standard oil pressure?

[Matt Cole]

I can't remember so can anyone confirm what the max oil pressure should be at max rpm? Also when using a 275 cam what would a target oil pressure be at say 7500 rpm?

[DaveL485]

I can't remember so can anyone confirm what the max oil pressure should be at max rpm? Also when using a 275 cam what would a target oil pressure be at say 7500 rpm?

IIRC its something like 3 bar at 3000rpm, it shouldn't go over that cos of the relief spring.

[Alex]

Yeah about 40-45 psi at 4k once up to temp. :)

[Sparkie]

problem being is that alot of google searches throw up the old 10psi per 1000 rpm quote. Which would mean that alot of high revving gtt c1j engines do not get adequate oil pressure up the rev range.

[Brigsy]

I make 50 lbs of oil pressure when hot at high rpm. You want a minimum of 45 lbs at 3k rpm to keep the turbo happy

[Matt Cole]

Briggsy, have you shimmed your pump? Mark has 40 psi constant when driving. Is this a worry?

Sparkie , what did you do when revving to 8500rpm?

[DaveL485]

Sparkie , what did you do when revving to 8500rpm?

The relief spring will relieve anything over the spring rating, so when oil pressure opens the relief fully at ~3 bar (or more if it's shimmed) you wont get any more oil pressure unless you spin the pump (engine) fast enough to totally overcome the relief capabilities of the bypass.

And if you're revving that fast, i'd be more worried about the bits of exploding C1J headed for my fleshy bits :laugh::laugh:

Quick google for a representative graph (Not R5, just generic) shows the pressure to RPM ratio rising until the max, where it levels out. Shimming the relief spring increases the "push back" on the relief valve, thus needing more oil pressure to open it and meaning that the increase would continue until further up before it levels.

https://caterpillar.lithium.com/t5/image/serverpage/image-id/397i7B06B8367AA4D060/image-size/original?v=mpbl-1&px=-1

[Brigsy]

Briggsy, have you shimmed your pump? Mark has 40 psi constant when driving. Is this a worry?

Sparkie , what did you do when revving to 8500rpm?

Yes the pump is shimmed, cant remember by how much. Change the oil for 10/60

[DaveL485]

Yes the pump is shimmed, cant remember by how much.

Be careful though cos if you shim it you only need a washers width or so. One of my buddies but a small nut in there as a shim and he had about 6 bar at idle LOL

[Brigsy]

I recall using one sprung washer. New pump internals make a worthwhile difference to hot oil pressure.

[Matt Cole]

Cheers chaps. So are we saying that if using a piper 285 and revving beyond 6500rpm, then he would require more than 40 psi? I'm talking C1J here and not in general.:agree:

[DaveL485]

I recall using one sprung washer.

Snap! *Fist bump* :D