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Discussion Starter · #1 ·
It's like this...I'm doing an auxillary oil cooler on the carb side of the motor.

The plumbing on the untouched motor is a fitting with a "Y" bolted to the top of the motor just infront of the clutch. It then splits left and right to the top of the motor just above the carb intakes.

On my project the line comes out the same place, goes rearward to the cooler mounted under the seat. After flowing through the cooler, the line comes back toward the motor.

Here's the question. I now have to divert the oil to the fittings just above the carb intakes. To do this I have a fitting that allows for the AN fittings to be employed in one of two configurations.

The first is a "T" configuration. The oil would be coming from the bottom of the "T", where it would be "stopped" at the top of the "T". Then the oil would flow left and right to the sides of the "T" to the motor.


The other configuration is what I'll call the "L+" configuration. The oil comes from the bottom corner of the "L" flowing in the direction of the top of the "L".


Here's what bothers me about the "L+" format...I learned years ago how to create a vacuum by flowing water through a fitting like that. The water passes by the extended portion of the joint creating suction. We use a machine just like that here in the clinic to aspirate fluid (ususally blood) away from things. I saw on JOEY-GSXR1100's motor the type of joint I'm worried about...


I'm NOT an expert at this kind of science...and I'll bet Joey's line configuration isn't pulling oil from the left side of the motor over to right.


Any guesses folks??

[ 10-09-2001: Message edited by: bcklrcr ]

[ 11-17-2001: Message edited by: God ]</p>
 

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If I remember correctly, the flow rate through one branch should be equivalent to the other assuming that the cross-sectional areas of the branches are equivalent. The flow rate on the input sides equals the sum of the flow rates exiting. The flow rate in each branch should be exactly one half the flow rate entering the system in this situation.

Assuming laminar flow (you shouldn't get turbulent flow with motor oil), the friction factors are constant. Each branch has one elbow so minor losses in the joints can be neglected for comparison purposes (they cancel each other out).

The equation for head loss for parallel pipes from point a (initial branch)to point b (motor) is:

Pa/gamma + Va^2/2g + Za = Pb/gamma + Vb^2/2g + Zb

Specific weight gamma of oil is constant. Gravitational acceleration g is constant. Fluid velocities Va and Vb are equivalent (flow rate Q = VA where Qa = Qb and areas Aa = Ab, so Va = Vb). The heights Za and Zb of the exiting oil at the engine are also the same. So the pressure of the fluid in each branch is the same. If the pressure is the same in each branch, the flow will be equal in both pipes.

If I am correct, you should have no problem running either configuration. If there are more complex considerations that should be taken, they are beyond my knowledge of fluids. Common intuition says that more fluid will tend to flow in the path that it is originally travelling due to momentum. Intuition can't describe the "wake" region or "washing machine" type of effect that occurs in the fluid flow at the junction point.

I only took two courses and I got an A and a B+. This was a little while ago though. Get a second opinion.


[ 11-17-2001: Message edited by: God ]</p>
 

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uhhh, guys, we have a problem here, DO NOT START THAT ENGINE!

[ 11-17-2001: Message edited by: God ]</p>
 

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Use the T if you want even flow to both sides. Use the Y if you want more flow to one side than the other. The straight thru side will flow more. This will cause uneven distribution of the oil in the head.

I would use the T.

Oil pumps are typicaly progressive cavity pumps. (A gear pump is a progressive cavity pump.) Typicaly, progressive cavity pumps can handle an extra amount of resistance and still provide the same amount of flow. However, the pump will require a little more input power to move the fluid. But, too much restriction, and the pump will begin to cavitate. This will eventualy destroy the pump.

For your oil cooler project, the pump will be safe. Don't worry. (As long as there aren't any blocked lines.)

Side note. Lochart use to make (I think they still do) oil cooler thermostats. If the oil is kept too cool it won't properly lubricate. The thermostats are available at almost any Harley dealer. (I would strongly recommend a thermostat) On second thought, the thermostats sold by Harley don't have AN type fittings. You may want to try Summit racing or some other race shop to get a thermostat with AN fittings.
 

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I agree, you will most likely get more uniform flow with the T. If you really want to get trick try to locate a Y fitting from NOS. I'm not sure what sizes they are available in but you may want to consider it. You will get the least amount of flow disruption and even flow. You may want to check Summit racing or a local speed shop for the fitting.

[ 11-17-2001: Message edited by: God ]</p>
 

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<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by KENNEDY:
....
I would use the T.
....
<hr></blockquote>

definitely. i agree.

[ 11-17-2001: Message edited by: God ]</p>
 

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I work in a CAD/CAM/CAE department, as the manager.
We do non-linear analysis thus the CAE part.

KENNEDY is correct in everything he posted. I do believe the "T" is far more efficient at even distribution, all else the same.

[ 11-17-2001: Message edited by: God ]</p>
 

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Let me correct myself. The flow will be UNEVEN since the branches do not rejoin and enter as a single flow before reaching the head. If the branches rejoined, the flow through each branch would be even. But that is not the case here.

As for cavitation, you'd need to determine the net positive suction head (NPSH) which is the head required at the pump inlet to keep the oil from cavitating. For this, you'd need the pump curve from the manufacturer for the pump you are using. That is the only way you can determine before hand if cavitation will occur in your system design. If it does, there will be pump noise, vibration, pitting, and eventual failure.

BTW, I would also use the "T." Why would you use the "L" anyway?

[ 11-17-2001: Message edited by: God ]</p>
 

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I've been pondering this all day, I'm an aerospace engineer so supposedly I'm allegedly somehow smart
, I'd say go with the T... it's your bogey

[ 11-17-2001: Message edited by: God ]</p>
 

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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by reznunt:
As for cavitation, you'd need to determine the net positive suction head (NPSH) which is the head required at the pump inlet to keep the oil from cavitating. For this, you'd need the pump curve from the manufacturer for the pump you are using. That is the only way you can determine before hand if cavitation will occur in your system design. If it does, there will be pump noise, vibration, pitting, and eventual failure.<HR></BLOCKQUOTE>

No need for NPSHr here. The NPSHa will be the same or higher (oil will be cooler and the suction will remain flooded). The oil lines being modified are on the discharge side of the pump. This will make the pump want to run to the left of the curve (if anything).

Changing the discharge side of the system will not make the pump cavitate. The pump will cavitate (or self destruct from too much pressure) if it is run at shut off for too long.

Also, gear pumps are forgiving on NPSH related cavitation. Look at how long scavenge pumps last (almost forever). They are subject to low NPSHa and poor mixture quality.


bcklrcr
Another thought. Make sure you get all the air purged out of the cooler and lines. I'm not sure if the stock oil pump has the guts to burp out the entraped air.
 

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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by jp233:
I've been pondering this all day, I'm an aerospace engineer so supposedly I'm allegedly somehow smart
<HR></BLOCKQUOTE>

Maybe I won't fly delta

Some of the aerospace stuff is tough. I got to visit Lear ROMEC's test lab. All I have to say is WOW!!!
 

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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Maddog:
Dammit!
So is Joeys' motor gonna blow up or not?
<HR></BLOCKQUOTE>

Don't worry it Joey's


Honestly, it will be OK.
 

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I was wondering because two people acted like it was obviously not going to work, and any idiot should see that.
And I just don't see the problem...
so I was wondering if I was an idiot.
(EASY there hunter! You can let some slide)
 

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Discussion Starter · #16 ·
Why would I use the "L" format? It would route better toward the motor.

I emailed a friend of mine with a PhD in fuel injection and his question was "what's the flow rate?" I don't know.

As for a temperature guage, I've ordered a very slick Yoshimura Guage to do just that.

[ 11-17-2001: Message edited by: God ]</p>
 

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Well, I spoke to my old Fluids professor about the two configurations. He said that there would be less flow through one branch if using the L configuration. If routing was important and you wanted to use the L, he said to figure out the extra resistance caused by the L to that one branch and just use a longer hose on the other side to compensate for it. You'd get more resistance overall but you would be able to use the L. ALso, he said that there wouldn't be cavitation in the pump. There wouldn't be enough resistance unless you are using some crazy straw configuration.

I dunno. He knows more than me with his PHD-having ass. I'm merely an undergrad.


[ 11-17-2001: Message edited by: God ]</p>
 
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