FlyingLow90 said:
when i started getting into cars when i was younger i was always told never use a platinum plug in sc or nitrous cars. it is puzzling me that these cars us platinum plugs. plus no where i go carries the right plug for me. where can i go to get some plugs and what besides bosch do i stay away from.
Ordinarily you
wouldn't use plats in a performance application. Various theories have been floated, such as the platinum changing the chemical reaction like in a cataltyic converter. Or, more likely, the harder platinum just doesn't lose as many particlesto help spread the heat in the igntion "kernel". Plus there are the issues of high-speed glazing that happens to any plug in acceleration contests. A SB Chevy will improve it's ET's by about a tenth or so if you change the plugs after about 10 passes. Ford V8's tend to go about 15-20 passes, supposedly due to better heat dissipation from the plug.
However, in the case of the SC it is such a PITA to change plugs that platinum is the only way to fly. That and the increased wear from the DIS hitting the plug twice each cycle (one power one exhaust).
FWIW, I have regualr plugs in my Cougar (and they're WAAAAAAY overdue for change by about 30K miles) and it operates normally driving around.
also being a sc car normally they would be low compression. if the SCs are low compression why do we have to run high octane.
As has been mentioned, the boost increases cylinder pressure which in turn increases the heat generated. Too much heat in the air/fuel mix will lead to the mix going boom before you want it to. This is called preignition. If the mix goes bang when you touch it off with the spark it called detonation. And yes they sound similar, yet different. Preignition is much more solid-sounding if you know what I mean. Plus the increased temp of the compressed air runs you closer to detonation with regular fuel.
Any forced-induction engine requires premium fuel for these reasons.
lastly i dont understand what i hear about intakes and exhaust. when putting free flow exhaust and intakes on why do we loose boost but gain power. sorry for the dumb questions but my freinds and i seem to be fighting over the reasons for each so i would just like to know for good.
Simple. These cars have VERY restrictive exhaust systems. The supercharged engine is just capable of creating more exhaust volume than the exhaust system can handle. So the supercharger just stacks more air on top of it. Put a better exhaust that can outstrip the 'charger better and the boost drops to about what it should've been in the first place.