V8 Conversion

[BoxsterLS376]

Originally Posted by martsink

I've also been trying to get the tach working. Unfortunately for me, all the older LS based engines use a 24 tooth reluctor wheel to keep track of the crankshaft speed and position (LS3 uses 58x. Lucky you!). The Porsche engine uses a 58X reluctor, meaning I cannot just plug in the GM sensor into Porsche DME. The other option is to use the tach output signal directly from the ECU. Unless both engines have the same number of cylinders, this will not work without some modifications to the signal. I've got something worked out with Arduino, but I still have to test it in the car. If you are interested, you can see more on this in my blog.

It took pulling some teeth from Renegade but apparently someone who did this conversion ran into this problem as well and created the solution I had envisioned~

All your tachometer worries can be solved by spending a few more bucks... about $80 of them I believe...

Check out Ashlock Technologies~

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[Bayley]

Originally Posted by BoxsterLS376

It took pulling some teeth from Renegade but apparently someone who did this conversion ran into this problem as well and created the solution I had envisioned~

All your tachometer worries can be solved by spending a few more bucks... about $80 of them I believe...

Check out Ashlock Technologies~

Home

I'm pretty sure you can achieve the same results by re calibrating the GM PCM.



This is how I plan on doing it:

Originally Posted by http://www.hptuners.com/forum/showthread.php?15112-V8-tach-output-for-6-cylinder-tachometer

I did a search for this information and could not find it using keywords Tachomter and Tach.

I am looking into adjusting the tach output for my 98 VCM due to putting the motor into a 6 cylinder BMW. The stock setting for high & low resolution is 6. What is the proper adjustment to make the tach output the same as a 6 cylinder motor? I know the LSx output is seen as a 4 cylinder by tachometers. Nothing else on the car uses the tach output.

EDIT
Did some math & research & some more math, this looks to be correct:
The number of crankshaft medium resolution pulses (24x pulses) to hold the tach output high (should match {G1205} "Tach Pulses Low").
The number of output pulses P is calculated as P=24/(N*2) where N is the value of this calibration.

Sample values for this calibration:
For 12 pulses, use N= 1
For 6 pulses, use N= 2
For 4 pulses, use N= 3 (Note- 8 cylinder tach setting)
For 3 pulses, use N= 4 (Note- 6 cylinder tach setting)
For 2 pulses, use N= 6 (Note- LSx 8 cylinder & 4 cylinder tach setting)
For 1 pulse, use N=12

N=6 same as you see in HPT (for Gen 3 motors)

Pulse Calculator: V8 tach reads 4 pulses per revolution, so 24/8=3. 6 cylinder reads 3 pulses per revolution, so 24/6=4. 4 cylinder reads 2 pulses per revolution, so 24/12=2. These are the "N" numbers for above that are plugged into the HP Tuners Tach Output fields.