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My oil pressure is dropping once I get past 5,000 rpms. Fresh engine. Checked the clearances myself when I assembled the engine. I'm thinking that the hi volume pump is sucking the pan dry.
It's a sealed power hi volume pump. I cleaned the pick up before installing and it was operating room clean before I installed it. Set the pick up 1/4" from the bottom of the oil pan. Three generous tack welds with a mig welder hold it in place. Heads are brand new so the return holes can't be plugged.
I can cruise all day and I get 50 psi @ 3000 rpm, but like I said, once I hit 5,000 it starts dropping rapidly! Thoughts?
I'm thinking of pulling the mill and installing a stock or Z-28 pump. Anyone have a part number?
All Speed-Pro p/n for sbc:
224-4146 -- OE replacement OP
224-4146A -- Hi Press Z-28 style OP
224-14227 -- OE replacement op SCREEN for corvette
224-6146E -- HD op SHAFT w/integral steel guide
put a reliable mechanical gauge on the motor and monitor your oil pressure. The oem gauges are not super accurate, especially after you kick of the pressure a little bit.
So, the 224-4146A is the one I need. I noticed it is about 1/2 the price of the dealer price of the GM Z-28 pump. Is it identical?
Mechanical Autometer gauges. Pretty sure it is accurate.
Dunno ... but since it's S-P it probably is. Most Hi Press pumps are also Hi Vol. Do you really need either? Unless your bearing clearances are on the loose side, the OE pump & HD shaft will probably do what you need. Or add a deep pan as others said. I run improved top end drainback, lifter valley pan/baffle, intentionally loose bearings, Hi-Vol Std Press pump, HD shaft and big oil pan.
A "possible" cause of low press at Hi rpm is oil aeration. Perhaps a windage tray/improved windage tray in your oil pan could help
If you're already going to change pumps, get yourself a rear pan baffle. This is a flat piece that goes between the pump and rear main cap and keeps oil from climbing up the rear of the pan under hard acceleration. They're only a few $$. I know moroso makes them as well as a few other companies too.
with 10w30 oil i noticed a big drop past 4500, std pump, high pressure.
20w50 made a big improvement.
i then added a rearbaffle and scraper.
found it is steady 65 if oil temp is under 230.
added oil/water heat exchanger.
Using a 3/16 oil line(stock 1/8 line reacts too slow)
I doubt you're sucking the pan dry at 5,000 RPM, unless you're flying around a sharp turn. If you WERE sucking it dry, that means that you'd be starving your engine of oil... and I don't think it would survive at 5,000 RPM, even for a second or two. It's either the gauge, as someone mentioned, or...
How fresh is the engine? You could have a lot of junk in your filter from the break in. Instead of buying a larger oil pan, maybe get a top quality, higher quantity oil filter.
I'm sure the pan isn't TECHNICALLY dry, but I do know that something is going on. Maybe aeration or cavitation.
Brand new Autometer mechanical gauge so I'm pretty sure it is reading right. Less than 5,000 miles on the engine. First couple of oil changes I cut the filters apart. Couple of TINY specks of RTV and cam lube in the first one, NOTHING in the others.
Yeah, you're probably right. Maybe an oil pan with baffels and all of the other cool features? :cool: I'm just saying that I've been told by more than one race engine builder that a high volume/pressure pump doesn't require a larger oil pan.
I agree with TSW. A few years back I installed a rebuild with a HV pump and a stock 5 qt pan. In about 2500 miles of city mid rpm driving, I spun a main bearing. Breakdown indicated oil starvation.
Most sources I've talked to since then recommend a GM OE design oil pump for street driving.
Hi Rocky1: I have a melling HV pump on my engine, It's had been past 5000 many times with no problems. I have the stock pan on my engine, I do have however a windage tray. Chuck D