Appropriate size breather box

[Zach Gomulka]

I've seen internal case pics of cranks at high speed. Engine oil is literally wrapped and
twisted around the crank like a thick rope.

In the likes of Nascar, Pro Stock and other high end engine categories the engine builder
will go to great lengths to reduce the amount of oil that is flung around inside the
block by incorporating baffles, screens, scrapers, custom shaped oil pans, trap doors etc
etc..... i.e. whatever they can do to take oil off and away from the crank.

I'm not sure it's even possible to squeeze in a set of oil scrapers like the V8 guys use
because of the upside down crank/cam orientation used in the VW. I've looked for a way
but haven't found one yet!

Just to clarify... these do abselutely nothing, correct?


This has turned into a very good post! I would also like to see some solutions on oil leaking out of the crank pulley when the motor is at high RPM's for extended periods of time... Preferably not a sand seal!

[John Maher]

Just to clarify... these do abselutely nothing, correct?

I wouldn't use one...

When I was building engines at Limited Edition in the late '80s, the boss decided each engine spec was to include a windage tray (same as in pic).
Often wondered what he thought when they later moved premises and discovered approx 30 brand new windage trays hidden behind the lathe 

Sure they'll help prevent oil in the sump getting picked up by the whirlwind going on around the crank but any oil being flung off the crank bounces off the tray right back into the storm.
It's also a hindrance to the oil's passage from crank to pickup tube.

You want to get the oil off and far away from the crank as quick as possible - cue dry sump tank 
Alternatively a deep sump with necessary case mods, venting etc to make it easy for oil to get detached from the crank and deposited down below
i.e. the less oil being flung around inside the case the better

Not sure if anybody mentioned this yet but running too much oil causes problems and costs power...
many of my customers are surprised when I tell them set oil level so it's barely touching the bottom of the dipstick.

I would also like to see some solutions on oil leaking out of the crank pulley when the motor is at high RPM's for extended periods of time... Preferably not a sand seal!

Most likely cause is one or more of the following: excessive blowby/inadequate case venting/poor quality pulley/too much oil
Plus all the other stuff I mentioned earlier 

[lawrence]

Not sure if anybody mentioned this yet but running too much oil causes problems and costs power...
many of my customers are surprised when I tell them set oil level so it's barely touching the bottom of the dipstick.

What is your definition of "too much oil" and in what circumstances do you use less oil than the factory marks on the dipstick? It make no sense to run less oil than is necessary if a lot of it is being flung around by the crank or sitting in the rocker box. I always have my oil level set at the top line of the dipstick. My engine has a 1.5 quart sump and a external filter. These accesories do not raise the level; they add capacity.

[Zach Gomulka]

You want to get the oil off and far away from the crank as quick as possible - cue dry sump tank 

I like the simplicity of these, especially for a street car. But I'm guessing that they probably aren't any good, either


http://www.cbperformance.com/catalog.asp?ProductID=189

With a 356 gen pulley, I don't think fan speed would be sacrificed too much.

And I agree about setting the oil level low... on an engine with a deep sump, of course

[Mike Lawless]

Not sure if anybody mentioned this yet but running too much oil causes problems and costs power...
many of my customers are surprised when I tell them set oil level so it's barely touching the bottom of the dipstick.

What is your definition of "too much oil" and in what circumstances do you use less oil than the factory marks on the dipstick? It make no sense to run less oil than is necessary if a lot of it is being flung around by the crank or sitting in the rocker box. I always have my oil level set at the top line of the dipstick. My engine has a 1.5 quart sump and a external filter. These accesories do not raise the level; they add capacity.

John is referring to race motors that see very high RPM. It's certain that an oil level close to stock is way to high for a drag motor. The oil vortex from the spinning crank with suck it up like a hurricane sucks up matter in its vortex. But you are correct that a street motor needs the extra oil and isn't hurt by a stock oil level. However, if you have a deep sump and are experiencing excess oil discharge out of the breather, try lowering the oil level a half quart and see if it helps. I would in no way advocate lowering the oil level without a deep sump.

These days, I don't even run a dipstick as it's just another leak path. I have a 4 quart sump and a filter and no oil cooler. I run 6 quarts of oil. As long as none leaks out, I don't need to worry about adding any. In theory, and assuming the case itself has a 2 1/2 quart capacity as a stocker, and adding in 1 quart for oil filter and oil lines, that should put my oil level 1 1/2 quarts below the top line of a dipstick. And for the record, yes. I have experimented to find a balance between having enough or too much oil.

[Fasterbrit]

Mike, what kind of rpm are you seeing on your race motor and what stroke crank do you run? Thanks

[Mike Lawless]

the motor sees close to 8500 at the shift, and around 8400 thru the traps. Stroke is 84.

At the PRA races where the car only needs to run 11.90, I back off on the shift rpm.

[Eric Justus]

What is your definition of "too much oil" and in what circumstances do you use less oil than the factory marks on the dipstick? It make no sense to run less oil than is necessary if a lot of it is being flung around by the crank or sitting in the rocker box. I always have my oil level set at the top line of the dipstick. My engine has a 1.5 quart sump and a external filter. These accesories do not raise the level; they add capacity.
[/quote]

As Mike stated, you can not run on a “full tank” of oil. I learned that lesson with my ghia when I was at the full line on the dip stick and burned half the oil on my header when I spewed it out of the top of the breather at Carlsbad. I always run my oil level so it is just touching the tip of the dipstick. With those high rpms the oil is getting shot around way too much and cause it come out where you don’t want it…the track.

I ran into this problem again at last drag day. Oversight of a race motor vs. a street motor as we were racing my dad’s car. He still drives the car on the streets regularly and runs his oil level at the marked full notch on the dipstick. Nevertheless, after my pass in the car, his breather box was spewing oil faster than Kate Moss can upchuck a cheese burger. Luckily nothing hit the track
 

[John Maher]

What is your definition of "too much oil" and in what circumstances do you use less oil than the factory marks on the dipstick?

For me the whole point of fitting a deep sump is to reduce oil LEVEL
You only need sufficient oil to ensure a constant supply at the pickup tube under all
driving conditions

There's no rule that states oil must be run to the top mark on the dipstick. On a stock
engine (no deep sump), the marks indicate factory recommended capacity. Fitting a deep
sump doesn't necessarily mean you must increase overall capacity by the equivalent extra
sump volume

Extreme example... if it were practical to fit a sump that extended downward to 1mm above
the road surface (maybe 10 quart?), I'd aim to run conservative capacity (3 to 4 quarts/litres)
but would have succeeded in dropping the LEVEL way below the crank. That would do all
sorts of good things for the engine. In the real world we have to be practical and take into
account ground clearance, potholes etc.

Drag racers can afford to go deeper and ideally keep all of the oil outside/below the crankcase

Some of the mods already discussed in this thread help reduce the amount of oil
pointlessly flying around inside the case (wrapped around the crank, stuffed up inside
the 3-4 rocker cover etc). If you can rely on that oil being efficiently returned to the
sump, you can afford to further reduce oil capacity, which has the added knock on effect of reducing oil level

For obvious reasons it's better to err on the cautious side, so my general (cautious) rule is...
1.5 quart sump - set to lower mark on dipstick
Larger sumps (3.5 & 4qt) - just touching the bottom of the stick
Never had a problem with that, street or strip

Droppping oil level from the top mark makes more power!
Seen it plenty of times on the dyno. If you have oil to the top mark and test the
motor at 6000rpm+ you generally see very aerated oil pumped out the breathers. Drop the
level, repeat the test and the puking stops... or at least reduces - depends on the
engine (oil mods, build quality, ring seal etc). Power gains may only be small but
happens due to the crank not getting as wrapped up in oil.
Which is easier.... running on land or in a swimming pool?

Anyone experimenting with even lower levels needs to make some oil
control/breather mods if they want to avoid sucking air and frying bearings.

Application has to be considered too.... a circuit car throws oil around in a different
manner to a drag car and has different requirements

Some of the mods people have discovered tend not to get shared, especially amongst the
circuit racers.... it probably cost them a few motors to find the tricks that work 

[JS]

Good info John, thanks for sharing! 

[lawrence]

Valid points, John. I have a hot street car, whatever that means,:-) entirely different topic somewhere on this site. It is not necessary for me to squeeze every last horsepower out of my engine, so I will leave the oil level where it is.

[Jon]

I had a little talk with Håkan Lundgren the other day about his breather set up:

 As I thought he only vents the crank case, "as per Pauters instructions", he said...

That seals the deal for me... I'm drilling a hole

[181]

This is a great topic!

[Jesse/DVK]

Bumping this topic back up . I have some questions. I'm in the process of building my very first engine. A nice 1915cc with IDA's. I want to do the following mods:

Vents
Fuel pump outlet
Generator stand

Sump
GB 3.5qt deep sump and lowering the oil level

Internal case mods
As John Mahers pics, exept for drilling the cam oil way. Should I mod #2 and #3 bearing saddles or only #2 when not drilling??


Does this sound ok to you guys? Motor will be street drivin and will see a blast up to 7000rpm.

Thanks!

[181]

I did only no. 2. Modyfying no. 3 bearing saddle doesn´t make sense without drilling the passageway.

[Jesse/DVK]

How much wider is it? Also deeper? Did you use a dremel with a bit on it?

[181]

I stayed on the safe side with a dremel bit

before and after:





http://www.dremeleurope.com/dremelocs/modules/oragetblob.dll?db=dremelocs&item=dremelocs.items&id=3958,1754,16&mime=image/jpeg&maxwidth=266&maxheight=266

[peach_]

Very interesting Thread

[kuleinc]

This is such a  great topic, is it a sticky?

[Steve DKK]

Agree, There is risk with a small box, Bigger is better and it not like it's weight issue.

[JS]

Bumping this topic back up . I have some questions. I'm in the process of building my very first engine. A nice 1915cc with IDA's. I want to do the following mods:

Vents
Fuel pump outlet
Generator stand

Sump
GB 3.5qt deep sump and lowering the oil level

Internal case mods
As John Mahers pics, exept for drilling the cam oil way. Should I mod #2 and #3 bearing saddles or only #2 when not drilling??


Does this sound ok to you guys? Motor will be street drivin and will see a blast up to 7000rpm.

Thanks!

Jesse, I have done the same mods to my 2276 this summer. Except I have a 3 quart sump. No major internal modifications except removed most of the "hat" on the oil pickup.

No venting on the covers, small empi breather mounted on the firewall. Works great.

[christophe]

Hello.
So where did you connect your breather box then JS?

[JS]

To the fuel pump block off and the oil filler. Drilled a 2nd hole in the front of the box and blocked the two on the sides.

[christophe]

Intressant,thanks.

[Frenchy Dehoux]

  Interesting post the problem i am having is I build a 1776 CC with single port heads small cam and my compression is 8.1 with a stock carburetor for my stock 1964 VW and I had to pull the engine out 4 times because of an oil leak at the flywheel seal . So I replaced the flywheel after i had pulled the engine out twice. I have looked all around the case behind the flywheel and cannot see any type of cracks thinking it could be the problem all looks good. Is it possible that the crankcase pressure is allowing the oil to force its way out the seal. So i decided to install the fittings at the valve covers to let them breath if this will help I never encountered this on my other motors which are bigger and have the dual 48 IDA'S .

 Thanks
 Frenchy

[Frenchy Dehoux]

  I am doing more research on this issue. Number one i did not smell to see if it was oil or transmission oil the reason was it was very thin oil so I had assume it was engine oil. I am thinking the transmission has much more pressure build up not because of the bigger size engine but possibly because the small vented hole on the nose cone could be clogged up from years of dirt build up around it. I also had a new pilot shaft installed so I know that part is OK . I will do all of these and let you all know if it was my main problem. Thanks
 

   Frenchy !!

[Frenchy Dehoux]

Well the issue here was the nose cone vent hole is clogged up so i drilled a small hole on the inlet side plug to vent it out problem solved .

Frenchy

[blue bullet]

hello
 drilling a hole in the case, it's not dangerous for the case?

[neil68]

I recently installed a Vintage Speed breather tower with a vent hose from the stock fuel pump outlet and one open-air filter.  Now I have no oil leaks or spray, even on the drag strip at 8200 rpm.