Well that was baffling...

"BiTurbo228 - Dr Frankenstein of Spitfires" (biturbo228)
03/28/2014 at 19:53 • Filed to: Spit6

PUNS! But really, I made a baffle for my Spitfire's sump :)

It's a bit tricky to find information on how best to make a baffled sump. There's info on basic construction as well as a few tips and tricks, but nothing on what sort of arrangement is best for general road use (a mix of lateral and longitudinal g) and what sort of construction will help baffle the oil but not starve the pump. So, after a couple of hours of googling I thought 'fuck this for a game of soldiers' and went and created something :)

First off, I cut a cardboard template of the windage plate (a horizontal plate to stop the oil flowing upwards when you corner, brake or accelerate card), with cutouts for the oil pump and dipstick.

Next I traced that shape onto some sheet steel and chopped it out.

As per this !!!error: Indecipherable SUB-paragraph formatting!!! , I turned down the edges of the windage plate to aid oil retention.

Trial-fitting showed that it fit rather nicely, sitting at the level of the oil at rest (measured from the dipstick). I also added a couple of drainage channels to direct oil back towards the pump. I've also based the design around a couple of elements from Kas Kastner's !!!error: Indecipherable SUB-paragraph formatting!!! (he was/is the Group44 of the East coast), so there's a 1/4 inch gap around the outside of the tray to allow oil to travel back to the sump.

The next thing, and the most irritating to find good info on, is the design of the baffles themselves. They need to restrict oil movement under sharp g forces both forwards/backwards and side-to-side, but not restrict the return of oil towards the pump. This is what I came up with:

You can do very clever things with gated baffles (plates with hinged doors in that allow oil to flow back to the pump but prevent oil from flowing away). However, I didn't like the complexity of that design. I'm sure it's fine in the vast majority of cases, but if the door gets stuck it could stop baffling the oil, or worse stop it returning to the pump. Also, if it manages to vibrate apart you could end up with something loose knocking around the bottom end of the engine. Bad times.

The curved plate fits into the sump like so. This should restrict the oil under acceleration conventionally, and as the side away from the pump is narrower it should also hold the oil close to the pump during hard left-handers as well.

Welded into place :) I also welded a little pillar in the opposite corner to provide a stable mount to affix the windage tray to.

I worked out where the tray would touch the baffles by smearing a layer of gasket sealant on top of the baffles and popping the tray in place, leaving a thin streak of sealant on the underside of the tray. I then drilled holes through the tray so I can puddle-weld it to the baffles underneath.

And hey presto, one baffled sump :)

Of course, it would have been better if I'd realised I wanted to do this before I painted the outside of the sump (and subsequently burnt off). So now the second coat of paint is drying and I'll fit it tomorrow :)