windage trays and crank scrapers

[carnage1]

I am hoping to put both on the 225 slant six i am building. I am having trouble finding any and was wondering about designing a set. also I am wondering about how much difference they really make. I am not building a HP monster but I want to pick up as many "free" HP as possible by reducing internal friction and loads as this gives better power and efficiency.

The crank scraper is the biggest question how close to the crank should it be?

 

[GregLocock]

I had figures for a windage tray. Definitely perceptible at high revs, something like 2 or 3 hp in 200.



Cheers

Greg Locock

 

[SMOKEY44211]

Try to construct the scraper so it is mounted tangent to the arc the crank travels rather then perpendicular. Contour the profile so you have .005" radial clearance around the rod caps, nuts, counter weights ect. Mechanicaly load the crank fore and aft and shoot for the same clearance. Run the other side of the scraper as close to the oil pan as possible ( difficult to guage) or take a section of rubber fuel line slice it and use it to provide a seal on the pan side. As long as you are in there think of some possible way(s) of redirecting the return oil from the top end and cam bearings to the sump without having to pass over the spinning crank. There is about 35 hp @5200 rpms to be gained if done correctly. Another benifit is reduced airation of the oil supply.---------Phil

 

[rpmag]

Smokey do you mean 35hp or 3-5hp?

 

[dreamspeed]

I don't know your application but I do have a bit of experience with drag race engines. I have found that the best pan is the largest volume pan you can fit under the car without any crank scrapers or windage tray. I have seen a perpendicularly mounted crank scraper kill 20HP on a 850HP small block Chevy race engine. Smokey's information on a tangentially mounted scraper may work...never tried it.

 

[evelrod]

Windage trays and scrapers are a couple of things that can make a marginally designed wet sump function better but are at best only a crutch. I have tried all sort of scraper designs with questionable results---some work, some don't.
The biggest improvement with a wetsump was going to a substantially increased capacity and lowering the oil level.
The pan should have all the gated gizmos and a windage tray to seperate the sump from the rotating mass. ALL the return oil should be directly routed to the pan and not allowed to drain back (via hoses, etc.). It's always a good idea to clean up the inside of the block in the sump to make drain off a little better. Lotus/Cosworth painted some blocks in this effort. I did not find it superior to just cleaning off the flash and irregular surfaces and I did not have to worry about paint chipping off.
A note here about why I mount the windage tray on the pan instead of the block---high frequency vibration tended to crack mine when block mounted---I've seen successful block mounts so my problem may not be universal. Also I have used "diamond cut" SS screen with indeterminate results.
Dry sump is truly the correct way with all upper end oil return via external hoses or extra scavenge sections on the pump if it is possible/legal. Take a look at last months Circle Track for a nice little article about the NASCAR engine dry sumps.

Phil---0.005" would be nice but not very practical in an engine with 0.003" to 0.005" end play. I always ended up in the area of 0.015". I had the opportunity to observe the bottom end of an I-6 Ford with a clear plastic pan installed. From what I could see the scraper should do it's job even if it had a eighth inch clearance.
I no longer use scrapers, per se. If I cannot use a romotely located dry sump tank I use what I like to call my "integral dry sump" wetsump design with the oil level as far away from the rotating mass as possible and a 3 qt. accumulator. Running two or three qt. "low level" can be scary and dangerous unless ALL the wetsump mods are made in one package. If you lower the oil level in a stock setup you will gain power but with a good chance of damaging your engine.

Rod

 

[dardengo]

I have built a number of oil pans for oval track and drag racing applications, and i have found bigger is not always better. A depth of approx. 7 in is more than adequate if possible. An oil pan with one way baffles, trap doors and possibly offset resevoirs in the case of oval track cars (the resevoir is at the rear of the pan on the right hand side.) One of my race cars has a Chevy inline six and we have used this style of pans for years with great success.

Another good setup is a piece of one way screen either bolted or welded in the pan. Depending on the pan depth, it should be about one third to one quarter of the way from the top surface of the pan. Basically you just need a hole big enough to get the oil pump pickup in and out.

 

[SMOKEY44211]

rpmag yes 35 hp. is not unrealistic at high cycling speeds. The power lost to the crank churning in its own oil supply is parasitic and is independant of what the final power output of the engine is. The higher the engine speed the greater the potential gain by reducing the amount of energy lost. The reasons I suggested mounting scraper tanget to the crank is that it chisels the oil away from the crank and prevents oil from the sump from getting drawn back up into the crank. I agree with dreamspeed that scrapers mounted in a perpendicular fashion is a step backwards. I don't think there is much to be gained by polishing or painting the internal surfaces to enhance oil drain back. The oil will cling to the rough sufaces and form a boundry layer which the return oil will easily flow over. evelrod I think the biggest advantage a dry sump sytem has is the ability to provide a dependable oil supply. However unless the chassis that the intended engine is going to reside in has the capability of generating forces over 1G I think a well thought out wet sump system should have a power advantage. (don't have to drive any scavanger pumps) not to mention the additional expense and associated plumbing. Your mention of the suggested clearance has merrit. My thinking that closer is better as long as there is no obstruction may be a bit of overkill.--------------Phil

 

[patprimmer]

Dry sump vs wet sump has a lot to do with space, RPM range and design efficiency of each.

A good wet sump will beat a poor dry sump.

the higher the engine speed, the more advantage you will get out of a good dry sump.

A good example of room can be in 2 different types of boats.

I have a centre mount ski boat with a fairly warm 350 SB Chev. The crank misses the bottom of the boat by about an inch, and with a good designed wet sump, reliable oil pressure cannot be maintained at speeds above about 5000 RPM, so a dry sump is essential for continuous high speed operation.

I have worked on a ski race boat that had a 350 SB Chev on an outboard leg. It had about a foot of clearance between the crank and the bottom of the boat. The sump was something like 7" long by 7" wide by 9" deep. With a decent tangential scraper and a tray, it was in effect a gravity scavenged dry sump, so I would expect nil gain from a dry sump, and probably a loss due to the power used to drive a scavenge pump.

The scrapers in both sumps are a copy of a late 80's Cosworth F1 dry sump pan and scraper.



Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[PowerDubs]

"225 slant six i am building. I am having trouble finding any "



try

http://www.crank-scrapers.com

 

[evelrod]

Yes, Phil. Even my vintage '63 Mini Cooper exceeds 1G in some corners and under braking. The Lotus is even quicker.
I wish I could use a dry sump on the mini as I rather like nice cool de-aerated oil but, an Accusump will just have to do. The Lotus-Cortina is restored as it was raced in the late '60's and has a "gravity scavenged dry sump"---THANKS PAT, I've been searching for a name for that thing.---Many of the so called "restored" vintage race cars these days reflect what the cars 'could have been' and not what they really were. Since I built this car in 1967, I can more nearly restore it to that condition...anyone can take an old street car and, with sufficient $$$ , can make a replica race car but, IMO, it will never be a "vintage" race car.

Rod

 

[patprimmer]

They are fairly simple sheet metal. It is not that hard to make your own, or have a sheet metal worker fabricate the basic bits, then hand fit it yourself.

Even for a SBC, I generally make my own pan scraper and tray, as they really need to be purpose designed to fit the chassis, application, and exact internal configuration of the motor. I have even been known to fit a two piece sump, so the scraper, then sump top half, then tray, then oil pump then bottom half or pan can be fitted in that order. That allows a full length scraper, and a tray that only has a very small hole for the oil pump shaft, and of course an oil return in the very middle, where even 3 or 4 Gs would not let oil slosh back up through the hole

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[carnage1]

I think I have a really good handle on a few things now.
I can make a custom high capacity pan. Build the windage tray into the pan. (welded or bolted) Use an accusump type device incase my level calcs are a bit off, and because it will preoil the engine. Polish the crank and do some edgeing and radiusing.
The last thing is the scraper. it was mentioned more than once to mount it tangently to the arc of travel. mounting directly to the bottom of the block would seem to be paralell to the arc. so can i bend the scraper to get the angle i need or would that be causing more problems than mounting it on the pan rail.

 

[patprimmer]

I make my scrapers in the form of two overlapping pieces of curved steel sheet that mounts between the sump and the block. These two pieces of steel are curved to match the swing of the crank. The one on the side where the crank is moving downward clears the crank and rods by about 3/8" or so.

The one on the side where the crank is moving up, only clears by about 1/8" or less.

These two overlap at the bottom, and bolt together with 1/8" spacers between them, so the opening faces toward the direction of travel. I use at least 1" of overlap.

I then carefully bend the closest piece, or top of the opening at the overlap so as to fit with about 0.020" clearance to the counterweights and rod bolts or whatever comes closest at that point.

I do not use a sump gasket between the block and the tray, as variable compression of the gasket will change the clearance. I do use a thin bead of silicone rubber to seal that surface as it will squeeze down to a consistent steel to steel contact, but still stops leaks.

Not finished yet.

I then make a channel or gutter to fit to the bottom of this, so it catches the oil coming out of the gap at the overlap. This channel falls from each end toward the oil pump pick up. It has hole directly over the pickup. Of course the hole is large enough comfortably carry the maximum oil flow, but no larger than necessary to do this. Of course it is at the lowest point in the channel. I also like to peen the edges of the hole down slightly to make a bell-mouth.

That takes care of the windage and oil return, and helps a lot with lateral surge.

To stop oil surging out of the pan (especially in a longitudinal direction) under G force, I also use flat plates, parallel to the ground, welded to and sealed to the pan, just above running oil level. This stops the oil running to the ends of the sump and coming up around the gaps between the end of the main scraper/tray and the sump.

I keep the pan as short, narrow and deep as possible, while maintaining chassis and ground clearance, and reasonable capacity.

Reasonable capacity varies greatly with the application. I like to see at least 6 (preferably 8)litres of oil in a SBC endurance engine, but 4 can be enough for a methanol SBC drag motor. With low capacity sumps on a drag motor, I would change the oil between runs.

Of course there are impossible compromises like the wet sumped, centre mount ski race boat, where there is no room for decent capacity, but a need for reserve capacity as it is an endurance motor where the skiers can normally outperform the boat.

Still not finished.

I make my own, simple cone shaped pick up that has little legs that sit on the bottom of the pan, thereby keeping the pick up as deep as possible, while ensuring it cannot close off against the bottom of the oil pan. I go to a lot of trouble to ensure there are no leaks between the pick up and the pump, as I want to ensure that no air will be sucked into the oil.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[evelrod]

I am ok with your setup for drag racing, Pat. I have a few different ideas for road racing where lateral forces are at play.
My pan is as low as is possible, usually about 2" from the ground (I use a little heavier plate with longitudinal ridges on the very bottom since it does touch now and again). On the Ford inline fours it is not the best idea to use a plate between the block and pan but instead I use a scraper plate braced and welded to the top of the windage tray at a ~30 degree angle to the crank centerline suitably notched to clear the crank and four rods by about a ~1/16" using the main caps/bolts as a brace/stop with suitable drainage holes in the appropriate places. Below the windage tray which is bolted in full pan width and 3/4 length with a 1 1/2" hole for the pickup and a 1/2" hole at the front for the "dipstick" and centered forward I have a 10" by 10" box with four hinged (inward only) doors. The pan is widened to the left to add an additional 2qts. capacity for a total of 7qts. (I only put five in). with the Accusump, filters, -010 AN lines and 19 row Mocal heat exchanger it all comes out at about 10 or 11 qts. total.

I have also seen several other setups that bolted to the main cap studs but, they have not worked well for me.

Rod

PS: 10-4 the seal up the oil pickup against air leaks. I cannot tell you how many engines I have seen that were ruined before their time by a small air leak at the oil pickup/pump.

 

[Azmio]

Here is an interesting concept that is currently patent pending and available for licensing. EP1482133; Oil scrubber for engine.

The windage tray serve many functions when combined with the bedplate.

 

[patprimmer]

Azmio

Did you forget to attach a link?

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Azmio]

Pat,

It's patent document from EU patent office. It can be accessed through patent search website. Try this link ie.espacenet.com and type in EP1482133.

 

[patprimmer]

Azmio

Your ID on this site now makes more sense to me.

I like the design. Congratulations on the patent.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Azmio]

Pat,

Many other designs (Porsche Cayenne's engine for example)make it difficult for the production people to assemble conrod from the bottom of the engine.

With the use of pressed plate, access is not a problem and the design is applicable to many existing cylinder blocks.