Dodge power wagon

[dearbug]

I am looking to buy a 1980 power wagon as a project truck. I am familiar with body work but I am not a mechanic. It is a 360 c.i. that is bored .030 over. Has a new Eldebrock 600 cfm carb on top of a Eldebrock RPM preformer intake. New distributor, ingnition, 272 crane cam, high volume oil pump, hypereutectic pistons. I am told that I must use 93 octane or higher or detonation will occur. What is this, and what will it do, major damage? Any other problems one could forsee with this build up? Thanks much for any insight.

[Josiah Rojas]

I own two Power Wagons and love them to death. With the type of buildup that has been done on this vehicle and engine, the compression ratio has been increased over a stock setup. Octane rating in fuels is only an extrapolation of how much anti-knock compund is added, and therefore it's AKI (anti-knock index). The octane number is based on a 100-point scale and expresses it's ability to resist combustion under compression.
Detonation, or spark-knock is erratic combustion. Just as a diesel engine uses the "diesel effect" to operate, a gas engine, if temperature (remember the compression of air and the combustion process causes heat) and pressure gets high enough (high-compression engine) the air/fuel mixture can auto-ignite erratically. Detonation is characterized by a knocking or pinging sound. All engines can experience detonation, or pinging as it is more commonly referred to, and it is not inherently damaging in the short term. If it is allowed to continue or becomes more severe it becomes extremely harmful to engines and can cause burning of valves if it is continued long enough. When I mean burning I mean literal burning and melting of the valve. In addition, the high dynamic loads placed on other engine components can bend connecting rods, crankshafts, melt pistons or spin rod bearings. The high pressures developed when multiple combustion fronts meet in the cylinder can blow head gaskets.
Most new computer controlled vehicles (not many Daimler-Chrysler vehicles actually) have anti-knock programming which will retard the timing until the knocking is stopped. In any event if you hear excessive or sustained pinging or knocking IMMEDIATELY get your foot out of the throttle and lower the load on the engine. Your engine will not have the vast array of sensors, if any, that these new vehicles have and will not automatically help you reduce the occurence or severity of spark-knock. That means it is up to you. Pay attention under heavy throttle conditions and use as high an octane of fuel that you can get.
I own a supercharged Chevy Tahoe and I always carry a couple bottles of the NOS-brand Octane Booster Racing Formula and it is good for a 6 octane number increase. It is the only brand that will get you actually octane number increases. Of note, 3 octane numbers is the most you can increase for street applications. That is why NOS lists some of their additives as off-road use only. A lot of other companies advertise larger numbers, some only increase octane by 7 POINTS. You only care about octane NUMBER increases and need to know that 10 POINTS equal one octane NUMBER. Carrying a few bottles is good insurance in case you are in the middle of nowhere and they only sell 87-octane fuel.


Josiah