BB wowbagger

Since i got my engine back from the builder there has been a "issue" about the oilpressure.
I use a Speed Pro(F-Mogul?) standard oilpump and the pressure at cold idle is about 35 Psi and at hot 3000 Rpm 45 Psi and about 20 Psi idle.Could i use the blue spring instead of the "normal" one to achieve more pressure?
I created a thread about this earlier and i know that the number are OK but not really what i want.
I got hold of a new LS7 oilpan and Oilpump which i`m planning to use since i like to go around the twisties in the woods.The LS7 pan has nice baffles and trapdoors to keep the oil in place during some "inspired" driving.
Does anyone use the LS7 oilpump and Oilpan and what kind of oilpressures to you get with it? I know that its depending on the wear an tear on the engine,but it would be nice to get some input. :cheers:

Fevre

Something I found odd was the oil pump that came in my cheapy GM crate eng has a pink high pressure spring in it. I always thought the pressure seemed high for what I thought was a stock vol/pressure pump.

427Hotrod

The genuine LS-7 pan is a very good setup. It will work fine for you.

There are essentially three springs for these pumps. There is the stock one in the std pump. It will provide exactly what you have. Maybe 20-30 at idle and 50 or so when warmed up.

You can install the "high pressure" spring that is usually packaged with most replacement pumps and get more like 70-75 psi at high rpm. It will be a little better at low end and mid range, but not much different.

Then there is the one that comes in the High Volume pumps. That pump and spring will give around 45-50 at idle and up in the 80+ range at real high rpm.

The idle/mid range oil pressure is based primarily on clearances in motor and oil pump capacity. Of course oil viscocity can be juggled to move it around some. The high volume pump supplies more oil at low speeds because it's bigger and can "outrun" the leaks in the motor (clearances). It's great for race motors with looser clearances, solid roller stuff(lifters are slightly smaller diameter than stock and leak more oil by them), or old motors that are loose. You do have to have a large pan though because it can typically pump oil out of the pan faster than it can return and it might run dry at high rpm.

I used the stock pump with high pressure spring with great results in my 427 for years. It routinely spun to 7000-7500 rpm with no issues. Idle was around 30-35 and 75psi at high rpm.

Another common thing to do is to use the high volume pump with the "midrange-high pressure spring from the stock pump". It will give the 45 or so at idle and the midrange will quickly be in the 65-70 range. The advantage of this is that you won't end up with the 80+ stuff at mega rpm (if that bothers you) but have excellent pressure while cruising around. The HV pump also allows you to get by with lower viscocity oil and still hold pressure.

Most all normal replacement pumps are made by Melling and sold as Speed Pro, TRW etc. They are excellent pieces and seldom ever have trouble. Usually no need to buy a high $$ whiz bang one. The $25 special will work just fine. I do always pull the end cover and make sure the end clearance on gears to cover is correct. I like it to be .002-.0025. Every once in a while a little sandpaper work on the end cover on a flat table makes it perfect if needed. Usually not needed, but I'm picky!


I know oil pressure "eats" hp, but you aren't ever going to feel it or measure it on a timeslip on the average street car, even very fast ones. I've watched dyno tests where oil pressure was varied with an external oil pump and the HP did move around, but oil temp seemed to be much more of a factor than oil pressure. Once oil temp was up, lowering the pressure from 80-90psi to only 40psi or so only varied HP in the 5-8 hp range on a 9000 rpm race motor. At lower speeds it was not measurable.

I'll err to having pressure any day as to not having it! For reference, my 540 is using a HV pump, big spring plus a couple of shims behind it. Mine cruises with gauge pegged over in the 70-80 psi range all the time and idles at 45-50 when hot. Not sure what it hits at over 7000 rpm, but I know it keeps the 80psi gauge pegged. Not much time to be watching it you know!

JIM


[Modified by 427Hotrod, 10:11 PM 4/21/2004]

BB wowbagger

Thanks Jim for your answer. :cheers:
My engine doesnt see past 6000 rpm and i shift around 5800,no need to go higher in the RPM band,since theres no power there for me :lol:
Does anyone know what the oilcapacity is on the LS7 oilpan? :cheers: