I have a TPIS stage 3 PROM. It works excellent from my experience with it so far.

The other day, I scanned it. While at WOT I am getting 4-6* of knock retard.

The initial timing is set at 6*BTDC per factory specs.

Is that knock retard hurting performance?

------------------
Mike L.

The Weapon of Choice:
1987 IROC Z 5.7 TPI A4 3.27 Borg-Warner four wheel disc
Mods: 2300-2500 Stall Converter, Shift Kit(GM parts), TPI Specialties Stage 3 PROM, Modified Airbox w/ K&N's, homemade cold air, Relocated MAT sensor, Gutted MAF, 160* thermostat, MSD 6A, Accel 8mm Wires, bypassed TB coolant, Flowmaster 3 chamber single 3" in/out muffler, 3" MAC mandrel intermediate, custom dual !cat Y-pipe. airfoil, ported plenum. !smog, few others I forgot...???

**BOYCOTT LAPEER DRAGWAY**

 

Yes, your EFFECTIVE Total Spark is reduced by 4-6* (from the Total Spark Advance displayed by your scan tool) thus you are not getting your full spark advance.

Encountering Knock Retard on a TPI car is VERY COMMON. The heads just don't like a lot of spark advance. The best way to obtain consistent performance is to "cap" the Knock Retard to a very low number, but now you run the risk of actually encountering AUDIBLE knock and damaging your engine.

This requires a lot of testing and tweaking to find out what your engine likes and not toast your motor. You may find my spark timing is either too much or not enough for your engine.

But, I have found that 26-28* of EFFECTIVE Total Spark Advance (after deducting the knock retard), yields the best performance WITHOUT causing audible knock to occur. Temperature also is a major factor as the hotter the ambient air temperature, the more prone TPI engines are to knock. I can run a couple more degrees of spark advance in cooler weather than I can in hot weather.

 

Thanks, Glenn. I was hoping you'd see this and respond.

TTYL.

I'm going to take a few degrees out of the initial timing and see what happens.

Mike