dual quad nitrous !!?!!

I run a locked distributor with 34 degrees of timing, as that's what my engine wants when it's running NA. I also have an MSD 8982 Start/Retard control and an MSD 8969 RPM Activated Window switch. In addition to those, I have a 3 position activation switch wired in.

The start/retard box uses "pills" to adjust the amount of retard that gets pulled when the retard is activated. You can get pills in one degree increments from 0-20 degrees, the pills I use the most are in the 0-10 degree range.

The window switch is used to set the rpm range in which the nitrous system can be activated. Nitrous generally delivers a constant flow fixed amount of horsepower, but remember horsepower is a function of torque x rpm/5252. That basically means that the lower the rpm, the more torque the nitrous will add. If you install a 100hp nitrous system, you will get a 100ftlb boost @ 5252rpm. At 7000rpm that added torque drops to 75ftlbs, but on the other end of the spectrum down at 1000rpm that 100hp shot will deliver an additional 525ftlbs!!! Since an additional 525ftlbs at 1000rpm may put cylinder pressures waay into the danger zone, it's generally accepted to limit nitrous use to 3000rpm and above. My window switch is currently set to 3000-8300, the 8300 high side shuts the nitrous off during the shift.

The 3-position switch's lower position is the "OFF" position that I use for casual driving or making NA passes. The "middle" position activates the retard only (no nitrous, but full time retard). The upper "ON" position arms the nitrous system and window switch (window switch then controls the retard box). That middle position is useful for calming down the annoying faceplate "bucking" when idling around town, but it's also useful for testing back/back timing settings without moving the distributor. For instance data shows my current engine likes 36 degrees NA in 1st gear, but 2nd/3rd gears NA prefer 34 degrees.

My learning curve included a glitch on one pass that caused timing to be pulled on the hit, but with the window switch working almost opposite of what was intended. Basically the launch was NA with 8 degrees of timing pulled, which caused a huge engine bog. But then when the bog reached 1700rpm, the nitrous then came ON! By the time the nitrous reached the cylinders, rpm was all the way down to 597. Theoretically the 175 shot at the time was delivering around 1540ftlbs at 597rpm. The car basically stood on it's bumper, but at the cost of total devastation as it took out two pistons and cylinder walls that put shrapnel in every other combustion chamber in the engine. Never made it to 2nd gear, ended up throwing away a set of 300cfm Brodix heads along with most of the rest of the engine.

Grant