(4) engine 2.5 260hp cat help

[502procharger]

I am putting 4 2.5 efi's on my 30' Chris cat, it is the race version so it weighs about 5k. I am looking for recommendations on how the hell to prop this thing. Same props across the board or different ones in the center. I do not even know where to start. How do you figure out potential top speed at 7800rpms on a boat with 4 motors? Anyone care to guess what kind of speed this thing will run? Thanks for the help.

[Tom Brown]

Are 4 engines really faster than 3 on that hull?

[STV_Keith]

Call Kevin @ R & R Prop Shop (http://www.randrpropshop.com) in Vegas (702-564-7502). I know he was the one that helped the guy with the big cat and 4 x 300x's in Havasu prop that one.

[502procharger]

tom, i know what this hull ran 110 or so with 4 2.4's but i have know idea what if anything was done to them. i guy with the same hull but that weighed about 1000lbs more ran 95 with 3 2.5's so even if the 4th 2.5 only adds 15 to 20 mph i am still looking at 110 or so. that would be nice. i guess we will wait and see.

[502procharger]

tom, i know what this hull ran 110 or so with 4 2.4's but i have know idea what if anything was done to them. i guy with the same hull but that weighed about 1000lbs more ran 95 with 3 2.5's so even if the 4th 2.5 only adds 15 to 20 mph i am still looking at 110 or so. that would be nice. i guess we will wait and see.

[Tom Brown]

Procharger, if he ran four - 2.4l Mercs there must have been times when one engine was in the shop. Have you asked the quad 2.4 guy how much the last outboard bought him? I find it hard to believe that you would get 15 mph more speed with a fourth engine.
Of course, I don't know anything about rigging quad engine 30' Chris cats. The only information I have is anecdotal from the various forums and talking to people. My impression, however, is that going from two engines to three doesn't usually add very much speed. I would think going from three to four would add even less.
Four engines is bad ass but it would be a shame if you spent a bunch of money you didn't have to. Again, I have very little idea what I'm talking about. Please do not make any decisions based on input from me. All I wish to do is encourage you to do some research on the benefits of four engines versus three on your hull.

[randy77zt]

i have a 4 seat mirage with a 96 260.with a 30 cleaver it run 102 at 7200 or so rpms-its hard to spend time looking at gauges at that speed .my rev limiter kicks in at 8000.if i do the math the figure ends up being 8% slip.if it would run to 8000 top end figures out to 111.the pitch # is how many inches the prop travels forward on 1 rotation.not counting slip %.with a 26 merc chopper rev limiter kicks in at 96.i run the big prop because i like to run at high speed alot-it keeps the revs down.the cleaver come off of some kind of big offshore type of race boat-supposed to be a merc lab prop.

[Twister22]

How's this project coming alone? With four motors which ones counter rotate? Do you have to shift all four at one time? Thats alot of shifting. Anyway, quad outboards look impressive no mater what speed it runs?

[snappertapper]

got any pics?

[Boat Racer]

(4) 2.5's ON ONE BOAT, got any cash left!!!!!! smile_sp

[502procharger]

Project is coming along well. 2 outside motors are mounted, all rigging with the exception of fuel pumps, trim pumps and inner 2 motors. This will all be completed within the next 2 weeks. The other 2 motors are being delivered and the guy bringing them is going to help me finish mounting the last 2 inside motors
As for question
Only 2 motors shift, you don’t start the other 2 till you are moving forward.
Prop wise i am looking for 4 cleaver 32p. I should be able to spin them and keep rpms at a reasonable place and speeds around 115 or so.
I am still looking for one tie bare for the steering and all 4 props 2 left 2 right
I will get some pictures soon.
Any advise or ideas for this thing let me know. This thing looks sick already.

[Twister22]

502procharger, Shoot me an email. I have some pictures of a boat you may like to see. (Chris Cat w/quad 2.5's) I don't know how to post them here. I'm kind of computer stupid. huskerfloors@cox.net

[HavasuDreamin']

Damn..........somebody post some pictures. I want to see four O/B's hanging of the back of a cat. smile_sp

[Tom Brown]

I'd love to see some project pictures too. :)
It'll be interesting to hear about his experience in rigging and running this thing. I wonder if it will shake violently as he passes mach one.

[502procharger]

sorry i have been away "Hawaii" ya that sucked NOT, i will post pictures this week.