Oil pan baffle trap door design?

[Bob_H]

Well, as many of you know, I've been on a long journey with my "Super Datsun" and the RB26. I'm now working on the baffle design for the oil pan. Originally was I was going to install some rubber flaps similar to what is in the E30 BMW M3's, (the 4 cyl ones). Pictures for what those look like are here:

 

http://www.brazeauracing.com/oilpan.htm

 

My oil pan pictures are at the bottom.

Two avenues I'm considering and am looking for input/experience.

First is the traditional trap door style. First problem is finding commercially available trap doors, or even just the alum. hinge. Second is what shape exactly to design the baffle - i.e. the diamond/square around the pickup. How far, etc..?

 

Second choice is similar to what is now in the LS2 oil pans,(Corvette C6's). It is a wall with a small opening at the bottom. This allows limited oil flow in both directions. It should be more than sufficient for normal operation - and when you corner, it will limit the amount of oil traveling to the other side of the oil pan, but will not completely stop it,(actually, no design really completely stops it besides the rubber flaps or a trap door with rubber around the outside).

After my pictures are some pictures of a new pickup for the LS1 camaro oil pan - there are two designs which recently appeared, same basic principle.

Any thoughts?

[Lunar240z]

http://cgi.ebay.com/ebaymotors/ALUMINUM-PIANO-BOAT-HINGE-boat-hinges-2-1-2-x-72_W0QQcmdZViewItemQQhashZitem320196970983QQitemZ320196970983

 

quick ebay search. "aluminum piano hinge"

[JMortensen]

Take a look at the Arizona Z Car pan. I don't think the hinges were aluminum, and the trapdoors are just rectangular pieces of sheet metal. They are arranged in a diamond shape probably about 5 or 6 inches square (I'm guessing because it's been a while since I've had it off and looked at it). I think you're over-analyzing it. Shouldn't be too hard to make what you need. I'm not as impressed with the pan with the small holes at the bottom. The trap door setup is simple and while I'm sure it's not a completely water tight seal it should keep more oil by the pickup than the other will.

[johnc]

The Nissan Comp pan also had a 4" tall diamond shaped box with sheet metal hinges and four trap doors. The top of the box had 1/2" flanges bent inward to reduce oil slosh up the sides and over the top of the box.

[Bob_H]

The Nissan Comp pan also had a 4" tall diamond shaped box with sheet metal hinges and four trap doors. The top of the box had 1/2" flanges bent inward to reduce oil slosh up the sides and over the top of the box.

I had the pleasure of playing with the Nissan Comp pan when it was out of a car. My original mockup had a diamond box - and i was looking for hinges.

Most aftermarket pans I've run into have a diamond box vs. a square box,(i.e. parallel to the sides of the pan).

Assuming a diamond, it comes down to a rubber gasket over a hole, (proven to work), a trap door, (on many "race" pans - again, proven), or a design similar to what GM has settled on with the LS2 corvette motors. A design which was influenced by the LS1 motors having issues, leading to many tracked cars grenading rods out the side of the block as they seized...

I'm leaning towards a traditional approach with trap doors. I also had an Arizona Z car pan to play with as well. I'd rather overthink/overdesign this as many have had problems with the RB motor in a track environment- specifically related to oiling problems. See Mark R. who also has a RB Z car for examples,(and he has a reasonably well designed pan).

-Bob

 

 

Mark's thread stating his failure, post 47/48:

http://forums.hybridz.org/showthread.php?t=115779&page=3

[JMortensen]

If you really want overdone just dry sump and move on.

[Bob_H]

If you really want overdone just dry sump and move on.

In spite of some ideas from my wife at times, I'm not made of money. 2nd, it doesn't exist in a production form - i.e. its completely custom and 1 off. Mark is supposedly getting one made, however it is still nowhere near completion and the fabricator hasn't returned my e-mails.

[CRAVED]

Bob H - is this oil pan been modified the be shallower than the std Sump? Obviously with the removal of the front Diff assembly some fabrication was required, just curous as to the thought process involved in the further change of the front sump pan. was it required for cross member clearance?

 

 

 

Tomei Japan has off the shelf baffles - http://www.nengun.com/tomei/oil-baffle-plate

 

also Trust has too - http://www.nengun.com/trust-greddy/oil-pan-upgrade-kit

 

- just a little off topic - there is alot of talk here in AUS in regards to excess oil in the heads of the RB26's, which lead to the use of restrictors in the oil feeds to the head, also if a track car then an additional oil drain from the rear welsh plug in the head.

 

Here seems to be a good site for ideas, turns out the Tomei baffles use the M3's rubber baffles

 

http://tyndago.googlepages.com/rb26dettoiling

[Bob_H]

My sump is far from the stock sump - its 100% custom at this point. If your not familiar with putting the RB's into the Z's, you must convert it to a rear sump - it won't clear the crossmember. So my choice is limited to a completely custom pan or utilizing the RB20 rear sump pan - which has some severe limitations for my intended use.

I have checked out the RB26 updated baffles/sumps and they won't really work as they are built if utilized in my setup, but I have considered their ideas.

There have been some excellent discussions here and on the RB mailing list,(for those putting RB's into Z cars) about the oil in the head and its not quite as it seems.

An engine builder who has built many very high hp RB26's,(up and over 1000hp), had some excellent input. Bottom line, his analysis showed me that what we have often attributed to the "pooling in the head syndrome", just doesn't fit that issue.

I can elaborate, but the data makes good sense and I will NOT be including a head drain in my setup, (but I did expand out the returns).

 

Bob H - is this oil pan been modified the be shallower than the std Sump? Obviously with the removal of the front Diff assembly some fabrication was required, just curous as to the thought process involved in the further change of the front sump pan. was it required for cross member clearance?

 

 

 

Tomei Japan has off the shelf baffles - http://www.nengun.com/tomei/oil-baffle-plate

 

also Trust has too - http://www.nengun.com/trust-greddy/oil-pan-upgrade-kit

 

- just a little off topic - there is alot of talk here in AUS in regards to excess oil in the heads of the RB26's, which lead to the use of restrictors in the oil feeds to the head, also if a track car then an additional oil drain from the rear welsh plug in the head.

 

Here seems to be a good site for ideas, turns out the Tomei baffles use the M3's rubber baffles

 

http://tyndago.googlepages.com/rb26dettoiling

[CRAVED]

Sounds fair, and i should have noticed the change in pickup point on the sump.

 

i've looked at a few, alot use a steel bar through a bracket on the wall and each trap door, and not actually a hinge.

 

wouldnt need to be alloy as it wont rust in there, but why not while your at it.

 

im thinking that the diamond shape baffle would still need holes under it to allow oil to level on cruise, and just using the trap doors to force fill the baffle on corners.

 

question though, how much space should you leave between the diamond baffle and the front and rear walls of the sump pan? should this be sealed to force the oil into the pickup area, rather than allowing it to go around it?

 

My sump is far from the stock sump - its 100% custom at this point. If your not familiar with putting the RB's into the Z's, you must convert it to a rear sump - it won't clear the crossmember. So my choice is limited to a completely custom pan or utilizing the RB20 rear sump pan - which has some severe limitations for my intended use.

I have checked out the RB26 updated baffles/sumps and they won't really work as they are built if utilized in my setup, but I have considered their ideas.

There have been some excellent discussions here and on the RB mailing list,(for those putting RB's into Z cars) about the oil in the head and its not quite as it seems.

An engine builder who has built many very high hp RB26's,(up and over 1000hp), had some excellent input. Bottom line, his analysis showed me that what we have often attributed to the "pooling in the head syndrome", just doesn't fit that issue.

I can elaborate, but the data makes good sense and I will NOT be including a head drain in my setup, (but I did expand out the returns).

[Bob_H]

im thinking that the diamond shape baffle would still need holes under it to allow oil to level on cruise, and just using the trap doors to force fill the baffle on corners.

 

question though, how much space should you leave between the diamond baffle and the front and rear walls of the sump pan? should this be sealed to force the oil into the pickup area, rather than allowing it to go around it?

 

Anything I use should be aluminum as steel to aluminum doesn't weld very well....

For the sealing question, absolutely you would take it all the way forward and backwards. No need to put holes if you go with trap doors as the oil will naturally push the doors open under no lateral/fore-aft load.

-Bob

[CRAVED]

No they dont weld, but have no issues bolting together

[strokerzedd]

I'm in the same situation, RB26 in a '72 240z. I cut the bottom off of the stock sump (my stock sump was slightly damaged in the accident in Japan which led to me being able to purchase the motor) and I'm using the base to build my oil pan. I've checked the available baffles but they won't fit my custom pan either. Why won't you install an oil return line from the back of the head? You think that opening up the oil return galley is enough in combination with the oil orifice restricter? Could you elaborate? Thanks.

[Bob_H]

craved - I knew I could bolt it, I just don't want to as they have a tendency to back out over time - the BMW oil pump bolts are prime examples. Rare, yes, but not something I want to deal with - so welding is the only option for me.

 

strokerzedd - I don't see a benefit of the rear drain. It won't hurt - but why spend money on tubes and connectors when they don't dramatically improve things. Below is a copied from the discussion about the oil drain issue. Matt owns/runs a shop in Japan building high HP motors - very high HP motors. This is long, but a good read:

 

If you're looking for soultions here, delete it because there are no

solutions for a fictional problem. It's going to be dripping with

sarcasm, too! What fun. Hang on to your shorts.

 

That's right. You didn't read it wrong. The Internet spread BS on

this subject has finally reached "urban legend" status and I feel

it's time to set the record straight, vent, shed some light,

whatever. What pushed me over the edge is a new post on Hybrid Z

where the guy (Boosted Z I think?) gets some good #'s on the dyno

but sees oil pressure falling off around 8,000 rpm. The first

questions asked are "Do you have the oil restrictor?" etc... sigh...

Are you serious??? Now we've reached the point where the drain back

issue is so bad that the engine can't even do ONE DYNO PULL without

all five quarts of oil ending up "trapped" in the head?? Give me a

break, man.

 

What's funny is that the RB26 is, what, 18 years old, but it never

had oil drain back issues until Tomei started selling the stupid

restrictor with a little hand drawn picture of high oil level

without the restrictor and low oil level with it. Actually, it's not

a bad idea, but I'm calling it stupid because of what it started.

 

A little perspective:

Obviously Nissan doesn't think it's a problem because they never

addressed it in the 33 or 34 engines. Oil returns and pressure

orifice are the same as far as I can tell. At least not any major

changes for what seems to be a catastrauphic problem (sarcasm).

Would someone PLEASE explain to me why Nissan can take a bone stock

R32, R33, or R34 to the Nurburgring and go at full throttle, lap

after lap, eight plus minutes per lap and never have oil drain back

problems that rob the sump of oil, but a guy on an Internet forum

can't do one lap of a two minute circuit or even one dyno pull, have

oil pressure sag, and have everyone under the sun call out for

restrictors and additional drain backs? No, not really; that was

rhetorical.

 

I've seen N1 and Super Taikyu race engines up close and even inside.

Never seen any additional drain backs. Not sure of the Super GT

engines, but they probably use a dry sump with scavenge in the head

and no drain backs, to keep oil off the crank. Saw the HKS Drag GT-R

up close too, and never noticed anything like that. There are

probably thousands of track GT-R's driven in Japan alone that don't

have this problem.

 

My experience:

Power numbers's? Don't know. Our dyno's here won't hold much over

700 without slipping tires (at least that's as high as I can get

it), and I'm not a big fan of numbers on a piece of paper, so I

really don't care. However, I can tell you that the most powerful

RB26 I've ever built burried a 320km/hr (198.838 mph and don't tell

my mom) speedo on the expressway at over 10,000 rpm. Modified HKS

pump, no aftermarket restrictor, no additional drain backs, oil

pressure holding at a rock-solid 115 psi.

 

In fact, I've never used an aftermarket restrictor or additional

drain back in any engine I've ever built... I've never had an oil

pressure problem in any RB engine. Ever. I build 'em loose, too.

 

Maybe some people are having problems. With the above, I doubt very

much it's a "pooling in the head" problem.

 

Here's why:

Suck air in the oil pump and oil pressure goes to zero almost

instantly. No "falling off in the top end". Some people shift gears

and the oil pressure is magically restored (even though all the oil

is in the head), only to have it fall off again as soon as the rpm's

climb back up.

 

Oil pressure falling off in the upper rev range can be caused by

several things, the most common of which is cavitation. I would put

money on it that most people running RB Z's are using the steel pans

from the Z31? This not only eliminates the excelent RB26 sump

baffeling, it also precludes you from using the RB26 windage trays.

Foamy oil cavitates. What happens is tiny bubbles in the oil enter

the pump under huge vacuum. A bubble that already exists is much

easier to expand into full blown cavitation than oil with no

bubbles. The bubble(s) expand to many times their own size, taking

up space originaly reserved for oil. Once it hits the pressure side,

the bubble collapses, but the damage is done. Less oil went through

the pump. The faster the pump spins, the more vacuum is created, and

the worse the problem becomes. Oil pressure that falls off as the

revs climb is almost always caused by cavitation. This can also be

caused by a too-small or too-restrictive oil pick up. Moving it all

the way to the back of the engine couldn't possible affect this,

could it?

 

I watched a video of a guy going around the track in an RB Z. On

braking and turning in only one direction the oil pressure would

zero out almost instantly. Once the car straightened out or throttle

was restored, pressure jumps back to normal instantly. Once again

the common consensus was the 'ol PIHS (pooling in head syndrome). On

decel or only turning in one direction? PIHS or bad baffeling in the

pan/pick up location? You be the judge, but use common sense.

 

The restrictor is good:

But for the wrong reasons. The right reason is the same as a small

Chevy or any other engine for that matter... The head doesn't have

heavy rotational forces for two reasons: There's no heavy stuff

swinging around, and it's only moving at half the crank speed. It

doesn't need a lot of pressure, especially because the cam to lifter

interface is fed by oil dribbling out of the cam journals. Pressure

in the head is wasted, which is the reason for the factory

restricotr. A smaller restrictor will keep the pressure to the

bottom end higher in the rev range due to decreased VOLUME wasted in

the head.

 

The additional return is bad:

There are two large returns in the rear of the head and several

throughout the length of the left side of the motor. Due to crank

windage, the ports on the left side of the engine are subjected to a

vacuum because the crank is pulling down on that side of the engine.

The one in the rear, right supplies windage to the head for crank

case ventilation. Air doesn't pull down the left side if it can't

come up the right. Under hard acceleration, oil wants to move to the

rear of the engine. Some people install a large line from the rear

of the head back to the right side of the front sump in the GT-R

pan. Anyone see a problem with this? There's actually two. Under 1g

of acceleration, not only will oil not move forward through this

line back to the front of the engine, it gives the oil in the sump

another path to exit the sump. Reason #2 is that the right side of

the engine is pressure side and not the suction side. Crank windage

at higher RPM can push oil back into the tube if it's not very

carefully baffeled. It could work well in a rear sump if the hose is

almost straight down and entering the left side of the engine. But

this as assuming there really is a drain back problem.

 

What I have seen/done:

An additional line from the back of the head, under the plenum, back

to the RADIATOR. Additional coolant movement out of the head. Very

common mod on drag engines. Maybe someone saw this somewhere and

mistakenly thought it was for oil and ran with it? Who knows.

 

With the additional oil restrictor in place, the oil level in the

hed would certainly be lower than without it, but I assure you that

even with the stock restrictor, it's not even close to a problem.

Especially not the problem it's been made out to be.

 

Anyway. I feel better and will now step off of my soap box. I'm sure

there will be arguments from people who had PIHS cured by these

mods, or whatever, but you really need to stop and think about it.

Especially given the factory stock cars not having problems on the

ring, etc.

 

Matt

[CRAVED]

those are some very good points he brings up there.

 

though i have never seen the examples he gives being attributed to the PITH syndrome. Most people here that give examples is relational to high rpm blow by (not attributed to a loose engine) and visual inspection of the the cam areas to specifically show too much oil there.

 

anyway, im hopefully be building a sump of my own soon for an RB30/25 conversion and this has some very good info on the baffle designs.

[Makenski]

I never really quite believed the oil drain back as a good solution.

 

Before I read Matt's comment, I had my mind set to a custom made bass restrictors of 1.6 to 1.7 mm and opening the returns on the heads.

 

Now After, I am confirmed my thinking is correct.

 

For oil upgrades in the head, I am still leaning towards a updated valve baffle plate, to help reduce oil in the blow-by gases. And further a oil catch can. If I decide to do a can, where can I recirculate back the oil to the engine?

 

Then, I been still trying to work on a oil pan baffling design that traps the oil, but has no mechanical moving parts. (Always been big fan of less moving parts, or total parts).

[strokerzedd]

I finally finished my rear sump aluminum oil pan and steel baffle with one hinged plate. The oil pan holds about 7.5 litres at the stock dipstick level and the baffles should be able to contain an adequate supply of oil around the pickup. It's not beautiful, my first attempt to weld aluminum. I used the base for the stock oil pan as well as the oil drain plug.

[260DET]

Re oil restrictors in the head. VG30DETT engine has them from the factory, while it may or may not be crucial it stands to reason that the less amount of oil in circulation the more there will be left in the sump.

[Bob_H]

I finally finished my rear sump aluminum oil pan and steel baffle with one hinged plate. The oil pan holds about 7.5 litres at the stock dipstick level and the baffles should be able to contain an adequate supply of oil around the pickup. It's not beautiful, my first attempt to weld aluminum. I used the base for the stock oil pan as well as the oil drain plug.

Good to see someone else using the stock flange. My only concern with your design is under braking - that is a very long sump front-rear and under braking you can see lots of fluid movement away from your pickup under even moderate braking. I'd seriously look at that trap door and do what you can to ensure minimal to no oil will flow forward under braking. Maybe a rubber edge etc... You just don't see long fore-aft design pans for that reason. Just something to consider.

BTW, nice drain baffle design.

-Bob

[mattyice]

well after reading the article you posted bob about what matt has said it seems like the my worries about the Z31 200ZR pan were correct in that...it isnt designed for the better oiling system in the RB26, and that it requires removal of the stock windage trays on the bottom of the RB26

 

since i for this information i am also going to be using the stock RB26 flange, am going to make my own pan from aluminum and will have it be around 5-6 quarts of capacity with a large trap door door with a rubber gasket sealing oil under braking and then a large diamond shape 4 door baffle surrounding the pickup tube

 

that seems like the best solution for all types of lateral acceleration, does that seem right to you? Also that way i can keep the stock windage trays and then that would solve all problems with the dropping oil pressure