28 Skater Repower--- 2.5 race to 300x's
 

After converting from 2.5 Race to 300X engines we put "Dust'n The Wind" in the water this weekend. The engines are still in break-in mode(computer limited RPM)...but I can offer these observations.

The boat feels bigger in mixed chop...because with the larger, lower RPM engines you have a lot more torque and power at 70-90 mph...so we use less trim and run steadily over wakes and holes that we used to rebound off of......Nice change.

I will be putting a few pounds in the nose to offset the added stern weight and leverage from the longer motors.

Top speed numbers to follow after engine break in is complete. Old max speed was 113-116 (depending on conditions).

I think I love these motors..........

T2x

Re: 28 Skater Repower--- 2.5 race to 300x's
 

Big statement for such a one-night stand.

Re: 28 Skater Repower--- 2.5 race to 300x's
 

Rich
Glad to here of the improvments.
Maybe I can come out to LI and catch a ride in that bad boy. We were tied up all weekend and only got out on the boat about a half day Saturday so I never contacted Joey.
Talk to you soon.
Chris

Re: 28 Skater Repower--- 2.5 race to 300x's
 

T2x,

I struggled with the decision 2.5's or 300x's at first. I'm very happy with my X's they shift nicely, run strong throughout the rpm band. These things really scream!!

The only negative that we have had to contend with is Mercury's new algorithms with regards to water pressure. We cant raise the motors to "optimal" speed height due to lack of pressure (anything below 9-10lbs). Also be very careful when they sense low pressure (or any thing else) they go into Guardian Mode NO WARNING just shut down to 3000rpm. So if you are testing at high speeds you may have your hands full (Not fun). Mercury has advised that they are supposed to give you a 4 second warning tone but this has yet to be the case.

Good luck with your new engines

Maximus

Re: 28 Skater Repower--- 2.5 race to 300x's
 

Yep....but I've enjoyed many "one nighters" with various Mercury "ladies" over the years........ and rarely been disappointed.

These things are a hoot.

T2x

Re: 28 Skater Repower--- 2.5 race to 300x's
 

One more thing...... no mixing of oil and gas...... That alone is worth the change.

T2x

Re: 28 Skater Repower--- 2.5 race to 300x's
 

how about being able to shift!!!! My friend with new 2.5's has popped two gear cases shifting his 2004 - 2.5 SS's

These 300x's really have a nice howl to them as well.

M

Re: 28 Skater Repower--- 2.5 race to 300x's
 

I don't know about your friend..... I shifted my 2.5's repeatedly and never had any gear case issues..... with a racheting shifter you get much more impact every time you come in and out of the water at speed than the little impact that occurs while shifting.

T2x

Re: 28 Skater Repower--- 2.5 race to 300x's
 

No pre-mix and able to shift! What a concept! Good luck with the new mills Rich. Can't wait to see her run!

Re: 28 Skater Repower--- 2.5 race to 300x's
 

Keep us informed, Im thinking of doing the same thing.

Curtis

Re: 28 Skater Repower--- 2.5 race to 300x's
 

Okay Curtis...will do.

Warmest regards,

Rich

Re: 28 Skater Repower--- 2.5 race to 300x's
 

Hold on.......The Merc guys said you could shift a 2.5, when he did it They broke....Then he got the wink wink... well maybe you shoulndt shift these things. Whats the real story here, Anyone? What do they idle at? Would solid hub props be the issue/problem. It really seems to be a pain in the ass for him around docks.

Maximus

Re: 28 Skater Repower--- 2.5 race to 300x's
 

2.5 race motors did not have neutral safety switches. 300X's do. The neutral safety switch actually shuts the engine down for a split second so the R's drop when shifting.

Re: 28 Skater Repower--- 2.5 race to 300x's
 

T2X after rigging my 30' motion I added lead shot ballast in the bow. The purpose was to stop the porpoising, Of course it did not fix that problem but the rough water ride greatly improved. I ended up with 4 25lb bags of shot way up in the nose. The speed lost was only about 2mph. Well I ended up building a tunnel tab , the porpoising was elimated and the boat handled the big water like a stern drive hull. Also with certain props top speed increased 1-2mph. I tossed the lead shot in the trash.

Re: 28 Skater Repower--- 2.5 race to 300x's
 

Actually the 2.5 race engines DO have neutral switches.....most of the "smart" guys cut the leads to them..... when you do that you can't shift the units..... unless you slam them into gear..... maybe that is what we're talking about..... a poorly rigged set up. You must also have a good mechanic set your TPI switches so the engines idle at 8-900 RPMs or below. They actually purr like kittens...when done properly.

Tell your buddy to install his cut off switches properly and check his TPI settings.

T2x

Re: 28 Skater Repower--- 2.5 race to 300x's
 

OOPS! I stand corrected. Thanks Rich.

Re: 28 Skater Repower--- 2.5 race to 300x's
 

Your addressing two totally different problems......

1. C/G can only be addressed with weight distribution as it affects the boats stability when airborne.....(A properly balanced boat exits and re-enters the water with the same attack angle and does not "rotate" or drop the stern when aloft.)

2. Porpoising...is most often caused by transitioning from hydrodynamic lift to aerodynamic lift as the tunnel compression begins to lift the boat off of its sponsons without being fully successful. This creates a "hobby horsing" motion that indicates a speed range where neither compression nor bottom lift are fully in control. I agree that a tunnel tab (or a wedge) can be useful in correcting this. But, be very careful...... If the tab closes the tunnel in rough water..... or trips the hull upon re-entry..... the results could be disastrous. One of the items reviewed and not discarded after the Jesse James accident was the fact that the tunnel tab (a brand new item in those days) was in a fairly dramatic(15 degrees) down position ....... it also was quite long .......3 1/2 feet or so.


Be careful

T2x

Re: 28 Skater Repower--- 2.5 race to 300x's
 

Gearcases, shifting, cutouts and shift interrupters. The merc 2.5 and 3.0 motors use the same gearsets. The 3.0 has a larger exhaust cavity in the sportmaster, a different bolt pattern, and a 2 piece drive shaft.
These gearcases are very reliable. Most failures stem from rough water pounding the bearing carriers out of them. Shifting should never cause a failure, and as T2x has stated before, because they ratchet, exits and specially re-entry's hurt them a lot more.
None of the merc hi-per motors have a shift interrupter, this is used on the alpha sterndrives to momentarily cut the ignition while the gear change is being made. All motors come with a cutout, this feature stops the motor from being started in gear. It is a simple remedy, there are 2 wires both yellow with a red stripe exiting your key switch, they go to your shifter, cut and solder them together. This is your starter circuit, you can see where it ends on your powerhead starter solenoid. There is no reason to start your motors in gear!. Proper set up ( idle speed ) is key.

RT

Re: 28 Skater Repower--- 2.5 race to 300x's
 

T2X Thank you for the advice. It is my goal to keep myself and my passengers safe. I am aware there are two different issues at work here. The ballast was a inexpensive experiment. The tunnel tab is very affective in eliminating the porpoising. I do have a indicator on the tab and motors. With very little down angle [maybe 5 degrees] rough water ride is improved as the hull lifts level.
Now get some more time on those new motors add post a full report!

Re: 28 Skater Repower--- 2.5 race to 300x's
 

I love Canadians. :D

T2x

Re: 28 Skater Repower--- 2.5 race to 300x's
 

Rich how much did you sell your 2.5's for ? I saw your post of Scream and Fly. Also how much were the 3.0's ? I would love to stop mixing oil.

Curtis

Re: 28 Skater Repower--- 2.5 race to 300x's
 

Firewalker,

Thank you very much for your response. You seem very knowledgable on this set up. After reading yours and t2x's post we were able to diagnose the problem. The rigging is PERFECT on the boat..the problem is with engine idle speed. They currently idle at 1000-1050 and stall out when adjusted lower. shifting into gear at this level WILL cause damage. The engines are scheduled to be looked at and adjusted by big John of lake x next week.

Thanks for your input.

Maximus

Yahoo...your gonna love thes things... I mght however wait and see what happens with the 4 strokes...That would be the ticket!!! 350hp 4stroke supercharged....Smokin!!

Re: 28 Skater Repower--- 2.5 race to 300x's
 

4 Strokes...... Yuuuuuuuuuuuuuuuuuuck!.

I have drag motors that idle at 7-800 rpm, and make 375 hp, set up, set up set up.
The 280 and 300 X are very civil motors, sadly they won't be around much longer, the last production run for the 280 is August, 225 pro max's are done.

Maximus, thanks!, not bad for a desk jockey EH!. ( I broke A LOT of stuff, it will make you learn fast that way......and I also have a rigging shop).

All these motors ( 260/280/300X ) should last a long time, but they are not perfect, and when they go, they go out in style, as T2x can apparently attest. These motors have ultra low quality parts inside them, reality is they should be replaced. Both the 280 and 300X are 150 hour motors ( MAX ), then they need new pistons, rings and bearings. I re-ring at 75 hours, or 8% leakdown. Good oil, and good warm up and cool down also help. ( try AliSyn oil ).

Re: 28 Skater Repower--- 2.5 race to 300x's
 

just go i/o and rebuild every 400 hrs instead Rob:)

Re: 28 Skater Repower--- 2.5 race to 300x's
 

I dont think 4 strokes will be the answer, too much weight. Weight savings is what makes the OB's competitive against sterndrive power. Nothing better than to see a twin engine OB cat smoke a single blower motor cat, IMO.

Re: 28 Skater Repower--- 2.5 race to 300x's
 

ok i have a ? my buddy just did the same change and ordered these props
3 blade 14.5 34 cleaver's labbed
is this a good way to go??????????????

Re: 28 Skater Repower--- 2.5 race to 300x's
 

those propps should be what is needed

Re: 28 Skater Repower--- 2.5 race to 300x's
 

hey Ryan did you get my e-mail?

maximus

Re: 28 Skater Repower--- 2.5 race to 300x's
 

I just blew up a lower unit on my 98 Pro Max 300 (Fleetmaster). The gear case cracked by the carrier, threw the carrier, prop shaft and prop right out. Is this common ? Also I have well over 250 hrs on my motors and haven't had major problems as of yet. They seem to be running strong and compression was ok last time we checked it a few months ago. I realize they are not x's but does the rebuilds every 150 hrs apply to these motors as well ?

Re: 28 Skater Repower--- 2.5 race to 300x's
 

250, I would be looking at rebuilding them. Check the leakdown. Compression tells you nothing!.
The 300 Pro Max is a low rpm motor, rpm kills that is why the 300x don't last as long.

RT

Re: 28 Skater Repower--- 2.5 race to 300x's
 

Im sorry maybe Im missing something, I thought there was only the Pro Max 300x. Is there another 300 ?

Is the weight diff significant ? 480 for 300x vs 401 2.5 efi

Another question the Verado is 635 lbs, but that includes the steering, does it also include the trim pumps ?

Something to ponder on a Monday.

Rich, why did you check out the verado ?

Curtis

Re: 28 Skater Repower--- 2.5 race to 300x's
 

Before the 300X was the 300 Pro Max.

My 300 weighed in at 498 lbs with no cowling and no trim pump.......the 2.5 at 401 is about right with no trim pump.

No idea on the Vercrappo yet.

RT

Re: 28 Skater Repower--- 2.5 race to 300x's
 

How were the 300 Pro Max's. There is a 28 Skater with '99 300 Pro Max's that looks interesting but I have know idea about the motors.
What are rebuild intervals?
Are they strong motors?
What HP?

Re: 28 Skater Repower--- 2.5 race to 300x's
 

They are about 290 hp vs 320 for the X, last about twice as lone before a rebuild, lower RPM band also. Limited to 6250 rpm.

RT

Re: 28 Skater Repower--- 2.5 race to 300x's
 

On the spec sheet from Merc the Pro Max 300x has 300 HP. Also it states it weighs 480lbs with the 20 inch shaft and the Torque master gearcase. I think the Sport Master would be heavier because of the prop shaft.

Curtis

Re: 28 Skater Repower--- 2.5 race to 300x's
 

I haven't had any major issues with mine except the gear cases. Other than that they have been solid.

Re: 28 Skater Repower--- 2.5 race to 300x's
 

Most of the X's are dyno-ing in between 315 and 329 hp and while the redline says 6800 they will run up to 7200.....at least my new 04's do.

I heard the 2.5's are unavailable, out of stock at this point.

Re: 28 Skater Repower--- 2.5 race to 300x's
 

I agree with just about everything Firewalker has written...... except for the 4 stroke part..... and even there I understand his point of view and have a sentimental place in my own heart for the older 2 strokes. However, we don't seem to have a choice about keeping 2 strokes since the EPA now controls most engine design projects. I believe that Mercury will find a way to make the Verado more performance friendly.....and hopefully a bit lighter..... Certainly 4 stroke development is at a fever pitch worldwide......so it's only a matter of time...and dollars.

T2x

P.S. We came out of break in...... but still have some gentle hours to put on the motors before any extended W.O.T. In spite of that after I ran the boat for about an hour yesterday in rainy wind squalls on Great South Bay (4000-6000 RPM (70-100+mph)..... on a nasty chop.....and was drying off on the beach,....Joey Imprescia jumped in and posted 116.8 mph on my GPS (simply to eclipse the old numbers).....while being careful not to let the motors wind out....... (63-6500 and climbing before pulling back on the throttles)......

34" pitch..... Diameter 14 7/8"....half tanks...bad cross winds ...... mixed 12-24" chop...Temperature 62 degrees F...light rain....1-2 degrees negative trim (The old motors would have struggled to break 110 in those conditions....as they needed relatively flat water to get over 105-110).

I repeat..... I think I love these motors.... We'll post a final top speed when the engines have over 18 hours apiece on them (approx. 4 at present.)

T2x

Re: 28 Skater Repower--- 2.5 race to 300x's
 

Curtis I don't think the Verado is ready for 100+ mph speeds yet..........

Maybe next year...... The development program is the first outboard project at the new Site X...... I'm keeping tabs on it.

T2x

Re: 28 Skater Repower--- 2.5 race to 300x's
 

The boat ran 119 Saturday Morning....not bad considering not holding her wide open over a few seconds...... and having a Port motor cooling issue......

Temperature 72 degrees..... moderate humidity..... light 2" chop...... 6600 RPM.


T2x