I own a 1989 Formula 357 sr1 with 454 stage 3 420 hp motors and TRS drives. The boat has Marine Machine Offshore water pick ups, sea strainers and belt driven raw water pumps as well as BBC engine circulating water pumps. The motors are stock, roller cams, high rise weiand intakes, holley double pump carbs with 420 hours, run absolutley mint. I am ready to service these units for the upcoming season. My question is I am thinking of eliminating the engine mounted water pumps and installing crossovers and t-stat housings to match, I will be installing new raw water pumps with housings and all new belts, etc...What are the thoughts on this? I'm certain the raw water pumps will deliver more than enough water for this application, so why be redundant with 2 water pumps per engine? Will hp be affected by running less belt driven accessories? All the high perf boats around seem to run this set up with crossovers so what do you think?

I have the same ques. Same set up...

With crossovers, will the motor run cooler or too cold? Will water press be too high?
What cautions would you guys suggest?

Thanks- Bryan

Just another thought....will I run t-stats or just restrictors in my housings?

Fuhgedaboudit, I like the part where you say your engines "run absolutely mint"!

I don't know much about the subject, but when I asked my engine guy about it, I was told I'd get about a 6 to 8 gain in hp {single BB 502 in a 23 footer}. Would you realize the gain in a 357?

I dont think I'll realize any 6-8 hp gain in a 36 foot 8500lb boat...the reason here is simplicity, less moving parts always equals greater reliability, yes? still looking for replies from the greater boating public. Thanks

Fuhgedaboudit - I have a 311 with the same setup as you except I am running blowers on my motors. I put crossovers on my engines last year because the circ pumps were leaking. I have heard all about the water pressure issue, but I have not tested the pressure on mine yet. I don't think that you will gain much hp, it just cleans up the plumbing and front of the engine look.

Most people here will tell you to buy the Merc pressure relief value (about $120 a piece) and install in infront of the crossover inlet. But then you need to install thru hull water dump fittings with check valves, etc. I have been considering doing this, but I don't know if I have a pressure issue or not, and is it worth the time and $$ to do it. I guess you can look at it that it for about $350 in parts + labor you can install the pressure dump setups, which would be far less if you blow a head gasket. I am still on the fence myself.

How about water temp?

I have nearly the same setup, 450hp 502 with crossover, T-stat with holes in it is a must!!! Water temp is around 160-180 for me however I think I have high water pressure issue, Im going to install a water dump from the back of both cylinders off of the manifold to help with hot spots, steam build up and hopefully reduce water pressure. Ill let you know how it goes hopefully in a month or so

Why mess with something that is working very well. The circ pumps help maintain constant pressure, volume and temp throughout the engine at all rpms. This is especially important for cold water areas and lots of idling time. How many maintenance problems have you had with the circ pump? Is removing it worth the potential for other issues? Probably not. Spend the money on the props or on fuel.

Greg,

Check this out.http://www.offshoreonly.com/forums/s...ght=crossovers