25 daytona questions
 

Hey guys i have a 2000 25 daytona with a 540 built to 650 hp dynod. It has a xr drive with a.1.36 drive and a 24 pitch stock bravo prop. All i could get out of it was 5200 rpm 83 mph on a good day. Well i broke the crank in half no idea how and now i rebuilt it and its 720 hp 680 foot pounds. U guys think.ill see a big improvement in top speed going to a 1.50 ratio and a taller pitch? Also do u guys recommend going shorter on the lower drive on this boat? And does anyone have pics of any diffrent exhaust on that boat besides cmi e tops?

cant help with the exhaust pics but I can tell you than mine has a 3" imco sc shorty and It works excellent. I have a 1.36 gear set and a labbed 30" prop. my motor is a 640 bbc and I spin it to 5600 rpm.

I am running 800hp with 1.36 gears and 30". As for lower I have was talking with Eliminator and Imco 2 weeks ago about this and they said to go up to 1" below sponsons. My x-dim is 2.5" below so for me I need to shorten 1.5". I am also considering the Imco SCX next year. I cant attach an image or else I would show you my exhause. I have imco powerflow. I can email if you like.

[email protected] wow 1 inch above. I think im around 4 inchs below. Think i have a really low x dimension.i know the oil pan almost hits the floor. That's probably slowing me down

No he said 1" below sponsons not 1" above.

sent you some pics. Like J.P. said, 1" below the lowest point. My transom housing is touching the rub rail at the top if that helps. My oil pan is about level with the upper part of the tunnels, so the highest part of the floor

Where is your transom assembly in relation to your rub rail?
A 3"shorty on mine would have put the prop shaft well above the bottom of the boat.

any issues with cavitation burns on the bottom of your drive directly infront of the water pick up opening?

what speed are you seeing from this setup?

What rpm does that turn? What speed?

PS, you cannot use the SCX lower. Too fat and high speed handling was the concern voiced to me by IMCO.

I went SCX upper, -1 SC lower. Probably could have gone -2 but heard planing could be tough.

Hey Guys...When I built my 25 Daytona I was also back and forth with Eliminator regarding the height of my drive...I also felt it was also mounted to low and it had a -2 shorty lower....the problem was, with the -2 lower and where it was mounted to the transom I was stuck on going up....I went with the 12in setback and 3in rise extension box from IMCO. Cant really relate how it performs cause my engine combo is 1 of a kind....I posted a pic so u guys can see it with the box...

http://i10.photobucket.com/albums/a1...z/DSC03798.jpg

I am not sure of rpm at WOT since I just bought the boat a few months ago and I'm getting use to it and don't want to blow the drive up. This past weekend I was running 4500 rpm at 80.5 gps. I probably could have trimmed a little more out of it.

As for the SCX I meant lower dimensions not SCX lower even though we did discuss that. They did say to run the SC lower but I will blow those up too. I am willing to lose a few mph to keep from blowing these up but what is the high speed handling concern?

SCX upper for sure is the plan.

Imco did recommened I go with the 12in setback as well because I have the twin step hull with an open bow. They said it would help with bow lift.

So is that 3in rise and a -2 shorty?

I like your power choice. I was just showing your boat and setup last week to a co-worker that has a supra. I am a fan of the 2jz and am surprised there are not more of them in boats. nice setup you got.

Imco thought the big gearcase could cause some stern lift at speed. Not Good.

I have 40 hrs on my SC lower and no issues so far. 900 hp and 870lbf. As long as you don't beat on it. an SC will live.

Hey Dirty.... Yes... that is the 3in raised 12inch set back Ex. box.... Like I explained before not sure ho much we can relate my x dimension set up cause the motor is so drastically different...(1 main difference is weight)I can tell you guys this at 7200Rpm with a 1.65 gear and a non labbed 30 Bravo ive ran a best of 110MPH....Have a 34 to try next....Also Dirty, thanks about the kind words on the engine package...im hopin to turn some real heads with it....was at LOTO but ran into some lil issues so I didnt run it..but I most definately will next year.....

WOW, 5in total raise. Looking at your pic, your box is the same height in relation to the rub rail as my assy. According to Eliminator the bottoms haven't changed just the tops. I don't know when they changed the steps though. Is that a single or twin step? What is your new x-dimension? Why not a 1.5 gear set and 30"?

OK, lets see where to start...when I purchased the boat from Eliminator it already had the -2in lower on it. When U measured the prop shaft (or front of the nose cone) in level trim it was about 3inches below the bottom. Ofcourse like everyone else thinks, including myself that it was too low and working closely with Grant from Grants custom rigging(throttle man of the STIHL offshore Skater) we figured we raise the drive and do the gear change. Also 1 of my biggest issues like everyone im sure knows already is planing, which is where we thought the gear change would help the most, I have a set of 1.50's that came in the upper when the boat was purchased and used them for about 10hrs before I opted to try the 1.65's....after using the 1.65's I dont think I would ever go back to the 1.50's.... Also I might add with the gear change, I had different cam profiles made along with trying many different turbos to help the planing issues...finally I designed and fabricated an Aerator to resolve the planing issues..... Regarding your question and the double step, Im assuming we have the same bottom but check the pic to be sure...

http://i10.photobucket.com/albums/a1.../boat035-1.jpg

From the look of that last pic the transom assy is not touching the rub rail. The bottom is the same as mine. They haven't changed them in 10 yrs then. That is what Eliminator said too just not sure when they switched to twin step. Did you measure from the lowest point on the sponsons? I think mine is only 2.5 in without a shorty.

Ken, didn't mean to take over your thread, hope all this helps since there is no clear answer on what height to go with.

Most definately didnt wanna take over Kens thread but give some of my feedback as well....I most definately did measure from the bottom of the sponsons...thats the only place to measure from! My biggest thing was...where the drive was mounted, I was basically stuck... 0 option to go up unless I put a -3 lower which the 15 1/4 bravo wouldna fit unless I cut the cavitation plate...wasnt gonna do that... so I went for the 3in rise and now if I want I can always lower it with a spacer....gonna keep testing with the way its set up and keep ya guys posted

I NEED SPEED!!!! LOL

are you guys measuring from the bottom of the sponsons before or after the notch?