The wet sump system is a simple, low cost lubrication system, and it stands to reason why ninety eight percent of production engines built across the world employ wet-sump lubrication, it is simple, cheap, & reliable for normal motoring use.
But whether you use a wet sump or dry sump, engine bearing failure generally points to poor oil lubrication. And if you rebuild your own engines, reliability will become a hell of a lot more important than outright horsepower.
There have been arguments to say that a dry sump will cure the lubrication problems of just about any engine, but that may not be so.
Following is a simple explanation and comparison between the wet and dry sump systems.
The competition style dry-sump lubrication system is definitely more complicated and expensive than a wet-sump – but it has the advantage of providing continuous lubrication under all conditions, and because of the specially designed shallow oil pan, the dry sump generally provides increased power through reduced windage or oil drag on the crank.
Familiar Problems With The Ford Lotus Twin Cam Wet Sump.
A well known nemesis of the Ford Lotus Twin Cam engine is that it suffers from terrible oil starvation problems during sustained hard cornering to the right; where the oil is forced away from the oil pump pickup pipe in the sump. If a cure is not found, the end result could mean that the connecting rods will provide an unwanted form of very expensive positive crankcase ventilation!
Original Twin Cam Sump Baffle – Pathetic design.
Examine the image above, it clearly shows the internals of a standard twin cam sump, now ask your self, how is it possible that a single longitudinal baffle can control and prevent oil surge? Well, to be honest, it cant. If you have ever heard metallic rattles coming from the engine at high revs during hard cornering, that would possibly mean the standard sump baffle does not provide sufficient control of oil surge (slosh) in the wet sump with the original design baffle.
The fix (With some sheet metal work) for the Twin Cam owner, is to fabricate and install a well designed gated oil baffle control system inside of the standard twin cam sump. The result of this unique modification delivers reliable oil control which is not far short of what one would expect with an expensive dry sump system installed in race engines used in serious track competition.
If the elan (Or Ford Escort- Cortina – Anglia) is driven in historic competition events, you may find that the sanctioning body may not allow the fitment of Dry Sump lubrication, and if that is the case then you either run the risk of destroying a well prepared engine with a wet sump, or you spend some time learning how to fabricate and install a gated sump baffle to prevent damaging oil surge (Starvation) and control the behaviour of the oil to ensure that oil is always available for the oil pump pick up pipe, no matter what the cornering or braking attitude of the car may be.
The Wet Sump:
The standard wet sump is a simple lubricating oil management design; it uses an oil pan attached to the underside of the engine crankcase as a reservoir for the oil, as opposed to a remote reservoir as used in a dry sump system.
The engine is lubricated by oil pumped through the oil galleries to the bearings which then drains via gravity back to the base of the engine into the sump.
Most production automotive engines use a wet sump system, they can vary in size from 4 to 12 litre capacity underneath the engine, the oil is then pumped back up to the bearings by the oil pump which can be either internal or external to the engine.
The wet sump offers the advantage of a design which requires only a single oil pump, no external reservoir is required, nor is a scavenge pump required, generally there is no need for hoses or tubes connecting the engine to an external sump.
The wet sump design can be problematic in a racing car which produces larger than normal cornering and braking “G” forces which cause the oil in the pan to surge and move away from the oil pick-up pipe, and briefly starving the bearings of oil and potential engine damage.
Take a look at the video below to understand how the gated baffle works.
It is not that difficult to do. Gated baffles can be fabricated and installed into most wet sump oil pans to control damaging oil surge.
How To Quick Prime The Oil Pump After Major Engine Rebuild.
Establishing oil pressure after completing an engine build or perhaps after the installation of the gated sump project will sometimes create angst with some engine builders, it did for me until another engine builder explained a special quick prime trick.
It is simple to achieve oil pressure from the outset. Luckily with the lotus twin cam, the oil pump is quite easy to access. So do the following, remove the outer cover plate and put it aside and keep it clean, take a small container of Vaseline and dip your finger in and pack several dobs of Vaseline into the pump gears, put plenty in.
Now, check that the “O” ring in the pump body is OK, then fasten the oil pump end plate back on the pump body, apply correct tension to the small studs. But before re-installing always check the inside surface of the plate to make sure it is NOT warped or badly worn, if there is any irregularity, the plate can be set up in a four jaw lathe chuck and machined flat, 1.5 to 2 thou is all that is required to correct any distortion.
Now that the pump has been pre-primed with Vaseline, it should be ready to pump oil.
Make sure the weber carbs have fuel, make sure the plug leads are all connected, turn the key to engage the starter, when the engine fires, watch the oil pressure gauge carefully, once the pump draws oil which should be within a few seconds, the gauge should read what ever the normal pressure is for your engine.
The thin Vaseline fills the voids in between the gears and expels any air present and creates the vacuum required to lift the engine oil up into the pump, because in reality, the pump does not really suck.
When vacuum is created inside the pump and pick up pipe, the oil is forced up the pipe by normal atmospheric pressure which is about 101 kPa or 14.7 psi, once the oil begins to flow through the pump it will keep on flowing until the engine is turned off, that is, as long as there are no air leaks anywhere in the system, the pump will remain primed, ready for when the engine is started again.
The Dry Sump.
With a dry sump set up, the oil still falls via gravity to a shallow “V” shaped designed oil pan sump where it is collected and removed by the scavenge side of the oil pump, it is then pumped into an external custom built holding tank where it is both cooled and de-aerated ready to be pumped and delivered to the bearings again.
A standard twin cam sump fitted with a gated and baffled device will be one of the most effective oil control methods for very fast road use, club sprint events, and historic racing where dry sump lubrication is not allowed.
The picture above shows a custom sheet metal fabricated dry sump pan. The pan is constructed from a Cortina or Escort sump pan, the original bottom part of the pan is removed from the top flange and discarded, the pan is then fabricated from sheet metal as shown. The sump pan is suitable for lotus twin cam & BDA, as well as Ford Escort and Cortina (Kent) engines, of course when building a dry sump system, there are several other ancillaries required.
There are dry sump pumps which are belt-driven from the front of the crankshaft. The pump on the lotus twin cam is bolted onto the block in place of the original pump. Oil is then drawn from the remote reservoir via hoses by the pressure pump and re-circulated through the engine oil galleries.
The dry sump system is not susceptible to the oil movement (Surge) problems that a standard non baffled wet sump system can/will suffer during high cornering forces.
As we mentioned previously, the oil in a standard wet sump during hard cornering is forced to one side of the oil pan leaving the oil pump pickup pipe briefly uncovered (And sucking air) leading to a loss (Starvation) of oil.
With a dry sump, because the return scavenge pump point/s are typically mounted at the lowest point on the sump pan, the oil flows into the pump suction aperture by gravity, there fore providing continuous removal (Scavenge) of the oil.
There are many hoses, couplings, clips, screw on fittings, filter mounts, not to mention the pump, remote holding tank, etc, to consider when installing an expensive dry sump lubrication system.
Dry sump systems are not cheap to purchase, can be complex to install, and not completely without their problems. So, if you don’t wish to go the expensive dry sump route with your twin cam engine, and the historic race sanctioning body that you race/compete under wont allow a dry sump.
Then what is the next best thing that wont cost you an arm and a leg?
What You Need Right Now Is The Gated Oil Pan Baffle System For The Lotus Twin Cam Engine.
The image above shows the major components required to build the gated sump baffle, if you are doing the work your self, the material cost is less than $30.00. You may not believe that, but its’ true, we are not here to BS to you. The build time of course is yours, perhaps we should call it love time, or beer drinking time, in other words it’s free.
One of the joys of being a lotus elan owner is that it provides the opportunity for the skilled home mechanic/engineer/fabricator to become involved with various projects.
One such rewarding project could be that of fabricating and building a gated sump baffle for the twin cam engine.
This project is 100% proven on the road as well as having had many, many years of historic racing competition in Australia. We provide a downloadable ebook which outlines and explains in detail how to construct this project.
You don’t need any exotic tools or workshop equipment, but you will need access to a small bench lathe, pedestal drill, Oxy welding gear, and some basic sheet metal working tools… and if you don’t posses a certain tool, you’ll most likely know someone who has.
Since we released this project ebook in 2008, a large number of twin cam owners across the globe have grabbed the “How To” knowledge to build a more reliable twin cam engine… lets face it, you don’t want to destroy your twin cam engine do you?
The other interesting thing about this project is that to the casual onlooker, your twin cam sump to all intents and purposes looks like the stock item, but hidden inside are the simple, but unique sheet metal parts that provide a rather sophisticated DIY oil control system.
Now you can actually do something really positive about preventing a ventilated twin cam engine block. We’ve also been known to modify and build a gated sump for customers, mind you, it’s not cheap, but some of our modified sumps have been sent to the UK and also to France.
The biggest problem is finding a spare Twin Cam sump to modify – The best idea, is to use the one you already have on your engine.