Looking for a specific pressure sensor

[Bugzilla]

So as I am saving up for an Accusump system, I would like to at least add in a fail safe for when oil pressure drops. I know how I am going to do it I just cant find the right sensor. Hoping this will be something someone has already done and can point me in the right direction. Looking for a 2 post sensor that connects as it hits around 20 psi and disconnects at anything below 20 psi. It cant be a single post that grounds through the body of the sensor. I would like it to have 1/8" npt threads (not a deal breaker). All the ones that I can find for something like brake lights turn off at 50 psi or less. My hot oil pressure at idle is 40-45 psi so that wont work. Anyone know of a sensor that will work for my needs? Thanks!

[GoodysGotaCuda]

Couple of thoughts:

• What about this?
  
  • Personally, 20psi seems a bit high for an oil pressure cut.
    
    • If this switch cuts something important below 20psi, then I assume the accusump will forever hold at least 20psi so that you can start the engine without bypassing this switch?
    
    
  • http://www.jegs.com/i/JEGS-Performan...11200/10002/-1
    
    • Recommended for all electric fuel pump applications, this safety switch shuts off a fuel pump when oil pressure drops below 5 psi. It is designed for placement in the fuel pump's wiring circuit to eliminate current if the engine stalls or another major internal failure occurs.
    
    
    
    
    
  • 7psi for this one https://www.summitracing.com/parts/c...4aAgMaEALw_wcB
    
    
  • ...12psi for this one https://www.pegasusautoracing.com/pr...MaAuELEALw_wcB
    

[Bugzilla]

Couple of thoughts:

• What about this?
  
  • Personally, 20psi seems a bit high for an oil pressure cut.
    
    • If this switch cuts something important below 20psi, then I assume the accusump will forever hold at least 20psi so that you can start the engine without bypassing this switch?
    
    
  • http://www.jegs.com/i/JEGS-Performan...11200/10002/-1
    
    • Recommended for all electric fuel pump applications, this safety switch shuts off a fuel pump when oil pressure drops below 5 psi. It is designed for placement in the fuel pump's wiring circuit to eliminate current if the engine stalls or another major internal failure occurs.
    
    
    
    
    
  • 7psi for this one https://www.summitracing.com/parts/c...4aAgMaEALw_wcB
    
    
  • ...12psi for this one https://www.pegasusautoracing.com/pr...MaAuELEALw_wcB
    

The reason I think 20 psi is good, is because the oil psi "should" never drop that low on my engine. If it does drop, I think 20 psi is a safe number to keep it running at. The lowest it should get under normal circumstances is 40 psi. I dont have an Accusump yet so this would not tie into it. This is more of a temporary safety feature. I noticed on my last race that the psi would drop bad on one of the sharp right hand turns. Its hard to watch the gauges through a turn as you know. So instead of having to watch the gauges, I would be using this 20 psi sensor to cut spark if the oil psi drops that far to avoid damage. I am trying to make this engine last a bit longer then the last one...

[andrewb70]

Sounds like what you need is a 20psi Hobbs switch.

Andrew

[Twentyover]

Just be careful about wiring it into the ignition. If you cut ignition, you'll have an immediate weight shift to the front end, increasing it's grip and reducing the rear grip. May find yourself looking at oncoming traffic

[Bugzilla]

Sounds like what you need is a 20psi Hobbs switch.

Andrew

Thats exactly what I need but I cant find one. I see they make a 10 psi version and then skip to 50 psi.

Just be careful about wiring it into the ignition. If you cut ignition, you'll have an immediate weight shift to the front end, increasing it's grip and reducing the rear grip. May find yourself looking at oncoming traffic

I didnt even think about that. Thanks for bringing it up. I am sure it wont happen on the streets, just during autox. I have 2 ways of setting up the spark cut. First way will completely kill it. Second way would be like triggering a rev limiter. Not sure which one would be a smoother cut. Any ideas?

[andrewb70]

If you were running an aftermarket ECU this would be fairly simple to program with a soft ignition cut...

Andrew

[Bugzilla]

If you were running an aftermarket ECU this would be fairly simple to program with a soft ignition cut...

Andrew

I am assuming by soft ignition cut you are talking about a DBW throttle body and having the blade close instead of cutting fuel or spark? I am running an aftermarket ecu but it doesnt support a DBW TB. Its old and way outdated. However it does have an option "for no lift shift". I wonder what plumbing it to that would do?

Also, I found this.

http://www.atpturbo.com/mm5/merchant...03&Screen=PROD

[andrewb70]

I am assuming by soft ignition cut you are talking about a DBW throttle body and having the blade close instead of cutting fuel or spark? I am running an aftermarket ecu but it doesnt support a DBW TB. Its old and way outdated. However it does have an option "for no lift shift". I wonder what plumbing it to that would do?

Also, I found this.

http://www.atpturbo.com/mm5/merchant...03&Screen=PROD

By "soft cut" I mean like a 2-step. I don't know how other ECU's do it, but the Holley ECU drops one cylinder at a time to maintain a certain RPM. So it isn't a all out ignition cut...per se...The software can also bet set to cut fuel, ignition, and/or both...The Dominator can also do the DBW, which I know you don't have, but is super slick...

Andrew

[Bugzilla]

By "soft cut" I mean like a 2-step. I don't know how other ECU's do it, but the Holley ECU drops one cylinder at a time to maintain a certain RPM. So it isn't a all out ignition cut...per se...The software can also bet set to cut fuel, ignition, and/or both...The Dominator can also do the DBW, which I know you don't have, but is super slick...

Andrew

I have a 2 step option but not sure off the top of my head what it cuts or if I can choose what it cuts. And I am on a batch fire system to make it worse... I will have to check when I get home.

But at the same time, how would it react? Typically you would hit the 2 step button, then bring the rpms up. The way its going to work for me is the opposite. I would probably be somewhere between 5-8000 rpms and then have it kick in.

[GoodysGotaCuda]

A couple more thoughts...

• Just to me, it sounds like a lot of work to workaround the underlying problem. Can you baffle the pan to mitigate the oil pressure drop during cornering?
• Can you overfill the engine slightly to accomodate the slosh? In the 2G autocross cornering I have done in an FSAE car, we used a motorcycle engine, which should never see lateral loads, simply running it 1qt high solved any starvation issues.
• What about a simple warning light that will tell you to back out of it, or that there is an issue with that?
• I am not sure how running off a rev limiter would fix a low oil pressure problem? DBW is not necessary for a progressive timing cut, you may be able to use this switch as a knock input or flat-shift input and pull timing that way.

[Bugzilla]

A couple more thoughts...

• Just to me, it sounds like a lot of work to workaround the underlying problem. Can you baffle the pan to mitigate the oil pressure drop during cornering?
• Can you overfill the engine slightly to accomodate the slosh? In the 2G autocross cornering I have done in an FSAE car, we used a motorcycle engine, which should never see lateral loads, simply running it 1qt high solved any starvation issues.
• What about a simple warning light that will tell you to back out of it, or that there is an issue with that?
• I am not sure how running off a rev limiter would fix a low oil pressure problem? DBW is not necessary for a progressive timing cut, you may be able to use this switch as a knock input or flat-shift input and pull timing that way.

To answer your questions...

- I know there is a problem. This is my temporary fix to make sure I dont push it to the point to make the problem happen. The pan is baffled from the factory but does not have any trap doors. The sump is also at the very center of the pan.

- Yes I have tried up to 1.5 qt more. Changed it from dropping to 0 to slowly going to 20 (I havent pushed to see if it goes to 0 but im sure it will).

- A warning light would work but I really dont want to cut another hole in the dash. The gauge has a working warning light but its small and the steering wheel blocks it.

- The idea of having it cut the spark is to get your attention. If there was just a light, I could miss it coming on. If it instantly cuts spark, you will know what is happening without having to look at anything. Again, this is just to prevent me from hitting 0 oil psi for the time being. Im not going to be racing it for a few months but I do have a few mountain trips planned.

Edit - also wanted to say I dont think this is a pan issue. I think the head is a bad design from gm. The oil drains in the head, only on one side, are tiny. I only get this issue on right hand turns.

[Bugzilla]

Alright, looking at my tuning software, I think the no lift shift option will be best. When that pin is grounded, I can set the timing to retard whatever amount I want. Retarding the timing will give me an instant notice of a loss in power without being too hard of a hit.

Also, looks like my 2 step cuts both fuel and spark at different times. But might be too harsh of an engagement. I can mess around with both.