Oil Pressure Shut Down Switch

[Simon-S14]

Hey guys. i recently built an s14 that has a neo RB25 in it which sees track in the form of grip and drift...mostly drift.. anyway long story short last event i had a major oil down which i didnt know about til after i lost all oil pressure and the motor was still running... luckly not at high revs tho. I was able to shut it down and repair the leak and get back outthere with no engine damage but thats to say that it wont be so lucky next time.

I have an oil pressure guage but its a little hard to pay attention to it all the time. So was thinking about rigging up a failsafe device. I work as a Forklift technician for Crown and most of our gas trucks have an oil pressure switch on them which provides power to the gas lock or fuel lock once it senses oil pressure... in short no oil press no power to fuel supply = no engine running.

Now i'm not sure if i should rig it up to cut the engine (i'd prob set it up to cut power to injectors or power supply to ecu) or rig it up to a relay to activate a big bright light on my dash when theres no oil pressure.. only reason i'm a little hesitent about having it cut the engine is that if the switch fails mid race then its all over. sure i can by pass the switch to get it going again but not during a race. If it was a light i would be able to verify with the guage if there really is a loss of oil pressure and make a call to shut down there and then.

what are your thoughts guys?

this is the hobbs type pressure switch in question. trips at 7 psi and rated to 100psi. commonily available and same thread pitch as SR/RB oil pressure switches.

[Dobz]

warning light all the way.

[unique1]

i dunno, by the time u see and react to a warning light, then check gauge if the motor is running i would think its done damage if its lost oil pressure.

The only drama i see with cutting the motor is then you lose power steering and mid corner could be dangerous if its unexpected.

Best bet is use an accusump, they are around $450 and set up a light to come on if its activated and you still have 60 secs or more of safe oil pressure to either shut it off or protect the motor from any oil surge etc. I cant understand why these are not more popular in Australia?

[DCIEVE]

The warning light when the accusump is discharging is a mint idea.

[Duncan]

The new car we have just put together is running an oil pressure cut out.

we have a similar oil pressure switch, plus an override switch so we can start the car. The switch cuts the earth to the ignitor. You need to work out if the switch is normally open or normally closed, if NO you will need a relay as well.

We've only run it at sandown once but all worked fine, no issues with unexpected cutouts around the track.

Oil light would have to be a big one to be effective....I once saw a car running a trailer indicator on the dash....if they don't see that....

[Swiper the Fox]

The new car we have just put together is running an oil pressure cut out.

we have a similar oil pressure switch, plus an override switch so we can start the car. The switch cuts the earth to the ignitor. You need to work out if the switch is normally open or normally closed, if NO you will need a relay as well.

We've only run it at sandown once but all worked fine, no issues with unexpected cutouts around the track.

Oil light would have to be a big one to be effective....I once saw a car running a trailer indicator on the dash....if they don't see that....

i run mine with both ignition (same as above) and fuel cut. I have a big Autometer warning light telling me if its all gone south.

http://www.autometer.com/cat_accessoriesdetail.aspx?vid=158

[O2 Autosports]

my defi guage flashes end beeps if there's a problem.

[SECURITY]

plx gauges have a 0-5v output afaik. couldnt you hook something like this up to your ecu to make it retard timing, cut fuel or limit rpm like the IAT or ECT temp function does?

Edited April 10, 2010 by SECURITY

[aerofocker]

im looking at doing somthing like this myself mainly because i run an n1 oil pump and im a bit worried, probably best to kill the spark as killing the fuel will momentarily run it lean which aint a great idea, as previously stated you will need an override switch for start up and it would also be useful for a case in which the switch malfunctioned .who honestly has time to look at gauges when driving hard?i know i have enough going on just to keep the damn thing between the hedges

[Deano 1]

If your goin to do it mate, don't rig it to fuel cut, nothing worse than your motor leaning out, rig it to ingnition cut, do the same job just be safer.

My 2 cents

[Guilt-Toy]

With the vipec you can set conditions, condition 1 rpm > 1500rpm and oil pressure > 1.5v so if the volts get lower then that you can have a 100rpm rev limiter activated to save the engine.

plx gauges have a 0-5v output afaik. couldnt you hook something like this up to your ecu to make it retard timing, cut fuel or limit rpm like the IAT or ECT temp function does?

[Simon-S14]

If your goin to do it mate, don't rig it to fuel cut, nothing worse than your motor leaning out, rig it to ingnition cut, do the same job just be safer.

My 2 cents

what do you think an engine limiter is? most of the time limiters are a solid fuel cut.

there is no lean out detonation if all fuel is cut off.

[Duncan]

i agree re fuel cut btw....would be a hell of a fluke to get enough fuel to fire but not enough to stop pinging. would be a very small window considering it would need to go over say 12:1 but not more than say 15:1

[Dobz]

Keep it simple with one bright warning light that you can't miss. Eg. your mid corner and the light starts glaring at you, all you do is back off and pull the car up on the side then switch it off for a minute. You can switch it back on breifly to see if you get pressure back, if not there's bad enough damage you won't want to drive it at all.

All this deal with cutting fuel or timing is pointless. The only way an engine will lunch it's self in the seconds it takes to see a bright warning light, pull over and switch off is if there is something seriously wrong.

[Don Dada]

I would use one of those amazingly annoying buzzers because u will still find yourself wanting to watch the light and it WILL be a distraction.

I have one wired off my greddy temp gauge and it makes life so much easier.....one less gauge to watch

Don't like the idea of cutting the engine, that could be catastrophic

[aerofocker]

if you loose oil pressure even momentarily under heavy load-(like the way we all drive) you will do EXPENSIVE damage, those pistons go up and down approxo 80 times a second thats 20 power strokes to the bearing without oil in one second. you will walk

[Simon-S14]

which is why im leaning towards aen engine shut down... can set it to come on at 7psi rather then 0.. so soon as it starts dropping to critically low its cut power.

[Dobz]

If you get momentary oil pressure loss under heavy load that's an indication of improper oil system setup. Anyone serious about protecting their engine from oil starvation would get a larger sump, even though it will cost more in oil it's better than starving the engine with a standard sump at high load in mid corner.

The shut down option sounds like a dangerous one. Eg. You're comitted to a fast corner entry, you steer in hard to find at mid corner you car shuts down causing you to lose drive and power steering. If the compression lock from loss of power doesn't spin you out the lack of power steering will make it hard to recover.

[Swiper the Fox]

what do you think an engine limiter is? most of the time limiters are a solid fuel cut.

there is no lean out detonation if all fuel is cut off.

yes i had a little giggle at the posts above...wasn't going to comment until someone else did.

btw...i use a 20psi hobbs switch. So engine must have at least 20psi of oil pressure to run. This has already saved i engine lunching an N1 oil pump at 9500rpm. Bearings and crank were in perfect condition...could have just replaced the pump, cleaned everything and gone again.

Edited April 11, 2010 by Swiper the Fox

[aerofocker]

im not saying momentary oil pressure loss is normal or ok,oil pressure loss can happen any set up,things break,pipes burst pressure relief valves can stick especially after rebuild,murphys law! and ive never seen det from fuel cut either but id still prefer to kill the spark or maybe both,break the cas signal ect,hey i duno just ideas its gona be done anyway,i just hope my n1 holds till then!