Guess I need more gauges and stuff.

[buster]

I was reading that "SCORPY" thread today, and you guys were talking about oil coolers, gauges, etc.

So far I hardly gave a thought to oil temperature on the 084. I have gauges set up to monitor CHT on all four cylinders, but now I suppose I'm gonna be thinking about oil temp, until I actually get set up for that.

I believe someone even mentioned checking oil temp in two or more spots.
I'm not saying an oil cooler and checking the temp is not necessary, or even a good idea, but gee whiz My dash is as full as my pockets are empty. Maybe I'll need to find a place for a second instrament panel

Really now, is oil temp. checking all that necessary on an aircooled engine? I don't think I ever have seen it on anything as it came from the factory?

I'd like to get some opinions on this.

Thanks, Dave

P.S. I'll save the EGT question for later

[chuckitt]

OK buster, here is my opinion. Most generator motors run day and night at 1800 rpm. They will last a long time at that rpm. Then we take the little motor, put it on an airboat and turn it wide open throttle at 3600 rpm. I don't know of any engines that last a long time at wide open throttle. We also take the big cooling fan flywheel off the engine and all the covers that force the air from the flywheel around the cylinders. Now we don't have a cooling system and the engine will get very hot. We have 2 methods to help keep it cooler. Oil cooling and fuel mixture. I like to keep the oil pan temp below 160 degrees. When you add a large oil cooler mounted in front of the prop, you are also adding more oil capacity which helps get cooler oil back in the engine. That is why i didn't run Scorpy this weekend, i didn't get time to install a larger oil cooler. We will probably install a B&M oil cooler that we use on the 6 cylinder aircraft engines. That will double my oil capacity. The fuel cooling is done by the setup of the carb and the design of the intake. Setting up the carb just a tad rich is better than a tad lean. A lean running engine will run hotter. If you only gain a few rpm's or lose rpm's from 3/4 to wide open throttle, then add a throttle stop to keep the the throttle from openning all the way. There is no benifit to open it wide open and the fuel/air will be cooler going into the engine.
Thanks, Chuck

[buster]

OK Chuck, when you lay it all out like that it makes a lot more sense. I guess it would be wise to start with an oil cooler first.

I just happened to remember that VW engines are equipped with an oil cooler. It must be for a good reason.

Thanks,
Dave

[Duane Scarborough]

Buster,

You know that I highly respect Chuck's opinion, and much of what he said in his reply is correct.

However, his reply may be a bit misleading, Many generator engines ARE designed to run at 1800 RPM, but then many are also designed to run at 3600 RPM. The usual difference relates to whether they are using a 2 pole or 4 pole alternator. Diesel generators are usually designed to run at 1800 RPM, and use a 4 pole alternator, so that they put out 60 HZ. Gas powered generators are usually designed to run at 3600 RPM, use a 2 pole alternator, and put out the same 60 HZ.

Like anything else, there are exceptions, but that is the way things generally are done.

The 4A084 falls into the 3600 RPM group. The 4A084 engine was designed and intended to run at 3600 RPM.

Yep, we have stripped it down, so it doesn't have the crankshaft mounted fan, or the cooling shroud anymore. But we also have a propeller which moves a HUGE amount of air when the boat is moving at anything much above idle speed.

Now, does that mean that we need to add an oil cooler to an engine that did not have one in it's original, out of the box configuration? I think it's a good idea, but do not know how to size it.

For what it's worth, I've read that oil needs to reach "about" 180 degrees F for water to start boiling off.

Just throwing it out there to think about...

Thanks,

Duane

[brlcla]

I agree with what you have to say Duane but one thing.... something that I have come across before and also again just recently.... the crank mounted fan and shrouds were engineered to direct the air to crucial areas of the engine.... and believe this.... the prop is not pulling near the amount of air across these areas as you think. I ran across this issue running VW with Magnesium blocks a few years back and just recently my Briggs that I got a little hot.... pulling the fan and the shrouds you better make up for the cooling somewhere else... aka a larger oil cooler. Or build a shroud that will catch the prop air and pull it across the cylinders... All I can say is if you pull any of the stock cooling off an air cooled motor better have something you can watch the temps really close with....

The main thing to realize is that the prop is not cooling like you think it is.... I cannot stress that enough and I should or realized that before I pulled my fan off my Briggs b/c of what I have seen in the past.............................................. .......

[Duane Scarborough]

brlcla,

All very good points. Thank you.

That's part of why I've saved ALL of my original shroud parts. I may need to add some of them back, in a different configuration, to be able to cool the engine properly.

But then, on the other hand, if someone isn't going to be pushing his engine HARD, (like you're planning), then it may not even be needed.

Back to Buster's original question.

Buster,

You have CHT gauges for all 4 cylinders. My "suggestion" is this. Determine which 2 cylinders are running the highest CHT, and keep those. Then replace one of those other gauges sensing unit with the temp sensor in the rear oil plug. That's close to the pump's pickup line. I haven't measured, but you "MAY" be able to use the same temp sensors.

Duane

[chuckitt]

OK, I'am sorry i mislead you on the rpm's of the 084 but i didn't mislead you on the oil temp. I have seen many aircooled engines where the oil temp was ran above 160 degrees and needed to be rebuilt in less than 100 hrs on them. Heat wears out parts. If the oil that drained back to the oil pan is 160 degrees at the temp sender then what is the oil temp at the cylinder head? I know airboaters that that ran their oil temp 180 to 200 degrees and said it was OK, It wasn't long before they needed a top end job.
The ducted fan on the 084 will probably move more than 3 times the air over the cylinders than an open prop will. A propeller does not work like a fan. A fan moves air while a propeller produces light air in front of the blade and heavy air behind it. Try this: Stand in front of your engine and run the engine wide open, you will feel a little bit of air being pulled around you. Now stand about the same distance behind the prop and run the motor wide open and you will have a hard time standing up.
Simple, Just add more oil capacity by using a bigger oil cooler
Chuck

[David]

Duane you can throw your shrouds away no since to holding on to them taking up wasted space add a cooler and a gauge an you will be fine all aircrafts are designed to run a type of shroud but we don't do it how do we get away with well we add a oil cooler and a gauge to monitor it

[buster]

Hurricane fiberglass used to sell a cowl for their airboat a/c engines. If I remember correctly they garanteed it to reduce engine temp by 100 degrees. It should be possible to copy, if someone could find an old one, or just start from scratch with a picture. An oil cooler may be just as good, and a lot easier, and not as big a pain when you tinker with the engine.

Duane, you are right about the 3600 rpms. The 084 manuel states that "The engine develops its full rated capacity at a governed 3600 r.p.m." It is possible that some applications only operate it at 1800. I don't know, but maybe Chuck does.

I don't think I will remove one of my CHT gauges. The hole in the panel would be bigger that most oil temp gauges. The sender may fit the oil drain plug since it is a ring that the spark plug goes through, but I think the temp range is different.

I may just eliminate the volt gauge, since I found out my gps unit beeps and flashes a warning if the volts drop below 12 volts. Who could miss that

I did snipe a bid on an oil cooler on ebay, so I'm on my way towards lower engine temps at least.

Thanks,
Dave

[buster]

Yesterday I got my oil temp gauge installed. I put the sender probe at the port that the oil re-enters the engine after it runs thru the oil filter. I did not hook up the new oil cooler yet, I thought I would like to get before and after temp readings.

I ran it for about a half hour, on the trailer. It got just about 180*. I think it may get even warmer if actually on the water. I just wanted to check it out before I hooked up the oil cooler, to see if it was really needed. My thinking now is that it probably is a good idea to have the cooler. I plan to do that, maybe tomorrow, and then I'll do another test. I will post results in the Thread "Plumbing an oil cooler onto the 4A084".

I used an infra-red thermoter gun and checked a lot of places around the engine. I thought it was interesting the the coolest place seemed to be the cylinder that is right up close to the starter. That is where I was concerned about, and I built a scoop to funnel more air to that spot. I have not replaced it on this new engine, and now I realize it isn't necessary.

Dave