Engine oil 'pick-up' location
Discussion
It's a Longitudinally mounted Vauxhall engine in a race car using a Vauxhall windage tray, bespoke shallow sump, modified pick-up pipe, and a foam insert acting as a baffle.
My question is this- The pick-up pipe is the standard vauxhall item cut shorter to suit the shallower sump. As such it is just a plain pipe (say 1/2" diameter) with no gauze etc. With this in mind, How close should the opening of the pipe be to the bottom of the sump pan, to minimise the chance of it drawing air but without restricting the flow of oil up the pipe?
My question is this- The pick-up pipe is the standard vauxhall item cut shorter to suit the shallower sump. As such it is just a plain pipe (say 1/2" diameter) with no gauze etc. With this in mind, How close should the opening of the pipe be to the bottom of the sump pan, to minimise the chance of it drawing air but without restricting the flow of oil up the pipe?
Let the radius of the pipe I/D be R and the distance from the pipe end to the sump face be H.
Jot down the equation for the area of the pipe I/D.
Jot down the equation for the area of the annulus between pipe and and sump.
Find the value of H where both areas are the same and you have your answer.
Jot down the equation for the area of the pipe I/D.
Jot down the equation for the area of the annulus between pipe and and sump.
Find the value of H where both areas are the same and you have your answer.
With a strainer the annulus perimeter is huge so it can go very close to the sump face. The basic equation stays the same though. You don't want any flow area to be less than that of the I/D of the pickup pipe.
You will also of course benefit from radiusing off any sharp edges to increase the flow coefficient. This can add 50% to the flow capability of a pipe.
You will also of course benefit from radiusing off any sharp edges to increase the flow coefficient. This can add 50% to the flow capability of a pipe.
A baffling effect is acheived by using a foam insert inside the sump, which is retained by the windage tray.
The car only uses road tyres so cornering 'G' is not massive, however I'm investing in a much more accurate oil pressure gauge and low pressure warning light to protect the engine. Further baffling is permitted but I've no reason to assume the foam isn't doing the job effectively, unless you guys know otherwise?
The car only uses road tyres so cornering 'G' is not massive, however I'm investing in a much more accurate oil pressure gauge and low pressure warning light to protect the engine. Further baffling is permitted but I've no reason to assume the foam isn't doing the job effectively, unless you guys know otherwise?
Thanks for that. My thinking is that I'm more likely to see an illuminated super-intensity LED cluster staring me in the face than a 52mm gauge. The light would come on immediately when the oil pressure drops below 20PSI.
Logging the data to an ECU is not an option because my car basically has no ECU.
Regarding the use of foam in the sump, I hadn't heard of it before either but whoever modified this engine for use in this car decided it was a good idea!
Logging the data to an ECU is not an option because my car basically has no ECU.
Regarding the use of foam in the sump, I hadn't heard of it before either but whoever modified this engine for use in this car decided it was a good idea!
I'm struggling to see how foam can slow down the oil movement enough to prevent surge and still let it flow back fast enough to not starve the pickup. The requirements of one would seem to cancel out the other. I also wouldn't be too excited by the prospect of a bit of foam getting loose and blocking the pipe anyway.
I agree with what you're saying and I don't doubt for a moment that more traditional baffles (trap door?) would almost certainly be more effective.
Would you be surprised if I said that every Caterham with a wet sump k-series, Vx 8v or Vx 16v engine would've originally left the factory with a foam insert fitted?
There is a lot of debate within Caterham forums over their continued use. As PumaRacing suggests, should the foam break up (and they have been known to), the result is a blocked pick-up pipe and ultimately a severely toasted engine.
Some advocate their removal and many cars are running happily without them, however I reason that if they help even slightly it is worthwhile having one fitted. Mine is renewed with every other oil change as a precaution though.
Would you be surprised if I said that every Caterham with a wet sump k-series, Vx 8v or Vx 16v engine would've originally left the factory with a foam insert fitted?
There is a lot of debate within Caterham forums over their continued use. As PumaRacing suggests, should the foam break up (and they have been known to), the result is a blocked pick-up pipe and ultimately a severely toasted engine.
Some advocate their removal and many cars are running happily without them, however I reason that if they help even slightly it is worthwhile having one fitted. Mine is renewed with every other oil change as a precaution though.
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff