Oil coomming from vent

[89tgreen]

I run the setrab to by the way. Seems like a great cooler.

[VMS Motorsports]

I dont run a temp gauge, but we run one in Dans car, and it hasnt gotten over 200.
Theyre not cheap, but they're worth it to me

[Gimpster]

 No fans or gauges here.

[IraceLegends77]

I run a temp gauge and a fan. I turn the fan on at the first caution or at about 10 lap mark. I leave it on after the race and put a house fan on the car also. Every two minutes or so I will crank the engine over to pump cool out of the cooler and get some of the hot oil out of the engine. I repeat this about four or five times after the race. Kevin Yeatts showed me this trick years ago and I think he learned it from Hank Scott. It is just what I have always done.

Scott

[knoxracing]

You know this is a good discussion,  we run our fans on the back side of the cooler, maybe alot of guys run the on the front and that would for sure restrict air flow, i figure if its on the back it cant really restrict air across the cooler. The Setrab is a nice cooler, but they are kind of heavy and i have seen alot of them leak after a while, I think it is because they are so thick and rigid. i like the Fluidyne because its flexible and thinner and it cools as well if not better. The thinner Fluidyne  coulpled with a low profile fan allows you to move the cooler back away from the grill about  an inch and a half.

[Bigmil]

Ok, I am actually a wind tunnel guy.......and an engineer (I know, boooooo)......I have worked in automotive and Air Force wind tunnels for the past 10 years primarily in cooling system testing.  And while I wasen't the technical test engineer I am around a lot of those aero guys (I know poor me, these guys are worse than us regular engineers ).

If the fan is not running it can likely run as fast as the airflow pushes it (assuming there are very little mechanical losses in the fan).  But you still do get a little bit of back pressure (reverse blockage) that increases the faster you go (I don't know how fast you need to go for this to be a problem except that at Mach 3.0 it's a lot).  You would have no current draw in this situation.  Infact if you were super smart you could actual use the fan turning to charge your battery (or boost your ingition power.....)

If the fan is running and the vehicle speed is less than what the fan is pulling then the fan will "make-up" the difference in airflow and increase your cooling (using less current draw the faster you go....to a point)

If the fan is running at the same air speed as the vehicle then in theory the fan would have little to no load on it thus drawing little to no current from the charging system.  So you won't need to worry about your battery draw.  And you are getting little to no "help" from the fan. 

However if the vehicle air speed is faster than the fan air speed and the fan is running the fan will likely continue trying to hold the max speed the fan is designed for (because most of these fans do not have a clutch).  Thus restricting airflow and increasing current draw on the charging system.  Of course this assumes that you will never be behind somebody who is slowing/disrupting the air in front of you.

If the fan is mounted on the front of the cooler it will likely block at least some airflow even when running.  I would not recomend this unless you do most/all of your racing at speeds less than what the fan pulls.  I'm not trying to say anything here but some of us maybe be that slow

I was wondering if there is a fan out there that has a clutch that would allow it to spin faster than it's max without increasing load or damaging the fan?  That would be ideal otherwise I'm thinking a fan is only useful if you remember to turn it on and off properly (which I could never do during a race this past year)

If I get a chance I will try and run some calculations on what air speed the fans are pulling the see how far off we are.  Does anybody know what cfm these fans pull?  I'm thinking arounf 500cfm (for an 8-9inch) but I'm not sure.


Gerad

[Bigmil]

Why do I always feel like I am the nerd who takes things way to far? 

Anyway, I ran the calculations on a 9" fan that runs at 500cfm and it is only pulling air at about 12.8 mph.

That's pretty slow, I don't know if we are really getting value from the cooling fan even under caution?  Maybe red flags?

I am begining to think that either these fans do have some sort of clutches or they aren't doing us any good, unless you can find an 9 inch fan that pulls nearly 3000cfm.....good luck.

[thunder938]

Also you have to think of the ppl that have fans on other areas than just the cooler...They are alot of people that have fans blowing down on the back of the head and tube tube fan on the fire wall blowing on the back of the head/jugs...

[89tgreen]

Thank u Gerad very interesting.

[JGRacing]

Now if Gerad can just help us sneak a legends car into a wind tunnel, we can have some fun.   

My cooler with the fan did not keep the oil temp below 300 by the end of a feature, so it sounds like I need to do something different.  To cool it down last year after the race, I put a leaf blower in front of the engine and left it going for a few minutes.  It did move a lot of air and seemed to help.  Leaf blower died so I went to a little Harbor Freight generator and house fan this year (for my one whole race).

[Gimpster]

 Makes me think.... suggesting the fan will charge the battery and supply lost power back to the ignition system. Only problem with this theory is the diodes in the regulator (one way) not allowing voltage back into or beyond the regulator into the charging system. Might charge the battery if the fan was wired directly to it's posts. If the fans could put charge back into the ignition system..... too much voltage would burn out light bulbs, tacometers and ignition boxes. I would have to throw that theory out the winder.
 Fans are a waste of time and money over here racing on dirt. We don't see the outside temps that most of you do. Majority of our races are at night and we don't see hot weather until around July.... cools down quick in the evening when we race too. Checking the head tempurature, after a run, with my mini temp gun (laser)  shows the same head temps if you are running a fan during the race or not running a fan. Maybe 20 degrees ? (remember I said around here) That could be the difference in humidity per night.  What I did find that made a difference for lower temps is having the header tubes wrapped and as many louvers in the hood as allowed, directing air flow to the head. I watch my oil temps after each race with my mini temp gun at the oil pan line fittings. When I pull in, the hood comes off while the engine is running and a box fan laid facing downward over the engine. Keeping the engine running while it cools with the fan will not only cool the head but the oil evenly. My concern is the fiber on steel of the clutch discs over and beyond the engine temps. If you turn off your engine..... cool it with a fan and fire it up after a short period, the oil, the aluminum, the steel and the fiber parts in the engine cool at a different pace. This my friend WILL lead to premature engine part failure and wear. Hard on rings, valve guides bearings, clutch fibers etc..... You know what happens with a hot piece of steel and cold water..... temper of the steel changes. Turning off an engine and forcing air on it then restarting the engine does the same thing to engine parts as hot steel and cold water.
 Maybe this is why my engines last so long without issue ? Maybe because I have been a tech in the motorcycle industry for 30+ years that I know this stuff second nature ? I have said more already than I intended to...... lol

----- Gimpster -----
 
   

[JGRacing]

How far down do you wrap the headers?  Just the runners or all the way down the muffler? 

[knoxracing]

Keep this in mind when wrapping you exhaust. i used the header wrap everyone uses, I believe it is suppose to be fire retardant.  I had a rod come through the block, the oil saturated the wrap and there was a fire. The wrap was like a huge torch soaked in oil, it caused alot of damage and heat in the cockpit.  That was the last of the wrap for me, lol.

[Bigmil]

I fully agree with gimpster!!

Yes, like I said the fan charging thing was beyond my mental capacity (and apparently the charging system capacities too  )

Sounds like the oil cooling fan again doesn't do much good.

I also agree with the cooling principle he brought up.  This past year after going through two engines (due to other issues) I borrowed an engine from a guy with one stipulation, that I "don't put a fan on the motor".
That guy and I agreed about  the thermal transfer through the motor and the danger in cooling certain parts unevenly and there effect on a sort of an uneven tempering condition.  And to prove that point the engine I was using was a 1250 orginally built in 2000 and had never been rebuilt and was still running pretty good.  It had over 300 races on it!

Leaving your engine running and cooling all down gradually is by far the best way to go!!!  In my opinion anyway.

I am know going to order header wrap!

[VMS Motorsports]

Keep this in mind when wrapping you exhaust. i used the header wrap everyone uses, I believe it is suppose to be fire retardant.  I had a rod come through the block, the oil saturated the wrap and there was a fire. The wrap was like a huge torch soaked in oil, it caused alot of damage and heat in the cockpit.  That was the last of the wrap for me, lol.

It will also cause alot of corrosion and you'll be replacing your header pipes every 3 years