Building for nitrous

[SDMAN]

While you can run a 300 hit on a fairly mild bottom end, eventually its gonna let go in a big way. For a motor that will take the hit time after time;

Forged pistons are a must. Good rods (forged or billet) are a must. Avoid long rod setups for big NOS use. A well done cast crank will be fine, but a forging would be preferrable. I would go with a studded bottom end. Make sure the block decks are flat as well as the heads and use a good gasket with head studs.



At 300 hp you dont need to do anything special with bearings, clearances or ring type. You might want to add a little end clearance to the rings to allow for more expansion. Stainless valves would be a good idea, but not a requirement.

If youre current fuel system cant deliver enough fuel, a seperate system is youre only option. Start jetting with the fuel side a little rich. Nothing can break parts faster than an NOS lean out.

You must use an ignition retard at these NOS power levels. At 300 HP you want to pull around 6 degrees out of the total timing advanve.

For safety, its a good idea to use a WOT switch, a fuel pressure sensor (placed right at the fuel solenoid) and an RPM window switch that only allows the NOS to be activated between a fixed set of RPM points (over 3000 and shut off at 6500). Run the bottle vent tube OUTSIDE of the car.

Lastly there is the day to day living with NOS. NEVER leave the bottle open when you park the car. Re-read the last line. Get lazy here and you will regret it. Leave the bottle closed until you want to use it. Close the bottle when you are done. I wont use the automatic openers cause I dont trust them. Manually closing the bottle valve is the only way to know for sure its closed.

If the bottle is left open, a small undetectible leak in the engine NOS solenoid, over time, will fill the intake manifold. Some of the intake valves will be open. Those cylinders will fill with NOS. Some of those cylinders will be in overlap. Those cylinders will fill the exhaust system. Some cylinders will have open exhaust valves. They will fill with NOS when the exhaust system fills. You come out in the morning, go to start the car and BANG!!!! Youre intake manifold just went thru the hood and out the garage roof. And it can be much worse.

On my car I have a purge circuit. By flipping a switch I can disable the MSD box and coil, hold the throttle wide open and spin the motor for ~10 seconds. This blows any built up NOS out of the motor prior to ignition.