Dry sump vs wet sump

[67FEfastback]

I am going to be changing pans (tagged it again)
I have the option of going with a custom low profile wet sump pan, or a dry sump system.

Obviously the dry sump is going to give me better insurance against pressure loss, in hard cornering, hill climbing etc.
BUT
For day to day driving, and long haul cruises, what is the reliability of a dry sump system and pump? It's important to me, not to be broken down on the side of the road.

[fordracing65]

It will be as reliable as you build it, meaning dont use cheap parts.

[blykins]

A dry sump system is going to be mucho expensivo. If the majority of your driving is street, there's absolutely nothing wrong with a good high volume pump, an oil pan with trap doors, and an Accusump for emergencies.

[RodKnock]

IMO, if there's more pieces (lines, pump, tank, etc.), it's more complicated and more things to go wrong. I thought about dry sumping my FE, but the dizzying array of extra parts changed my mind. When I see extra oil lines and connections, I see potential future leaks and leaks in general drive me nuts.

Also, with an oil cooler, the oil takes a long time to heat up. I can't imagine how long it would take to get the oil over in a separate oil tank to heat up, unless they make some sort of oil heater to go along with it.

[Jerry Clayton]

well they do make heaters to warm up the oil--and when you consider all the lines and fittings for a cooler, remote filter and accusump you will be about as complex as the dry sump system---

[patrickt]

Originally Posted by blykins

A dry sump system is going to be mucho expensivo. If the majority of your driving is street, there's absolutely nothing wrong with a good high volume pump, an oil pan with trap doors, and an Accusump for emergencies.

Brent speakum truthem. When I toyed with the idea during my build process six years ago the ballpark estimate for a nice Aviaid system, with all the additional accessories, was going to top out at over three grand. And that was then....


EDIT: Here is a price sheet, I don't know how old it is: http://www.aviaid.com/pdfs/fe.pdf

[patrickt]

... that if I put my car on flatbed and sent it to Jerry or Brent and told them to put in a new Aviaid dry sump and to make it look perfect the bill would start with a "4" -- maybe.

[RodKnock]

Originally Posted by patrickt

... that if I put my car on flatbed and sent it to Jerry or Brent and told them to put in a new Aviaid dry sump and to make it look perfect the bill would start with a "4" -- maybe.

Sheesh. With cutting the fender and mounting all that stuff, including the tank, using top quality parts like Aviaid, making sure nothing leaks, etc., my guy, who I would trust to do that kind of work, would charge $10K. I'd bet.

[patrickt]

Originally Posted by RodKnock

Sheesh. With cutting the fender and mounting all that stuff, including the tank, using top quality parts like Aviaid, making sure nothing leaks, etc., my guy, who I would trust to do that kind of work, would charge $10K. I'd bet.

Uhhh, Brent and I will hop on a plane and fly out and put it in for you for ten grand. Right Brent?

[RodKnock]

Originally Posted by patrickt

Uhhh, Brent and I will hop on a plane and fly out and put it in for you for ten grand. Right Brent?

Who said I trusted you guys, especially with cutting into my polished aluminum fender.

[D-CEL]

Ok, Ill play.

It seems that I have read about alot of wet sump issues on this board. Twisted and seized drive rods, stripped dist gears and sheared roll pins seem almost common. As dry sump pumps rarely drive off of the cam, those wouldn’t exist, thus removing a common oil system failure source.
Dry sumps pumps seem very reliable, the NASCAR guys sure spend good money on them.
They are more expensive and more complex from a plumbing standpoint. But in return they provide many benefits, Uninterrupted oil flow, actual scavenging and crankcase vacuum (without a separate pump), higher pumping efficiency, tunable pressure, increased ground clearance, greater system volume etc. In addition to the obvious performance benefits, the pump is outside the motor, service can be done without pulling the pan.
From a performance standpoint there is no comparison, dry sump wins.
Is it worth the added cost/complexity? That’s your call..


Jason

[Jerry Clayton]

Well-----I have used lots of aviaid stuff over the years and some of the stuff I developed and/or helped Davis and Rodney with are still popular items---

And just to be specific---I was there working on my camshaft driven oil/fuel pump in early 70s I got pressed into helping make the scavage pumps for the bearings on the turbo chargers for the Offies---

[RodKnock]

Originally Posted by D-CEL

Is it worth the added cost/complexity? That’s your call..


Jason

Well, yes, if you set aside the cost and complexity issues, I agree, dry sump wins.

And, if you set aside the calories, carbs, fat and sugar, then chocolate cake wins too.

[Jerry Clayton]

do they have fuel injected chocolate cake????

[Z-linkCobra]

There is the option of doing a wetsump external. you can run the shorter clearance pan and still get the pump outside of the engine. Then its just a single stage pump, no tank simple lines. You get the added 20 to 30 hp, the constant supply, adjustable pressure all the benefits while eliminating alot of the headaches. We had setup like that on our supercomp dragster...worked well. Just food for thought.

Gene

[Tom Kirkham]

On a wet sump the oil pump drive shaft is enclosed by the engine.
On a dry sump the belt drive is open to the weather.
On a wet sump the camshaft is driving the oil pump.
On a dry sump the crank shaft is driving the oil pump.

If you are eating lots of distributor gears...

[Mark Thompson]

It seems to me that there is no benefit to spending a lot of money on a dry sump system unless you are building a race and not a road car. If you fit the right sump and keep it full of oil you can reliably drive as hard as you want, even occasionally on the track, and keep your oil pressure at a reliable level.

Your question did get me thinking about why there are a few road cars that have long been fitted with dry sumps for the road, the Porsche flat 6 (997) and the Ferrari V8 (430 & 458) come to mind, and why their engineers concluded the complexity was necessary. In both cases the tank and some of the plumbing are integrated into the engine and incorporate water/oil intercoolers to eliminate the remote oil cooler. The oil comes up to temperature very quickly as a result of the intercooler. The additional reliability gained by having the oil brought rapidly up to temperature and the offset of remote cooler appears to tip the balance, particularly in engines with very high rpm capability. Porsche uses this to specify 10000 mile oil changes. Ferrari combines transmission fluid intercooling through the same block (separate fluid) in the F1 box as well, so it is more difficult for some hero to try one of the sub-100ms shifts with cold transmission oil. None of these reliability benefits will translate in an aftermarket fitment.

I'd spend the money on more horsepower!

Mark

[67FEfastback]

Thanks for all the responses;
My #5 bearing, last year. (the last bearing in the topoiler FE to get oil)



I just want to make sure, whatever I do, the pan does the job.

[madmaxx]

I have seen a couple high powered engines loose oil pressure on hard acceleration. My theory was the oil is getting pushed to the back of the pan starving the pump suction, this included a car with a baffled 8 quart pan. Same engine going in 2nd gear steady at 6000 rpm had 60 psig oil pressure, during hard acceleration it would drop to 50 psig before owner got nervous and let off. I told him dry sump but had no idea of the cost.

[mreid]

All the failures of wet sump systems referred to earlier in this thread are almost entirely the result of improper part selection. You can make the same poor part selection with a dry sump system, but you have many more opportunities for mistakes. I would never run a dry sump system in a cobra or any other project unless it was exclusively used for racing with a regular racing maintanence schedule.