Dry sump vs. wet sump
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Joined: May 2000
Posts: 799
From: Redmond, WA
Dry sump vs. wet sump
Someone asked why I don't have a dry sump setup on my engine, so now I'm curious. 
It's my understanding that the major benefits of a dry sump system are as follows...
1. Reduced height allows engine to be mounted lower in chassis.
2. Remote oil reservoir can be of any volume.
3. Reduces parasitic losses by eliminating oil splash on rotating assembly.
4. Oil pump cannot run "dry" under hard cornering or acceleration.
Now with a Canton 7 qt. road race oil pan...
1. Who needs a remote oil reservoir when you've got 7 quarts?
2. Parasitic losses are reduced by the integrated scraper and windage tray.
3. Internal baffles in the sump keep oil around the pump pick-up under hard cornering and acceleration.
Add a Canton Accusump to feed pressurized oil to the engine should the pump ever run dry and pre-lube the engine prior to startup. The only benefit you're missing is the reduced height, as far as I can tell, and if that's not an issue, or not something you can easily take advantage of, it's not really a benefit in my book.
Now... add in the fact that you'll have to drive a multi-stage pump from the crankshaft, and although you've reduced parasitic loss internally, you've just added some on the front of the engine. Add in the expense of all the parts and plumbing required to make up a complete system. Add in the trouble of finding a place to mount a remote reservoir (holding the oil under the engine is pretty damn handy when you think about it...) and what have you got? Not much benefit and quite a bit more expense.
Is a dry sump system really realistic on a street car? And I quote... "IF your thinking was correct it should be used in indy car, F1 etc... but its not! Not to many hi tech racing levels use wetsump..." Obviously a totally different scenario, and one where you'd want a flat-bottomed engine to keep the center of gravity as low as possible.
So... do I just not get it? Or is wet sump just fine for even the highest horsepower production street/strip cars?
It's my understanding that the major benefits of a dry sump system are as follows...
1. Reduced height allows engine to be mounted lower in chassis.
2. Remote oil reservoir can be of any volume.
3. Reduces parasitic losses by eliminating oil splash on rotating assembly.
4. Oil pump cannot run "dry" under hard cornering or acceleration.
Now with a Canton 7 qt. road race oil pan...
1. Who needs a remote oil reservoir when you've got 7 quarts?
2. Parasitic losses are reduced by the integrated scraper and windage tray.
3. Internal baffles in the sump keep oil around the pump pick-up under hard cornering and acceleration.
Add a Canton Accusump to feed pressurized oil to the engine should the pump ever run dry and pre-lube the engine prior to startup. The only benefit you're missing is the reduced height, as far as I can tell, and if that's not an issue, or not something you can easily take advantage of, it's not really a benefit in my book.
Now... add in the fact that you'll have to drive a multi-stage pump from the crankshaft, and although you've reduced parasitic loss internally, you've just added some on the front of the engine. Add in the expense of all the parts and plumbing required to make up a complete system. Add in the trouble of finding a place to mount a remote reservoir (holding the oil under the engine is pretty damn handy when you think about it...) and what have you got? Not much benefit and quite a bit more expense.
Is a dry sump system really realistic on a street car? And I quote... "IF your thinking was correct it should be used in indy car, F1 etc... but its not! Not to many hi tech racing levels use wetsump..." Obviously a totally different scenario, and one where you'd want a flat-bottomed engine to keep the center of gravity as low as possible.
So... do I just not get it? Or is wet sump just fine for even the highest horsepower production street/strip cars?
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Joined: Jun 1999
Posts: 329
From: TEXAS
Guess the biggest benefits I have heard for using Dry over Wet are
1. Reduced oil temps (its easier to keep 12 quarts cooler than 5)
2. Again the smaller pan
3. You always have pressure in high g turns
4. Vacuum. Dry sumps make most of the power because they can pull 20-25" of vac. to help build more power. In some cases upwards of 40hp. But the motor also has to be built to do this as well. I've never built a dry sump motor so I do not know what all goes into it, but just from the few that I have been around and/or worked on I know it has to be done a little differently to benefit from the dry sump and survive it
1. Reduced oil temps (its easier to keep 12 quarts cooler than 5)
2. Again the smaller pan
3. You always have pressure in high g turns
4. Vacuum. Dry sumps make most of the power because they can pull 20-25" of vac. to help build more power. In some cases upwards of 40hp. But the motor also has to be built to do this as well. I've never built a dry sump motor so I do not know what all goes into it, but just from the few that I have been around and/or worked on I know it has to be done a little differently to benefit from the dry sump and survive it
Registered User
Joined: Feb 2000
Posts: 35
From: Chickasha, OK
Jim,
Some other advantages to a dry sump, or external oil pump setup are:
1. Reduced load on the rear of the cam (can be important in high valve spring, small base circle applications)
2. Reduced spark scatter (not applicable in LT-1 or crank-trigger systems)
3. Allows more effective rear baffling, since oil pump is removed. Escpecially important in drag applications. Rear of pan can be built with full width baffle to stop oil from climbing back wall and getting into rotating assembly during accelereation.
4. External oil pump allows for external pressure adjustments.
5. External oil pump also allows pulley ratios to be changed. This allows to to custom tailor the oil volume to your needs.
One other option is the external wet-sump system. That's what I installed on my engine. Not quite the expense or complexity of a dry sump, but keeps all of the advantages listed above. I built my own oil pan, so the external pump allowed me to build a very effective baffling system for drag racing. I also used 34 tooth pump and 16 tooth crank pulleys, so the oil pump rotates at 47% engine speed. With the increased volume and efficiency of the gerotor pump, there is no need to turn the pump 50% engine speed, at least not with a small block. Just a waste of hp IMO.
Anyway, you can check out my web page if you want to see what my system looks like.
Good luck.
Shane
Some other advantages to a dry sump, or external oil pump setup are:
1. Reduced load on the rear of the cam (can be important in high valve spring, small base circle applications)
2. Reduced spark scatter (not applicable in LT-1 or crank-trigger systems)
3. Allows more effective rear baffling, since oil pump is removed. Escpecially important in drag applications. Rear of pan can be built with full width baffle to stop oil from climbing back wall and getting into rotating assembly during accelereation.
4. External oil pump allows for external pressure adjustments.
5. External oil pump also allows pulley ratios to be changed. This allows to to custom tailor the oil volume to your needs.
One other option is the external wet-sump system. That's what I installed on my engine. Not quite the expense or complexity of a dry sump, but keeps all of the advantages listed above. I built my own oil pan, so the external pump allowed me to build a very effective baffling system for drag racing. I also used 34 tooth pump and 16 tooth crank pulleys, so the oil pump rotates at 47% engine speed. With the increased volume and efficiency of the gerotor pump, there is no need to turn the pump 50% engine speed, at least not with a small block. Just a waste of hp IMO.
Anyway, you can check out my web page if you want to see what my system looks like.
Good luck.
Shane
Thread Starter
Registered User
Joined: May 2000
Posts: 799
From: Redmond, WA
Originally posted by kmook
Hey Jim dont go changing to a dry sump configuration
Hey Jim dont go changing to a dry sump configuration
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Joined: Oct 2002
Posts: 6,518
Jim,
It's good to see that you are using some decent headers now. On top of that the dry sump might settle the header clearance problem, but that kind of takes alot of work on the motor, specifically block to get everything right.
Cool oil on the other hand is not always the best thing. Oil that is too hot is a bad thing but oil that is too cold needs to be a lower weight. Hot oil and cold coolant is the best situation of all.
As everyone said the benefits of the Dry sump are great, yeah 7 quarts and a baffled pan are good, but they are not even close to a dry sump for road racing type situatuions. Smokey Yunick talked about this years ago, even Mark Donahue with his wet sump Trans Am cars found that there is no way a wet sump could ever effectively oil a motor in a road race situation not matter what amoung of oil control you have.
The vaccum and the oil scavenging FROM OTHER PARTS OF THE MOTOR are very big benefits to a dry sump. When you can plug and plumb the oil from the top of the motor down to the pump without having it hit the rods & crank it's going to help with windage issues, less oil there is just as important. Having that vaccum allows lower tension oil rings on top of that, which greatly reduces drag in the motor. IMHO for a street car adry sump isin't needed, in a high lateral g motor like a road rae setup you do need it, circle track motors can get away with a wet sump, but it's still not optimum.
Bret
It's good to see that you are using some decent headers now. On top of that the dry sump might settle the header clearance problem, but that kind of takes alot of work on the motor, specifically block to get everything right.
Cool oil on the other hand is not always the best thing. Oil that is too hot is a bad thing but oil that is too cold needs to be a lower weight. Hot oil and cold coolant is the best situation of all.
As everyone said the benefits of the Dry sump are great, yeah 7 quarts and a baffled pan are good, but they are not even close to a dry sump for road racing type situatuions. Smokey Yunick talked about this years ago, even Mark Donahue with his wet sump Trans Am cars found that there is no way a wet sump could ever effectively oil a motor in a road race situation not matter what amoung of oil control you have.
The vaccum and the oil scavenging FROM OTHER PARTS OF THE MOTOR are very big benefits to a dry sump. When you can plug and plumb the oil from the top of the motor down to the pump without having it hit the rods & crank it's going to help with windage issues, less oil there is just as important. Having that vaccum allows lower tension oil rings on top of that, which greatly reduces drag in the motor. IMHO for a street car adry sump isin't needed, in a high lateral g motor like a road rae setup you do need it, circle track motors can get away with a wet sump, but it's still not optimum.
Bret
Thread Starter
Registered User
Joined: May 2000
Posts: 799
From: Redmond, WA
Originally posted by SStrokerAce
Jim,
It's good to see that you are using some decent headers now.
Jim,
It's good to see that you are using some decent headers now.
Cool oil on the other hand is not always the best thing. Oil that is too hot is a bad thing but oil that is too cold needs to be a lower weight. Hot oil and cold coolant is the best situation of all.
IMHO for a street car adry sump isin't needed, in a high lateral g motor like a road rae setup you do need it, circle track motors can get away with a wet sump, but it's still not optimum.
Registered User
Joined: May 2002
Posts: 199
From: Seattle Area
Ya, keeping the oil from 185-200 is perfect, and using a thermostat its easy to do...the dry sump only helps the situation.
A street car will never see the G's that would make it a candidate for a dry sump system, but it wont hurt anyting but ur wallet. If you road race your car, then yes the dry sump will help. The biggest thing that it wil help with besides keeping the oil flowing during hard cornering, is taht most road racers spin at 6500-8500 rpms for long long times, depoending on the engines, and the dry sump makes sure you have a lubricated engine.
Hunter
A street car will never see the G's that would make it a candidate for a dry sump system, but it wont hurt anyting but ur wallet. If you road race your car, then yes the dry sump will help. The biggest thing that it wil help with besides keeping the oil flowing during hard cornering, is taht most road racers spin at 6500-8500 rpms for long long times, depoending on the engines, and the dry sump makes sure you have a lubricated engine.
Hunter
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