Two pissers

[whipper]

Whipper ran my promax Monday did 100mph with a 24 pitch prop motor only has 140lbs compression,16 amp flywheel and a tuned a6 box with a non rev fuel curve great all around motor with lots of holeshot for what it is...

Thats awesome!! Ive been told by several guys now that I should just get the promax worked on and add a few things and save my money for now. Until I actually may require a built 300. Its not that i havent given it TONS of thought. As got closer and started adding everything up and having to basicly get one from out of Canada it started to look pretty bleak price wise as compared to adding SVS,lighter flywheel, new pistons,some chest work,Tuner, and 8000+ revs. So basicly a rebuild with a few add ons and this motor will pull harder than I thought they could.:beer:

 

[Bobalouie]

Thats awesome!! Ive been told by several guys now that I should just get the promax worked on and add a few things and save my money for now. Until I actually may require a built 300. Its not that i havent given it TONS of thought. As got closer and started adding everything up and having to basicly get one from out of Canada it started to look pretty bleak price wise as compared to adding SVS,lighter flywheel, new pistons,some chest work,Tuner, and 8000+ revs. So basicly a rebuild with a few add ons and this motor will pull harder than I thought they could.:beer:

I am no expert, but I dont think those mods are going to put you into the same catagory as a full on DBR 300XS at 335HP. You are going to be faster for sure, but not as fast as a DBR built 300XS. You will still be giving up quite a bit of HP, probably around 50 at least. I dont think there is any way that a built 225 is going to match a lightened/built 300XS on your hull, certainly not "eat it alive".

 

[fnshrmaster]

Who are you going to have build your motor? Kurt

 

[njj502]

Man I dunno. ~335 3.2 vs ~320 2.5 ..... I think I'd be closer than you think just b/c of weight and being able to get an extra~1000-1500 rpm out of the two five.

Btw I have two pissers on my promax. I only did this to help relieve some water pressure

 

[Bobalouie]

Man I dunno. ~335 3.2 vs ~320 2.5 ..... I think I'd be closer than you think just b/c of weight and being able to get an extra~1000-1500 rpm out of the two five.

Btw I have two pissers on my promax. I only did this to help relieve some water pressure

I wouldnt think he will be anywhere near 320 with the mods he is talking about. More like 250 is what I was thinking. Unless he is going to do a bunch of stuff that he didnt list earlier in the post.

SVS = 10HP
lighter flywheel = 0 HP (reliablility mod + easier to turn more RPMS)
new pistons = 0 HP
some chest work = 10-15 HP (I take this to mean exhaust work, not porting, if its porting then all bets are off)
Tuner = 5 HP (maybe)

All together = 250-255 HP with increased reliability to run at 8000 RPMs.

Like I said before if he is porting it then all bets are off, same with stuffing or other mods to increase crankcase compression, or cutting his heads even more than he has now.

I would agree though, if he is actually going to be at 320 its a no brainer, stick with the promax.

 

[njj502]

Hell promaxs are 240ish out of the box. I must have missed the mods he was talking bout.

 

[Bobalouie]

Hell promaxs are 240ish out of the box. I must have missed the mods he was talking bout.

I didnt think about that, but even an extra 15 on the front end wont put him close.

If it is that easy to get 320 out of a 225 PM then I am kicking myself in the butt for having a 280 that has all the bells and whistles that JSRE does to a pump gas motor, Drag Electrics, and no rev limiter, LOL. I dont think I am at 320 with all of that, and that makes me sad :very sad

But like I said before, you are right about being no contest if he gets that much HP out of it. Even if he only got 300 HP, he would still be better off with the PM.

 

[GotMyAlly]

320 out of a promax is some serious mods.......

 

[Yellowallison]

best mod to a promax leave it stock or sell it and buy 260-280,300x/xs :very happy

 

[fasterbass]

i got a 02 225x and it looks like a diesel truck flywheel.any body chucked one up in a lathe and cut off all the excess on top and can u get the motorola ecu curved up for reeds and port and headwork

 

[LakeAnna]

i got a 02 225x and it looks like a diesel truck flywheel.any body chucked one up in a lathe and cut off all the excess on top and can u get the motorola ecu curved up for reeds and port and headwork

Simon can cut about 5 lbs. out of that flywheel and do the ecu for raised revs. He did my junk last winter. Lets see, flywheel 250.00, ecu 600.00 (7500)limiter. I couldn't tell much difference except for having the limiter moved up. I'm sure the powerhead is thankful not having that anchor on top though. It's a reliable river motor for sure...not a racer. As for doing internal mods and remapping the ecu you would have to talk with him. I know they can do it from my conversation with him last winter.

James sounds like you'll have a nice promax with what your planning. :big grin

Should wake it up a bit.

 

[whipper]

Hell promaxs are 240ish out of the box. I must have missed the mods he was talking bout.

248 is bone stock out of box 96 225 promax dyno sheet specs. SVS alone is additional 20hp with no other mods as tested by several sources. I would think way quicker with a 24 pitch wheel to 95-100 even with a loss of 40hp to a DBR 335hp motor? Power to weight and revs. Not to mention about 10000 less out lay since i have the base motor all ready. And of couse port and chest work whats the point other wise.:big grin and 8000 was on days when I didnt want to spin more. I would say revomved limitter for the odd run when ya need it. Also the SVS and exahst tunner alone added 30hp in this quaote from B&W test.

This a dyno of a stock 2000 PM.

 

[whipper]

Brucato SVS intake and a performance exhaust tuner change were all that was needed to gain nearly 30 hp on the 225 Pro Max and add 8 mph to our Bullet 20XD.

 

[njj502]

So that puts you at a solid 275. Man a little exhaust work clean up the ports and you'll be knocking on the door of 300!

 

[whipper]

So that puts you at a solid 275. Man a little exhaust work clean up the ports and you'll be knocking on the door of 300!

Thats all im looking for. 290+ Ill take it. ya i don't know but I can tell you that some guys with done up 225,s say they pull way harder than there stock 260,s on the same hull. So thats saying something also. Pluss every thread Ive started about this topic keeps coming up the same. I asked on S&F what's the fastest 21ft or less hull to 100 mph and with what power on the planet.:same ole song Got some very interesting answers. The whole point of the thread was to help me decide BB or 2.5 for the GS. I didnt want to ask that q i wanted it as unbiased as possible. The answers always came back to 2.5 especially when someone brought up in 800ft. The bottom line was the lightest boat with the most power to weight will always win the race all things equal. No matter how many times and sheets of paper I did the math on the BB ,even if I could get it to come all the way down to 435lbs with 335hp it never won out on paper in the power to weight ratio dept. I thought it would or could if the weight was down. But it cant be done. YET. Maybe someone will make a carbon fibre midsection with the same strength as Aluminium or something but that hasn't happened yet. They also need to prove the new motors can last a decade without failure spinning over 7500 rpm. Time will tell.
I have no doubt adding a turbo would work on the Hondas and Yamahas but that also isnt happening with results to just go buy one and stick it on and go yet.

What i have found out is there is a point were the size and weight of the hull will dictate the need that a 2.5 cant deliver even with power to weight because of the torque equation needed to propel those bigger hulls like the 28 skater or 32 ft Spectra. The 20ft Allisons seem to all be quicker with a 2.5 on the back in a merc. Then theres OMC like Garys. Ill take Garys motor over all others. But then were talking a whole different apples to oranges in the 450HP + range of factoring.:beer:

Bottom like over months of researching and asking 100,s of questions all related to this decision to go BB or not benefits and costs, power to weight analysis, sounding dumb but with a purpose? there might be some 3lt+ on Allisons that run great and work perfect. Im not saying there isnt. I know there is. Im saying when PRICE is an object its pretty hard to beat the 225 promax or X modded or not. If you all ready have the motor is makes dollars and cents to explore the maximum of what you have before you decide to go bigger. Its not how big it is its how ya use it! Oh wait that's bS

 

[SLOmofo]

James all I can say is a stock engine will go to the lake, start and run every time. A lightly modified engine will almost all the time. When you start using pieces from the aftermarket then fitment becomes the issue in reliability.
I have been fighting an intermittent problem for 3 months. I've found many possible reasons, but found the John Deer tractor alternator intermittently charging 18+ volts. That shuts the engine computer down. Runs like a harsh rev limiter, not a fun thing. OK throw a new Chinese voltage regulator in it. Now 3. I've come to the conclusion today the rotor inside the unit is shorting when it spins and is knocking out the regulator.
OK, pop the belt off and run it as a total loss system. Well that's OK for a short time but because the engine is electronic fuel injected and battery powered ignition and the big fuel pump, the computer doesn't like the voltage surges and constantly dropping voltage. Then the starter gets s l o w.
That said I still was going to run a few miles with the car motor boat guys any way, up to Las Tables where the topless show usually starts about noon. I'm waiting, and decide to make another quick pass, crank the engine but the starter doesn't sound good, sorta spins weird. Pop the cowl and find one of the after market starter mounts broken and the starter moved away from the after market flywheel. Luckily one of the allen bolts no the second aftermarket mount had backed out and gave me a clue something worse was about to happen had I just run it. Second lucky thing I had the correct allen wrench in my boat tool kit.
So before I run it again I have to have a friend machine a new am mount and find another am alternator then have it machined so it will fit under the am flywheel.

So if you want to do it, do it. But remember I are a mechanic, I don't charge myself to do all this trouble shooting and work.

All in all I did Open the Can O Woop A$$ on the 800+ hp blown jet , the flat bottom and some big tunnel that thought they were quick. My friend with the blown jet did greet me by asking if I was going to give him his a$$ wooping again, I just said yep. And smiled. And told him I'd try not to embarrass him in front of his friends to much. I post a video but my GoPro and Photo Bucket aren't talking nice nice.

 

[whipper]

James all I can say is a stock engine will go to the lake, start and run every time. A lightly modified engine will almost all the time. When you start using pieces from the aftermarket then fitment becomes the issue in reliability.
I have been fighting an intermittent problem for 3 months. I've found many possible reasons, but found the John Deer tractor alternator intermittently charging 18+ volts. That shuts the engine computer down. Runs like a harsh rev limiter, not a fun thing. OK throw a new Chinese voltage regulator in it. Now 3. I've come to the conclusion today the rotor inside the unit is shorting when it spins and is knocking out the regulator.
OK, pop the belt off and run it as a total loss system. Well that's OK for a short time but because the engine is electronic fuel injected and battery powered ignition and the big fuel pump, the computer doesn't like the voltage surges and constantly dropping voltage. Then the starter gets s l o w.
That said I still was going to run a few miles with the car motor boat guys any way, up to Las Tables where the topless show usually starts about noon. I'm waiting, and decide to make another quick pass, crank the engine but the starter doesn't sound good, sorta spins weird. Pop the cowl and find one of the after market starter mounts broken and the starter moved away from the after market flywheel. Luckily one of the allen bolts no the second aftermarket mount had backed out and gave me a clue something worse was about to happen had I just run it. Second lucky thing I had the correct allen wrench in my boat tool kit.
So before I run it again I have to have a friend machine a new am mount and find another am alternator then have it machined so it will fit under the am flywheel.

So if you want to do it, do it. But remember I are a mechanic, I don't charge myself to do all this trouble shooting and work.

All in all I did Open the Can O Woop A$$ on the 800+ hp blown jet , the flat bottom and some big tunnel that thought they were quick. My friend with the blown jet did greet me by asking if I was going to give him his a$$ wooping again, I just said yep. And smiled. And told him I'd try not to embarrass him in front of his friends to much. I post a video but my GoPro and Photo Bucket aren't talking nice nice.

Gary I always like your {logic} it both entertaining and to the point. Ill take all these things into consideration for sure. It needs to be freshed up again so Ill take the path of least resistance and make sure the parts for a merc not a John Deer.:beer: Keeping the acu because its reliable and I under stand it finally. Theres some more in the iar dept so SVS or some kind of intake with some light porting with a reed change and injectors cleaned up with my already 33CC heads and a fuel regulator setup should be most of whats needed for a little stouter performance. Going to find a modded or Mod a SM also. This repairing the gear-case once a month is for the birds.

Its been 8 years since the inside has been touched. Time for a look see and some newer parts to go in. If i won the loto a 300XS with Daves mods and Mikes cowl would be an awesome combo I think. The top speed potential with that motor far exceeds what a built promax will do. But the promax will get to high 90,s to 100 quicker I have no doubt . After that is were the BB would walk away and could do it with 4 aboard with a 33 or 34 pitch prop. I really think the 300xs with mods could get a GS to that 110 mark with the right setup. Setup as always is key for speed and doing it as safe as possible.

As much as that appeals to me the cost as got closer to doing it was getting out of hand. I was getting close to 17000 with the setup I had calculated out. i would have needed to get a differant setback. The time isnt a problem as I work on my GS almost daily sanding and adding trying something differant almost every time out. Thats the part I enjoy is the setup. Mine changes almost weekly.:banghead Ive tryed tunnels on the pad flat bottomed ,winged, lip, no lip 15inch setback 9-10-12. :shock: drilling more holes in the cowl and reading plugs playing with the acu has taken most of my time this week. Two weeks ago I tryed flat sides on the gearcase. That was a disaster!! This week blunted the nose again after turning it up a little and drilled out the intakes and filled a new shape pluss added add-tech to the sides and tapered it to the prop. That actually worked real good for speeds over 90. I could take my hands of the wheel. The side steer cuts 20lbs of off set . Used to cut 30 untill i gained 10lbs!! All good fun. Ever since i started fooling around designing boats 30 years ago I wanted to play around with a fast proven hull . This Grand Sport has given me what I needed to not go crazy and actually learn how to drive one of the best hulls in the industry!! Darris,s design is so awesome I love every line of her!! As you always say. I cant leave well enough alone!!:beer:

 

[SLOmofo]

Here's an example. Of a fitment related failure. This piece gives a 3rd point of attachment for the Cross Flow starter adapted to a Looper block to allow use of a light flywheel. The shiny area that the leaf is pointed to is where this piece is forced against the block. You can see how it was formed so it shouldn't hit (45 degree back cut) but it still did just a little bit. The other problem with this piece is the sharp 90 degree angle, this causes a stress riser. Which if it is stressed is where the crack will start. There was a 1/16" spot at this corner for a few years of use.


This is where it lives. So what we have is a stock 3.3 looper block. Cross flow starter, Mad front half, starter mounts, flywheel.





The new one will be wider across the top and longer to reach to the second hole. The 90 degree will be rounded.

Now what to do about the alternator!

 

[hack02]

Throw a little shot of nitros at that puppy Whip. Stock motor for cruising and bottle fed for the need for rapid acceleration. Chummy on this board could probably point you in the right direction.

 

[whipper]

Throw a little shot of nitros at that puppy Whip. Stock motor for cruising and bottle fed for the need for rapid acceleration. Chummy on this board could probably point you in the right direction.

Haha ya now were talking!! Hows bottle fed motors survive?