Im posting this here cause mostly FI guys have this problem, with headlift. i was in my friends car, a 2005 Mini Cooper w/ the john works package, and he had a oil pressure gauge. He's always had turbo/supercharged cars, and when I told him his oil pressure i shella low, at 35 at WOT at 6500RPM, he said thats fully normal on all his turbo cars. He also has 2 Supras and an RX7..daddys a doctor.

I noticed on our cars, it runs at 120-150 at WOT and when cold, it can peak 160. I was thinking and if the oil pressure was so high, at 150psi or over 21600 lbs/square foot, would this cause oil to leak into the coolant and cause hot coolant to rush in as well? I've also noticed now, even the big v8 guys purposely run low oil and water pressure to relieve stress on teh block, but bore out the passages. Many guys switch to synthetic who run FI, which can lower or raise ur oil pressure. Can a increase in oil pressure w/ other conditions possibly cause headlift? Just a thought...

 

150 psi ???? are u sure about that ? I've never seen more than 90 (maybe 100) @ WOT

 

Damn, I need to get my oil pressure gauge working.

 

there is no way his supra and rx7s are running that type of oil pressure, they both run way more then that. i have never seen what a mini runs, but i doubt its only at 35 psi by redline.

 

mine is only high when its cold and i get on it a bit...

 

the oil pump is directly driven off the crankshaft, so oil pressure is pretty linear with RPM. However, there is a pressure relief valve to keep it from going too high... and it is also highly effected the the type AND temperature of oil in the engine. Some engines that I build, I will modify the pressure relief to get a little more pressure.

Some engine builders will go by a general rule of 10 psi per 1000 RPM but the conditions are a little more dynamic then that, and application really does matter.

 

Some engine builders will go by a general rule of 10 psi per 1000 RPM but the conditions are a little more dynamic then that, and application really does matter.

+1

 

Yah i was watching his mini and it was 35-40 at redline, which is pretty low. The engine is a 1.5liter if it matters.

His supra tops around 60ish both of them. The rx7 i never rode in(scary..) but i know its around there too.

 

oil pressure all depends on ur bearing clearences and manufactures specificiations. Old V8s will run alot less pressure then our hi-tech cars. Newer nissian engines run around 120psi at redline. Honda's run 80-90psi at 4000rpm->redline.

When ur oil is cold, its thick and hence u will get more oil pressure. Pressure doesnt mean more flow though. Both are important. Low oil pressure will kill an engine much faster then high oil pressure though. 35psi is very very very dangerous to run on our engine, esp at +4000rpm.

PS. This has nothing to do with 'headlift'. THe heads dont actually lift, its the cylinder sleeves moving around which causes blown headgaskets. GO read up on open deck blocks.

PSS. the supra/mini engines are closed decks.

PSS. It seems as though this guy is taking the oil pressure off the wrong source. My guess is that he has the sender T'd into his oil feed line. This line will be pressure/flow capped at around 30psi to stop over oiling of the turbo.

 

Subscribing....

 

Ihave no idea on the setup for the oil lines on my friends car. However, the oil guage on the mini max at 70. It usually stays around 40 at most.