High Rev's and No Oil

[gareth]

After fitting the Omex and getting more power I've been having a few problems. After finishing the last two rallys there is no oil left in the sump. It's my own fault really, because to start with I didn't wire in the oil light. Used 2 1/2 liter on a 130 mile rally.

Thinking that the engine is f@@ked I've spooke to john hardman about building a engine. He told me that the reason for the oil use is to much oil pressure on high revs. When he is building engines he must do something to the oil pump.

Has anyone had the same issue, is it a quick fix (how is it done)
Or could I just use a thiner oil.

 

[frank]

how can you have too much oil pressure when there is a pressure relief valve built into the pump ?

 

[Low Rider]

I've heard that from John too but never experienced that problem sub 8krpm. Up until recently John's specialised in Super1000 CG10 motors pulling 10krpm or so, so he may have identified an issue there.

What rpms were you pulling and what oil were you running?

If you approach John for an engine good luck getting a price out of him

 

[frank]

excess oil pressure wont affect oil consumption tho surely ? excess crankcase pressure maybe

 

[gareth]

The rev limiter is set at 8k. I'm running 10/40semi oil.

I've had an estimated cost plus the parts off £800. That is for a full rebuild port and skim head, dail in the cams fit new rings.

He also said that he would use the group A cams I've bought off Humphrey's but there not the best one's. And that I shouldn't run flat top pistons because off the fuel that is available at night event.

Has anyone seen the 200bhp micra that he has built.

 

[pollyp]

I'd try to investigate why exactly it's losing oil or losing oil control before forking afew hundred more £ at a rebuild.

from past experience, the stock oil pan ain't exactly gr8 at oil control during extremely long or frequently harsh cornering.
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-59#post-525088

during right turns the pool of oil simply pours to one side away from the pickup, causing oil starvation, aeration, cavitation.
when the pool hits the fast churning crank on the left side, it foams up further.
the higher engine/pump rpm ain't helping cos the oil in the pan has even less time to recover from foaming.

many things to research into such as:
physical oil control mechanisms - baffles, trap doors, windage trays
gear pump limitations
properties of the oil to help reduce foaming, etc

interesting read bout aeration
https://www.highpowermedia.com/blog/3733/oil-aeration

and heres a link to the oil pickup trap door and windage tray I made to help retain oil during trackdays
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-66#post-536819

 

[Skinner_87]

I hold mine flat out in 4th at just over 8k rather than going to 5th on hills.

It loses a little oil (maybe 1/5) of the dipstick line but I always thought this was due to the high crank case pressure forcing oil past the rings at high revs.

I've a cylinder head from John (through Matt) and I carnt fault it

 

[Low Rider]

The rev limiter is set at 8k. I'm running 10/40semi oil.

I've had an estimated cost plus the parts off £800. That is for a full rebuild port and skim head, dail in the cams fit new rings.

He also said that he would use the group A cams I've bought off Humphrey's but there not the best one's. And that I shouldn't run flat top pistons because off the fuel that is available at night event.

Has anyone seen the 200bhp micra that he has built.

Hmmm Interesting, no different to our last setup and we didn't lose any oil even during sustained events.

Last time I spoke to John he refused to discuss budget with me, perhaps he's had to change his approach. It's why I reluctantly had to turn him down despite the recommendation, as I couldn't sanction a blank cheque build.

200bhp Micra? No. Any details?

 

[Low Rider]

I've a cylinder head from John (through Matt) and I carnt fault it

Any photos Paul? Would like to see a JH head.

 

[Skinner_87]

Any photos Paul? Would like to see a JH head.

Im sure i have some somewhere Dave, if not the heads coming off over the next month so il be sure to get some