oil pressure safety switch

[khall]

I have a Holley oil pressure safety switch (3 pin) installed on my stroker to protect my investment against catastrophic oil pump failure. I was surprised to find that my motor will run for 30 sec at 3000 rpm with the fuel pump shut off. So it appears that placing it in the pump circuit is not such a good idea. Wiring it to the ignition system makes more sense. However, I am using the Crane HI-6 ign and I assume that voltage to the coil is variable. Any suggestion on how to splice this sensor into the ign system?

[Richard Hudgins]

Keith,

I would not recommend putting the oil pressure switch into the ignition. Nor would I put it on the fuel pump.

I have found that a nice big bright red light on the dash right beside the tach works quite well.

The reasoning is this:

1. If you put it in the ignition circuit and you are in the middle of a corner (With a little speed, which I am sure you will do now and again) and you have oil pressure loss, the ignition cutoff will cause immediate trailing throttle oversteer. Quite unexpected by you. A sure way to have a crash. This could happen quite easily as oil sloshing during cornering will often give you a low reading right at the wrong time.

2. As you noticed, a cutoff on the fuel pump lets you run until the bearings are certainly toast.

A big bright red light will get your attention right away and will allow you de-clutch and cut off the motor once you have the vehicle well under control.

Also, I would make sure that the sensor is set to 15-20 lbs. This will be above idle pressure so that the light does not come in normal use.

But, it will give you a early warning of the problem and you can shut down prior to major bearing damage.

[pderouss]

Do you have a mechanical or electric fuel pump? If it is the latter I would recommend a cut out to the pump as as well as a big red light. As a result in the unlikely event of a crash the pump will shut off as soon as the engine stalls and not continue to flow petrol into the (hot) engine area.

[Roscoe]

For crash protection you can throw in an OEM inertia switch.
Roscoe

[mr0077]

Guys, just FWIW...it might be okay for a race-only car, but you may want to think real hard about having an automatic engine cutoff on a street-driven car...it might shut off the motor, save the motor and end up killing you if it happens in front of an 18-wheeler as you're crossing an intersection...might want the BIG RED LIGHT instead, and let the driver respond...he may chose to fry the motor and avoid an accident or incident...

[khall]

Hmmmmmm.
Those are good points, guys. I think i will tap into the pump circuit and add a big red light.