De-Tuning 850's???
 

Question for the motor guys. Looking at some possible new to me boats.Would really like a 700 Merc or Illmore set up.But see a few good deal on 850 and 1075 packages. When top end or re-fresh time is due,can anything be done to get 200-300 hours out of them. Even if it meant de-tuning to 700-750 hp??
Thanks,Jeff

im sure they can after one of the premier engine builder's get a hold of them.
as far as bringing down the HP. once you have that power and run the boat I doubt that you would want to loose so much power and speed .
IM sure they can keep the power and still make them live a lot longer then merc recommended rebuild's.
plus if you keep the rpm's down on the higher power motor's and run it like a 700 or so I would think they would live longer .

mike

example , let say you buy a 850 merc boat that doe's 110mph and cruise's at 90 mph , well if you now cruise the boat at 60 mph and don't go past 90 I think they will live a lot longer , but we all no how hard that would be :)

I'll swap you my 700HP 575's for the 850's. See how easy that was.

Just don't use the top end and keep the hp!!! 1075's need top end matinence I have heard but not so much the 850's. What kind a boat are you looking at?

The problem with them is the solid roller camshaft. That's why they have the short top end rebuild intervals. When the top end needs to be done, switch them over to a hydraulic roller and they will live for 200-300 hours. The bottom end can certainly handle it. You can keep the power and have the longer interval. Us, along with others, are getting 300+ hours from 1000+ hp with hydraulic rollers. There is no reason that the 850 can't do the same.

Let me know if I can help.
Eddie

Just curious because I'm not an engine guy but why don't they have hydraulic rollers OEM if there better? Thanks

Honestly, I couldn't tell you for sure. I never understood why Merc used a dry sumped, solid roller 557 ci with a quad rotor to make 850 hp. It makes absolutely no sense to me. Hell, I don't see why they put a solid in the 1075.

The only reason that makes any sense to me is so they can get the money on the rebuilds do to the short rebuild interval. I hate to think that anyone would deliberately do that, but I can't think of any other reason.
Eddie

Thanks for the response's guys.Don't really have any hard interest in any one particular boat,but I do like the 2005 Outerlimits 42 Legacy in the classifieds. Blue/Lime Green.I understand running the 850/1075 at a lower rpm for longevity,just didn't want to pull them apart every year.
Eddie (YPM) great info on the hyd vs.solid set up.
What would be an estimated cost on changing over 850's to hydraulic at top end re-fresh time?
Thanks,Jeff

Not to Hi-jack this thread but......Eddie have you put closed cooling on a 850? There are some good buys out there on 850 and 1075 boats. For what I am looking for I would need closed cooling and hydraulic lifters.
Thanks
Steve

Thanks Eddie, sounds about right.

Steve,
I don't see why you couldn't fresh water cool it. The biggest hurdle would be the packaging. That's a pretty busy engine, so you may have to end up putting the heat exchanger in the boat some place. There are a few aftermarket companies that make DIY closed cooling systems. I doubt anyone makes a specific bolt on kit for the 850/1075, but I would think a "kit" could be put together from individual parts.
Eddie

Why would you ever want to detune an 850?

With the new advancement in lifters..they will last...

Monitor Industries in Florida builds the closed cooling for the merc engines I believe.

Mercury already makes a kit (almost positive although never heard of anyone running it) (Monitor Industries) to adapt to the 850 and the 1075sci, it's an option. I'm trying to find where I saw it in the parts manual, I was shocked to see it the first time I ran across it.

All in all Eddie will not steer you wrong.

Jeff,

The exact price will depend on the components used. In order to convert to hyd. roller, you need to change the camshaft, lifters, valve springs, retainers, locks, valve seals and pushrods. I would also change the timing belt while I was there. For the parts, you are talking about $1500-$1600. Like I said, the exact price will vary based upon the exact brand of parts that you use. The labor would depend on a few variables as well.....are the engines in or out? What other items you want to do as well, etc.???
Eddie

If you only want 850hp, this is very easy. You can put a hydr roller in there and not sacrifice a thing and you can easily get 300 hours out of it. The 1075 is similar, but you will lose power. I don't care what anybody says, solids make more power. I've done many back to back test with equal specs on lift/duration. At this power/lift/duration level, the solid is worth 30-50hp pretty much across the board and more significant as the RPM exceeds 6000. So, it can be done, but you'll be closer to the 1025-1050 range.

You can easily detune the 850, or make 850 on 87 octane with some cal changes.

The lower end of the engine can well exceed those parameters so the valve train is technically the only thing that needs the short service/rebuild time.

Get hold of Bill Steppi/sutphen30...he isnt far from you and has a mass hole accent too:D...he can get you set up properly.

Will make you a good deal on a 06 42 Legacy with 1075s. No time to use it. Still has less than 140 hours on boat. Motors gone through at 100. PM me if interest.

I met Bill about a month ago.Did a season end Poker Run.Good guy for sure.I'm still trying to finalize the sale on my boat.Certainly appreciate all the interest in the thread.Probably should have titled it "How to get 700 type longevity out of 850/1075's??"Just checking my options.Seems to be some good deals on the big power packages. As far as Mass Hole,I resemble that remark!
Jeff

I have used Monitor Marine they are local to me, good company.
Steve

i built my 700+hp engines in 2006.these engines have never been out.you don't need a lot of cam for those numbers.
my engines will be available after i build some turbo ls motors.going to the bone yard to find some canidates on saturday.i needed a winter project besides the 1300hp 581ci whipple motors.:evilb:

Don't take on too much. You're no spring chicken anymore.......old man:lolhit:
Give me a shout if you want to bs.
Eddie

:lolhit:

Sounds good,I will.

Couple more question. Other than the obvious HP,what is the differences between 850's and 1075's? Both solid lifter,twin screw.Are the super chargers larger?Are they the same cubic inch? Maintainance wise,is there any difference between the two.
Searched Merc's site,but not much info on the 1075 now that it's discontinued. Thanks for all the info all ready,got some informative P M's as well. Jeff

I had my 850's rebuilt to 1075's. Cam change, new (smaller) blower pulleys and reprogram ECM.

The only differences in the 2 are the camshaft (1075 is larger), blower pulleys (1075's are smaller for more boost), and the program in the ecm. The 850 has a little longer top end interval.
Eddie

1075's are good for about 110-125hrs before the lifters let go.
You might want to talk to Mark at Precesion Marine. I think he has some solid lifters that they are gettin 200+ hrs out of. This would make the 1075's even more attractive.