prop decisions

[Speedman]

I just don't get it, from what I have read on props, it seems like everyboat runs a little different and you have to balance and tweak everything to get the max out of a prop, Some guys want holeshot, some carry heavy loads, some want all out top end, soem lift the bow, some lift the stern. :? :?

So here'e my story...94 xb2002, 97 225 fresh rebuild, Marhles cut and top pinned the pistons, balance rods, new everything. still running the rev limiter at 6750. I have a 28 ron hill 3 blade and a 29 SRX. I don't care about take off cause even with a fully fishing loaded boat, with the Ally foil on, I get on plane fast than any other boat I have seen including my buddies flat bottom v-8 jet boat! What I don't get is you guys with all of those 260 and 280's out there running like 26 pitch props at 8k? I don't get it? With the extra HP what happens if you put on a 32? If I can run to the limiter with 29 and you all got way more HP, how come you run those small props? Marhles reccomend I keep the limiter where it is, but will be able to run a bigger prop so I will look for a 30 or 31, any reccomendations? Remember all I want is top end!! The 28 definatley handles diff and is actually easier to drive but 3-4 mph slower, it does get on plane faster but that is no help in a tournie. I usually use it when the family of 4 and all the crap my wife brings weighs the boat down, but again, with the Allyfoil on, it still hops on plane and will run like 16 mph on plane! Up here, there are not many gofast boats so I have no group of buddies to switch back and forth. what do you think I should try, thanks

 

[FLYING BUTCHER]

rpms

to try to keep it simple your 225 is just plain a different animal than a 260 or 280, I have had one and she would pull a 30 chopper 11 to the limiter, now take a 260 or 280 and they like smaller props and higher rpms, they develop their power at way over the 6750 rpms They are ported and many other differences over your 225. If you have all that done to your engine and want top end with the rev limiter still on you are going to have to go to a much bigger prop. I really liked the 30 chopper 11. The 260s and 280 I have had really like a smaller prop my two cents

 

[whipper]

gears

Speedman the difference is the gear ratio. Yours is a 1.87 . There are other options in ratio for 250-260-SS-Drag-280 ect. Also some turn 9000+ some have limitters and some are tuned with out. A drag moter can turn 9-10000 with a 26 pitch and run 107 in a 1000ft or less! With a real good driver if they put on a 30 120+!!! in a 2002. Hence the world record holder in Bass boat unlimmited David Shook he puts a big wheel on for those numbers! Because they can spin higher rpm they can run smaller props and get unreal hole shots and top end numbers. If we put a 23-24 pich on we would get a great hole shot but hit the limmiter at around 70 or so. They have 2000-3000+ rpm still to burn. Gears/moter/varyables. James

 

[ziemer]

Re: gears

Speedman the difference is the gear ratio. Yours is a 1.87 and 260 I believe is 1.62 or lower.

Actually, most of the 260's/280's drag's etc. come from the factory with the 1.87 gears. I believe only the 3.0 liters have the option of the 1.62's. Your choices with the 2.5's is 1.75, 1.87, & 2:1.

I run a 28 with my 260, and it'll turn that in the low to mid 8000's. With good oil and a well built 2.5, 8000 on occasion isn't hurting the motor, they were built to turn the higher RPM's.

Don't forget a stock 280, with consumer ECU is rev limited to 7750, and the offshore ECU is at 8250. That's 1000 RPM's over your p-max. (My lake box is rev limited to 8250, and that put's me at about 102, just before I'm bouncing off the limiter, not fun by the way. :shock: :shock: :grin: )

 

[whipper]

Prop

Thanks Ziemer I just woke up then. At work working hard now cant ya tell. Speedman if play around with the prop calculator in the racers thread sticky. {link provided} You can figure out all the speeds/rpm use around 6-9 for slip. James

 

[whipper]

rpm

There is no advantage to tweeking the ECU or new one to accomidate say 7500 revs out a 1.87,225 PM from the 6750 stock limitter is there. The HP and gearing if the same can spin a 30 chopper to 6500 so to use the higher RPM I would be going down in pitch witch offsets any potential gain of a modified ECU unless I was gainning more HP also, correct? James

 

[chad202]

I've always read and heard and witnessed with my 225 promax that they like to turn 7000-7200 rpm. Mine really liked to be propped for that rpm. I had my limiter set to 7500 but propped it for 7200. My slightly warmed up promax turn a 29 RL cut chopper around 6900 rpm and 93+mph. My 260 drop on powerhead which had 1" intake spacer and 33cc heads spins the same prop 7300rpm and 99+.

 

[whipper]

Chad

I hear ya Chad but with a good 30 chopper at 6400rpm you can get the same top end with the 225PM 93mph. All as I mean is if ya want more top speed you will need more power. If you spin a smaller wheel at a higher rpm your top speed will be the same as a bigger wheel at a lower rpm because to get faster youll need more power to spin the bigger wheel to the higher rpm for more top speed with a 225pm. I see the only advantage to more RPM than stock 6750 being better hole shot with top end props because you can spin a lower pitch.That is a big plus though dont get me wrong I would love to have the extra grut outa the hole and still reach the top end numbers for that power range. It kinda gets ya closer to that perfict balance. Thats it, I want a bigger moter now! :cry: James

 

[propmanjay]

RPM'S

RPM'S are a real advantage, with a 26" I turn 8800 with my 260 and about 9200 with a 24". They run close on the top but the punch differince is alot. I also have a 28 " that I use to run but even for a lake prop the loss of that punch is big so I run my 26". The 26" gives me a compromise good punch and 104.9 on top.

 

[Speedman]

so if you can turn a 24 at 8600 rpm's why not turn like a 32 pitch? if your motor has the Hp, you should be able to do 130? I know my holeshot is fine with a 29 and a 225, so if you got an 9k rpm motor with almost 300 hp. shouldn't that make the hole shot even better all while getting more top end?

 

[propmanjay]

port's

It is a matter of porting, the 260,280,and 300 don't have as wide of a power band as the 225. They require a higher rpm to build the horse power because of the porting. You can lug them with too big of a prop. If they are on a light boat and can turn 7500 or more with a large pitch they will run big number's. As far as acceleration I thought mine with a 28" was a freek ripping out of the hole. Then I ran a 24" and all I could say is wow. The punch is addicting.

 

[Bill Kemp]

with two boats that run the same top end speed the one with smaller pitch prop and high rpms will get to the topend speed first and the other boat will never catch up thats the advanage of the smaller pitch and high rpm. i changed from a 27 trophy to a 24 predator still have the same top end but with more rpm motor seems to like it sounds alot better

 

[Speedman]

So if you are looking at absolute top speed and don't care about hole shot, than you should find the largest prop that will turn the max rpm. and If you can't get to the max rpm than the prop is too big. Ex, if my 29 srx can only get to 6500 on my 225 promax (6750 limiter) than if I run a smallier prop, I would get a better hole shot and at least if not faster speed at 6750 on the limiter, but if I can go all the way to the limiter with both props, then the 29 would be better top end, right?

 

[whipper]

Have you tried a 30 speedman. With a 30 you will get in the 90,s witha 225 promax. I get there with a 30 chopper, I would talk to Tod at Hydromotive I did yesterday like every one seems to say great guy and he will set you up with the fastest prop for your set up. He has an Allison also as a test boat and had a 225 on it now running a 260. So he has 225 knowledge and a real good policy if ya dont like what he sends ya and a 1 year warrenty on most of the props. The prices arnt bad either. Im steering toward a 4 blade in a 30 from Todd the one like 2fast4mom was talking about with the 15 inch hub. I wont loose very much top end at all and have all the versatility of a 4 blade. The 3 blade will only be 1,2,or 3 mph more at the most. A 4 blade will be much more efficiant over the 3 aswell way less slip so more mid range ect.. James

 

[chad202]

It's not just the holeshot that we like about the 260, 280, and 300, it's the accelleration. Typically, once you feel it, you're hooked. I know I was. :grin:

 

[propmanjay]

PUNCH

Amen!

 

[whipper]

Chad if I could afford a 300x thats what I would be hanging on my GSE. :mrgreen: The next motor I buy will be a 300 for sure. I just cant let the wife know that I do love the power curve of the 225 Promax but I use all of this motor all of the time. It would be nice to have a motor that Im not maxed out on every day. I had a 1000 ninja that had power to spare it was capable of 180 mph+. I never had it over 150. But if the time was right it was there. Thats what I mean I guess. Now that I can drive my boat well I feel the need for more speed! I went 100 on a texas tunnel this summer it had a highly modified 2.5 and that was prety fast, I was very comfortable the second time I did it. I beleive I can achieve this with the 225 with an ACU,SVS, and the right prop. But like you said its the acceleration with the high revers that are the ticket.I would be spinning a 31 to get those speeds with mods. Where a stock 260 and a 26 will get me there.Big differance in pitch! Did I mention I love Allisons. My wife thinks I have a new girl friend and I think shes right I just sit and stare at her sexy curves all day long. I go out in the garage an sit in her when I cant go out and talk to her about our next outing. Is there something wrong with that :mrgreen: I guess after 5 years with a GSE as my screen saver and finely getting one in the garage and going 8000 miles round trip to get her I am a little obsested. My wife and kids love her too. :grin: Allisons Rule! James

 

[John Richied]

Speedman… I would remove the rev limiter on your 1997 freshly rebuilt 225/XB-2002…

I use to run a stock 1996 225 Promax on my XB-2002 and with a 29 SRX I could run about 94.4 mph… with a 30 pitch Lighting ET 96.6 mph.

I did more then one thing at a time but with the rev limiter removed and a 30 pitch ET the only thing holding your boat back is the rev limiter… light loaded she will run 100!!

 

[baitcaster]

Hey guys, found the posts interesting and informative.

 

[Speedman]

So John, 94 with a 400.00 SRX or 96 with, what everyone here considers the holy graile of props, the Lightning ET at $1000.00, It aint worth a grand for 2 mph! what do you think? and why does everyone like quad 4's? How much top end is really lost on a 4 blade vs 3? I don't care about holeshot, midrange, acceleration, or handling, just top end!