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Discussion Starter #1
Is a single -16 scavenge line back to the tank enough ? I have 4 scavenge stages, 3 in the pan and one in the valley. The tank is going to be in the back seat area. Probably 8-10 foot line back to the tank. I'm worried I should have two -12 lines going back instead.

Thoughts? This is on an endurance engine as well.
 

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T/S 368E
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That is exactly what I have, 3 in the pan, 1 in the valve cover.
No issues so far with a custom Weaver Bros pump with the tank a few inches away.
I went with a single -16, instead of the -12's it originally came with.
I figured it would be easier to plumb and less fittings, less things to leak.

No clue about your deal.

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Discussion Starter #3 (Edited)
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That is exactly what I have, 3 in the pan, 1 in the valve cover.
No issues so far with a custom Weaver Bros pump with the tank a few inches away.
I went with a single -16, instead of the -12's it originally came with.
I figured it would be easier to plumb and less fittings, less things to leak.

No clue about your deal.

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Is your feed back to the pump (from the tank)-12 or a -16?

I was wondering how I would know it there was not enough scavenge .... Not pulling enough vacuum maybe ?
 

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Is a single -16 scavenge line back to the tank enough ? I have 4 scavenge stages, 3 in the pan and one in the valley. The tank is going to be in the back seat area. Probably 8-10 foot line back to the tank. I'm worried I should have two -12 lines going back instead.

Thoughts? This is on an endurance engine as well.
One #16 is enough, all the NASCAR stuff ran that for years. In the early 2000's most of them went to two #16's or one #20 and claimed a slight increase in crankcase vacuum. I have ran NASCAR trucks, Xfinity and Hooters Procup cars with one #16 with zero issues.
 

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Discussion Starter #5
One #16 is enough, all the NASCAR stuff ran that for years. In the early 2000's most of them went to two #16's or one #20 and claimed a slight increase in crankcase vacuum. I have ran NASCAR trucks, Xfinity and Hooters Procup cars with one #16 with zero issues.
Awesome thanks! I got this engine from a 2000 era stock car and this is how it was setup.

So I was assuming it was fine. But it seems more people are going dual scavange return these days .
 

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T/S 368E
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All my lines are -12 except the return line.
I was worried when they made the returns all internal a -12 would be a restriction.

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Awesome thanks! I got this engine from a 2000 era stock car and this is how it was setup.

So I was assuming it was fine. But it seems more people are going dual scavange return these days .
2 -16 return lines are the norm today. There is a small but measurable loss going from dual -16 to a single -20. Your single -16 will work, but definitely not as efficient as duals.
A single -16 is the smallest I would ever run for sure.
 

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Discussion Starter #8
2 -16 return lines are the norm today. There is a small but measurable loss going from dual -16 to a single -20. Your single -16 will work, but definitely not as efficient as duals.
A single -16 is the smallest I would ever run for sure.
My main concern is the location of the tank. It is a decently long run... I willlook into adding a second scavenge return line. I think I can change up the pump configuration and just run one more. The tank has two upper fittings on it
 

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T/S 368E
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Single 16 is perfectly fine for nearly all drag race applications.

Thank you, they had me ffreaking out for a second!!
It's been perfect for 20 years, why would I change now!!!

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In a non drag race application with the tank in the back seat area, would this still be OK?
I'd say 80% of those applications run a dual return, most of my dirt late model customers run dual 16's. Some do run a single 16, just depends on the engine builders preference
 

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Discussion Starter #13
I'd say 80% of those applications run a dual return, most of my dirt late model customers run dual 16's. Some do run a single 16, just depends on the engine builders preference
thanks, i will look into changing one of my sections so I can add a second return line then. Seems it would probably be better, or a single -20...
 

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Is a single -16 scavenge line back to the tank enough ? I have 4 scavenge stages, 3 in the pan and one in the valley. The tank is going to be in the back seat area. Probably 8-10 foot line back to the tank. I'm worried I should have two -12 lines going back instead.

Thoughts? This is on an endurance engine as well.
Not a lot of oil is returned to the tank in a drag car vs a circle track car during a 1/4 pass. Even less in an 1/8 pass. Single 16 is plenty.
 

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T/S 368E
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So it's like fuel.
I was always thinking I needed the giant ass monster pump, and giant lines when during the pass you really only use a few ounces of gas.
Obviously different for meth & fuel cars!!!


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This is going to be a road race engine though
I told you in post #4, a single 16 will work. I would bet your supply line from the tank is no larger than #16, possibly even #12? You will be pushing the same amount of oil back to the tank that you pull through the supply line, I promise you it's not a problem. The one #16 versus two # 16's may result in 1-2 inches less crankcase vacuum and maybe a couple of horsepower at the most.

In the late 90's we did plenty of GT1 cars with 311 SBC engines and all anyone ran then was one #16 return, no issues.
 

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Discussion Starter #18
I told you in post #4, a single 16 will work. I would bet your supply line from the tank is no larger than #16, possibly even #12? You will be pushing the same amount of oil back to the tank that you pull through the supply line, I promise you it's not a problem. The one #16 versus two # 16's may result in 1-2 inches less crankcase vacuum and maybe a couple of horsepower at the most.

In the late 90's we did plenty of GT1 cars with 311 SBC engines and all anyone ran then was one #16 return, no issues.
I know.. You know how it is , so many people, so many different ways of doing it...

Ill just stick with it though I am sure it is fine thanks.. Yeah it has a -12 on the pump, but my tank has a -16 for the feed so I was thinking of just running a 16 at least to my firewall bulkhead, and maybe a 12 from there to the pump..
 

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I know.. You know how it is , so many people, so many different ways of doing it...

Ill just stick with it though I am sure it is fine thanks.. Yeah it has a -12 on the pump, but my tank has a -16 for the feed so I was thinking of just running a 16 at least to my firewall bulkhead, and maybe a 12 from there to the pump..
#16 to a #12 at the firewall is common for what you are doing. If you have room for a #16 line all the way to pressure in side of the pump, XRP makes a 90 degree hose end that is #16 hose to a #12 AN just for this application. That is best if you have room for the #16 hose. XRP part # is 209017.
 
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