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Hi im going to be racing my lancer so i want some sort of fuel pump cut off switch just incase the car endes up on its roof. Ive been told to use a a switch with the oil pressure to cut off voltage to the fuel pump when the engine looses oil pressure, but im concerned that the engine may run for a few seconds too many while upside down and not cut the fuel pump quick enough.

Is there any other appceptable methods?

Tachymetric relay, it's designed for what you want and used in LPG setups. Either an auto electrician or LPG installer will have one.

HoonBoy wrote:Tachymetric relay, it's designed for what you want and used in LPG setups. Either an auto electrician or LPG installer will have one.

HoonBoy, correct me if I'm wrong, but I thought a "Tachometric relay" works off the coil signal, and is used in vehicles on LPG to kill the gas flow when the engine isn't running but the ignition is on.

astronturbo77 wrote:Is there any other acceptable methods?

The only other thing I can think of is the oil pressure switch, an expensive piston style oil accumulator, a non return valve, an oil filter re-locater kit and a bit of fancy plumbing.

Apart from that, all I can suggest is to practice keeping the roof facing skywards.

Cheers

Superscan811 wrote:HoonBoy, correct me if I'm wrong, but I thought a "Tachometric relay" works off the coil signal, and is used in vehicles on LPG to kill the gas flow when the engine isn't running but the ignition is on.

Exactly - which is what you want (ie. when the engine stops running, the fuel stops pumping .... regardless of whether the ignition is on or not).

Put a proper FIA-type kill switch in it as well (ie. one that cuts the ignition as well as disconnects the battery).

davetrees wrote:

Superscan811 wrote:HoonBoy, correct me if I'm wrong, but I thought a "Tachometric relay" works off the coil signal, and is used in vehicles on LPG to kill the gas flow when the engine isn't running but the ignition is on.

Exactly - which is what you want (ie. when the engine stops running, the fuel stops pumping .... regardless of whether the ignition is on or not).

I was under the impression that astronturbo77 was trying to protect his engine from running without oil as well as stop the fuel delivery.
An engine can run for quite a while without oil, so just using a Tachometric relay to trigger the fuel pump/ignition kill wouldn't be that useful.

While I have thought of a few electronic circuits capable of handling everything astronturbo77 needs, a relatively "low-tech" solution to the problem,
which also has a few other benefits (ie: no more oil surge), I feel would be a more robust/reliable option.

davetrees wrote:Put a proper FIA-type kill switch in it as well (ie. one that cuts the ignition as well as disconnects the battery).

I take it it's a manual switch. Good idea.

Cheers.

davetrees wrote:Put a proper FIA-type kill switch in it as well (ie. one that cuts the ignition as well as disconnects the battery).

If you fit a battery isolate switch, make sure you can reach it easily when fully strapped in by your harness. I've seen too many isolate switches mounted under the dash board which can't be reached when your strapped in tight.

panda

Does this style of inertia switch comply with your regs?

This one is from a Jaguar

youd really want all three wounldnt you? oil switch to cut ignition at loss of pressure... tackymetric relay to cut fuel pump when engines not firing... and inertia relay to cut everything when you fecked up...

cheers,
rob

a Mercury switch and relay is your answer it will only rip if upside down. Isolator switch is a definate must as pointed out make sure you have reach of this and it also can be turn off from the outside. Lastly keeping the car upright is the best solution...means more fun....

Cheers

oldn64 wrote:a Mercury switch and relay is your answer it will only rip if upside down.

You would need a bit of hysteresis with a mercury switch, ie: a time delay before it will kick in (I would say around 3-5 seconds), otherwise if you hit a big bump, it would kill the ignition immediately.
Not Good.

Cheers.

correct the way I do it is a small timer ciruit. 3 seconds is what I have mine set to, run with mosfets. you want something that happens automatically so that if you are unconscience you or someone else does not need to activate it. This setup works really well in my race car but I must admit I have never tested it out in a roll over... ;)