Brian
Geraint Owens is obviously Welsh and to the best of my knowledge they
still don't have any Circle Tracks (only sheep tracks) in Wales so why
don't you mail him a copy and cement international relations.
I did notice that he is now working in Bath and I tried to come up with
a pun about us road racing types refering to circle track racing as
toilet bowl racing - but the rest of the list will be glad to know I
failed!
Cheers
Derek
Brian Evans wrote:
>
> You might give us a bit of an idea as to what the problem actually is, but I
> presume that you simply have insufficient scavenge. Does the sump actually
> overfill, or is the problem somewhat less?
>
> How many scavenge stages are you using? If it's a cosworth type pump, you
> can get pumps with several scavenge stages.
>
> What type of engine is it? What type of oil pan does it have (purpose made
> for dry sump, or modified standard pan?)
>
> Most people run a simple mesh type filter between the pan and the scavenge
> pump if they run anything at all. The full flow "real" filter should be on
> the pressure side of the pressure stage, although you can also run a pretty
> fine filter on the output of the scavenge stage. If you have a paper
> canister type filter on the input side of the scavenge section, you'll
> almost certainly have problems.
>
> The usual order is: pan to scavenge stage to oil cooler to tank to pressure
> stage to filter to engine input. The options are to add very free flow
> filters between scavenge and cooler, and to add screen type filters between
> the pan and the scavenge stage, just to catch big chunks!
>
> You can sometimes get suction leaks when using hose and connectors not set
> up to handle vacuum (input side of either scavenge or pressure stage) and
> the tough part is determining that you have a leak - air gets sucked in,
> rather than oil getting squirted out! Stainless Aeroquip line is normally
> used, and I have good success using the blue fabric covered Aeroquip with
> push-on hose-ends.
>
> The temperature thing is just a factor of viscosity - the pump can overcome
> problems when it has really thick, cold oil to work with, while the hot oil
> is far harder to get pressures with. This exactly the same effect as you
> see when you get very high pressures when the engine is cold, falling off to
> normal pressure when the engine warms up.
>
> The best discussions of dry sump systems tend to be in Circle Track
> magazine, BTW, and they just happen to have an article in the current issue
> (October) that gets in a fair bit of detail. Hope these ideas help to some
> degree...
>
> Brian
>
> At 11:30 AM 9/2/98 -0400, you wrote:
> >
> >I am having a problem with the dry sump scavenge on 6 litre engine when
> >teh oil gets hot (85 degrees plus). I have three main theories. Any
> >suggestions as to the likehood would be much appreciated
> >1. The pump is knackered (thought unlikely)
> >2. The oil filter (full flow type) for some reason is not of sufficient
> >capaacity
> >3. I have some rubber tube on the scavenge side of the return pumps. This
> >could be internally collapsing (no external evidence). A bit like sucking
> >too hard on a thick shake!
> >
> >My feeling is that it is #2, but I dont know if pumping the air/oil
> >mixture through a filter designed to take just oil is a problem. And if so
> >why should it be temp dependant?
> >
> >Any ideas
> >
> >Geraint Owen
> >
> >
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