The 300 xperiment
 

Well after many years of bs about how much faster a 300x is over a 300xs I decided to find out for myself. Not that I needed another project. I know it will be faster but the question remains how much faster. There are different years supposedly better than others etc. I went ahead and bought a set of motors with the intentions of doing a complete overhaul. I totally disassembled them and have inspected all parts and components. I have begun the reassembly process with the clamp brackets and mids. They were stripped down to the metal, Rebuilt with all new components and repainted by Supreme Marine in Ft. Lauderdale. I have installed the exhaust temp probes in the exhaust plate and replaced the poppets.
The short blocks are almost done getting new pistons, rings, bearings, 1 new crankshaft, a few rods and good clean up.
I will keep you guys posted with the progress. I will be using my 300xs cowlings in place of the old style x ones. Eliminating the need to rerig the back of the boat.

I guess all Skaters are projects haha. Hope you reach the numbers you have in mind.

Yep, you need bigger power to haul amplifiers, stereos, woofers, speakers, night vision, dash panels, windshields, huge chart plotter, and140 gallons of gas. Just kidding ole bud, you have a beautiful Skater and are building some very fine engines. Your work is always excellent. Carry on.

Now if I could get one of those very cool Skater T shirts.........

This should be very interesting.

So you are rebuilding two sets of engines. Are you doing the rebuilds. If not you have deep pockets of cash. Thought 300x have 20 or so more hp from factory. Figure they would win the battle.

I'm on the fence on giving up the 2.5 OS lu/mid
platform and going to the 3 ltr. Get me motivated! I'm subscribed!

The Talon Guy until I can afford bigger!

It's a disease in general. Not brand specific. Lol! I spent $250.00 in fuel yesterday and loved every mile!

Great project youve got going on Ron
Did you have corrosion issues when tearing down the midsections?
The torch became my best friend when I disassembled my 2.5s
It looks like you're restoring better than new, i appreciate the hard work involved in a project like this, way to go!

Regarding the questions, I am doing the rebuilds myself but with some help from Guy at TNT. He is one of the best Mercury outboard guys around. Has seen it all in his day. My company does a lot work with TNT and their guys are all great. I try and do everything myself but looked to him to assist with the inspection and reassembly of the blocks. I am also buying all parts through them.
David, I was lucky in the fact the motors came from a fresh water boat and not too much corrosion. Only had to use the torch a couple of times.
I will have a bunch of used parts for sale soon that will still be good for someone on a budget. I really believe these motors will be better than new.

his will would cool to watch. Have you considered using the 3.2 stroker cranks in the 300x motors. I know simon has built some stroker efi 3.0 based motors that make 375hp or more.

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DR,

awesome thread!


what size mids will you use?






.

two 375hp outboards would be nice to have on my 308!!!

I did a lot of research on mods etc. There are a lot of engines guys out there with their own opinions. The only thing that mattered to me was facts and MPH that was documented and not bs. Skater Jim posted a big number at LOTO last year. He is not running 3.2 cranks. Other boats I know of that had engines built by someone etc did not fair well. In talking to Joe at DBR the 300x requires a lot of port work to make a 3.2 crank work effectively. I am opting for higher RPM versus stroke. I also do not want a pair of hand grenades. I want reliable HP and not something that needs race fuel. Motors will run on 93 octane.
NOLI
I am using 20" mids. Being that I boat in the ocean 15"s might allow water in the cylinders. Other than some CG I do not see the value other than a cool factor. I know a 28 with a stock 300x set up and good conditions, weight etc should run 118mph or so.

How many hrs on the 300x core engines,salt water?. When you pull them apart please post were you have found severe or even mild ware. What was wrong with the crankshaft?

Hey double I have a set of perfect 2005 x motors .let me know what parts you have left over always looking for good spare parts .thanks

Any of you fellas going to the shoot out this year ?

Andy, The motors were came from fresh water use. Corrosion was not bad. They had approximately 230hrs on them. They still had good compression. The reed cages had lost a lot of the rubber where the reeds hit. Also the edges on the reeds were burnt. Personally I would have reused the crankshaft but Guy found a little wear he was not happy with so we went ahead and replaced it. He knows that I want these motors as close to new and perfect as we can get them not trying to save any money. I have also had all the injectors tested and cleaned. All came back good. Another funny thing was we found the rubber velocity stack down inside the throttle body.

Tom, I will have some parts for sure. Most them in decent condition. I have pistons a couple of rods, a crankshaft, used set of cowlings
If you are interested send me a pm and I can send you some pics.

I'll be there as well as David with his 36' quad

I'm there but still not with a Skater taking the Midnight or Avance.

any updates?





.

Here are some pics from today. Got one short block back from TNT and have started reassembly of starboard motor. Painted and polished thermostat housings. Waiting for new thermostats and gaskets. Painted starter brackets/starter. Installed new alt bracket/bushings. Install all new bleed lines stbd side on polished fittings and secured with tywraps. Install computer/oil tank. Lastly also got injectors back from being tested/cleaned and calibrated. Installed in fuel rail/reed plate. Still waiting on some gaskets to complete instalation of the intake. More parts to clean, bolts/fittings to polish and paint work!!!!
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I;m going to check that one out tomorrow. One of my engines has one other doesn't. Wondered were it went!

Stock reeds and cages? Am getting my injectors flowed also, seems like cheap insurance.

Yes. When I took the motors apart I found some of the reeds burnt on the ends. The other thing to look for is that he rubber around the outer part of the cage starts to get eaten away. This does not allow the reed to seal and motor starts to run a little rough at idle. There are some options out there but the Mercury ones are carbor fiber also and with the rubber seals we thought they would work best. Some of the guys are machining the Mercury cages and removing the rubber coating and installing aftermarket reeds to save some money. The Mercury ones are expensive. If you need any let me know. From both motors I have enough for a good used set to sell.

DR,

lots of good info!

if it isn't too much work, I'd luv to see the burnt ends...please take pics of old parts vs. new parts

just tryin' to learn t'is all :)

Very good work. Lots of attention to detail, that is necessary for longevity. Good thread.
Is that workshop / storage facility Air Conditioned? It sure is hot outside8-)

I'm somewhat new to outboard wrenching so...is it a quick and fairly easy swap form 300xs to 300x power head??? or do you have to do mids etc???

Craig, It is easier to go from a 300x to a 300xs. The tuner for the xs is different than the x along with the mid section. Both blocks have the same bolt pattern. All the power of the x is in the porting and exhaust. If you wanted to switch you would need a x mid section. DBR sells a tuner that is designed for the 300xs and will fit the x mid or 15" Wayne Taylor like Rayzor did. DBR is going to have a level 2 kit for the Optimax at some point. Not sure exactly what that will be exactly yet but a throttle body and tuner are for sure. If your xs motors have the offshore clamp brackets they will accept the 300x mid with no mods.
You can also run a xs cowling on a x engine also. I will be using my Nass cowlings. The big question is do we gain 10mph like everyone says! I will know the answer to that pretty soon.

thanks Ron

we will be wanting to know what the outcome is for sure :cool-smiley-011:

He been quiet, must be working on it :)

As a matter of fact I have been!!!
Installed tuner on exhaust plate and mounted. Installed mid section to clamp bracket. Ready for powerhead.
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Also before and after of the throttle body. Primed, painted and polish all bolts. Installed reed cage with throttle body.
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Cowling Trouble
 

Well was getting close to have one motor complete. After we had fit the 300xs pans to the mid section all looked good until I tried it again with the powerhead set on the mid. Rear section fit good but the front part would not close up. It hit the Intake???? After some close inspection on my XS's we determined the reed block on the X motor is about an 1" thicker thus pusing the intake more forward. Now I am in the process of repainting 300x cowlings and baseplates before being able to finish this motor. Oh well the $$$ keep going!
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[ATTACH=CONFIG]528690[/ATTACH][ATTACH=CONFIG]528691[/ATTACH][ATTACH=CONFIG]528692[/ATTACH]Pics from this weekend. Installed wire harness and rerouted/clamped factory cabling. Finalize fuel system. Just need to splice 14pin connector on harness and install cowling pan. One done one to go.

:D looking good

Motors Nearing Completion
 

Motors pretty much done. Just need to splice 14 pin harness. Waiting on cowlings from painter. Found bad linkage on throttle body during checks also. Will start preparing for swap over next
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lookin good your gunna be happy when u slam those throttles down

Newly painted cowlings with custom decals to match paint scheme. Ryan (Kinetic Animation) did an awesome job as usual! Also thanks to Lightspeed for the nice stainelss steel rig tube adaptors. They have a backing plate also. Steering plates new by Latham Marine.
Just need to finalize harness and hope to start them up this weekend on the stand and pray the smart craft works!

Looks great. We want a full report! Good luck

Yes with video too!