How much volume is delivered by a "High Volume" oil pump?

[tigretr]

I am building a 1.8L motor with many new mods that require extra oil (Turbo, lifter spray bar) and I am trying to decide if my pump can deliver enough volume to do the job. What I am looking for are some benchmark numbers (Gpm,Lpm,...) . The words "High Volume Pump" are so often thrown around in the V8 world, but what does it really mean? What kind of volume are we talking about? I have looked everywhere for oil pump performance numbers, but with no luck. Obviously every motor has different requirements, but I am curious to know where my 4 banger oil pump stands relative to a V8's.

Thanks

 

[EngJW]

Oil pumps are positive displacement pumps, so you can easily calculate their capacity in gpm by using equations that can be found in handbooks. Most automotive pumps are either spur gear or gerotor, and the equations are different for each. You could compare different pumps if you have their measurments. There could be small differences in efficiency but you could just assume a number.

Oil pumps are oversized so that they put out more flow than the engine requires under most conditions. The excess flow is bypassed by the relief valve, otherwise the pressure would be excessive. It is possible that your pump could work as is with the engine modifications. If it produces rated pressure with hot oil, it is probably ok. If the pressure does not come up to rated, or if it is really low at idle, then you would need a larger pump. Note that if the pressure does not come up to the rated value, shimming the relief valve spring is not going to do any good since the relief valve is not opening. The additional downstream flow paths would not be offering enough resistance to build up the pressure.

I don't know if this is making any sense. You are looking for some actual numbers so hopefully someone else will reply.

John Woodward

 

[Warpspeed]

It is difficult to know for sure, but as John says, they are a positive displacement pump, so flow varies pretty much in proportion to Rpm. The most critical time is when idling with hot possibly quite thin oil. The lower the idle speed the more the oil pressure can fall off.

Oil squirters usually have a ball and spring check valve located inside each squirter. A typical release pressure might be around 30psi, so if idling oil pressure drops below that, the squirters each shut themselves off.

Turbos can vary quite a lot, but the old sleeve bearing Garretts have two approximately 1mm metering holes in the thrust bearing which allows typically around half a gallon per minute of oil flow at typical full (hot) oil pressure. These old turbos use the oil to cool the turbo, so that amount of flow is required.

Modern water cooled ball bearing turbos typically have a single restrictor of around 1mm. I have never seen a specification for oil flow, but a wild guess might be around one litre per minute.

The standard oil pump in the stock engine should give you a rough idea of what you need, and then increase the capacity to feed the extra goodies you plan to add.

It really comes down to your planned idle speed, and minimum oil pressure at that speed. If you are building a racing engine with a planned 1200 Rpm idle, the stock pump might work fine. If it is a road car with twin turbos and 600Rpm idle, a larger volume pump might be a very good idea.

 

[SMOKEY44211]

All oil pumps have a gallons per minute or a liters per minute rating at a specific rpm. "High volume" is a relative term comparing one pump against another. One factor I think most people overlook is the effects air bubbles being worked into the oil supply as the engine is running and the loss of pressure at low engine speeds. In most cases there are modifications that can be made to return the oil to the sump minimizing the amount of air that gets churned into the oil supply. There is usually a power and fuel economy bonus that goes along with this. An easy test is to bring the engine up to operating temperature and drain the oil. Pour in fresh pre heated oil (put the containers in hot water for an hour or more) and guage the pressure. #'s will be almost as high as it was when it was started up cold. (don't take my word for it do it). Another interesting test is with the oil supply at the recomended quantity set the throttle for 3,000 rpms. and shut it off. Drain out a quart or liter of oil and restart the engine. A fairly acurate tachometer is needed for this. Depending on the engine I have always wittnessed a gain in the range of 50-200 rpms. I hope this may give you a possible better alternative to swapping out the pump for a larger one.----------Phil

 

[evelrod]

Phil, I find it comforting to see a universal trend (finally) toward deeper/larger wetsumps with proper oil pickup/windage tray/scraper designs coming from most OEM's. No more ridiculous little 4qt sumps on 6 liter engines. With ~7qt. sumps, scrapers etc., windage has been much reduced making higher hp figures and lower oil temps possible for the newer, high revving engines in the current crop of cars.
Better fuel economy, more power, lower oil temps---seems like what the hot rodders were doing 40 years ago.

Rod

 

[Tranger]

For what it's worth, a small block chevy pump is rated at 7 gallons per min. I don't remember the RPM, but it's probably 3000 or there abouts. A big block pump is rated at 12 GPM.