6 replies to this topic

[jeffblanco]

Hi Guy's,

I'm looking at re building my instrument cluster on my LX hatch and I have been asked

 

"the number of pulses per revolution of the crank"

 

How do I find an answer?

I have an LS 3 crate motor I bought from the states.

I don't know if this matters but my motor has a 58 tooth reluctor wheel.

 

Regards Mando.

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[Bigfella237]

DOH! I just replied in the other thread...

 

Yep, 58 pulses per revolution. But it will depend on which ECU you're using because different computers have different tacho outputs. Some are even programmable to send however many pulses your tacho needs and some have a CANbus that an electronic tacho can simply read the RPM value from.

[jeffblanco]

Thanks Andrew,

it seems obvious now.

I'm using a Holley ECU my tuner told me to get.

I hope I got the right one.

 

Regards Mando.

[Bigfella237]

Did you go with the HP or the Dominator ECU?

 

Either way there is a blue/white wire on pin A28 on the P1A / J1A connector that can be configured in the global file to output a 12V square wave signal that can be used to drive a typical tachometer (regardless of however many crank trigger pulses you have).

 

For more detail see the Holley EFI forum here: https://forums.holle...47583#post47583

[jeffblanco]

Thanks Andrew,

Iv'e bought the Holley EFI ECU + harness kit.

Iv'e tried to load up a picture but can't.

 

Jegs 510-550-603

 

Regards Mando.

[Bigfella237]

Ah yep, the HP kit (see: https://www.holley.c...s/parts/550-603 )

 

Yes, that looks like the correct kit for your engine: "GM LS2/3/7 (58x crank sensor) with USCAR (EV6 Style) connectors on injector harness, Includes Bosch Oxygen Sensor"

 

AKA the Dominator's little sister!

 

Bloody hell, prices have gone up since I last looked, you used to be able to buy a Dominator for that sort of money not so long ago.

 

The Holley units are great, they are probably the best around at learning/self-tuning but can still benefit from the hand of a good tuner, there are a hundred little tweaks that the self-tuning doesn't quite get spot-on, but if your tuner recommended the Holley then I'm sure he/she will be all over it.

[jeffblanco]

Thanks Andrew,

it's good to know I'm headed down the right path.

I get a lot of advise, but because I don't know much about how mechanical things work,

it's easy to end up with the wrong gear.

 

Regards Mando.