[Alex W]

A dry sump has always been in the back of my mind. But they tend to get very expensive very quickly. Just the pumps usually start at about 1k, and go up quickly from there.

One way to lower the cost at least some is to use the pressure pump that the engine already has and just run a scavenge pump, but even those are not generally cheap.

BUT, this is a little out there I know, what if you could use the stock power steering pump as a scavenge pump? Does anyone have any idea what the flow rate on the engine oil pump is? Or what the flow rate on the power steering pump is? If it just happened to work, all of a sudden you have a very affordable pump that bolts on with no custom brackets and already has a pulley that will work with the stock serpentine belt. If the flow rate is too low, maybe you need a smaller pulley to over drive the pump.

Looking at the Wikipedia page on vane pumps, it sounds like it could be OK for the application. Says they work pretty well as vacuum pumps, so it should be self priming. Rotary vane pump - Wikipedia
Possible down side even if it would work from a flow rate perspective is that it would only be a single stage scavenge. So any drain back / oil entrapment issues on the sides of the pan wouldn't be solved. You would need to just "wait" for oil to come back to a single point in the sump and suck it out from there.

Thoughts? Is this completely crazy, or maybe worth looking into further?

 

[DefSport]

I don’t think the clearances in a PS pump will work for a dry dump scavenge.

keep in mind a lot of scavenge pump operation is with a lot of air mixed with oil. So they are primarily sized to move a lot of volume at a low pressure rise.

A ps pump is going to move relatively low flow volumes but a much higher pressure gain capability.
Now TWO PS pumps, maybe you’re starting to get enough flow and scavenging from two different parts of the pan to make it start working. Can you fit two of them? Alternatively, old smog air pumps have been used as cheap scavenge pumps, but not common these days.

I’d also worry about how loud a PS pump would be with some air continually going through it. They tend to moan quite a bit when introducing air in the system.

 

[Alex W]

Yeah, that's a good point about the air mix. Generally speaking I know you are right that they are intended for relativly low volume at a high pressure. It's been a while since I heard a power steering pump with some air going through it. I wonder if they would still be noisy if pumping at very low pressure? Definitely a valid concern. I guess that begs the question, are dry sump systems generally a bit noisy, or do the pumps that are usually used not have that issue.

Honestly trying to fit two power steering pumps, or retrofit a random smog pump, defeats the purpose of doing it with a power steering pump (no longer an easy, OEM, bolt on piece). At that point, even though the pump would be more expensive, it probably makes sense to do it right with pump designed for the purpose.

On the subject of flow rate, this article suggests flow rates in the 15gpm range from a GM pump https://www.hotrod.com/articles/ccrp-1304-gm-power-steering-secrets/ No idea if the 2GR pump would be similar, but that sort of flow rate seems like it's in the ball park of what is needed. But I don't know the flow rate on the OEM oil pump, so again just guessing.

 

[cpchri1]

Moderator please delete my comment

 

[scottgas]

A dry sump has always been in the back of my mind. But they tend to get very expensive very quickly. Just the pumps usually start at about 1k, and go up quickly from there.

One way to lower the cost at least some is to use the pressure pump that the engine already has and just run a scavenge pump, but even those are not generally cheap.

BUT, this is a little out there I know, what if you could use the stock power steering pump as a scavenge pump? Does anyone have any idea what the flow rate on the engine oil pump is? Or what the flow rate on the power steering pump is? If it just happened to work, all of a sudden you have a very affordable pump that bolts on with no custom brackets and already has a pulley that will work with the stock serpentine belt. If the flow rate is too low, maybe you need a smaller pulley to over drive the pump.

Looking at the Wikipedia page on vane pumps, it sounds like it could be OK for the application. Says they work pretty well as vacuum pumps, so it should be self priming. Rotary vane pump - Wikipedia
Possible down side even if it would work from a flow rate perspective is that it would only be a single stage scavenge. So any drain back / oil entrapment issues on the sides of the pan wouldn't be solved. You would need to just "wait" for oil to come back to a single point in the sump and suck it out from there.

Thoughts? Is this completely crazy, or maybe worth looking into further?

1st question, is it needed?

 

[ztarchitecht]

Very interested in this as well. However, if you're willing to get a used pump, the dry sump pumps can be found for as little as $300. In my opinion that would be a better option, because at SOME point you will either decide the PS pump doesn't cut it, or that the PS pump goes out.

 

[Alex W]

1st question, is it needed?

Yes and no.

No, in that lots of people are racing these motors with the stock sump without seeing an excessive number of oiling related failures.

Yes in that, despite the fact that they seem to survive it, there IS a g-force related pressure drop issue with these motors, particularly on RH turns. And for me, part of it is I am a little annoyed that I wasn't able to completely solve that with baffling in the pan (although it does help), and a dry sump should be the ultimate solution to the issue. However without having multiple scavenge ports, I'm not sure it would truly solve the issue, although it might delay it enough that you wouldn't see it any more.

I also would prefer that the sump not hang quite so low, and a drysump pan would likely be much lower profile than the stock pan.

 

[Zigspeed10]

Just sharing to give you some inspiration that a budget dry sump is doable. This isn’t a 2GR but I bought a used pump on eBay, built my own bracket, had an adapter made to bolt the pulley onto the stock damper, cut and modified the stock pan, modified a generic oil tank. The most expesive aspect of this are the cost of all the AN fittings.

My reason for this was to spin the motor higher rpm than the stock pump can handle as well as lower the engine mounting position.

Some things to consider is if you want to pull vacuum on the crank case to make a few extra hp you need to make sure the main seals are up to the task. You can inadvertently pull clutch dust through the seal and contaminate the oil. Also if I did mine again I would invest in a good oil tank, I don’t have evidence of mine being an issue but there are some videos out there showing the the oil foaming and how a good tank design can help.

 

[ztarchitecht]

Just sharing to give you some inspiration that a budget dry sump is doable. This isn’t a 2GR but I bought a used pump on eBay, built my own bracket, had an adapter made to bolt the pulley onto the stock damper, cut and modified the stock pan, modified a generic oil tank. The most expesive aspect of this are the cost of all the AN fittings.

My reason for this was to spin the motor higher rpm than the stock pump can handle as well as lower the engine mounting position.

What car is that in?

Anyway i remember seeing a post on a different MR2 forum, guy had a dry sump on his 4age, he actually ran the cam seals backwards, maybe even the rear main, because there was such a strong vacuum it would pull the seals inwards at high rpm. As long as the shape is a symmetrical, this should be perfectly doable.

 

[Zigspeed10]

What car is that in?

Anyway i remember seeing a post on a different MR2 forum, guy had a dry sump on his 4age, he actually ran the cam seals backwards, maybe even the rear main, because there was such a strong vacuum it would pull the seals inwards at high rpm. As long as the shape is a symmetrical, this should be perfectly doable.

This is a 2.5L Mazda KLZE swapped into an NB Miata.

I’m not pulling vacuum on my set up as I don’t need the extra power and running the risk of seal issues. When researching this what I found was they would machine crank to use a smaller diameter seal. Something about the smaller diameter held a better seal.

 

[DefSport]

Smaller seals have less total force acting on them at the same pressure, and are much stiffer in bending that the pressure will load it.

Stock lip seals like a stock main front and rear seal actually seal a bit better with small amounts of crankcase pressure. Flipping them when running a dry sump and creating that negative pressure differential puts them back in this orientation.

 

[teranfirbt]

If it's a one off setup you can usually find NASCAR pumps on ebay for less than half of new. Same with the tanks.

 

[merryfrankster]

Nothing against dry sump system and I am all for dry sumping just for the sake of dry sumping (just like Everest, because it's there) but why not just Accusump it? Less cost, less complication, seems to serve the desired purpose.

 

[Alex W]

Nothing against dry sump system and I am all for dry sumping just for the sake of dry sumping (just like Everest, because it's there) but why not just Accusump it? Less cost, less complication, seems to serve the desired purpose.

I guess I have always felt like the Accusump doesn't really solve the problem, just bandaids it. I mean, if the oil pump is sucking air, that air has to go somewhere right?. Even if the Accusump is buffering the pressure, you are still going to end up with an air/oil mix aren't you? Unless the Accusump is providing enough back pressure that the pump doesn't really suck up any air with it in the system, but it's a positive displacement pump, so it can't really help but to keep pumping right?

I know they WORK, I know a lot of people swear by them and that they do solve oil starvation problems for a lot of people, I just am not crazy about the overall concept.

 

[merryfrankster]

I guess I have always felt like the Accusump doesn't really solve the problem, just bandaids it. I mean, if the oil pump is sucking air, that air has to go somewhere right?. Even if the Accusump is buffering the pressure, you are still going to end up with an air/oil mix aren't you? Unless the Accusump is providing enough back pressure that the pump doesn't really suck up any air with it in the system, but it's a positive displacement pump, so it can't really help but to keep pumping right?

I don't believe a word of this - it is even framed as purely rhetorical speculation unsupported by any fact. If an Accusump had character this would qualify as assassination. It might even qualify for a Pinocchio score. Seriously I have come to expect better from you in terms of engineering analysis.

I know they WORK, I know a lot of people swear by them and that they do solve oil starvation problems for a lot of people,

This I know to be true.

 

[DefSport]

The stock oil pump still definitely picks up air if the pickup is starved with an accusump. It’s a question of will much more aerated oil still provide enough film strength for the bearings if the accusump helps the pressure stay up.

 

[Alex W]

I don't believe a word of this - it is even framed as purely rhetorical speculation unsupported by any fact. If an Accusump had character this would qualify as assassination. It might even qualify for a Pinocchio score. Seriously I have come to expect better from you in terms of engineering analysis.

I'm sorry, but please explain without the hyperbole what is wrong with that estimation of how they work? They are simply a pressure reservoir after the pump. If the pump is sucking air, why do you think that air won't go through the oiling system and be fed to the bearings? Where else is it going to go? Best case you end up sucking up a smaller amount of air than you otherwise would and compressing that air into a smaller volume, so the flow rate of the pump is reduced (but it would be anyway if sucking air without the accusump). But once the pickup is fully submerged and sucking oil again there still must be some air in the system that must be purged, how could there not be?

I suppose the benefit of the accusump is that they buffer that reduced flow rate time period so the bearings don't see the flow reduction, but the air still has to go somewhere.

The other thing I don't like is the need to essentially over fill the pan in order to account for the oil that the accusump is going to take up when fully pressurized. I happen to know that if you over fill the pan by about 1qt, idle for a while (say, waiting for your run at an autocross), then launch, you will emit a large cloud of oil smoke on launch. If the accusump valve is open all the time, it will dump most of it's oil when pressure is low (as it is at idle) I expect leading to exactly that.

 

[Zigspeed10]

Has anyone tried to modify the stock pan with some “kick outs” or “wings” to increase the oil capacity? Theory being that too much oil is pumped to the top end and not draining fast enough leaving the sump oil level too low. If that is happening no matter how good the baffles are there just isn’t enough oil left in the pan. That might be the cheapest and simplest way to fix the issue.

 

[ztarchitecht]

Has anyone tried to modify the stock pan with some “kick outs” or “wings” to increase the oil capacity? Theory being that too much oil is pumped to the top end and not draining fast enough leaving the sump oil level too low. If that is happening no matter how good the baffles are there just isn’t enough oil left in the pan. That might be the cheapest and simplest way to fix the issue.

Corvettes do this with their pans. GR il pan is cast aluminum, right? probably wouldn't be too hard to make a whole new pan out of sheet metal because I know, and I'm sure Alex has had the same experience, cast alum is a bitch to weld to.

Side note: I wonder if any other GR pans fit the 2GR and might have better baffling or capacity

 

[Alex W]

I have thought about trying to build a bigger pan like that. Wouldn't be too terribly hard I don't think. And I have data showing that over filling the pan by a half quart or so helps quite a lot, but I'm not sure if it's because of increased depth, or increased volume, or both.

The lower half of the stock pan is steel, the upper is aluminum. Adding capacity would be all on the lower half, although welding cast aluminum isn't too hard usually.

There is also the Moroso pan, although I don't know how well it works (no data).