Da*****rcury
Is this what you speak of....:) I must say I loved the boat at first with the quads, looks we're hard to beat, boat ran 137mph and consistently 130 ish, sound at WOT was insane and sounded like a small fleet of champ boats. The downside for me however outweighed the positive. Fuel consumption was very high, was not pleasant in the ocean, needed 80-82mph to "pop". If I was running mostly inland water I probably would have kept the quads but that's not the type of water we ran in. The boat was 100% better with the twins
http://i433.photobucket.com/albums/q...ps8e485ce6.jpg

My 32a had triple 300's when I got it, eventually repowered w/2 300xs's. much better overall boat.

Three years ago when I started considering a build to replace my 28' the 32B flat deck with triple 300XS or twin DBR highly modified 300Xs where my first choice for power. Pete loves outboard boats but hates triples. He made it very clear he did not want to build a triple. Next we looked into DBR mods but Dave got hurt so we went with inboards and a 338 build

Now I've come back full circle to what I grew up with and could not be happier. I cannot believe how well the 308 runs with stock 300XS and the fuel economy it's nuts compared to a 300X. Is it a 28 with the acceleration and speed? No but I can't wait to see what she will do in some serious water. It's a tank with the huge tunnel.

So..... With triples out then who has modified a 300XS and what works? Definitely the billet seal kits and vent are on the to do list. How about DBR kits. Who has done one and what's the performance and reliability? Advantages disadvantages? Any others out there like Simon and Diamond doing 300XS mods?

Is a 110mph twin 300XS 308 or 32 build possible?

Does anyone have more photos of the flatdeck with triples? I've seen a few small photos of it, but never any decent shots.

I think 110+ is possible:

[Reference: Offshoreonly; "Mixing in Some Pleasure"]

"...the catamaran recently ran 107 mph without any dialing in or prop testing, according to Ballough."

Note: his 32 is all carbon, cut low, wide body

http://www.offshoreonly.com/articles...-some-pleasure




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I took the counter weights off, removed the silencer foam under the cowls and had Rapair flash my PCM's. Couple of MPH faster and a noticeable increase in acceleration

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tzr, would you have pics or a thread , would luv to learn

Noli
Yes just follow this thread

Noli, some other mods I have done.....,I did the Wayne Taylor, vertical and shift shaft billet bearing seal kit, keep it sealed down and check gear case lube, every time after a weekend run , custom exhaust tuner,it added some power and....my 300XS sounds a lot better....not as good as my 2.5s sounded,....but definitely better sounding than stock 300XS. Bumped up the rev limiter, still reving in factory specs . Lightened Flywheel, crossover for water distribution in turns, and custom side water dump to avoid water back spray on motors. And as Paul said removed the foam insulation on top of the motor.

Paul, I really liked your 32b quad set up. Just wondering
What where your rpm, prop pitch and gear ratio running at 137 ? I'd love to know more about what the prop shaft height and engine spacing too if you don't mind sharing :)

Steve,
Do you have any issues with the motors stalling when shifting in and out of gear. When I played around with the flywheels from DBR we were doing some testing but I did not like the fact the motors stalled from time to time while trying to dock.
Are your aluminum or just cut with dampner removed?
I have seen the dyno run with the Hydra tec tuner on the 250xs and it did work pretty good. They have not tested it with the 300xs. DBR says they did not see any gains with the tuner nor did Adam who did a ton of testing on a single engine talon over on scream and fly. Also if you look at the HP curve the motors really fall off over 6150 rpm. Do you know who sells the taylor tuners?
Thanks

I think 110mph will be a tough number to reach with a 300xs with normal everyday, real world conditions and temps. Not a flat out run with 5 gallons of gas, 30 knot down wind, 5 knot current and 40 degree temps LOL
And to add more insult if you run down here in the high humidity you will loose another couple of MPHs.
I will know in the future if the 300x is that much better than opti. I not sure how far I will take the motors but really want to run them in a stock configuration first to see the real difference for myself with my set up on my boat. The compressor on the opti eats about 20hp according to DBR. The 300xs stock is around 305hp. I have heard numbers for the 300x anywhere from 325hp to as much as 340hp.
Bob says his 30' Skater ran 112 set on kill. That equates to 108 real world with 300x's.
What are you guys seeing with the 300xs configuration?
Lastly Noli, You cant use the 32' Gary has as it is totally different hull configuration and weight set up. He has run 110mph light from what I heard.

you guys blew this thread up with info LOL.

looking like we are limited...very limited at this point with the 300xs's. the milky gear case oil has a fix, we just need some REAL hp gain mods for these engines.

skate it think at this point with the 308's with 300xs's, upper 90's is going to be our everyday #'s. I'm confidant that 105 is there in good conditions though. I'd like to be able to run 100-102 consistently. guessing you will run 3 mph faster than that so there's our 105 # right there LOL.

I think the drag coefficient on your 308 wrap is going to cost you 2-3 MPH over my Skater "Special Edition" Kermit Green paint!:lolhit:

That depends on how much fairing compound and primer you have on your boat to get rid of the traditional Skater print through!!!!

Didn't Nascat say the wraps save a few pounds over the paints?

I know, I know, no dog in this one.

Carry on.

I think this belongs on this thread!:evilb:
http://www.youtube.com/watch?v=Qv-li8FjOXM

and the wrap can be removed :D


jmp, I've never seen that video... I liiiiiike it!! lol.

skate, is there something special about that green paint? :snide: :lolhit:

Stay out of the 21s' with twin 260s'. They are killers literally. A friend rolled his at our PR two years ago. The balance is awful, but, the acceleration was incredible and she hopped like a bronco.

That's a good one!!!

Great thread!

is that a 21 or 24 in the video.

noli, I was told that the converted 32 race boat was running 6 blade Herrings. wonder what that hull actually weighs?

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I'm never ever given those secret information :(

Maybe Blume can chime in.




But hows about some pics of Victory race boats!

Photo Credit : http://www.xcatracing.com

"Luke, I am your ..."

http://i1238.photobucket.com/albums/...13Raf_0141.jpg
http://i1238.photobucket.com/albums/...13Raf_0363.jpg




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well I gladly offer up my 308 for testing of herring props...hell merc, dewalds, etc. as long as I get to keep a set :party-smiley-004:

Not sure who made the tuners......I know they were re worked. ...Yes, I had some idle issues. ....till I changed my fouled plugs....LoL. Again not sure what was done to the flywheel, as far as lightening them....Shaun had these done and the exhaust tuners, by one of the guys that builds his F1engs.Looked at a picture of top end....I was generous with RPM #s more like 6280.....

It's a 21 with twins

Edit: per a thread on S&F, it was propped for 120mph that day but has seen 126+mph.

don't have any desire to do those kinda #'s in a 21 !!!

It is a converted race boat that was a one off build. It is a wide body, cut down deck and the tunnel has been reworked.
I saw the boat at TNT. Also did have some six blade round ear Herrings on it as well. I have a set of 15 1/2" + 29" round ear/thru-hub Herrings 22 degree rake that I run for my everyday ocean set up. Boat runs a solid 105mph and accellerates like a rocket. It blows right through hop.

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DR,

just curious, what the speed range is when hop occurs?




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It really depends on how your boat is set up. CG is very important as well as rake/lift of the props you run. My boat starts slight around 60 and it is gone by 75mph.

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how does one find the CG?

can't imagine having to put the cat on a big titter-totter scale to figure out the CG that way.


if the boat is stern-heavy, does one just keep adding weights in the bow till the desired weight distribution is achieved?


what if the CG is right smack in the middle of the boat. say it's a 30 foot cat, and the CG is 15 feet from the bow (CG is right smack in the middle) that's obviously not a good place for the CG to be at. In this case, where would the ideal location of the performance cat's CG be?






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yep that boat was at cumberland marine right? I went to the add many times when it was for sale LOL. I should really give dewald a call. I know I can do better with different props.

I tested a set of 14.75X34 four blade Dewalds this weekend on my 28 Skater w/ 300xs's. What a great prop. Essentially got rid of the "hop", less buzzing, lifted the stern nicely and increased top speed. Raised the engines to 1.75"(spinning out) and was able to get to limiters at 109.8MPH. Pretty good for the lake conditions and a totally stock new boat and engines, in my opinion. My boat rides completely neutral as rigged - no need for ballast. By the way all, Shaun Torrente came up to Oklahoma to help me with the boat this weekend. I can't say enough about him as a humble yet knowledgeable guy that truly loves our boats. Regarding the Dewald props., Dave is still probably another month out on having ones for our types of boats due to casting issues from his vendor. David.

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What performance upgrades can be made to Merc 300 Promax ( not the 300X )

why is there still such a big demand for the 300 Promax ?

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I'm curious as to how props can remove hop in a cat?






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If I nail the throttles and have my trim just right in the 28 after it get on plane noli it has limited hop, it just powers on though it.

According to my "Man" Shaun, a prop that induces more stern lift will lift the stern up sooner under acceleration which reduces the tendency for bow oscillations up and down because of the tunnel packing air then burping it out. if the stern is already up, lift is continuous and minimal "burping".. hope that makes sense! Feeling it first hand is amazing...David

How about
http://i27.photobucket.com/albums/c1...pse9c49aa6.jpg

Mine starts to hop at 50, stops at 62-65. If a slight turn is started during the acceleration, there will be no hop. Bow lays Down at 70, then the fun begins.