Dual Cooler Bellhousing
 

I'm thinking of converting to dual cooler bell housings. I'm around 725 HP and was thinking of using one 8 plate for the engine and one 8 plate for the transmission. It appears that this will be ok but I'm interested in any input. Also It think these were used on both TRS and SSM applications? Is the bell housing the same for both or is there one that's better? I am aware that some bell housings only had one cooler...

Thanks for the help

I had a customer with an 850, 548 8-71. Single 8 plate cooler wouldn't keep oil temp below 240. Seems like the bigger power needs both plate style coolers.

the bell housing coolers for ssm and trs are the same,imo the eight plate cooler is not big enough for 750 hp,i run a fifteen plate cooler on my 1200s and never go over 200 deg.

there are a few variables in determining weather or not the 8 plate cooler will be sufficient... total system oil volume, how hard you run the boat (as in sticks welded to the dash) the harder ya load the engine the hotter the oil will get, and what the engine running temp is... all these factors influence oil temp.. IMO 8 plates might be a tad light, but hot oil isn't the end of the world... 240ish is ok USE GOOD OIL

Ha! I went from a 13 plate to an 8 plate cause the temps were too low with cold lake Michigan water with the 13 plate. Condensation issue got better with the 8 plate. I made the change after talking to a guy from Hardin marine about it .

Same here Danny... I am trying the same on my end for this summer... maybe the heat from the oil will bring my overall engine temp up... :lolhit:
most guys with single stage water pumps don't have that issue but we who run multiple stage pumps sure do!!

I have 8 plate cooler for my oil. The only time my oil went past 210, was in lotos warm water, holding the engines at 6000rpm for a few miles.

Normally, the oil stays about 180ish on my gauge.

I would go with the 13 plate cooler with a thermostat. This will help maintain the temp. Also, all dual cooler bell housing are the same. The only difference is if they were set up for a rear engine plate. If they were the bell housing was cut down to make up for the plate thickness to keep the trans input shaft engagement correct.

There is a certain amount of oil that still goes thru the cooler even when the oil stat is closed. So having a stat (which we all do) doesn`t mean you`re going to get the temps the oil thermostat is rated at, hence the smaller cooler.

@6000rpm+ my bearings see 200* (after cooler before engine)and the oil in the pan is about 240* according to my 2 separate gauges.

At cruise it`s 40* lower

I have dual 8 or 13 plate both cooling the 750hp engine with nothing cooling the crash box.....210deg Mercury Racing oil thermostats. Zero issues fwiw. We run 4500-6000rpm for 100+ miles at a time, so harder than the average.

On the other hand My Baja ran much cooler, never broke 150deg water or oil temp and had zero condensation.....Zero issues

Lots of great info and theories on here hard to know what's best, good question though!

Can you post more info
Engine details
Water pickup
Water pump
Hose sizes
Etc.

Thanks to everyone so far for the input

572" carbureted engines, standard mercruiser sea pump, transom mountned pick-up, sea strainer, stainless crossover inlet, 1-1/4" hose plumbing. Pretty basic in my opinion

The 900sc and 1000sc engines, used the flywheel housing coolers. They used the 8 plate cooler, one on each side, as oil coolers, plumbed together. So they had two 8 plates for oil cooling. For the transmission, they used a tube style cooler. I believe the 750 supercat racing engines were set up that way as well.

From what it seems, mercury marine, was never fond of hot oil. Most black engines never got over 200*, and i believe on the newer EFI engines, the oil temp alarm comes on at 220 or 230* , on the 525, 700sci, etc , if i recall. I am not 100% sure on that.

Even though we get excited about the moisture thing, we must remember that even though the gauge is reading xxx temp, its an average. I am sure if the gauge is showing 200, the oil at some point, is seeing higher temps. Whether its coming off the cylinder walls, the pistons, the bearings, the valve springs, etc.

I dont really care that an oil is "rated" to lubricate well to 300 degrees. Oil doesnt just lubricate, it also cools parts. And in a marine engine that sees extended high loads, parts are getting hot.

Just my opinion. Im not an engineer.

I will say I had a lot of condensation issues from the start and tried solving it for years , I was able to get it to be better but ultimately with the new motors Ive had no issues whatsoever. Not sure if the problem was.. maybe all the blowby from the Choo choo motors ?? but it`s all gone now so it may not have been an oil temp issue but making the oil hotter was probably just a bandaid but it did help somewhat.

I struggled with this goo issue for way too long, should have just rebuilt em the first year. Live and learn

http://33outlaw.zenfolio.com/img/s/v-2/p6930144-3.jpg

http://33outlaw.zenfolio.com/img/s/v-2/p183216250-4.jpg

Gentlemen, this is all good info. I'm in the process of rebuilding my engines and trying to address the appropriate items while the engines are out. I'm also looking into oil t-stats and that's a whole separate issue that needs researching. For the way I plan to run the boat I think the 8 plate is worth a try as I think an upgrade to a larger cooler is pretty easy if necessary. Most of the used set ups are 8 plate so it's an easy thing to try. My target oil temp was the low 200's, enough to address moisture issues and well within the limits of most quality oils. As Mild pointed out the oil helps cool things like the bottom of the pistons.

This turned out to be a good (productive) conversation, any additional input is appreciated. Now I just have to find 2 good flywheel housings with coolers.

If you're interested I have 2 mercruiser bellhousing oil cooler combo transmission style that I would be willing to sell. They're in great condition. Pm me a number and I'll shoot you some pics. I have the plate coolers adapters and bell housings.

4500 to 6000 for 100+miles at a time,what size gas tanks do you have?

Based off of his lbs/hour fuel usage on the dyno and the speed his boat runs, he is still around 1 mile to the gallon. His boat is very efficient, so around a hundred gallons.

PM sent

1 mpg at 6000 rpm seems high to me,i was hoping he would answer.

HA! Joke of the week.
1mpg is a dream. How can you compare a dyno pull and pushing a boat thru the water?

1.1mpg with a pair of 500EFI and bravos.(boat test)

75hp robbing #4`s and 560 extra hp= 1mpg?? Those are some magic motors.

No reason to derail this thread I will start another

Btw, there`s no 11 plate, it`s 8, 13 or 15

And their all interchangeable with a different cover, correct? Or do they make spacers so that the same cover can be used?

They make a special cover for the 13 and 15 plate coolers.

My bad, I thought it was 8,11,13......either way, I have the 8 or 13 NOT the 15, but the important part was I use BOTH bell housing coolers for the engine, combined with 210deg oil thermostats.

I think thats how the 750 supercat mercury engines were setup, and the 900sc mercury engines.

Makes sense since Unleashed had Mercury 750 Supercats and we copied the plumbing when building the new engines, but REPLACED ALL the lines and oil coolers.

The aftermarket bellhousings have an additional water line , that runs external, from bottom of stb side, to port side, for additional water flow. The old merc bellhousings, have a fairly small water passage internally. I wanna say eddie young adds the external crossover line to the merc housings. More water flow makes the coolers more efficient.

Are the Merc housings notorious for being a restriction and is there a noticeable difference with the external line? Seems like Merc would have that worked out...

Cant say if it makes a difference, never tried modifying thr merc ones. But, the merc bellhousings cooler deals have been around since the days of the old 370 and 400hp 454 engines, which were not quite 6000rpm , monsters lol.

If they were used on 900SC's it would seem like they'd be adequate for all but the most extreme applications. Unless their was some mod done for the later engine packages.

Personally I would rather have more cooler then needed and run an oil thermostat then not have enough of a cooler. Especially if you run hard.

Check out Mr. Cool, Russ has taken great care of us. Took his family for a ride in unleashed this summer to thank him. They offer tube and plate style, if you don't see what you're looking for call. http://www.mrcool.us/hi-performance-coolers.html

Offshore your point is well taken. At this point it seems like it's not completely out of the question to use one 8 plate in my situation, after all for 20 years the boat has relied on (1) 2" x 19" cooler without issue. I have ordered t-stats. There are a lot more used dual cooler set ups available with 8 plate coolers than anything else so I'm going to try it. I believe it'll get me too and from initially, if an upgrade is needed it sounds like a 13 would certainly suffice and I still have the other side for the the transmission. Mr Cool has plenty of cooler options, too bad he doesn't sell new bell housings....

One 8 plate should be more than sufficient. We hand to restrick the water flow to get any water temp.

Thanks

Be careful when buying used oil coolers, very hard to flush all the metal out if there was engine problems or neglect.

i will go a little farther,don,t buy,don,t even take if free used oil coolers.buy new,a lot of fresh engines have been ruined from crapped up oil coolers.same goes for trans coolers.

Good point on the use coolers, thanks