High oil temps in jet boats..What's up??

[DiverDown]

I am a small town engine builder and new to the performance jet boat arena. I have a couple of friends/customers that have come to me over the winter and asked me to build them new engines for their jet boats. After discussing what they thought they wanted/needed in their new motors,(which will both be 496ci's) they both expressed concern that the motors they have seen run in performance type jet boats have all seemed to have very high oil temps and wanted to know what we could do to help this problem. While I know what to do to lower oil temps in most types of engine applications I would like to know what kind of oil temps you guys are seeing in your boats and whether or not any of you are running oil coolers and large capacity pans to help the problem, and what kind of results are you getting. Sorry to jump into y'all's "Jet Boat" forum with a question like this, hell I don't even own a boat right now, I am just trying to do a little research for some good customers of mine who are trying to get me into the hotrod boat motor business. Thanks in advance for any help!

[Heatseeker]

In my application, if anything, the oil temps are low. I'm lucky to get it up to 180. Most jets run cool, due the high pressure and volume of water being pushed through them at speed.
I have seen a couple of guys running oil coolers though.

[HammerDown]

It's not uncommen for a marine Engine due to the extream load on the Engine to see oil temps almost 100 degrees higher than the water temp. Now this is during extended periods of wide open throttle or close to WOT.
Several combat the high temps with a oil cooler of some sort but some (jetters) don't run a thermostat at all in their engines thus they run kinda cold. However...even with a cold running Jet lets say at 130 water temp...at extended rpm's the oil temp will rise.
The large oil Pans will only slow the temps from riseing...but not stop it. And will also take longer to bring the temps up to a warmer temp for proper operation.
Personally I run a thermostat By-Pass System, temps right at 160-170, a 10 qt Oil Pan and run straight 40 wt. Kendall. The thicker oil doesn't break down as easly as the multi. I've gotten some lifter noise after a long heated run that I don't get with the straight wt. Also some use synthetic oil...not me.
I'm one that won't go wide open for very long as I don't run a oil cooler...if I did it would be a plus. 3000-3500 RPM cruise is good enough for me. (With the occasional HammerDown):cool:

[wsm9808]

Oil cooler and 10 Quart or more pan are mandatory if the owners/drivers think they have to run WFO for minutes at a time.
Jets put quite a load on an engine at peak output. I would keep full throotle runs to 30 seconds or less. My oil temp will go up about 50 degrees and will lose about 10 pounds at idle for about 2 minutes after a hard pass. That is with a 7q pan and no cooler.
But, if the driver is sane and cruises in the 3800rpm range or less there should not be a big problem with oil heating. Dont let the cool temps on the water temp gauge fool you. The water temp is not going up because it has an endless supply of cool water curculating into the system from the lake. The oil heats extremely fast due to the load on the bearings etc, And cannot exchange the heat at a faster rate than it is being produced, because the oil reserve is mostly setting in the pan and is not in contact with the (relatively)cooler block. But, after the rpm drops after a hard pass, the oil passes through the engine slower and under less load, and it cools back to normal.
Since you are doing the machine work, it is very important you understand clearancing inside a marine engine. The same thing happens(heating cycle) in the combustion prosess. You must run extra clearance for the piston-to-wall and valve guides. The cold incoming water limits the expansion rate of the bores and heads, but the severe duty demanded of the engine causes high combustion temp spikes and causes the pistons and exhaust valves to expand at a very quick rate while the surrounding lake cooled metal has almost no expansion. Seize, ouch, $$$$$$
I,ve repaired several marine engines in our area built by the local self proclaimed hot rod gurus that didnt last 100 yards outside of the no wake zone.

[quiet riot]

yeah, what hammerdown said. If the motor is going in a heavier boat that will run 4k+ rpms for extended periods (or spinning a small impeller which creates higher rpms for cruising) then oil temps will run higher and usually warrant a cooler. I run an A (steeper impeller) which allows me to cruise at lower rpms (3-3500) and my oil temp stays pretty normal. I have a deep vee, light jetboat that will get squirrelly when going very fast in rough lake chop. A tunnel or larger boat that stays more stable can sustain higher speed for more water conditions and thus would have more rpms and oil heat if used that way. I would have to say its based on the type of boat, jet/motor rpm setup, and driving habits.
.02,
jd

[Aluminum Squirt]

I have no idea what my oil temp is running but I'm at about 140-150 on the water side. I figured because of the large difference between oil and water temps that I would try to bring down my oil temp. I added an oil cooler and have not had any problems. My motor is a stock fuel injected 350 with 120 hrs on it and I normaly run it wide open (4900-5000 rpms) for 15-45 minutes at a time, yes, minutes, that's not a typo. I obviously am no scientist/profesional as I don't even run an oil temp gauge, but I'm guessing a boat oil cooler is extremely efficient with the endless supply of cold water and the liquid to liquid heat tranfer vs. a non-marine engine that can only use air flow to cool the coils-Aluminum Squirt

[LakesOnly]

Originally posted by DiverDown
I have a couple of friends/customers that have come to me over the winter and asked me to build them new engines for their jet boats...they both expressed concern that the motors they have seen run...all seemed to have very high oil temps and wanted to know what we could do to help this problem...I would like to know what kind of oil temps you guys are seeing in your boats and whether or not any of you are running oil coolers and large capacity pans to help the problem...
DiverDown,
Under full load, a jet pump causes the engine to hit a "stall speed," much like the torque converter of an automatic transmisson. Typically, this stall speed is somewhere between 4500-5500 rpm. Imagine moto-ing a car with a 5000 rpm stall converter, and your flooring it almost all the time.:rolleyes: The constant, severe load on the engine is the primary cause for the increased oil temperatures. Once fully warmed up, it's not uncommon for jetboat oil temperatures to exceed a whopping 300 degress F. Anybody that has an oil temp gage on their boat knows this, and most eveybody knows better than to estimate their oil temp by viewing their water temp gage.:o
Motor oil has several very important functions, including acting as a lubricant, as a seal, as a coolant, as a corrossion inhibitor, etc. All of these properties (and others) are diminished with its increase in temperature.
Some ways to combat this problem include:
-a hi-volume oil pump. This can include modifications to the block's oiling system for better oil distribution.
-a larger capacity oil pan. Most marine pans are a minimum of 8 quarts capacity; I myself run a 10-quart pan and my engine holds a total of 13-quarts with all my additional oil lines, filters, etc.
-heat exchanger. Not as common as the above mentioned components, but a very important one if you must combat a serious oil temp problem. I think more jetboats should be equipped with them.
-a good quality lubricant. Anybody that is apprehensive about running a synthetic lubricant specifically engineered for the application is probably not well educated in the area of engine lubrication, engine lubricants and their differing properties. As you are an engine builder, I don't believe I need to go into the details.
Anyone feel free to add to the list.:)
LO

[DiverDown]

Thanks for the info guys.
LakesOnly originally posted
-a good quality lubricant. Anybody that is apprehensive about running a synthetic lubricant specifically engineered for the application is probably not well educated in the area of engine lubrication, engine lubricants and their differing properties. As you are an engine builder, I don't believe I need to go into the details.
I build a lot of engines for the off-road guys around here that encounter some pretty extreme conditions including sustained RPM for long periods in 100 degree plus heat, and I can tell you that I have become a firm believer in synthetic oils and oil coolers in these applications.
I almost always use trap door type pans and run windage trays on the off-road deals. Do any of you do this with the boat set-ups?

[LakesOnly]

Originally posted by DiverDown
Thanks for the info guys.
I almost always use trap door type pans and run windage trays on the off-road deals. Do any of you do this with the boat set-ups?
Marine pans are engine-orientation specific; it the engine sits forwards or backwards, the pick-up tube is placed accordingly to be aft of the engine...
Crankshaft rotational speeds can cause a roping effect on the crankcase oil much like a tornado looks, except horizontal and wrapped around the crankshaft...Since our engines are usually around 5000 rpm, most all of us run a windage tray and gated pan.
LO

[Hustler]

I almost always use trap door type pans and run windage trays on the off-road deals. Do any of you do this with the boat set-ups?
I'm pretty sure most large capacity jet boat pans from either Dooley or Dan Olsen have both trap doors and windage trays

[cyclone]

I'm pretty brutal on my engine. I run it hard and haven't had any oil temp issues with it. The longest i've kept the pedal to the floor was for about 2 minutes long during a run from Topoc Gorge to the Avi hotel. My oil temp (according to an autometer electric gauge) never went over 220 degrees during that run. I keep the water pressure to the engine regulated at 30 psi and the engine idles with 140-150 degrees of water temp and cruises with 120-130 degrees of water temp. I was running 20W50 Valvoline racing oil in it last year. The engine is a BBC with a 11qt Moroso oil pan, windage tray and trap doors. It takes about two minutes for the oil to get up to operating temp at start up and the pressure to drop down to an acceptable level.
Now my 455 was a different story. With the same type of Moroso pan, same oil and essentially the same water temps, this motor would run up to 300 degrees oil temp if i ran the engine over 4,000 rpm for more than a few minutes. The folks i boat with have fast boats so i was always on the floor trying to keep up with them on longer river trips. I'd routinely stop and shut the engine down for a few minutes at a time to let the oil temps drop and the pressure increase before boating again. The oil system did have restrictors in it. I'm unsure if this is strictly related to the engine being a 455 olds or what, but my BBC doesn't have the same oil temp problem.

[fourspeednup]

The longest i've kept the pedal to the floor was for about 2 minutes long during a run from Topoc Gorge to the Avi hotel.
Holy Shit! That's friggin haulin!:eek: :eek:

[Chris J]

Anytime you stall out a BBC on high rpm you're putting one serious load on it. An oil cooler is cheap insurance to protect your motor. I can't imagine spending big money on a motor then risk burning it up becuase you don't want to spend the money on an oil cooler.
Might as well run with sizzors while your at it.
Oh ya, I have a 5500 stall in my Vega and running a motor at 5500rpm with minimal load is not even close to running 5000rpm with a full load. Motor oil temp has never been an issue on my Vega even with no oil cooler, tranny temp now that another story. My point I guess is that its not the rpm its the load the pump puts on the motor that cause the high temps. Even if you have a stock motor that never goes above 4500rpm. If you run WFO for extented periods you're building some serious heat in the oil

[Taylorman]

What kind of oil coolers are you all running?

[cyclone]

Originally posted by fourspeednup
Holy Shit! That's friggin haulin!:eek: :eek:
you should have seen the other guys. Tom Bandy and Randy were right there running 3 wide as we headed back to the CBBB gathering. Ill bet we made quite a bit of noise as we flew through needles. :)

[DiverDown]

Hey Cyclone, I am new to the boards and as I stated I am a small town small shop custom engine builder,(among other things) that is being talked into getting started in marine engine building so I have just been lurking around and reading different things on these boards about boaters and what their experiences are and what not. In my reading I came across a couple of different threads where some of the members had expressed to you that the Weind blower you went with was some how inadaquate and a non desireable piece. I just wanted to let you know that although I admittedly have very little marine experience, I do have a lot of experience building engines for extreme environments and we have used several of the newer Weind blowers with nothing but success and I think you will be happy with your decision for what it's worth.

[Chris J]

What kind of oil coolers are you all running?
I have a Dan Olson that bolt to the block in place of the oil filter. Then the remote oil filter adaptor bolts to the cooler. Fits nice and tight to the motor. Easily fits inside 26" wide stringers. Water runs from the pump to the cooler then off to the motor.

[cyclone]

Originally posted by DiverDown
Hey Cyclone, I am new to the boards and as I stated I am a small town small shop custom engine builder,(among other things) that is being talked into getting started in marine engine building so I have just been lurking around and reading different things on these boards about boaters and what their experiences are and what not. In my reading I came across a couple of different threads where some of the members had expressed to you that the Weind blower you went with was some how inadaquate and a non desireable piece. I just wanted to let you know that although I admittedly have very little marine experience, I do have a lot of experience building engines for extreme environments and we have used several of the newer Weind blowers with nothing but success and I think you will be happy with your decision for what it's worth.
well that is good news. i wasn't worried about the blower but hearing that helps alot. thanks!

[Bense468]

That was me that said that, and I was asking? I did a little research myself and it looks as if the problem was with the old style blowers. Superdave then came back and said the same I thing. So thats good news as I am looking into one myself.

[cookieman]

I have a blown 509 and my oil temp will increase to over 260 when I get into the 5000 rpm range. I use Mobil one and have a 10qt oil pan. My water temp will run about 160 and soon as I get off the gas it will cool back down at the 3000 rpm range. I know that most of my heat in the oil comes from the blower building the boost. I run about 5-7 lbs of boost at the higher rpms. I know that with regular oil like the Vavloline racing oil my temp was a little higher, but with the Mobil 1 it seemed to run a little cooler. Just a little input on what happens on my jetboat.

[1HOTGMCJET]

Originally posted by Chris J
What kind of oil coolers are you all running?
I have a Dan Olson that bolt to the block in place of the oil filter. Then the remote oil filter adaptor bolts to the cooler. Fits nice and tight to the motor. Easily fits inside 26" wide stringers. Water runs from the pump to the cooler then off to the motor.
Hey Chris - can you provide a part/model number for that cooler? Thanks!

[Jungle Boy]

Man, you guys baby those engines of yours. "don't hold her wide open for more than 30 seconds?". "2 minute wide open!!"
You should come river boat racing. I have held my 434ci wide open for 40 minute legs in some races. Then the next day, do it all over again! 500 miles is a marathon race. I've used this engine for 2 races and lots of running around. The leakdown and compression test says that it's in great shape. Your motors should last longer than you. :D :D
Oh ya, I run a 8 quart Dan Olsen pan and Steiger cooler and once the temp hits about 240 / 250, it stays there for the full leg.

[shaun]

Any of you guys have some pics of where you put th coolers?