Baffled Sumps for the Rover V8

If you have a standard wet sump on your Westfield you will probably suffer oil surge if you use the car for track days or competition work. This is caused when the oil gets thrown to one side under hard cornering and the pickup becomes exposed allowing the pump to suck up air. What is worse, because there is no oil pressure warning light on the dash you probably won't even notice it until your engine expires. This happened to me. I didn't notice I was getting oil surge until I had completed 2 events. By this time the main and big end bearings were wrecked.

There are 3 sumps available for the Rover V8, the old P6 type with a well in the centre of the sump, the SD1 type with the well at the back of the sump and the Range Rover with a much larger well at the back. The P6 sump is virtually extinct now. The SD1 sump is most common. It has a small braking baffle welded in as standard and is used with a windage tray bolted to the block. The Range Rover sump has a horizontal baffle welded in across the top of the sump and has no windage tray. 2 types of pickup are available for the Range Rover sump, the older large diameter unit and the newer, considerably smaller pickup. The choice of pickups plus a larger oil capacity and better ground clearance (about 1/4") mean that the Range Rover sump is the best one to use.

In order to stop oil surge you have to prevent the oil from moving away from the pickup under hard cornering or braking. There are several approaches to this and they are often combined.

A horizontal baffle placed across the sump with a hole that is just big enough to allow the pickup to pass through can be quite effective. This needs to be placed at a suitable height so that it is usually level with the top of the oil that remains in the sump when the engine is running. If it is higher it will allow the oil to slop around before the oil hits the baffle and has its movement controlled. This is the minimum that you can get away with and I have used such a system on my car to good effect.

Another approach is to box in the pickup so that it is sitting in a tall, narrow box. The sump is constructed so that the oil returning from the engine is directed into this box and it remains fairly full. If this box also has a horizontal baffle across its top then it is quite difficult for the oil to move about so much that the pickup becomes uncovered. The standard SD1 and the older Range Rover pickups are too large to box in as they come close to the sides of the sump. They either need modifying or, with the Range Rover, you can buy a smaller pickup. This sort of arrangement is sold as a 'full race' sump by some people but may not be good enough if you are running slicks.

Any vertical baffles, e.g. the sides of the box described above, can be fitted with trap-doors. These swing inwards towards the pickup and are arranged so that under cornering or braking forces one or more of the trap doors are forced closed to prevent oil being flung away from the pickup while other trap-doors swing open and allow oil to flow into the box from the rest of the sump. This is about the best sump that you can readily buy.

To make your sump even more effective it can be fitted with wings to increase its capacity and provide even more oil to flow through the trap doors in long corners. You can also compartmentalize the area of the sump outside of the pickup box to try and improve oil flow through the trap doors. This is what Rover did with the Group A Vitesse sumps. The work involved is so great that it is not the sort of thing you can easily buy. You would also be pretty sick if you did manage to buy one and then wrecked it on a speed-bump!

If the explanations above are awkward to understand then here are some examples of some baffled sumps so that you can see how to go about constructing one.

SD1 Sump & Horizontal Baffle

Here is a home made SD1 sump with horizontal baffle. The baffle is placed at the 3 litre level on the assumption that about 2 litres of oil will be flowing around the engine when it is running. The baffle is bolted to 2 brackets that have been welded to the rear of the well, and to the standard braking baffle that is at the front of the well. It is a tight fit into the well so that no oil can escape past it without leaving through the central hole. The central hole is narrower than the diameter of the pickup so that there is as much metal as possible preventing oil from climbing the sides of the sump (As a consequence it has to be hooked over the pickup when installing it - make sure you can do this with the engine in-situ). The baffle is bolted in so that it can be removed for easy cleaning of the sump, or it can be transferred to a spare sump quickly. This sump is adequate for sprints and hillclimbs on road tyres.

Professionally Built Trap Door Sump

Here is a beautifully constructed sump made by J.E. Developments (not to be confused with J.E. Engineering who make a simpler version without the trap-doors). The sump has a boxed in pickup and uses the latest specification small pickup. The box extends to within about 1mm of the bottom of the sump. The horizontal baffle can be clearly seen on the top of the box. This has a hole for the pickup to pass through and another for the dipstick. The entire top surface of the sump is sealed against the edges so that all the returning oil is directed into the pickup box. The 2 gutters visible in the top plate are a neat trick that helps to ensure that oil is returned to the box even while cornering. There are some overflow holes at the top of the box so that when it is full the oil flows into the rest of the sump. The pickup box has 2 trap doors, one on each side:

This sump would be very hard to build at home and represents good value for money at around £200 (in 1999). My brother and I both run these sumps on our cars and we never have problems.

How Not To Do It!

This sump was sitting under a Ginetta G33. In order to gain some ground clearance it had 1.5" cut from the bottom. The sump was then extended forward to regain the lost capacity. The original downward part at the forward end of the sump well was left in place so that the sump was divided into two portions. This divider was supposed to act as a baffle to prevent the oil from flowing forward. There are several problems with this arrangement. Firstly by making the sump shallower, especially by 1.5", it becomes much harder to control oil movement. Secondly the 'baffle' has a large gap at the bottom that it allows oil to flow forward under braking. A trap-door would have been better. Finally, for reasons known only to the person who built this, the pickup has had large sections cut out of the vertical edges of the shroud. A pickup should normally sit between 3mm and 6mm from the bottom of the sump. These cut-outs have effectively raised the pickup so that it becomes even easier for it to become uncovered. The end result of all this craftsmanship was a car that suffered bad oil surge under moderate braking or cornering on the road, let alone the track.