Oil pump drive losses
 

I don't know if this topic has already been hashed over, so thought that I might bring it up for those who are looking for lower parasitic losses from their engine. Over the last few years major vehicle manufacturing engineers have been developing more efficient engine oil pumps, it seems that most engines have way over engineered oiling systems which results in unnecessary power wastage. There is at least one easy gain to be made by fitting a bypass oil filter to your car's oiling system. The small reduction in engine oil pressure experienced when using a bypass filter means less power is required to drive the oil pump, and cleaner engine oil along with possible extended oil/filter changes is a bonus! Of course there is always the risk of engine damage if the oil pressure gets too low, like when you're at full throttle pulling 6000 revs,(or full throttle at 1000 revs), but if you are driving for mileage then the risk factor goes down somewhat. I have ran a "Jackmaster" bypass filter on a previous vehicle, and kept the bypass filter when I changed vehicles a couple of years ago, even though I haven't got around to mounting it on my present suv yet. I might run 2 bypass filters in parallel, but first I want to set up a 12 volt solenoid cutout on the pressure side of the bypass filter so that the bypass is only active at light throttle settings where lower oil pressure won't cause any engine problems.

I doubt a bypass filter will pay for itself in savings. As is, the variable displacement pumps on newer cars are only saving less than 1% of total fuel consumption. Plus, the oiling system is a bit harder to work with when it comes to these sorts of upgrades.

Probably better to save energy at the water pump instead.

Good points Serialkiller, but how many of us drive these newer cars?.... For those of us who drive older vehicles there are definitely savings to be had. While the later model 4 banger with variable oilpump displacement running 5/30 (read thin) weight oil might only save 1%, an older car that runs a rootes style oil pump (which is rated at around 50% efficiency ) and uses 20w50 engine oil along with high operating oil pressures leaves more gains for the taking. From what I have read on this forum for many here the best mileage is the goal, not necessarily saving money, otherwise why would anyone buy a new "economical" car and suffer the thousands of dollars (pounds?) in depreciation as they drive out of the showroom floor?
I'm not having a go at you Serialkiller (with a username like that I'm not sure that I would want to upset you :) ), just pointing out that for many the challenge is to get the best mileage, while for others the goal is to save as much cash as possible. The often overlooked gain when running a bypass oil filter is longer engine life, which can only help to stretch the possible life of the vehicle. The bypass filters have been around for decades, and are usually sized to take a tightly wound toilet roll as the filter medium, so replacement filters are cheap. For even more economy the used/replaced bypass filter which is now full of carbon/oil at the end of its service life can be used as excellent firewood if one uses a combustion heater for warmth in the winter.(just don't breathe in the fumes produced by the combustion). I like your suggestion of slowing down the water pump, which I have done in the past in a quest for more power from less fuel, obviously the readers here will make their own decisions regarding potential fuel/money savings from this mod, I only offer the idea as another avenue to pursue for those who are determined to try anything that may help them along the road to better economy.

Years ago (maybe 25) Ford dropped the spring pressure on their relief valves, so max oil pressure was reduced by almost 50%. That alone netted them an estimated .5 MPG on the EPA cycle. They also found that modern oils work just as well or better using the philosophy of higher flow versus viscosity as had been done decades ago. The variable displacement pumps are another step in reducing oil pump drive losses.

I would just run the lowest viscosity oil recommended for your engine, but beware of manufacturer specific limitations. I know Nissan still recommends 5w-30 weight due to cam lobe wear issues, where they have finer surface finishes that need that viscosity.

regards
mech

This is an interesting idea and worth at least poking about I think. I don't think we've delved much into reducing oil pumping losses and I am interested in that subject. Obviously OEMs feel its a worthy area to look at and we're usually doing more than they are.

I had to look up what a bypass oil filtering system was since I'm not super familiar with them. Basically, they take a small amount of the oil being pumped through the filter, and run it through a very fine filter, and return it to the sump.

Obviously this is good for the oil and the engine life by keeping the oil cleaner, but I'm wondering where the fuel efficiency comes from? Are you saying that by running this bypass filter, you're gaining fuel efficiency by decreasing the pressure drop across the filtering system?

Want to reduce oil pumping losses? Here is how I would do it.

1 like mechanic said, reduce the relief pressure on the pump.

2 intentionally put an undersized oil pump on the engine and an additional electric oil pump. The electric would run when the engine is cold and below a certain RPM so you don't get near 0 oil pressure at and near idle.
I almost did this with my suburban when I rebuilt the engine, put the undersized factory non-turbo oil pump back on the motor and back it up with and electric but I couldn't find an electric oil pump and filter I liked.

How about just put the biggest oil filter that will fit on the oil filter head?

I have to admit that I haven't followed the oil pressure specs of many different types of engines over the past few decades, but I have noticed a few trends in some vehicles. In the high performance small block chev builds from the 70s/80s virtually everyone would go for a high volume oil pump (Mellings high volume pump was extremely popular), the theory being that it would help with long engine life when forcing the engine to tolerate loads that the om never intended, but this thinking changed somewhere along the way, and now the pro's (David Vizard for one) use the standard volume pump for the purpose of saving a few horsepower. The small block chev has a well designed oiling system, so more volume apparently isn't needed, as the original pump is already bypassing oil at reasonably low revs. (2500ish from memory).
The most often quoted hot oil pressure in small block chev performance builds is usually around 60-70 psi. Ford's Cleveland engine doesn't have a particularly good system, and there was talk of owners using 160 psi of oil pressure (along with oil gallery restrictors to keep more pressure in the crank with less going up to the top end of the engine) in high performance apps. to help the bearings survive.

Obviously the intended use of the engine has a bearing (no pun intended) on "safe" oil pressure in the older engines, so running a lower pressure in an engine can theoretically work if engine loads are kept on the low side.

The bypass filter effectively drops oil pressure, so the oil pump doesn't have to work as hard. The various bypass filters will no doubt have varying flow rates, they usually have a restrictor in the outlet side of the canister, mine has an outlet hole of approx. 1mm in diameter. The oil pressure in my previous engine dropped maybe 5 psi after fitting the bypass filter, but it is hard to tell exactly because of oil pressure varying with oil temps.

If the pump pressure release valve is accessible this can work, but for those that are not it could turn out to be a lot of work

Personally, I don't trust electric pumps enough to do this, and would probably find myself watching the oil pressure gauge constantly.



This should help with better filtering, but don't forget that most oil filters have a bypass valve built in, so I'm not sure what net effect this would have on overall system pressure.
Here is a link to an engineering forum, where required engine oil pressure is discussed, the last post is interesting-
Eng-Tips: Engine & fuel engineering - Determining necessary oil flow volume for main and rod bearings

If the oil filter has a by-pass valve its because the engine needs a bypass and does not have a permanent one installed.
All engines have a couple of oil bypasses built in some where. GMs have the bypass in the block and oil pump its self most of the time. Others use the oil filter to contain the filter bypass.

My 6.5L diesel has an in the block bypass for the filter and a bypass built into the oil pump. I installed a couple of washers to shim and increase in the filter bypass pressure, because I would rather have more filtered oil than unfiltered oil going to the engine.
The oil pump its self has a bypass set for up to 70 psi which it will never come anywhere near that pressure when warm. The oil filters I use (larger than OE spec) do not have a bypass valve.

For example my bug had an incorrect filter installed. When I got the correct one I noticed one key difference, the oil filter had a relief valve. Yeah that's not good for during winter cold starts.

No matter what you do include a filter by-pass relief some where, even if you set it to a higher pressure. Mainly for cold starts.

Messing with the engine oil pump is not an easy task.

The filter bypasses I have seen will open any where between 5psid and 50psid across the filter media. The idea being dirty oil is better than way too little or no oil.
Piston engines usually run pretty low psid , turbine engines run higher psid.