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.
© Ian Crocker
Last updated on October 12th 1999
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