jarednut4ever

iTrader: (14)

I bought a new gm crate engine about 1 year ago and I am getting ready to put heads and a bigger cam in but recently noticed that At high rpms my oil pressure seems to drop a bit. The engine runs great no knocks,ticks or anything, Oil has no metal at all. Changed oil and cut open filter and it was clean. Is this a normal thing for a stock pump to loose a little pressure at high rpms. At idle when engine is 200 degrees the oil pressure is steady at 35 psi at around 3500-4500 oil pressure is around 60-70. But then at 6100 when I shift gears oil pressure drops to 50 psi. then it goes back up. It is most noticeable when you just rev it up. past 4500 rpm it starts to fall to 45-50 psi. I thought maybe the pan was sucking dry but I added a 1/2 quart and nothing changed. I would hate to put 1500 dollars into the motor if it is going to have problems. let me know know if this is normal for a stock oil pump. Thanks guys, Jared

ZONES89RS

iTrader: (25)

I had the same gay *** problem, just pulled the motor out, a brand bnew engine. I assume a cam bearing. I swapped the pump, pickup, pressure line, oil, filter and gauge. Nothing helped, i have built several engines and never had the problem.

1 FMF

iTrader: (1)

http://en.wikipedia.org/wiki/Cavitation

maybe oil pump cavitation?

gold98Z28

iTrader: (7)

if it happens durring a shift i sounds like the pump is starving for oil momentarily, if you have a high volume pump with a stock pan they are known to suck the pan dry after a long WOT pull. big pumps need big oil suply. i would try a 6 or 7qt pan with a windage tray and trap door to keep the oil where it belongs so the pump dont starve for oil.

opps, i started typing after reading half way thru, if it does it from reving then i would lean to cavitation as 1 FMF said. try differant viscosity oils and see if it changes. if that doesnt do it, you might need a better quality pump for your higher rpm needs. but keeping the oil in the pan is important too.
(damnADD)

jarednut4ever

iTrader: (14)

And also when i bought this engine I have never looked at the pressure at wot. I always make sure it has good pressure and then I watch the tach so I know when to shift. The crate motor might of always done this. Do you guys think I should worry about it. Like I said there is no metal flakes or glitter in the oil. no ticks rattle and carries good oil pressure. Like 35 at a Hot idle. Let me know if you guys would through the good heads on it and try it. Thanks, Jared

John Overton

I would definately check the clearance between the oil pickup and the bottom of the pan. Sounds like cavatation as stated above.

MrOverkill

iTrader: (1)

CHUCK the oil filter bypass and intsall a block off, or tap and plug your factory unit. I will NEVER have oil run threw one of my engines unfiltered, just my advice and .47 cents.

Try this 1st and go from there, you will be suprised when you see 15-20 psi@idle because its not slipping by the filter.....


Cheap and easy way here....
http://www.jegs.com/i/JEGS/555/23604/10002/-1

1997bird

iTrader: (2)

If you do block the filter bypass you will need to run a Wix brand oil filter to keep from collapsing the inner filter media. Your other cheaper brand oil filters are not designed to be able to handle over 60 psi. The filter brands that I know are Wix filters are the following: K&N, Mobil 1, Napa Gold, and Carquest Racing.

MrOverkill

iTrader: (1)

Well I run a billet oil filter and have no issues, and have run off the shelf Fram filters in the past and never had a porblem. I used to cut all my filters open so I know they were fine, but now I use a killer reusable unit from Truefilter. I wouldnt trust an off to shelf filter to one of my race engines but this should not be a problem under normal driving conditions for his engine.