Dry Sump

[HIQ]

Can anyone please explain to me the advantages of a dry sump configuration?

Thanks!

[computerworks]

When Pat B. gets home, I am sure he'll add to this, but...

Dry Sump has the oil in a reservoir tank, not the bottom of the pan.
The pump is external and belt driven, not by the distrib.

No 'oil starvation' on those hard turns.

[RallySnake]

HIQ,

The "oil starvation" issue is an important benefit of dry sump oiling. Another is the fact that with the flat dry sump oil pan, the engine can be dropped lower in the chassis to lower the car's center of gravity. With a small diameter flywheel and clutch, the engine can drop several inches. On a race track this can make a significant difference.

Side note: all Porsche 911's have dry sumps.

Paul

[PatBuckley]

Try this site .... Article #21

howstuffworks.com

He explains it better than I could. One reason not mentioned is the benefit of a dry sump when using a roller cam - as the gear doesn't have to drive the oil pump, it will last quite a bit longer.

Not sure if this link is clickable....

Pat

[Sizzler]

PROS:
1) allows for lower installed height of engine in car providing a lower center of gravity. This helps in Cobras, but is mostly associated with GT40's. In fact, an FE in a GT40 virtually REQUIRES a dry sump to fit the engine in the compartment. The new Ford GT uses a dry sump today for the same reason.

2) provides better oil control, as mentioned. The pickup never gets uncovered, no matter how extreme or extended the side load on the car. Also allows MORE oil to be on onboard, some systems measure oil quantity in gallons. This tends to keep the oil cooler, which leads into one of the cons (see complexity below).

3) a dry sump pump can have multiple stages by design, and not all stages need be concerned with pumping oil. Some stages of the pump can be dedicated to evacuation which aids ring-sealing and can increase horsepower (if the rest of the parts in the engine are selected to take advantage of it).

CONS:

1) complex...external (usually) pump with a belt drive needs to be mounted. A LARGE oil tank needs to find a home somewhere. Oil lines running hither and thither. Because of the volume of oil, it may require a heater for the tank to warm up the oil. The tank may need either two chambers or a system of breathers or some other means to prevent foaming of the oil.

2) costly...all in, you're probably looking at something north of $2K.

3) reliability? the pump is usually driven by a belt, which is subject to damage from road debris or just age. When it goes, you have no oil flow (so along with the oil reservior, add in the space needed for something like an Accusump).

4) unsightly...tanks, lines, hoses, breathers, pumps, belts, all snaking or stuck on or sticking up or cramming up your engine compartment. Just my opinion on this. Some might think it looks good.


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The above relates to the old style dry sump systems. GM and Ford both have new systems which are much cleaner looking, don't rely on belt drives (usually driven directly off the crank), and less complex that are installed on standard production vehicles today. But they are designed for the modular and LS(1 and 6) engine families so I don't know how relevant this advance is to you.

HTH

[ToyCollector]

Sizzler,

Nice summary. The NASCAR boys run a dry sump the "old fashioned way", and for that app, I must say it is well integrated into the "car". It takes 40 minutes to pre-heat the oil in an old '94 era Cup Car I am familier with, so certainly not meant for casual users. Although I am sure the belt guys are holding back as much as the light bulb makers in technology, I would not worry about a belt failure as a reason not to install one. Main concern in a Cobra is space for all this but the space is there with some sacrifices.

[HIQ]

Thanks

[RICK LAKE]

HIQ Dry sump is the way to go if you are Racing alot. Dennis Gage did that show with the guy that owns the Shelby GT500 that made all the speed records, He also owns one of the only SC 427 with a dry sump from Shelby. The tank fits in the r/s fender, the rest is hoses. The pump is on the lower R/S of the motor. As long as you put filters in the correct places you will have no problems with these pumps. I think they are rebuildable. Avivad sells the complete setup minus hoses for an FE motor. I am going with one as soon as the checks come in. Add an Accump to the system for per oiling of the motor. I don't know all the in's and out's of the preheat for the oil but if it's in the R/S fender I am sure that 5 minutes of motor running will warm it just fine. You can set the oil pressure too. Good filters are the key to a long dry sump life. Get the info from Avivad and read the whole thing. If you are worried about a belt thing,buy a spare and put a big red light on the dash for low oil pressure to turn off the car and save the motor. Good luck Rick Lake

[coyled]

I have been running the external oil pump with a wet tank. I have never changed or had any issue with the dry sump belt. I was thinking about going to a dry sump tank. I was quoted 1500.00 to build the tank. Plus, I would need a different pump, oil pan and lines. As Rick said, dry sump is the all out best way to go. Anyway, I just pulled the motor apart after many really hard track miles. The bottom end looked good, plenty of oil to the bearings. Based on that, I am staying with my existing oil set up. I have the external oil pump, an accusump, and return lines from the valve covers to the oil pan. It seems to be working for me, just another way to go. Scott

[cobrashoch]

Todays synthetic oils do not require the warm up periods mentioned above. Very old school. If your engine is clearanced tight with aluminum heads then maybe a bit of warmup is required to let the heads expand, if you are running solids or a solid roller cam. But generally, todays engines are clearanced "loose" for both performance and fuel mileage, and they also take advantage of better materials used in their constructions. (the build)
A racing wet sump, together with the proper windage setup AND a vacuum system will give you the same horspower net gains you would get with a dry sump, on a purpose built engine. No differance there guys. OF COURSE a dry sump is better for cars that are tossed around hard though.
As for the road clearance issues;
A engine can indeed be set down lower in a car to take advantage of a dry sumps lower pan height. But to do so though, in a way, you are designing a car around the dry sump. See my next paragraph for the disadvantages.
I am puting the parts together fo a dry sump conversion on my car. But my cars engine height was set with a wet sump pan in mind. And on my dry sump conversion, I for sure, am not going to set the engine in lower either. The reason being that the lowest part of my cars road clearance is at the flywheel bell housing and not at my original custom wet sump pan. Regarding custom built cars using dry sumps, they would have to address tranny clearance issues to take advantage of a lower pan height on a dry sump. Of course in a racing type car you can set the engine in lower than you can for a street type car. Nothing new there.
And I, for the life of me can't understand why you would want to run a accusump pre oiler system with a dry sump system. With a dry sump all you would have to do is turn on the oil pump under the reservoir tank prior to starting your engine. I must be missing something here. We put on dry sumps to do away with things like accusumps I thought.

Cobrashock

[Richard Hudgins]

Ron,

You said: "With a dry sump all you would have to do is turn on the oil pump under the reservoir tank prior to starting your engine. "

I am not familar with this system. Could you give some details please?

I can see a great benefit to this. By using a electric prime pump, you could indeed pre lube the engine. But the plumbing and check valves needed might be a bit difficult

If you have a source for this part of the system, I would be quite interested. (It would save me a bunch of design/development time.)

Thanks in advance.

[cobrashoch]

Richard - RE oil pumps; That's the peice I am fitting together right now, the electric oil pump and it's sel. valve set to run at the same time. Been pokin' around some Indy Racing League shops of recient and the general consciences revolves around the surge tank design it seems, and not the pump itself. Kinda hard to get these guys to admitt to anything you know. Will update you via e-mail if and when I come into anything thats different from the standard design stuff. Right now I'm looking to just take a standard Melling high vol. pump and attach a motor to it, setting the bypass to go back to the surge tank. The sel. valve on the outlet side of the oil pump of course. That way the res. tank oil will keep the pump emersed in oil on shutdowns. No one way or check valves required of course. But I'm in the investigating mode right now too.
cobrashock

[RICK LAKE]

cobrashoch Ron You have me confused? If a motor is not run for say a week, when you crank it over it is DRY starting, any motor even your car motor. It takes 3- 10 seconds to build up pressure. Your may run a loose motor with .003 rod clearance and .0034 rod clearance. It depends on the drain back of the system from the pump and pickup tube. 80% of all engine wear and tear is done on start ups. It does not depend on whos oil you are using. Dry is Dry. If you are looking for a pre luber, JC witneys sells one you could hook up into a tee off your oil pressure switch. A one way check valve would work just fine. You are looking at a pump, I am using a accump to do the same thing. 2 1/2 quarts of oil with the right pressure gives me 30 psi to oil the motor. I run alot tighter clearances than you I guess. I don't think that any wet sump system can make more HP or Tork than a Dry sump. If so Pro Stock and Nascar would be using them. You might want to get info from Avivad also, they have a complete setup for the 385 motors. Rick Lake

[What'saCobra?]

Geesh, now i'm confused. I have never seen anything but a Gilmer belted power source for an American engine dry-sump system. Perhaps electric ones exist, but i wouldn't trust an electric motor in a race car for such critical duty on expensive motors.

So, sans some sort of slip clutch or something on the dry sump pumps, pre-oiling requires a separate electric pump motor with associated checkvalves and hoses or an accusump system (my choice).

i have seen an electric drill powered pump that is externally powered, just before start-up. At least it wets the journals. And modern oils do "cling" much longer on surfaces, particularly on close fitted non-race engines.

i have even seen guys slip a flexdrill line down the distributor hole to run the wet sump pump, with the distributor removed, of course. This is the el cheapo way, but perhaps bettter than zip? Big risk of re-installing the dist wrong just before the race, though.

Is there something here i am not grasping?

[PatBuckley]

Just crank it without touching the accelerator for three to five seconds - that is about all the pre-oiling you need.

[Bill E]

could not a pump pick up at the tank or pan and out put in the sender hole with one check valve.. Or is this just to simple By the way a electric fuel pump works grate.

[What'saCobra?]

Pat
You are correct, that is similar to another good method of avoiding start-up wear (or instant failure) on a race engine, so why not on the street?

Install an ignition cut-off switch, click over with zero throttle for a few seconds, watch the oil pressure move upwards, wait a little more, let it splash a bit, throw the ignition on and Voila! you have dodged MOST of the wear, particularly ring wear.

But, a proper Accusump is so much better.

Bill
Yep, electric pumps would be fine on a pre-oiler (but certainly NOT as the primary oil system), but I still worry a little about the reliability of extra hoses routing around the engine bay and cheap electric pumps with sintered or rubber-like cheap pump vanes. How much money do you have in your engine that you can afford to risk?

But, perhaps you have the craftsman's skills to engineer this up Bristol-like and the risk is quite minimal.

Good luck.

[Richard Hudgins]

Originally posted by PatBuckley


Just crank it without touching the accelerator for three to five seconds - that is about all the pre-oiling you need.

Pat,

I agree. That is the method that we always used with race engines.

But we would on first cold start of the day, remove the plugs and crank until we saw good pressure for about 10 seconds.

This was more for upper end lubrication then any other reason. (Also, some of the engines idled at 2500 rpm and there was worry that the high rpm at startup would do a bit of damage without fully lubing the cam followers.)

I really wonder if a pre-oiler such as a Accusump/pressure pump etc. would do any good for upper end lube on cold start?

Or is pre oiling really needed at all for the relatively mild engines one puts in these cars?

(I am speaking of road cars here.)

[PatBuckley]

Richard-

I would assume that the Accusump would do as good a job as the oil pump in oil distribution - also on an edgy race engine we always made sure the oil was thoroughly warmed up before doing anything which I think has as much of a benefit as making sure there was pressure before hitting the ignition.

Your question about is it really needed with the relatively mild engines that most have? I doubt it - but it doesn't hurt!

Pat

[cobrashoch]

Rick - Sometimes I get ahead of myself and forget what the standard stuff is about. Re; Dry sumps. I forgot that most dry sump systems combine both the excavating side and the engine pressure side pump into a belt driven system. What I was talking to Richard above was about splitting both sides of the pumps to seperate components, resulting in some different advantages.
As for how a engine is clearanced,,,,,,, way too complex of subject for this thread. Generally though, on most automotive builds for todays cars if you can turn the engine on a stand with a breaker bar at the damper kinda easy then you have a loose build. If you can't then it's a tight build. That todays builds are built loose on purpose, is what I was talking about above. As for horsepower gains on wet/dry sumps about 1/2 of the pro stock NHRA cars ran wet, 1/2 ran dry. Generally it's reconized that there is no gains to be made going either way. The same thing for fuel injection too by the way, according to most of those same guys. Yes, there is such a thing as a "dry" engine start. But todays oils go a long way towards aleiving most of those issues. A engine that has sat for a week or even for 2 or 3 weeks is NOT a dry start situation in my eyes. I've also heard that same 80% wear junk on startups all my life. It's wrong IMHO, just advertising really. Ask anyone that builds engines for a living and I'm sure most will tell you that 90% of a engines wear is in the last 10% of it's life, or there abouts, when things get sloppy. In my opinion it's by far more important to change your oil every 3K regarding wear, IMHO.
Richard, Pat - I agree that a few seconds of pre oiling is all that is needed. Yes Pat, it doesn't hurt either. Richard, we have millions of cars on the road and some of them are hefty performance cars that require no pre oiling. Hmmmmmmmm. BTW - I thumpk I've found a relable electric oil pump, maybe, maybe. We will see.
cobrashock