Smug git's oil pressure

[Peter Carmichael]

I have practised what I preach, with happy results.

 

Over the last few weeks I have been watching my oil pressure decline. Just when everything has appeared to be back in working order this was making me very worried that another big bill was about to hove into view. I was especially concerned because at the Llandow sprint (first track driving with new gearbox and new diff ratios) I managed to get thoroughly confused between the gears and buzzed the engine to 10500 more than once. Where I once had a minimum of 60psi, I was seeing 43psi at >4000rpm as oil temperature rose 😳.

 

So the lesson I didn't forget was: "Check the senders on the worry gauges". The sender behaviour was so plausible that I was seriously worried... until that one time when flicking on the electrics at standstill the stationary engine registered 42psi; I determined that something fishy was going on.

 

Last night I completed my conversion from Sprint spec to Trackday spec by fitting the heavyweight oil system, complete with Apollo tank. While I was about it, I swapped in a spare oil pressure sender, restoring oil pressure readouts to their former glory. That has given me a lot less to worry about.

 

 

 

*thumbup*253 bhp, up and running

[CHRIS CLARK]

Glad to hear it Peter!

 

I have got a 10 bar pressure gauge and have just fitted a 5bar sender. Why? Well it gives me a double scale deflection that I can (just about!) halve in my head, but importantly it gives a clearer definition of the pressure dropping off. The drop between its 7 bar at 4,000 and its idle of 2.5 bar is certainly easier to see and so hopefully would be the eye catching loss of pressure (as the needle deflection is much more obvious).

[AMMO]

Let me start by saying that I know almost nothing about dry sumps. I've been told that race cars run around 2 bar / 30 psi as they produce more power at these oil pressure levels. So I automatically assume as long as the pressure doesn't drop below 2 bar everything is OK. I know from racing bikes at Daytona that the riders were told not to come in unless the oil pressure dropped below 2 bar.

 

I suppose where you take your oil pressure reading is also important. On the engines we were running the oil pressure was measured at the camshaft feed. By the time it had got there it had been all around the houses and one could assume that the bottom end was OK.

 

Is running lower pressure on something like a K-series a no no?

 

AMMO

[Jimbo]

Different engines will run at different oil pressures. No doubt Peter can tells us what a K should be. However if the oil pressure on an engine is dropping for given conditions (ie similar oil, oil temp etc) then there is a strong implication that something is starting to wear/break inside the engine.

J

 

[Nick M]

I was recommended to run my 1.6 16v VX engine (dry sumped) at around 75-80 psi. It's fully sealed (no breathers apart from the one from the tank to the catch tank) if that makes a difference to the pressures being run. Drops to about 35psi when the oil is warm and it's idling.

[julians]

When my engine was rebuilt, it initially showed a hot oil pressure (at 3krpm+) of around 5bar, over the next 1000 miles or so this started dropping but has stabilised at around 4bar now (3000 miles or so later). I had put this down to the new pressure sender bedding in, but maybe it was actually the engine bedding in, anyone know whats most likely?

 

[stevefoster]

Dry sump and Apollo eh? Some of that K series weight advantage gone then, but not much!

 

Steve

My racing pics here

Hants (North) and Berkshire area club site

here

 

[edmandsd]

I thought carefully before I changed my BD dry sump system to the BDT set up. Although I now have circa 5 times the scavenge capacity of the original x/flow set up, which I've been told gains around 4/5 bhp at high rpm as a result of significantly reduced windage, the draw back is that it's added a few kilos.

 

Interestingly percentage increase in power to weight is a quarter of that obtained via similar mod to say a 1,000kg vehicle using the same engine.