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253 convincor handling

mkhammer

mkhammer

Well-known member
I have full hydraulic steering, Zeiger helm , twin w.p.m. rams, 24" billit k-planes, 30" pitch bravo prop turned by a hp 500 carb with a 7 psi procharger that I installed two weeks ago and this labor day weekend was my first outing with the procharger installed. To say the least it was an adrinalin rush. I never opened it up all the way it was too scarry. I experianced chine walk at 80 and it felt very unstable and still had more left about 600 more rpm I figure. That was with the tabs and the drive trimmed out just enough to let it fly. the water conditions were not that bad and when I crossed another boats wake it laid on its side then straighten back up with some wheel imput. this about left a load in my paints. In could use some advise about handling on my boat at this speed. add a sportmaster case? differant prop, if the trim and drive were in any more it would of scrubed off to much speed. any advise about my boat would be helpfull. MKHammer
 
I have full hydraulic steering, Zeiger helm , twin w.p.m. rams, 24" billit k-planes, 30" pitch bravo prop turned by a hp 500 carb with a 7 psi procharger that I installed two weeks ago and this labor day weekend was my first outing with the procharger installed. To say the least it was an adrinalin rush. I never opened it up all the way it was too scarry. I experianced chine walk at 80 and it felt very unstable and still had more left about 600 more rpm I figure. That was with the tabs and the drive trimmed out just enough to let it fly. the water conditions were not that bad and when I crossed another boats wake it laid on its side then straighten back up with some wheel imput. this about left a load in my paints. In could use some advise about handling on my boat at this speed. add a sportmaster case? differant prop, if the trim and drive were in any more it would of scrubed off to much speed. any advise about my boat would be helpfull. MKHammer
 
I also have a 253 with a procharger, and I have the same issues as you, except mine only does 80 max.
There was a guy at the lake that had a 253 with twin turbos and he did 93mph with my buddys gps on board. my buddy asked him about handling, the guy told him "you have to learn to stay ahead of it" I'm doing much better with mine now, I would say start out slow and practice.
Remember that boat wakes are not good at 80 or above, when my boat was stock I could go wide open almost any time I wanted, not anymore.
be carefull and you will get the hang of it.
 
Thanks overboard, Thats some good advise. take it slow and get use to it. I spent alot of time and money setting my boat up and I feel everything reacts and works correctly. what engine did you procharge? my boat did 74 mph on gps before I procharged it. my hp 500 is not stock I changed the cam and did alot of head work I went from a 26p bravo1 to a 30p Bravo1 I was turning the 30p @ 4800 rpm and it still had more there was to much boat traffic to hammer it I will try it on a off weekend. after I get some more time driving it. It feels wicked I was thinking I over powered my boat so I'm glad to hear it can be dealt with. My boat does become stable when trimed all the way in. I have been told a nosecone or a imco or a sportmaster lower case helps at high speed. I would like to find out before I spend the money so any info on this would be helpful.
 
I procharged a 454 mag efi. I put gil exhaust, inconel exhaust valves . fel-pro marine head gaskets, arp head bolts, had my ecu reprogramed, and put a extrude honed lower intake from asm on it, had my areomotive fuel pump updated by areomotive, ran my fuel return away from the back of the pump and routed it to the fuel tank, and increased my fuel pickup to 1/2" removed the screen @ the end of the pickup that checkmate epoxies to it, removed the check ball in the fitting on top of the fuel pickup put 1/2" fuel line all the way from the tank to the fuel pump. I got rid of the merc. fuel filter ( it doesn't flow enough fuel). I went with the areomotive fuel filter with the washable screen before the pump, and the areomotive filter with the throw away paper element after the pump to protect my injecters. I think that about covers it.

I talked to a guy that has a 242 checkmate that is running 550 hp. He said he had trouble with chine walking. He told me he sent his prop to R&R propellers in arizona and they cut the tips off his hydromotive quad 4, he claims this took care of his problem. You might want to give them a call.
 
I have driven my boat with two different drives, the stock bravo I and the Bravo XR with the Imco shorty nosecone that I have now. Night and day in terms of handiling. More gear case in the water. I have the stock HP500.
 
Sorry, the imco lower handles much better. When I said more gearcase and better handiling I was talking about the nosecone. Seems to drive much better, plus I gained 3-5 MPH on the GPS by switching drives.
 
The best way to seal with chin walk is to drive it.
Start off slow and learn each speed. FEEL how the boat reacts to different waters.
Then once you feel comfortable with say 3500 rpm move to 4k and repeat. Trim in and out, tabs up/down.
Driveing the boat on the pad is a balancing act.
The biggest problem I had was that I was over correcting with the steering inputs.
Once you get the hang of it it will be like riding a bike.
 
Ihave an xr drive on my boat now with a standard lower case. Is the imco lower case better than the sportmaster? I am definetly going to change out the stock one this winter.
 
checkrocket That explains why your boat runs so well with a stock hp 500 3-5 mph gain is alot for changing the lower case and better handling its well worth it. I just need to find out sportmaster or imco. and are you still at stock x deminsion or 2" shorter?
 
I have the shorty, it raises the x dimension. I have been happy with the drive. I have the nose cone water pickup. Just be careful when you get air, two inches shorter and different x dimensions, will pop everything out of the water.
 
I' m going to put a standard hieght Imco lower case on my xr drive. Imco said their case is faster than a sportmaster and if I'm happy with the speed of my boat don't change the X demnsion and their case should make it handle much better. so I'm going to give it a try
 
Overboard I'm intrested what you have to say we have the same boats. I am now finding comfortable trim angles at high speed. I have 24' billet tabs made by eddie marine I found I can trim them in and the boat is stable. I'm finding the right trim angles for my drive and tabs. its a little defferant at all speeds. I'm still getting use to it but it feels better more predictable every time I go out. I'm still going to change my lower case this winter I can boat all year round here its still cold we have some 75 80 deg. days in winter so I'll be able to try it out before next summer.
 
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