diesel pump plus reduced diamter sprayer bar

#1

if i was to use the better flowing diesel pump to get more oil flow at idle to feed a pressure fed cam/rocker follower would a MM reduced diameter sprayer bar help stop over filling the head at higher rpm like MM claims happens ?

#2

Maybe.

If you need more flow, the diesel pump will give you that. I don’t know that playing with your sprayer bar is going to change anything tho.

Your peak pressure is set by your oil pressure relief valves, so your oil pressure isn’t going to go above 70(ish) psi no matter what you do at the pump. If no increase in OP, then no increase of flow out of the sprayer bar. So your oil pressure will spend more time up high, but it still won’t go above 70psi.

How much flow does pressure fed rocker follower’s need? I thought not too much.

Let me bounce this thought of you. I have this theory that oil that goes to the head takes longer than we imagine to get back down to the sump. So at high rpm a lot of oil goes to the head and the oil level in the sump drops quite a bit. So the MM reduced dia sprayer bar’s biggest role is not so much to reduce the amount of flow to the head because the oil pump doesn’t push enough oil, but instead the reduced dia sprayer bar minimizes this problem of oil taking it’s sweet-ass time to get back to the sump.

Support for my theory. My oil temp sensor is in my pan about 1.5cm from the bottom. On long stretches where the engine gets to wind out, my oil temp sensor briefly spikes about 50deg. I’ve always interpreted this as the oil level dropping down enough to uncover the sensor.

Why the above theory matters for this discussion. If the oil pressure rocker follower doesn’t need a lot of flow, then the ideal fix isn’t going to be a mod the primary affect of which is to prevent oil from pooling in the head.

If, on the other hand, the oil fed rockers need lots of oil flow, then it sounds like your tdi pump idea is a good one.

I played with a diesel pump a bit years ago when I was scheming re. oil issues. As you probably know, it’s purpose was to provide more oil at lower rpm. The problem for a high revving motor tho is that the diesel pump creates a potential for overstressing the pump’s driveshaft at high rpm, especially with oil that is not yet hot. Sure, the pump has it’s own OP relief valve in it to protect it from exactly that sort of stress, but Chuck Baader, an AL based engine builder, says the OP relief valve in the pump is a crappy on/off switch unless you pull it apart and machine it a bit.

#3

yeah i dont want higher pressures than 70 anyways. i want more idle pressure (or more correctly flow actually) to get more flow to pressure fed bearings in the rocker as there are now extra feed holes in the rocker lubricating the follower. how much extra do i need? i dont know but a little more cant hurt i would think. on other engines ones without oil feed holes need to be serviced at reasonably short intervals they like to idle them faster to get more flow but its a different mechanism and loading etc so…

the sprayer should work as restrictor so if its sized correctly the flow at max rpm from the smaller sprayer holes might offset the flow gains so i wouldnt be adding any new problems?

#4

At the risk of sounding like a smart-ass: Since I ain’t no BMW engineer I tend to leave their design alone. It would be different if we had had a nagging problem with this part since the start of this series in 2003. We haven’t.

Learned my lesion with adjustable fuel pressure regulators…factory dude knows best at 40psi.

RP

#5

I’m running a totally different follower system which requires good idle lubrication, it’s not a spec engine otherwise I would agree stock is more than sufficient with regards to this area