Rb20det oiling issues.

[Twmw2011]

I recently got my rb20det in my s30 and running decently, however when the engine gets up to operating temp the oil pressure starts dropping rapidly. So I have decided to replace the pump, however it seems that the rb20 pump is nearly impossible to find anymore. So the question is will an rb25 pump work as a replacement or is the bolt patter different? Or should I go with the n1 pump?

Cheers,

Rolly Steele.

[Croustibat]

First:
What oil are you using, what pressures are you reading, and what temperatures are you reaching ? We need numbers, not feelings.

Second:
RB20 engines are maybe the crappiest engines nissan ever made. No torque, no power, heavy ... why on earth would you use one ? There is a reason you cannot find parts for these: there is no market.

[Twmw2011]

I really didn't ask to be criticized for my choice of engine, the rb20 will reach my goal of 300whp just fine, as for heavy, it doesn't weight any more than the 25 or 26 so I don't see the issues there. I was using royal purple 20w-50 and the temps stayed below 150. The pressure at this temp was one 0 when I turned it off. Also I fixed the issue the n1 pump fits fine and oil pressure is good now.

[Croustibat]

Whatever. I am just telling you it is going to cost more to get an rb20 to 300whp than it would cost to build a 300whp sr20, rb25. Even maybe a KA-t. the rb20 is really not an engine of choice.

Anyway you should use a thinner oil since you don't live in the saudi desert. If the engine requires a 20w something to make 15psi per 1000rpm up to 4000-5000rpm, it usually means the oil pump is dead, which seems to be something you fixed.

Now, since oil pumps are regulated by pressure, more pressure by thicker oil = less flow. Lower oil flow means oil can have trouble returning to pan, gets degraded faster ( heated longer) and cools less. Hence you should run the thinnest oil that accomodates the manufacturer recommended min AND max pressure.

Your oil pump is new, if the engine is fresh it should be able to take a 5w40 oil without problem. Make is a 5w50 if you thrash it or oil temp usually goes higher than 210. Or a 10w40 / 10w50 if it is not that fresh and it starts burning oil. Thicker cold viscosity will only kill your bearings and rob power.