1905Cc Mi16 Solid Lifter Conversion - Any Experiences?

[petert 641]

More action in Run 2. Again, keep an eye on the gauge between turns 8 and 9. Guess who's in the white 205?

 

[DanteICE 72]

So, what have we learned here then?

 

Can you recap what you've done and also, why does the pressure dip at all, if there is oil available shouldn't the pressure remain constant at the given engine RPM, if there was no oil avail I'd expect a drop to nothing. I'm no expert, so I'm probably wrong; clarity on this would be nice.

 

Geoff

Edited April 10, 2013 by DanteICE

[petert 641]

So, what have we learned here then?

 

That you'll only get constant oil pressure with a dry sump. If you can live through the pressure peaks and troughs, then wet sump is ok.

[DanteICE 72]

But why does the pressure drop exactly? what is causing it? Because as I said above, the pressure will drop to nothing when there is no oil for the pump to move surely? So where is the pressure being lost?

 

Geoff

[Henry 1.9GTi 38]

I imagine that the large volume of oil is moving up the block walls and being whipped a little by the crank even with a windage tray. No scavange pumps here so the ~ 1/2 drop in pressure is probably due to sucking up airated oil near the surface.

I run extended pickup, more oil, extended pump baffle, extended GTi6 sump baffle and a gti6 head. Still pressure drops on right handers to 30-40psi. And this was in the wet :/

 

Atleast its not dropping to ZERO like the old engine which had the same setup but an Mi16 head. Although that was dry! hmmm dry sump for the next engine.

[petert 641]

As a gear pump is not a positive displacement type of pump, it relies on a head of pressure above it to keep it primed. It can't suck. The head of pressure (the height of oil in the sump) is proportional to the outlet pressure.

[Henry 1.9GTi 38]

still could gear up some airated oil

 

I thought gear pumps were positive displacement pumps?

Edited April 16, 2013 by Henry 1.9GTi

[petert 641]

yeah, you're right, they are +ve displacement.

[DanteICE 72]

Still confused, so does it need oil level pressure above the pump or not?

 

Geoff

[Henry 1.9GTi 38]

In my limited knowlegde, no. They can create a partial vacuum and are subsequently self priming.

 

interesting doc here: http://www.michael-smith-engineers.co.uk/pdfs/Liquiflo/Liquiflo%20Pump%20Engineering%20Data.pdf

 

edit: All I mean by that is if the pump is exposed to air (surge / starvation or whatever) it will then re-prime and build pressure once returned into the oil pool. I donno what I'm talking about. Best to read the article

 

apologies for deviation from OP. I think the answer here is to go to town on custom baffling or dry sump.

 

One thing I did notice from the in car camera on my car is that the oil pressure drops a little under braking. Might be worth considering a lip on the top/front of the sump protruding towards the rear of the car with some trap doors. Mine always surges after hard braking then chucking it right, which is basically evey race track, very rare not to have a braking zone before a corner.

Edited April 16, 2013 by Henry 1.9GTi

[petert 641]

Yes, the best wet sump, if there is such a thing, would have four doors, arranged in a diamond pattern. Thus under any situation, two doors are working.

[DanteICE 72]

apologies for deviation from OP. I think the answer here is to go to town on custom baffling or dry sump.

 

I wouldn't think this is deviation, trying to get to grips with what is happening, it's the start of problem solving.

 

Not saying I can solve this problem, I just want to really get to grips with what the problem is.

[brumster 135 1 Cars]

I'm glad this supports what I've found from experience for a long time - that decent sump baffling and oil control can result in a healthy oil pressure in an XU9J4 without resorting to effort in the cylinder head, be it with extra drainage, solid followers or restrictors. I'm constantly touching wood whenever I talk about this, because I'd hate to jinx myself, but we'll find out soon enough - my 'spare' mi16 engine is going back in the car soon while I refresh my Longman lump, so I'll have an opportunity once more to rag it senseless and see if I can break it

 

Good work!

[petert 641]

I had the first run yesterday with a new ECU which enabled me to monitor & datalog oil pressure and oil temperature. The results are pretty much the same as Adrian's 1905cc engine above, with a minimum of approx. 38psi and max 59psi (excluding idling pressures in pit lane). I was surprised to see how high the oil temp went, 120+, over the sensor limit. You can see how the oil pressure average slowly decreases as the oil temp increases. Bigger oil cooler needed? It already has over 8 litres of oil.

 

 

 

[wicked 107 3 Cars]

Be aware that you (probably) measure the oil temperature in the sump. To proper evaluate your oil cooler, you should measure the oil temperature after the oil cooler, before it enters the engine.

 

The oil pump pumps the uncool-ed oil from the sump and probably will 'leak' more pressure as the oil get thinner once it's hot.

On my Mi16 I'll use 10W60 oil to reduce that.

[petert 641]

Good point about the measuring point, but you can see how the temp effects oil pressure. I had been using Castrol 10W60 and only recently changed to Mobil1 5W50. The rod bearings didn't look very happy after the Castrol, thus the change. I'll leave it for the rest of the season and see how they look.

[DanteICE 72]

Why did you switch to 5w50? Surely that's not as good as 10w60 when the engine is being raced? Or is it, just that you believe the Mobil1 stuff to be better suited to the engine?

 

If you look back through the posts I did ask about an oil cooler (a question which had already been answered) because I do remember reading somewhere about someone who rallied an Mi16 205 and didn't have any sump control, but did have a sizeable oil cooler. Although I was never sure how significant that information was because I'm sure rallying doesn't create the same sideways G-Forces that track racing does (no slight on Rallying; I believe it to be far harder than track racing.). But hot oil can easily be a killer; maybe 13 row isn't good enough?

 

Geoff

[wicked 107 3 Cars]

I've read to many opinions about Castrol 10W60, so I'll pick either Shell Helix Racing 10W60 or Redline 10w60. (