low oil presure after engine heats up
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From: elyria, oh, usa
low oil presure after engine heats up
i put a b18c1 head on a b16a1 block and got every thing running but when im racing at the track at idel after the engines hot the oil pressure will drop under 15 psi and after i race its running real lean
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From: strathcedar, nsw, australia
Re: low oil presure after engine heats up (joehondafreak)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by joehondafreak »</TD></TR><TR><TD CLASS="quote">i put a b18c1 head on a b16a1 block and got every thing running but when im racing at the track at idel after the engines hot the oil pressure will drop under 15 psi and after i race its running real lean </TD></TR></TABLE>
I doubt it's a real worry, unless pressure at higher rpm is also quite low. If you're worried then fitting an oil cooler (a proper one, not the stock Honda coolant / oil heat exchanger to which the filter attaches) will help stop the oil thinning out quite so much and keep the pressure up a bit. Or you could use a thicker oil. Both these 'solutions' will cause more oil drag from the thicker oil, and you will lose a tiny bit of power.
A lot of engines have quite low oil psi with hot oil at idle. My Alfa Romeo used to sit on about 10 psi at idle and never had any associated problems (would reach 80psi at higher rpm). Some older Ferraris even less idle psi than that. Engines that run high oil psi at idle most probably cause the relief valve to open at fairly low rpm, and 'waste' at least some power pumping oil at higher than really needed psi(?).
The most important thing is that you have volume of flow more than outright psi. The pressures in the bearings are way higher than the pressure the pump can produce because of the 'wedge' effect in the bearing, i.e. the real working pressure in the bearings is created within the bearings themselves, so long as the pump is supplying enough oil volume flow.
Having said this, if you know the stock psi is supposed to be higher than you're getting, then you might have worn bearings...?
I doubt it's a real worry, unless pressure at higher rpm is also quite low. If you're worried then fitting an oil cooler (a proper one, not the stock Honda coolant / oil heat exchanger to which the filter attaches) will help stop the oil thinning out quite so much and keep the pressure up a bit. Or you could use a thicker oil. Both these 'solutions' will cause more oil drag from the thicker oil, and you will lose a tiny bit of power.
A lot of engines have quite low oil psi with hot oil at idle. My Alfa Romeo used to sit on about 10 psi at idle and never had any associated problems (would reach 80psi at higher rpm). Some older Ferraris even less idle psi than that. Engines that run high oil psi at idle most probably cause the relief valve to open at fairly low rpm, and 'waste' at least some power pumping oil at higher than really needed psi(?).
The most important thing is that you have volume of flow more than outright psi. The pressures in the bearings are way higher than the pressure the pump can produce because of the 'wedge' effect in the bearing, i.e. the real working pressure in the bearings is created within the bearings themselves, so long as the pump is supplying enough oil volume flow.
Having said this, if you know the stock psi is supposed to be higher than you're getting, then you might have worn bearings...?
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