oil pressure or lack of?

[woollymoof]

I know this is a broad question, but would anyone know what the minimum oil pressure is for their engines at different RPMs? At what pressure would you turn your low oil pressure light on and does this vary at different RPMs? I assume it would.

[woollymoof]

I know this is a broad question, but would anyone know what the minimum oil pressure is for their engines at different RPMs? At what pressure would you turn your low oil pressure light on and does this vary at different RPMs? I assume it would.

[bigfella]

Usually 12 - 16 psi dude, in cars anyway. It's a simple presure switch. Don't know about bike motors but I'd assume the pressure would be pretty much the same.

[BryanH]

Wooly, Rule of thumb is 10psi per 1000 rpm for pressure fed plain bearings.
Orig equip oil press switches are set to 3-4psi, seriously too late!
I use Autometer 30 or 35psi switches & LED / no guage, so the driver can detect oil surge before damage occours. Datalog oil press if possible. Don't bother with a guage, the driver will never read it and many people have had leaking feed lines kill engines.
Bryan H.

[woollymoof]

Halfast,

We run a VDO pressure transducer and are able to log. I'm trying to work out what pressure to turn the low pressure light on at different RPMs. Is that 10 psi per 1000 the minimum or what the engine would run at on average?

Does that Autometer 30 or 35 psi switch turn on at say 2000 RPM when the engine is making about 20psi of oil pressure? And I assume it turns on when your making only 30 psi at 12000 RPM, is this too little pressure for those speeds?

Thanks

[BryanH]

Woolly 10psi/1000 is minimum for race engine. This figure has been used by many engine builders.This does not apply to roller bearing cranks.
Don't know if it is OK to platau oil press to 85-90psi to take load off oil pump drive, I've never tried to run a Auto engine to 12k.

Yes the light is usually on at hot idle, tells you the light/switch is working!
30 at 12k sounds scary. Maybe bike engines have some magic properties I am not aware of.
Bryan H.

[Charlie]

If you can log, just log the engine through the RPM range statically. If you deviate from that curve during dynamic runs then you have a baffling problem.

[woollymoof]

ok, thanks guys

[woollymoof]

Me again,

We have two types of baffling in our sump,

1. a horizontal one with a wide slot up the middle that is sandwiched between the sump and crankcase

2. two hinged flaps foward and to the left of the pickup

but starvation is still a concern especially since the sump is 30mm high.

I've read all the previous posts on the subject and read about baffles preventing oil from traveling up into the side covers etc etc. On the f4i I can't see much advantage in adding baffling around the side covers simply because there isn't many holes for the oil to travel up, maybe i'm wrong. I'm worried that adding more baffeling will be as much of a restriction for oil traveling back towards the pickup as traveling away.

I'd ask for photo's of peoples setups but wouldn't want people to give away their secrets.

Any advice would be muchly appreciated.

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by woollymoof:
On the f4i I can't see much advantage in adding baffling around the side covers simply because there isn't many holes for the oil to travel up, maybe i'm wrong. I'm worried that adding more baffeling will be as much of a restriction for oil traveling back towards the pickup as traveling away. <HR></BLOCKQUOTE>

Have you looked closely? There aren't many holes; just a couple giant ones. http://fsae.com/groupee_common/emoticons/icon_wink.gif I would take another look.

Oil drainback is not something I would be too concerned about. After about 10k RPM or so the relief valve opens and puts the oil back directly in the pan, also if you make your baffle correctly you can make arrangements for oil to drain back under braking or accel (or both).

[schumafer]

hey woolly

i dont know what the minimum oil pressure is at different RPM but i can tell you what the normal pressure is at: 3000, 6000 and 11000.

at 3000 25psi
at 6000 50psi
at 11000 or higher 75 or 81 psi (dont remember now)

we use a led connected to the stock pressure switch, it lights on when the pressuere drops.

like charlie said, there are big holes, the alternator and flywheel hole is your major problem.

another thing..the relief valve starts to open at about 5000RPM, at this moment begin the oil recirculation directly to the pan. and at 11k the relief valve is fully openned.

hope this information helps you..

Fernando Gómez
Universidad Simón BolÃ*var
Caracas, Venezuela