f4i dry sump oil tank size? and other dry sump questions.

[joshua lewis]

Our 06/07 car has an oil tank that i think is large. it is 14 inches high with a 5 in diameter. and we put 4 quarts of oil in. This is more oil than with no dry sump, and dry sumps should reduce the amount of oil. what size tanks are are you guys using.

I cant find any inline screen filters so i designed a part so that the oil goes through a normal oil filter before it goes to the pump could this cause problems with pump flow?

so if the pressure in and the scavenge out are the same theoretically you would only need enough oil in the tank to keep the outlet submerged right?

[Mike Flitcraft]

From what I have seen dry sumps usually use more oil.

Look at the Chevy LS series of engines. 6 quarts of oil. Look at the LS7, the dry sump. 7 quarts.

Same exterior block dimensions.

[Maverik]

You have to ask yourself how much oil will be thrown around in the engine... for example the worst case scenario for you would be an extended sweeper with the scavenge pickup uncovered. How much oil do you need in the tank to ensure the scavenge pickup gets covered again before the pressure pickup is uncovered?

[VFR750R]

dry sumps usually have more oil because now you have lines and a seperate tank, and the pan is usually not dry unless you did a great job of designing your dry sump pan. But designed correctly you should be able to use less oil. For reference, Nascar tanks are 24qrts. I've heard of F1 tanks as small as 1.5 qrts. The limit for oil is exactly like you say...plus oil consumption during the race...plus time for oil to purge itself of air. F1 engines have air-oil seperators on them so the oil is very pure that is in the tank (low percentage of air). Dry sump tank design is also critical for de-aeration of oil. make sure your scavenge returns enter the tank tangential to induce the oil in the tank to spin. Tanks should be twice as big as you need and only run half to two thirds full. this lets the oil spend some time on the walls of the tank before reaching the stationary oil. tanks should be tall and narrow, especailly at the bottom. This may lead to a cone shaped tank, that's better then a square tank or fat tank. there are typically baffles inside the tank as well, to limit sloshing without being restrictive to oil making its way to the pickup as well as added surface area to help release air from the oil.

Nascar tank levels are typically set while the engine is running. My guess would be a 6 qrt tank 3.5" in dia run half full with engine at fast idle...but it depends on your pan, and lines.

the correct way to do it, would be to log tank level while you're on track with a much bigger tank until you find out how much you need. You can do a system check on the dyno but you really need the track to know how much the level will change with g loads. site tubes on the side with a spy camera or do skidpad and have somebody video tape the car as it comes by.

[nickmpower]

Why are the NASCAR tanks so big? seems like they could just put the pickup on the right side of the engine and run 5 times less oil. I guess it doesnt really matter when you have to hit a certain weight anyways.

[Poe]

The pickups are on the right side of the engine...

[murpia]

I am curious about 2 things:

1) can you get scavenge pumps that separate air and oil, or do you always have to do that in the oil tank?

2) when the engine is shut down, do you get much oil leaking through the pressure pump from the tank into the engine? (the level in the tank must be much higher than the pump inlet)

Thanks, Ian

[Marshall Grice]

Why are the NASCAR tanks so big? seems like they could just put the pickup on the right side of the engine and run 5 times less oil. I guess it doesnt really matter when you have to hit a certain weight anyways

My understanding is the engines last longer with more oil due to decreased oil break down/contaminates.

[Dave M]

"You can do a system check on the dyno but you really need the track to know how much the level will change with g loads"

And higher rates of rpm acceleration. Theres a time delay before the oil can make the loop. We made that mistake. We ran the correct amount for the dyno, then ran it in actual testing and blew a motor or two.

They do make on pump air/oil separators. most pump manufacturers make them. I would still build a good tank though

As for sweet in-line filters. Dailey engineering has some trick ones that fit between two AN fittings.

Im pretty sure nascar tanks carry more oil because of the amount of miles between oil changes (500 ish).

[VFR750R]

One issue is Nascar mandates tank location behind the driver. We run so much oil due to oil consumption over 600 miles, and there is so much oil in the system it takes a tank that large to hold it all if you pump it all back to the tank.

air/oil seperators are overkill, you don't need them but they are nice. it's always better to have a proper oil tank design regardless, there really or no cons except packaging.

I would suggest againt any oil filters that are metal screens instead of a paper or fiberglass element. They seem cool but they have vERY low capacity, meaning they plug up easily. Because of this they also usually have a fairly large micron rating which means they filter less.

[joshua lewis]

SO i was thinking of making a triangular tank for packaging concerns. i would make ramps that go back and forth down the tank with holes on the ends like a normal baffle to de-airate the oil as it goes down the ramps. do you guys think this would work?

[VFR750R]

put a cicular tube inside the triangular tank and have the return oil enter tangential to that. The corners of the tank can still be there for increased capacity.

[joshua lewis]

ok that sounds good i was messing with desings and there would be a 3 inch cylinder in the triangular tank do you think 3 in is to small?

[VFR750R]

3 in should be fine. you know what will happen to the oil in the cylinder (high angular accel), think about jerk(der of accel) too and how you might want to introduce that oil.

[Mike Cook]

VFR, a lot of good information.

With our drysump, we found that there was a very find line between putting to much oil in the tank and having it overflow into the catchcan and putting in not enough and sucking air. This problem could have been solved by having a larger tank. With our setup, we kept reducing oil during testing until it stopped filling up our catch can.

VFR's advice of having too big a tank and testing to find out how much oil you need, is a good idea.

[Michael Palaszynski]

ditto...great info VFR, you teach wihtout telling, i like it