Over Hub Props

[Lightning]

I have a GS with a 2.5XS and it had a 26 Trophy Plus on it when I bought it. It runs good all around with this prop, but it hits the rev limiter at 7K at right at 90. So I buy a 14 1/2" 28P lab finished Mercury Lightning ET for top end expecting it to get off the limiter and a few more mph. It's slower out the hole, mid range feels about the same and it still hits the rev limit and it's slower!!! Is 7K not enough RPM to get over the slip from the exhaust going over the blades? I've never tried another prop on it, until this one, and I'm disappointed with it to say the least. I think I spent alot of money on a prop that just makes it look better on the trailer!!!

 

[BP1]

Have you experimented with engine height at all?
Might like to run higher up than the trophy.

 

[Lightning]

Have a hydraulic plate. Moved it around and the best speed was slower than the Trophy Plus.

 

[whipper]

That is that saying you cant try to many props. Ive had an experiance like that also. I had two 28 drag 4s at the same time and they both ran competly differant! Personaly I gave up on 3 blade props for my GS. I unlike a lot of folks love the way the trophys work with the 225 and a GS. Darris even is a trophy kinda guy on GS,s. The 27 Alli cut I really like. You might need to get the ET worked by a reputable Allison Prop man to make it work better on a GS? I havent had to much luck with the ET cut I had. Wasnt a true ET mind you. It was cut from a Chopper. If you like your Trophy then youll love one of Todds 28OT,s When he had the 225 on his GS he said the TX4 that he polished with all the bells and whistles was a great runner also. You might ask Ziemer if he run ets with his GS and if they needed to be worked for best results? Some good props just need a little tweek to run great. Espectialy with Allisons because of the high shaft hights we run. After many many props last year I ended up with the 27 Alli cut and a special 28 Drag4 as the only keepers. I still need one of Todds high quality Hydromotives when I can afford it. I had a couple now but they werent the ones for me. The TX4 all done up is one i dream off.:big grin Pinky though not a GS owner runs pretty much only ET,s. He had a 225 before also on his 02. Im sure he has had many stock and worked and could tell ya the differances how they run for comparisen.

 

[BP1]

Have a hydraulic plate. Moved it around and the best speed was slower than the Trophy Plus.

Hopefully a GS owner will chime in here with real advice.
Best of luck.

 

[GotMyAlly]

Have you experimented with engine height at all?
Might like to run higher up than the trophy.

My experience with over hub 3 blades vs over/thru 4 blades was that the over hub 3 blades need to run deeper to hook up. The slip numbers were higher on the over hub if ran at the same height.

 

[BP1]

my experience with over hub 3 blades vs over/thru 4 blades was that the over hub 3 blades need to run deeper to hook up. The slip numbers were higher on the over hub if ran at the same height.

Was just suggesting.
Anyway...

have a hydraulic plate. Moved it around and the best speed was slower than the trophy plus.

 

[harrells]

I've got a GS with a 3.0L and run all Hydromotives, 26ot,28ot and gonna try the 30ot as soon as the weather permits, hopefully easter break. My deal with the 3.0L is it has so much torque i use the blow out ring and i plug the holes on the 26 and 28 and it still spins up real quick out of the hole. Not really comparing apples to apples though with the 2.5L. Give Todd at Hydromotive a call. I've run a couple of trophies, but the Hydro's are much better in every way, bottom,middle and top end.

 

[Darth VMAX]

Not sure if this is any sort of factor or not. You have a very rare motor. The 2.5xs weighs (450lbs). Between a 400lb(ish) 225 Promax and the 500lb(ish) 3.0L You have 225 Promax hp and torque but with an extra 50 lbs. As weight sensative as these boats are that may be effecting the performance with various props.

You might call Todd and see if he can come up with something.

 

[whipper]

I would think just based on the design of the ET they would need some cup added to run best on a GS. The props that work best and that Ive had worked for my GS always ran better with a little more cup. Just an obsevation but most of the guys I know that love the ET are high revers. They may realy need to get spun to work best? Thats why a little cup has helped and always worked for me only spinning to low 7,s. The Bullit cut props ive had were a little to much cup so something in the middle from stock is what Ive always had done and worked best. Not sure if theres an Allison cut for a ET? I like both types of props on my boat. Over and under no real prefrance. Had both types that worked great. Just had to find the one that worked. Thats the hard part. Lots of testing at differant hights. If ya still cant find the sweet spot you might need to have it tweeked.

 

[catfish123]

Although I have an XB2003 with a 225X, I have a fair amount of experience with ET's in various pitches, 26,28, and 30 as well as 25 and 26 pitch Trophys. How much slower on top end was the 28 ET? At 7000 rpm's assuming 1.87 gear ratio, you should definitely be running faster than 90 and it sounds like you aren't even hitting that? I have had the limiter at the original 6850 and now at 7300. At 6850, the ET was hitting about 91 into the limiter and 7000 would have put it at around 93 or a bit higher.I know your boat and motor are slightly different but comparatively, I would certainly expect more speed from the 28 ET than you are apparently getting. I have had excellent results with both ET's and Chopper II's. On top end with 30 pitch in each of these, the speed was nearly identical.

 

[whipper]

CATFISH were your ET,s box stock or worked at all?

 

[catfish123]

I have run both stock and worked ET's with similar results. The worked ones may have handled a little better with less steering torque, etc, but top end speeds were about the same.

 

[whipper]

Have you experimented with engine height at all?
Might like to run higher up than the trophy.

From what Ive read so far this may be what it needs also what DARTH said. For sure it will need to be run higher than a trophy. Lightning whens the last time you checked your prop shaft hight to your gauage? Any chopper/ cleaver style is going to want to run half in half out. Stock Trophys like 1/4 below and accually loose a MPH or so run the same hight as a Chopper should be unless its an Ali cut. The ali cuts like to run as high as a Chopper. Im running even with the pad and some times a little above 1/4 above. My motor according to my manual says its 350 lbs. If your motor is over 400 LBs to achieve the same results as my GS as an example you will need to do one of two things in my opinion. Run an even higher prop shaft hight OR off set the extra LBS by adding the differance in the bow. You also could run less setback. When your changing the setup you have to be EXTREMLY Carfull!!! I changed my setup last fall and have run the new setup only 10 times or so. I raised my motor so I can run it 1inch above if I want. Way to high for most. I also took some lip off thats why. So far the tests Ive run were awsome!! Picked up several MPH even at my Altidude. Running a 27 Trophy over 90 at 2500ft with 225PM.

That would be 95ish at sealevel.

The only thing I can figure is your running it to deep. That can be because of the wieght of your engine if your running even already. Take thing advice caoutiously because i dont want you to get hurt. {But if you realy feel the need for speed do so at your own risk.} I would start simply by adding 30-40LBS to the bow forward of the foot rest. You could take your balast from the side and try moving it forward if its not all the way, but youll need more weight for the offset balance point the further you go forward if your also trying to compinsate for extra stern wieght. I put my lead shot in the port gunnels from under the bow threw that little hole below the glovebox. I would use the same wieght you have then add 50 lbs in the center forward of the foot rest. With your engine setup the way you have it see if that picked you up some speed jsut by adding forward weight. If it does then you might not have to do anything else. Theres way more to this but thats a simple test to see if you can get the stern to run higher so your even with the pad so your propshaft hight is accually getting surfaced the way that prop is intended because of the extra motor wieght. Take it slow and try to realy feel whats going on back there with dead calm water for testing. If you picked up speed then theres lots of ways to accompish setup but i would just see if changing your fulcrum point to were the boats were designed to run helps this way first. You might need more wieght than 30-40lbs?? Youll have to test it and determan that for yourself. I know when I was seting up the offset for my weight i added 2-5 lb dumbells at a time untill i had exactly what I needed no more and no less. What your doing is what some of the guys with 3.0LT are doing but there motors are 50 lbs more again. Some use less setback and others are just adding wieght to the bow with good results. Dont do this if your not confortable trying it!! This is what I would try but any sign of the bow dropping or listing I would lower the motor and try again. Also if your to the floor and your rpm,s go up even the slightest and you dont pick up even .2 of a mph your at the limit with trim for that prop hight hight. Be Safe.

 

[catfish123]

I think he has referred to getting less than 90 at 7000 rpm's with a 28 pitch.

 

[whipper]

I think he has referred to getting less than 90 at 7000 rpm's with a 28 pitch.

:big grin There should be MPH there still at 7000 I would expect 92-93 would be a conservitive number. That differance Ill bet comes with a little weight forward and even with the pad.

 

[RedAllison]

I think I spent alot of money on a prop that just makes it look better on the trailer!!!

lol NOW you know why most prefer over/hubs. :big grin

Tie a rope around the Trophy and you'll have a nice purty anchor. Sell that ET here or on S&F and with some of that cash have Todd Bucknell build you a QIV OT that will do it ALL + drive and run better. :beer:

Never have cared what they LOOK like, only what they PERFORM like!!! :wink
RA

 

[catfish123]

I agree Whipper.....with the 28 ET at 7000, I would expect at least 92-93.

 

[RedAllison]

I didn't think a 2.5XS would even turn 7k???


RA

 

[GotMyAlly]

If he's turning 7k but not getting the speed, I would think it's because the prop is slipping. Dropping it down may help it bite better and reduce the slip %. Going up will gain you RPM, but if he's already turning 7k....he doesn't need any more R's. I'm thinking the prop is slipping a lot.