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Dry Sump Pan Ideas


zim
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Afternoon,

I'm busy getting some bits together for my dry sump system on my rover v8 4.2.

I am planning on making my own sump pan, but looking for some ideas. I guess most of the dry sump systems are made for racing cars and the likes, and not for us that plant our vehicles at stupid angles !

What you generally see is a really shallow flat sump with suction at front and back. Space below my engine isn't a massive problem, as the gearbox bellhousing drops down a fair bit anyway.

I guess it'll have to have a channel down the middle.

My pump has 2 scavengers. So i need 2 suctions which will obviously have to be front and back.

So if you had a blank piece of paper, how would you design one ?

Or better still photos :)

Cheers

Gordon

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I'd have thought a V shaped pan with a pickup at each end. You should be able to calculate the optimum angle for the V based on the angle you think you can get to before your truck will roll over and how much residual oil you expect to keep in the engine. Maybe with a (normally) horizontal baffle near the top.

You don't actually have to keep the sump "dry" so even with a shallow V, if you don't skimp too much on the tank, when the engine is in it's worse orientations oil being pumped in will exceed that being scavenged so you'll essentially fill the sump until it reaches the scavenger pickup. Obviously it's important that you don't run out of oil in the tank before the scavenger outlet is covered regardless of the angle you are at.

Are you using a combined pressure/scavenge pump or relying on the RV8 pump to provide the pressure ?

If you're using the RV8 pump positioning of the tank might be a more taxing problem that the sump design as it's not exactly renowned for it's "suction" properties. Again, it's not a problem on a road motor as you just mount the tank higher than the engine and let gravity do the rest. Mount the tank at the rear of the engine though and on a steep uphill you may end up with the tank at the same height or even lower than the oil pickup.

I've been pricing up a system for my motor and haven't been able to get any definitive answers on the tank positioning as most of the combined scavenge/pressure pumps seem to use the premise that the tank will gravity feed it.

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Cheers Dave - i have a 3 stage pump, so doing away with the standard dizzy driven type. Like used by tvr (i think).

I've just come back from work, so will have a play with some ideas... just looking for others :)

G

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  • 2 months later...

Here goes my first post on here :D

I've been waiting for me authorisation to post, as I'm on for the same dry sump conversion. A really steep nose down drop finished him off at Bridgenorth. So time for an engine rebuild, and a method to stop us killing the new parts.

I'm as far as stamping the new dry sump blank out. I'll try to get it bent this week. I've gone for a shallow 'V' with a 40 x 50mm channel down the middle. (Assuming I press Brake it in the right place). This seemed fair, looking at others and reading above.

I was going for a bulkhead mounted tank leading to a flexi hose through the sump to the original pickup pipe inside. Then I only need to drive two scavenge pump stages which won't take much belt power. I'd go toothed belt, but I'm not a fan of running anything but 'V' belt in mud and sticks :unsure:

My main concearn is that scavenge pumps are oil lubricated. So I'm trying to baffle the dry sump so the high-and-dry pickup can get some splash oil.

My main reason for posting was to see how far you'ld got fabricating yours?

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I've not done mine yet, it's on "The List" :lol: When i've got somewhere i'll post.

Put a picture up of your sump once done though, i'd be interested.

G

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DrySumpMay2011.jpg

Though I'm not sure the front and rear don't want tapering off a bit more? And it's definately a few mm's too wide and needs jumping on. You never know till' you've got it's sat in place :)

Middle hole is sump plug, the end holes are scavenge, the little bits are the internal baffles and the single hole by the plate is the scavenge pipe break-out point to the tank.

I need to go find some mesh, which is why I saved the old fire gaurd ;)

I think I've found a suitable external relief valve. I wonder whether to tap a hole in the remote filter housing (nice and high) or go into the pump housing (local to pump and maybe the same thread)? Either way, the old shuttle releif is getting wedged shut!

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Ok, it's not a dry sump - but the principle is the same....

On my 'buggy' I adapted it to have indi front ( and rear) suspension. The front diff needed to be higher in the vehicle - where the front of the sump was. I fabricated a new sump with about half volume which has a shallow slope from the front of the engine to about the middle of the sump then a steep sided funnel (above the input flange of the diff). I then re-plumbed the pickup to sit in the bottom of the 'well'. The result is that the pickup is still submerged at an angle of 50 degrees or so in any direction.

Although the oil volume is reduced, it seems to work pretty well. If not, my plan was to add a secondary electric oil pump to raise the level of the oil to feed a flexible bladder type tank with no air in it. Then the oil can simply drain from this into the original pickup pipe.

When the engine is switched off, the oil from the bladder would drain into the engine which would present a problem. The solution is just to switch on the pump for a few seconds before the engine is started. You could even have a starter inhibit switch operated by the bladder pressing on the side of it's container. That would also inhibit starting if the oil level is too low.

Si

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I hear exactly what your saying Zim, and I'm hoping your a step behind, and not one on front ? Because I'd hate to get this crank-chewingly wrong.

Our thinking is logical, but my descriptions usually dyslexic, but here goes.......

On a race car you put the pick ups at the extremities of the sump so they drain all the oil. Because of flaps and baffles the scavenge pumps are never without oil for long. Maybe only until the next bend. Pace do a '3 scavenge-1 pressure' pump pack. I'm guessing any of the 3 can out-pump the pressure feed? (10 liter/min at 1000rpm.

But the smart money says that ten minuets nose down in a ditch and that system will sieze the pump, or really make it miserable :(

So those small 'mid baffles' are going in to dam up oil on the high end, around the pick up tube. The distance in from the ends is a guess, and is a hope that the oil from the rear crank throw, will chuck oil onto the dry sump surface. It will run down the channel, get stopped by the baffle, and feed the high-end scavenge to keep it lubricated. Because its a simple hard-ware solution, it should be more reliable than oil injectors connected to the scavenge pump inlets (just another joint to leak). The sump will stop being 'dry' for a bit as a pool forms at the back or front. But inbetween, on the flat, a pool forms between the baffles in the sump plug part of the channel. Which may be good or bad :unsure:

Does above sound fair? It's a bit of a puzzler. We have spent a fair amount of thinking time on it, looking at dry sumps, semi wet, pump back (small scavenge takes front oil and fills pan), external pressure pump using OE pump as scavenge. And electric pump back as Simon suggests, even as a 'pump back' on a tilt switch.

So like my Sliding Fairled, we seem to be re-inventing the wheel :huh: But seeing the anticks of other challenge trucks, I think it will become more common a fitment. Good job the auto has two pumps ;)

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Ok, it's not a dry sump - but the principle is the same....

On my 'buggy' I adapted it to have indi front ( and rear) suspension. The front diff needed to be higher in the vehicle - where the front of the sump was. I fabricated a new sump with about half volume which has a shallow slope from the front of the engine to about the middle of the sump then a steep sided funnel (above the input flange of the diff). I then re-plumbed the pickup to sit in the bottom of the 'well'. The result is that the pickup is still submerged at an angle of 50 degrees or so in any direction.

Although the oil volume is reduced, it seems to work pretty well. If not, my plan was to add a secondary electric oil pump to raise the level of the oil to feed a flexible bladder type tank with no air in it. Then the oil can simply drain from this into the original pickup pipe.

When the engine is switched off, the oil from the bladder would drain into the engine which would present a problem. The solution is just to switch on the pump for a few seconds before the engine is started. You could even have a starter inhibit switch operated by the bladder pressing on the side of it's container. That would also inhibit starting if the oil level is too low.

Si

Si, sensible idea. To get to oil volume back I'd think about an oil cooler and remote filter - that'll add a bit. Your idea also sounds a lot like an Apollo oil accumulator system. Personally I'm not convinced dry sump is the best solution for anything involving mud because of the scavenger pump and also you just move the issue with the pick up from the sump to the oil tank..... For my LS I've got a nice gated sump and these seem to work very well. If I have any oiling issues I'm planning on adding an Apollo accumulator as this'll give you about a minute of oiling at idle with the pickup uncovered - enough to get out of the situation or shut down the engine.

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One thing I will say: Have you guys thought about airation? You are going to have an enormous amount of air in the oil, which needs seperating out before it is going back in the engine. If you buy one of the ARE oil tanks with a swirl pot build in, that will be ok, otherwise that is a point worth thinking about.

Daan

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Team Idris, i see what you're saying. Basically trying to avoid running a section of the pump dry for too long.

Have you thought / do you have the intention of running an accusump as well ?

I intend to do so on mine. For the simple fact that when it rolls it doesn't do any damage by lack of lubrication. Might actually give you that little bit more time to self righten if you're lucky.

(I run an accusump already on my standard wet sump)

Gordon

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We're thinking the same as Daan here with airation. Normally the oil light tells you when the engines wrecked, so it being 'out' isn't a sign of sufficient oil volume, just some oil volume.

If your keeping good gauge pressure, then all must be okay? But is airation still allowing metal-to-metal contact in the engine? I guess it would?

Accusump looks a good piece of kit. Hopefully a 200mm round/deep dry sump tank will eliminate the need for one on a cluncky old V8. I wouldn't run on my side (though it is a neat trick) as many other on-board oil based systems would suffer.

On the whole, as plant fitters, we think dry-sump is somthing we should have fabricated years back :D

As a footnote, I was talking to my father the other day, who was saying how the local post-knockers were working on a steep bank and knocked the crank out of their unimog :blink: I am begining to suspect that the time spent at steep angles is the critical decider on engine damage, not the severity of angle.

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Indeed, if you have oil, it works ok, if you have foam, your engine nukes in a matter of seconds. This I have seen happening 4 times on a row on an engine dyno, so be really sure what you do before starting the thing up. If you are on a steep angle, one pickup will pick up 100% oil, the other will pick up 100% air > resulting in 50-50 oil air. You put that back in the engine and there will be tears before bedtime. even in normal use, the pickups are never fully covered in oil, and you probs have a 50-50 oil air rate.

The angle/time argument doesnt stack up to me; as long as the oil pickup is picking up oil youre ok. I only once had a case of the oil light flickering because of angle, that was downhill vertical, hanging of a rear winch

Daan

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Indeed, if you have oil, it works ok, if you have foam, your engine nukes in a matter of seconds. This I have seen happening 4 times on a row on an engine dyno, so be really sure what you do before starting the thing up. If you are on a steep angle, one pickup will pick up 100% oil, the other will pick up 100% air > resulting in 50-50 oil air. You put that back in the engine and there will be tears before bedtime. even in normal use, the pickups are never fully covered in oil, and you probs have a 50-50 oil air rate.

The angle/time argument doesnt stack up to me; as long as the oil pickup is picking up oil youre ok. I only once had a case of the oil light flickering because of angle, that was downhill vertical, hanging of a rear winch

Daan

Strimmer / chainsaw fuel tank tecnoligy might be a better way to go, have the pickup waighted and free to move within the sump, Then graverty is working for u, and pulling the pickup into the oil

:unsure:

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Strimmer / chainsaw fuel tank tecnoligy might be a better way to go, have the pickup waighted and free to move within the sump, Then graverty is working for u, and pulling the pickup into the oil

:unsure:

If it works, than yes why not. If I am totally honest, I would explore every possible avenue to avoid going dry sump myself. Although you are probably able to make it work, there are an awfull lot of scenarios I can think off that have disastrous consequences, that I would have (even) more worries when driving the thing offroad. for example fan Belt failure normally is a bit of an inconvenience, but solved in about 10 minutes, off you go. A belt failure for your scavenge pump is a dead engine. So you really need to have a very good reason to do it on an offroad vehicle.

Daan

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A 'clack' as we used to call them, only sorts out oil starvation. There's still the problem of half-a-sumps worth of oil round the front 2 pistons. This is smelly and wrecks the plugs :(

I see the V8 Ibex on Difflock already has a dry sump system, so we're not alone in our thinking. The belt snapping is a fair point, but thats an 'if' rather than an 'is'. We're sure we are causing damage with foam oil every outing. And I carry a spare belt around the front PTO shaft, so a quick fix. I see that £36 gets me a hand operated boat 'sump pump' which gives me a bit more system control (if I get pump bypass during storage).

On the whole I'd say its personal preferance based on the task and the engine type. If it were a four potter I could lay hands on easily, I'd be less inclined (virtical piston run). But a re-built RV8 is quite a wallet slapper, so in many ways I'd call a dry sump 'investment insurance' :D

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  • 3 weeks later...

I just started making the dry sump tank before the engine block returns from its boring week away.

As somebody who knows nothing of dry sump systems, I assume the engine breather connects to the dry sump tank, and it breaths to a drain tank, thereby sorting the gas out for everything. And all at low pressure to stop leaks.

But, every normal factory screw compressor I’ve seen has no lubrication oil pump. The compressed air forces the oil through the filters and up the lube points on the compressor head, which is at atmospheric pressure. The oil goes through the compressor and back into the separator reservoir. Simples :D

It’s an extreme example of what I wonder is normal on dry sump?

Because, some positive pressure makes pressure pumps work better. (especially really crappy rover ones) So the logical thing to do is to connect the engine breather to atmosphere, and fit the dry sump tank with a 5 psi gas relief valve. That means the pressure pump is always fed oil rather than sucking it. And rolling over means the relief valve holds the oil in.

Is this logical, or normal, or something to avoid?

I ask because I saw on the net a description for a pug dry sump. The bloke blanked off the engine breathers, which is like the reverse. So scavenge would be excellent, but he risked blowing the seals out of the engine. So I assume he was nuts?

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Its not RV8 but i used to run BSA & Triumph motorcycles and they were dry sump. The scavenge pump was twice the capacity of the pressure pump and there were no crankcase breathers. The gas separated out of the oil in the tank and vented from there to atmosphere.

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No atmospheric connections to the sump, You need a vacuum in the crankcase. In the end we just fitted another scavenge stage and connected it to the rocker cover and dumped it in the top of the tank. That solved our problems, but it took a long time to get there.

Daan

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It is to stop fumes come out of the breather. You are actually trying to create vacuum when the oil pick up is not covered, in which case the scavenge does run dry. It all depends on how much blowby you have, the one I was involved in had lots of blowby, creating lots of problems.

Daan

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  • 2 weeks later...

I spoke to David Lazenby who worked for Lotus and Pace. My work mate worked for him at at Pace and he also helped us with our aluminium brazing oven when were at our whitts end. A sound bloke indeed!

I rang him as we were thinking of keeping a slight pressure in the tank to reduce pressure-pump cavitation. He'd had the same idea years back, tried it and had no luck. The pressure stops the air bubbles coming out of the oil. If the system could stand it, a vacuum would be better!

We also disscussed the problem of running pumps dry at steep angles. He has a solution! He can change the pump he already sells to 'self lubricate' the scavenge sections. It'll look the same on the outside, but do the job! No need for strange dam-baffles to keep both pumps wet :D

You could drill conections into your existing sump I recon, and still get the benefit ;)

This is extra good news for me, as I suspect my sump-trough is in the same vicinity as my axel breather and diff wire :( Putting them on the top-left side of the diff pumpkin seemed like such a good idea in March :rolleyes:

I was going to use the existing RV8 pump. I have totally gone off this idea. It's a complicated way of using a bad part and would have took hours to sort out.

I'm intending nicking the alternator belt for the pump-pack, and putting the twin pulleys on the power steering pump for the alternator. (like later RV8's) I'll have to run a crank sized pulley on the pump, as it would normally run at half crank speed on a racing car with a small crank pulley. But my PTO shaft is in the way and I only rev to low amounts by comparison. So no reason it won't work and bigger pulley means more drive area :D

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We also disscussed the problem of running pumps dry at steep angles. He has a solution! He can change the pump he already sells to 'self lubricate' the scavenge sections. It'll look the same on the outside, but do the job! No need for strange dam-baffles to keep both pumps wet :D

You could drill conections into your existing sump I recon, and still get the benefit ;)

rev to low amounts by comparison. So no reason it won't work and bigger pulley means more drive area :D

But I dont see a problem with it running dry; running on a steep angle is for the pump the same as driving fast through a corner I think. The thing is that 'running dry' isnt really happening, it is more a case of running damp, very oily air as such. As said, I haven't seen a problem with this myself.

Daan

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