to an additional 112 ft lbs. if my math is correct.. It would make a differance of 14 ft lbs for every 100 that the engine makes.. Even though the prop pitch would be lower running a 1.36 over a 1.5 (lower pitch obviously being easier to push) you are still attempting to push the same diameter prop, which may add to the equation as well..

That being said I'm not so sure I would listen to a dude who doesn't even have a running boat, however I have stayed at a Motel 6 before so ?? :stooges:

I believe both you and Chris are correct. I have talked to many people about this in the past few days. Imco, my engine builder, etc. The consensus is the same. Imco flat out said the acceleration would be sightly less even if the top speeds were the same. My engine builder said I probably wouldn't tell a difference. Pantera said the same. This all came about when I saw the SCX 1:35 pop up for sale last week.

Either way dude, We both know your not exactly lacking in the torque category so you will be just fine with a 1.35... If you put a 1.5 on it you would probably be lighter on the stick through midrange anyways, and that brings all back to equal... ;)

If you were making 550 ft lbs. the story would be a bit different..

In other words quit holding out and post the pics.. haha !!

All jokes aside you indeed have one of the coolest, classiest & cleanest 28's out there period, and I can't wait to here "she's wet againt"

And tell your neighbor "too tall jones" I said: Hello

Too funny......I'm getting closer.

The drive I was looking at sold in less than a day .dang-it :angry-smiley-038:

Tom, how much $ would it have been to change it to a 1.5?

Imco said 2500. to swap gears and set up. I believe it's all done in the lower. Found some used around that price also..

Anyway I'm still looking. Missed a pretty good deal.