prop help
 

looking for help on prop selection. Currently installing B&M 250 blower to my 500hp carb.I own a 2001 conv 270. said hp will be 625-650.Where do I start?

hirshy, i have a friend that is running a 280zt with pro-charger on a 500hp motor! he is running a 29 pitch bravo. speeds are 87mph. hope this helps!! bill

Hi Bill, Again I need your expertise, My motor man installed b&m blower 250, 2lb boost pulley, with a 1050 dominator carb.Looks awesome!!!Had to modify backrest, and notch hatch, but did outstanding work!! He just called me with results.Prop was a 30p labbed bravo, clocked 81mph , with 50 gal gas and 3 poeple in boat. rpm was 4900. the problem was it was very squirrely and wanted to walk alot.Did your buddies boat handle well at 87.We want a 4lb pulley but need to correct chine walk.He thinks its the hydrolic stearing, claims its very loose!! he figures quite abit more testing! What do you think? I figured this hull or boat should handle 85mph with no problem.I appreciate your input or anyone with simular problems. thanks

The 1st thing I would do before you change anything else is put a Hydromotive Q-IV prop on it. Go with a 28 pitch for starters and also try a 29. I'll bet you a round of beers it'll settle down with a simple prop change.

My 25 Convincor was all over the place with the Bravo 4-blade. They have too much bow lift for the Checks.

Let us know how it works!

Eric

Local guy has same hull and ran 99mph on gps last summer...boat was very stable. In fact he won his class at the L.O.T.O. shootout last year so the hull will definately handle speed.

Thanks for input , I'll try hydrmotive 28-29, I'll gladly pay round of beers for correct dial in.:p

Last year at the RPBA radar shoot a 251 Convincor went 103 on radar. It had a blower motor on nitrous. The owner was expecting 110 but was hitting the rev limiter. The 270 is wider beam which may slow you sown a bit but the range you're in should be no problem. Hydro's the way to go for props. Look on the prop for sale section on the board, some great deals there.

Hirschy, I'm glad you asked the prop question. I've been trying to figure out what type to go with. It seems most people have single engines. I have twin 454's in a 280 Convincor. It would get squarrly with the 25p Mirage Plus 3 blade, running about 75. I'm putting Whipples Superchargers on that should put out around 1000 hp combined. It sounds like the Hydromotive Q-IV prop may work for me also. I guess the starting place would be 28p. I hope it will settle it down.

yes guys eric is the one who put me and other check owners onto the right slection of prop for our hulls!!the hydro prop makes our hulls run a more level attitude with out chine walking!! kudos to eric of checkmatef1 for all his input!! eric i hope you get to make it out this week-end!!!!!! bill:) :) :) :) :)

Hey Man I have the pulley your looking for brand new never used it you can have it for 1/2 of whatever a new one is plus shipping....
Don 616-786-3829

Thanks Bill! I just want to pass what I have learned with this boat. Seems I learn something new every time I hit the water.

I should be able to sea trial on Sunday. I hope!:rolleyes:

Eric

OK Eric we will be waiting for the update on sunday evening you have evrything about buttoned up??

Thanks for all your input gentlemen, after installing 6lb pulley and some minor mods, we did another trial run today. 63 degrees, light chop. 26p bravo 2x cup prop. boat ran extremely strong!!! boat also staightened out with minor chine.Hit rev limiter, with some throttle left. 5400 rpm, about 82mph. Exelleration from 65 to 80 was amazing! Called hydromotive( todd, gary), sending me a 27p Q4 to start.Tryed to get me to erase rev limiter for extra rpm and hp, do not know how to do this with carb engine at this time.Will let you know how next prop works. Boat should run middle 80's.If you have any other suggestions please keep it coming. thanx Mark

hdromotive
 

5/18/02 ---- ran 27p hdromotive 58deg , 2ft chop , 3 onboard, full fuel, 78 at 5050 rpm. trying 29p 3blade today! will post results.