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Cylinder head drainback lines

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Cylinder head drainback lines

Postby BOOT » Fri Sep 13, 2013 11:38 pm

After reading another thread and someone mentioned returning the oil from the head right to the oil pan. I am interested in learning more, like for example placement of the line in the pan. I know some open up the holes, restrick passages or vent the intake to help drainback and even read something about how round holes don't drain as well. Stiil possibly reducing oil draining on the crank is interesting to me. From what I've read the sbc drivers side rear valley oil return dumps on the crank.
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Re: Cylinder head drainback lines

Postby BOOT » Fri Sep 13, 2013 11:51 pm

Or even plugging the block and running a line form the rear valley to the pan.
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Re: Cylinder head drainback lines

Postby racear2865 » Sat Sep 14, 2013 8:42 am

BOOT wrote:After reading another thread and someone mentioned returning the oil from the head right to the oil pan. I am interested in learning more, like for example placement of the line in the pan. I know some open up the holes, restrick passages or vent the intake to help drainback and even read something about how round holes don't drain as well. Stiil possibly reducing oil draining on the crank is interesting to me. From what I've read the sbc drivers side rear valley oil return dumps on the crank.



To stop oil dump on crank--drill a hole in the pan rail so oil runs back to pan without hitting crank. Been doing it for 20+ years.
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Re: Cylinder head drainback lines

Postby ctk30 » Sat Sep 14, 2013 11:00 am

I've been searching around, looks like you can just tap the back of the head

This is a BBC, I'm not sure about the sbc. I am thinking 8an minimum

If we keep the valve springs dry though will this have any repercussions on an engine that is running 30min to an hour at a time?

I really think on something like a road course engine it would be beneficial to have them in the front and back

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Re: Cylinder head drainback lines

Postby user-3597028 » Sat Sep 14, 2013 11:15 am

I do it on Mopar B1 heads. Right in back and down to the pan.
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Re: Cylinder head drainback lines

Postby Kevin Johnson » Sat Sep 14, 2013 1:43 pm

BOOT wrote:After reading another thread and someone mentioned returning the oil from the head right to the oil pan. I am interested in learning more, like for example placement of the line in the pan. I know some open up the holes, restrick passages or vent the intake to help drainback and even read something about how round holes don't drain as well. Stiil possibly reducing oil draining on the crank is interesting to me. From what I've read the sbc drivers side rear valley oil return dumps on the crank.



It is worthwhile studying the Ford modular engines. You need to be careful about setting up secondary or tertiary flow patterns of gases in the engines.

There are numerous other examples of OEM drain tubes. It is very instructive to examine engine families that were redesigned specifically to address issues like this. Look at the BMW m20 engines transitioning to the m50.

Be careful about placing return tubes directly in the path of windage flow so there is ram pressure generated.

The Studebaker Type R oil drain entry from the supercharger to the oil pan should be considered an exemplar of sound engineering in this respect.
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Re: Cylinder head drainback lines

Postby BOOT » Sun Sep 15, 2013 1:37 am

racear2865 wrote: To stop oil dump on crank--drill a hole in the pan rail so oil runs back to pan without hitting crank. Been doing it for 20+ years.
reed


Don't supose you got a pic? I only read bout the oil dumpng and would appreciate all the info on where and how big a hole your talking. I'll see wht info I can find but this is the 1st I've herd of it and that might be the eiaser/better route for my use.



Thx for the pics ctk30, I was thinking the same 8an and maybe alum line, like I saw on a helicopter motor.



Kevin Johnson wrote:It is worthwhile studying the Ford modular engines. You need to be careful about setting up secondary or tertiary flow patterns of gases in the engines.

There are numerous other examples of OEM drain tubes. It is very instructive to examine engine families that were redesigned specifically to address issues like this. Look at the BMW m20 engines transitioning to the m50.

Be careful about placing return tubes directly in the path of windage flow so there is ram pressure generated.

The Studebaker Type R oil drain entry from the supercharger to the oil pan should be considered an exemplar of sound engineering in this respect.


Yah I've herd with the intake venting the heads drain better and that could be a problem if you needed the cooling. Still for normal street driving I wonder if there is much oil up there and drag racing it would be short(also using full roller rockers). From what I can tell the pooling oil is more fo a sustained/very high rpm issue(or pump volume overkill) and my intersst is more of a way to keep oil off the crank. When dumping it into the pan I think a baffle inside to direct it down would be a good idea. In a normal drag car it might be a wasite of time, but when your driving around and hop lapping? Thx I'll check out those other engines.
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Re: Cylinder head drainback lines

Postby BILL-C » Sun Sep 15, 2013 6:24 am

If you use the proper restrictors, either oil galley, or pushrod tip, then you won't have to worry about any bandaid fixes. I have valve covers that we put plexiglass windows in for use on dyno to look for issues like this. Things are not always as you would imagine they are. Seeing is believing.
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Re: Cylinder head drainback lines

Postby Kevin Johnson » Sun Sep 15, 2013 8:25 am

BILL-C wrote:If you use the proper restrictors, either oil galley, or pushrod tip, then you won't have to worry about any bandaid fixes. I have valve covers that we put plexiglass windows in for use on dyno to look for issues like this. Things are not always as you would imagine they are. Seeing is believing.



What did you see?
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Re: Cylinder head drainback lines

Postby Supercomp517 » Sun Sep 15, 2013 1:19 pm

A few weeks ago I spent about 20 min talking to a guy who was wrenching on Bubba Stanton's ProMod engine at the ADRL race in Memphis. I was fishing for info regarding my SBC blown injected build. He asked me what kind, (brand) of motor and I said, "Chevrolet". His immediate response was, "You are going to have to vent the heads back to the oil pan." That was an unsolicited comment from a reputable source......or maybe it was just opinion :lol:
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Re: Cylinder head drainback lines

Postby BILL-C » Sun Sep 15, 2013 7:14 pm

While sorting out some valve cover breather problems on a sb ford road race engine,we made an interesting observation. With "windowed" valve covers installed, we saw very minor accumulation of oil in pass side valve cover at steady 7k rpm, but on drivers side, the oil was being sucked down the oil drainback holes in heads-mainly in back. My only explanation for this is that there must be a low pressure area in the crankcase on the drivers side, right where the ford drain back exits. Since then we always try to route any drains to drivers side of pan when possible . Very seldom do we ever have to install any external drain back hose on engines other than heavy blowby applications like supercharged and nitrous.
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Re: Cylinder head drainback lines

Postby racear2865 » Sun Sep 15, 2013 9:17 pm

Boot
I sent u a PM
reed
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Re: Cylinder head drainback lines

Postby ptuomov » Sun Sep 15, 2013 10:39 pm

BILL-C wrote:While sorting out some valve cover breather problems on a sb ford road race engine,we made an interesting observation. With "windowed" valve covers installed, we saw very minor accumulation of oil in pass side valve cover at steady 7k rpm, but on drivers side, the oil was being sucked down the oil drainback holes in heads-mainly in back. My only explanation for this is that there must be a low pressure area in the crankcase on the drivers side, right where the ford drain back exits. Since then we always try to route any drains to drivers side of pan when possible . Very seldom do we ever have to install any external drain back hose on engines other than heavy blowby applications like supercharged and nitrous.


Some opinions below, none based on experience, and all should be discounted heavily:

Chrysler engineers call the driver side the suction side and the passenger side the pressure side. The small suction is generated by the rotation of the crankshaft. According to Chrysler simulation, their new 6.5L engine that is vented from the valve covers flows gas up continuously on the passenger side oil drains, while the direction of the gas flow in the driver side oil drains fluctuates with the engine cycle. As a side note, for a 6.5L V8 at 6000rpm, the piston pumping pulses are the elephant in the crankcase and the gas flow patterns due to crank rotation are of second order compared to piston pumping. This may be different for a small four banger, just talking about big V8's here.

Based on those simulations, I believe (but do not know) that it's a lot more important to provide another flow path for gas from the crankcase to the heads than to try to drain oil. Once the piston pumping pulses can communicate to the heads by some other channel than the oil drains, the oil will drain to the sump without a problem. Modular Ford Coyote engine was designed with inside channels in the block valley to create precisely that effect, which then cured their high-rpm drainback problems. Of course, one should make sure that the oil does not drain on the crankshaft.

Another result from the simulations that I found interesting is that if the windage tray design is not thought out carefully, it robs a significant amount of power in terms of increased pumping losses. Unless one has a high budget (money and time), my guess is that one is better off with a really big pan and no trays. Now, if a big pan won't fit in the chassis, then one is stuck with the problem of coming up with a windage tray, and it's not an enviable position for anyone without a car company budget.

I've also come to the opinion that it's not a productive exercise to try to get any scrapers as close to the crankshaft as possible in a big V8. The pressure differentials directly caused by the crankshaft rotation are not very significant. If the scraper blocks the piston pumping pulses, the losses are likely a lot bigger than any benefits in reducing the crankshaft rotation pressures. The one thing that I think scrapers can help with is preventing oil from rebounding back to the crankshaft, and for that purpose it's much more important to get the scraper angle right than get it very close to the crankshaft. On a small four banger, this may also be different, just talking about big V8's here.

These are my opinions and my qualifications are limited to having stayed in Holiday Inn once or twice.
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Re: Cylinder head drainback lines

Postby ctk30 » Sun Sep 15, 2013 11:00 pm

Some oil drains connected to the pan in the middle of cylinders on each side up high, that would help provide some balance that you mentioned

I'm pretty sure I'm just going to buy a dry sump after researching how to make a wet sump work :lol:
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Re: Cylinder head drainback lines

Postby KnightEngines » Sun Sep 15, 2013 11:27 pm

Drains from heads to sump & front cover breather + rocker cover breathers:

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