Ironhead Oil Cooler installation on an early Ironhead

[mikethebike61]

Originally Posted by kitabel

IME if you can keep your hand on the tank for 5 seconds it's cooler than 160 degrees = no cooler needed.

Read the race car books: cooler must be bled or burped.

Nothing in the manual of my LockHart cooler with 2 down facing fitting said a thing about burping

And race CARS are not the same as street BIKES

In the early 1970's my BOSS 302 Mustang had no reference to burping the oil cooler...neither did my motorhome

[11B40]

Piemonte: "I disconnected the rear chain oiler but left it in situ, capping off the supply point."


Consider you target reader: We will accept "Where it was" but Latin??? These are Harley people...
D

[Ferrous Head]

I have no idea what the PSI on the return side of a 900 style pump is but given that the feed runs at 4 PSI or less I'm going to guess much the same.
And unlike a gravity feed system like your gas tank there will be positive displacement.

Meaning, if you put a blockage in the line (or even a restriction) the pressure will build.

If an "air lock" became a blockage the pressure would build until such time as it shifted that blockage. Or blew the hose off, whichever cam first.

On the feed side of a system that depends on gravity for it's motive power, yes, an "air lock" would be a serious problem if it occurred in or near to the pump gears.

[Jeff]

Originally Posted by mikethebike61

Nothing in the manual of my LockHart cooler with 2 down facing fitting said a thing about burping

And race CARS are not the same as street BIKES

In the early 1970's my BOSS 302 Mustang had no reference to burping the oil cooler...neither did my motorhome

Yeah... I've been running air cooled 911 race cars for almost 40 years now. These are dry sump motors with a separate tank, just like our bikes. My current car is a '72, with the oil tank (of about 10 quarts capacity) mounted in the right rear fender ahead of the wheel well. I run two oil coolers on this car (raising capacity to 16 quarts), one each in each front fender, ahead of the wheel well and behind the headlights. There is about six feet of oil line under the right rocker panel from the tank to the right cooler, and about four feet of crossover line in the trunk to the left cooler. Both coolers' inlets and outlets are on the top. Absolutely no way to bleed such a system. And, in that 40 years of playing this game, no one I know has ever even thought they had to. Non-issue.

[Ferrous Head]

If you run these things hard for any length of time when the ambient temperature is what we consider "high" in Australia, they will get too hot.

Same reason Chevy wouldn't sell you an LT-1 in a Corvette with air conditioning for years.

High comp and cast iron heads. Makes heat.

[11B40]

The great Cook Nielson pointed this out about his Sportster Drag bike. Robert decided to put a oil pressure gauge on the Turbo Bonneville bike. At 180 MPH it showed less than 15 PSI. Couldn't stand to look at it, so he took it off. Same with the expensive waste gate.

Gravity feed oil: most race Sportster engines are running fine on a 1 or 1 1/2 quart oil tank. 5 or 6 miles at full throttle.

[Jeff]

What is "too hot"? The reason I ask is that "too hot" seems to vary a great deal both by machine in question and individual answering.

Our target temperature, under race conditions, was always just hot enough to boil the water out - about 220 degrees. 230-240 was getting "hot", 250 and up "too damn hot". Yet I've raced near Bakersfield, CA (Buttonwillow Raceway) when the ambient was over 100 degrees, and the car regularly hit 280. No ill affects whatsoever. Sent an oil sample from that day to Blackstone Labs for analysis, and they said it was still "fine". No signs of breaking down. Semi-synthetic Brad Penn 20w-50.

Since I actually enjoy building motors, buddies have called upon me to build an unusual variety. Air-cooled thumpers (big Hondas) in the '90's and early 2000's for desert racing are one example. These things ran at 320 degrees all day long, with no oil related damage. Again, samples sent to the lab were reported to be just fine, with no breakdown of any kind.

So, I was reading Car and Driver some time when they were testing the last real Corvette, the last front engined ZO6. They had it at Willow Springs, in the California desert, on way too hot of a day. The oil temperature safety shutoff kept kicking in and putting it into "limp" mode. I was astonished that it didn't kick in until something like 325 degrees. The inference, of course, is that Chevy thinks it's o.k. to run that car up to 320 degrees oil temp. Yikes...

I've only ever raced one bike (unfortunately, an "agreement" was negotiated with my lovely wife wherein any future such activities would only be pursued in automobiles, with a cage, harnesses, etc... One little "off", one in which I was not even injured, was enough to spark these "negotiations...). The bike was (still is, I guess) a thoroughly prepped 1993 Ducati 900 Super Sport. That thing ran at 270-ish all the time, and had no trouble approaching 300 degrees in the right weather. I still have it (it has plates and lights on it now). I refreshed just the top end after "retiring" it, and it now has over 90,000 miles on it (I rebuilt the whole motor twice over five years of racing). Never saw any indication of damage caused by oil breaking down or anything like that. And, again, I regularly sent samples in for testing, just 'cause I'm kind of a nerd like that.

All of that leaves me pondering just how hot is "too hot" with today's oils. With a street going Ironhead, can we even get there? Myself, I just change the oil regularly and never even think about it. As a matter of fact, at my last rebuild, I removed the original Lockhart cooler. It looks a lot cleaner without it, and there is a little less plumbing to leak.

[Ferrous Head]

Kind of different situations we're talking about here.

When I build race engines I am on the "loose" side. If the clearance is 0.005 to 0.009 I will aim for the upper range - 0.008 or so.

On a street bike you generally run tighter. The bottom end of the range.

Things expand when they get hot. Just a fact of life.

And most car engines and certainly Honda's bikes run slipper bearings, not rollers. They have high pressure high volume oil pumps. We run low pressure low volume in our roller engines. Your Duke of course fits that (or does it that late in the years ?)

Anyway, running the engine right on the edge all the time isn't a good idea.

What you risk by letting engine temperatures rise is the failure of the oil to allow two moving bits of metal to "float over each other in hydrodynamic lubrication.

ie, the metal bits contact each other.

I think you'll find most manufacturers recommend temps in the 180-210F range.

On a race engine that's going to be rebuilt fairly often it's not as big a problem. On a street machine it can dramatically shorten an engines life if you constantly run it "hot'.

If the ambient temp at Lakeside is 100f the track temp will be 170. Now that's horrendous for my tires but certainly adds to the heat load on my engine (Not to mention me !)

I've run my gas burning engines until I can't put my hand on the oil tank at all. Didn't die but it sure sounded like a chaff cutter running thin water rather than oil.

From memory the cylinder head temps were around 320. Way too hot for my liking.

[Jeff]

Agreed - I'm comparing apples and oranges. Kind of on purpose, though. In our case, we have a roller bearing motor with cast iron cylinders and heads. The 911's are, of course, plain bearing. They will either be biral cylinders (cast iron sleeve pressed into aluminum fins) or nickasil plated aluminum, in both cases with aluminum heads. The Honda desert racers were roller bearing with biral cylinders and aluminum heads. The Duke is based on the newer Pantah platform, with plain bearings and nickasil plated aluminum cylinders, with aluminum heads (and belt driven cams rather than the earlier bevel drive).

So a real "dog's breakfast" mix of bearing and cylinder types. And yes, I've seen heat related failures in all of 'em (not necessarily my own examples of each). Mostly in the form of scored pistons and/or cylinders - I'm not sure I've seen bearing failures that I can attribute to heat.

And yes, our cast iron heads and barrels are certainly a problem in this regard. Hell, the first gen XR750's were less than competitive due to heat soak, and couldn't really run hard enough for long enough until aluminum heads and barrels were introduced.

I'm unconvinced, however, that any amount of oil cooling would have helped that situation. Nor will it, in the context of this discussion, help our street ridden Ironheads. These do not evacuate cylinder head, cylinder, or piston heat through the oil going through or being splashed onto them.

Some newer engine designs have oil squirters that direct a pretty good spray of oil onto the bottoms of the pistons, which actually do a very good job of getting heat out of the pistons. Both my 911 and Ducati motors feature these. I, or course, have no way to measure or quantify their effectiveness, but technical papers from both manufacturers have been published that contain that data. They are apparently quite effective.

Which is, of course, all moot on our old Ironheads. As little oil as goes through them (heads and barrels), the oil is not helping to cool anything. As such, the oil cooler is only there to protect the oil from overheating. In other words, the oil cooler is not dropping engine temperature, it's dropping oil temperature. Two entirely different things.

Many years ago, one Gene Berg (the hot rod Bug motor guru) conducted a test. This was when synthetic oils were new-ish, and all the rage for lowering temperatures in everything in which it was ran. So, Gene ran tests on a drag motor, running both dino and synthetic back to back. Sure enough, oil temps dropped significantly with the synthetic. He knew they would, but that was not what he was looking for - he was monitoring head temps as well. They went through the ceiling with the synthetic. Turns out the only reason the oil temps looked so good with synthetic is because it was not absorbing, and thereby evacuating, the heat from the metal engine parts as efficiently as the dino oil. Some lessons to be learned there...

Anyway, that's all kind of long winded, I know. What I'm getting at, in a nutshell, is that lowering oil temps doesn't always have the affect we think (or hope) it might. In our motors, the "destructive" heat is generated in parts - the heads and barrels - that do not see enough oil flow to help them. So while lowered oil temps make us all feel better, in our case I'm not sure it helps in any way.

[Iron Mike]

For what it’s worth, I too have raced numerous types of engines at Buttonwillow, Thunderhill, Sonoma and just about every road course across the US. Lots of rotaries and numerous other styles of engines as well as some pretty hot 4 cycle karts (lots of laps at big Willow, roller brg eng). Along with those, I have spent long hours racing through Death Valley in August. It gets slightly warm there. At one time or another with all of those packages, oil samples were taken. We generally use a quality oil. Never once have I received back an “overheated” oil analysis. Through collected data I have seen sustained 320F with spikes of 340F.
When first started campaigning a top tier off road racer, I questioned the engine builder about when and if we should back down a hair to let temps creep down. He wasn’t concerned at 320F.

I never run coolers on my IH in Phx, but then again it is mine.