Guest Anonymous Posted April 17, 2002 Share Posted April 17, 2002 I've heard that if there's not enough back presure that it can damage your valves is this true? Quote Link to comment Share on other sites More sharing options...
Owen Posted April 17, 2002 Share Posted April 17, 2002 Must be, because when I first was investigating mufflers and how to get the car to a muffler shop, someone told me not to drive the car there with no exhaust because I might burn the valves. Guess it's true? Owen Quote Link to comment Share on other sites More sharing options...
blueovalz Posted April 17, 2002 Share Posted April 17, 2002 The way I've heard it is this: A factory cast iron exhaust with extremely short runners (especially the one toward the O-ring) allows the cooler outside air to come in contact with the hot valves (especially if you have a lot of exhaust duration on the cam) with no exhaust pipe hooked up. The longer tube headers will prevent this. Obviously this brings up the question of overlap on a cam. Does this mean that the cool intake charge will do the same thing. Obviously not, so if this explaination is a bunch of masculine bovine feces, I don't know. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 17, 2002 Share Posted April 17, 2002 Does anyone know how 'cool' a intake charger really is? I know the underhood heat will have to do with it, but doesn't it get heated up plenty going through a carb and manifold that are sitting on a hot engine block? Just curious. Regards, Lone Quote Link to comment Share on other sites More sharing options...
fl327 Posted April 17, 2002 Share Posted April 17, 2002 i dont think its true, if that were the case why do top fuelers not run anything except a shell of a muffler looking type thing staright out the headers? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted May 15, 2002 Share Posted May 15, 2002 Ok, partly true; but there's more to it. No backpressure will lean out an engine severely and the increase in combustion heat can not only burn the valve edges, it can melt the piston tops and/or start detonation. Detonation can blow holes in pistons, break ring lands, bend rods and all sorts of nasty stuff. Top Fuelers are another animal all together. Nitromethane is an oxidizer/fuel combination and is run rich to keep the valves and piston tops cool. They run a very thin line between making power (lean mix) or saving the motor (rich mix). There is actually enough chamber pressure and heat in a top fuel motor that if you could suddenly stop one, it would melt or explode. Quote Link to comment Share on other sites More sharing options...
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