The E7's, compared to modern heads, just don't flow enough. Because we cannot control the amount of air (well, a turbo or supercharger does provide some measure of control, but this is a whole other topic) like we can fuel (remember, air is the limiting reagent) it is important to pick parts that flow well and similar to each other. They have a maximum limit of what they can flow.įuel, on the other hand, is infinitely variable. Cylinder head airflow is essentially static, determined by the passageways and contours of the head. This means to make the most power, an engine should be optimized to flow the greatest amount of air. Thus, the limiting reagent is air! Hey, chemistry can be useful! The ideal stoichiometric ratio between air and fuel, to make maximum power, is 13:1 (13 parts air to 1 part fuel).įuel, because it is controlled by a pump, can be added or removed at will with no impedances to whatever quantity is necessary. If you double fuel (now 2x) but keep air the same, y amount of air can only react with x amount of fuel, thus you have x amount of fuel left over, meaning it is unburned. Meaning, if you have x amount of fuel and y amount of air, there is a ratio between the two (x:y) that results in perfect burning efficiency. As it turns out, there is a maximum threshold for a fuel and air mixture. Of course, why not just dump in more fuel? Wouldn't that make more power? It seems it would, but actually, no, it won't. The interesting AND important notion here is that the power output is related to the quantity of air and fuel you can mix. Gas mixture ignites, engine spins, car moves forward. Air enters the cylinder chamber, fuel is sprayed in and the combination mixture of oxygen and hydrocarbons is ignited (courtesy of the spark plugs) and resulting explosion drives the piston, which in turn rotates the crankshaft, which in turn spins the flywheel mated to the clutch and transmission.yada yada yada. If you wish to understand WHY the E7 heads are the restriction, read on.Įssentially, an engine is one massive air pump. It is common knowledge that a major restriction point, from a power perspective, is found within the factory-cast E7TE heads that originally came equipped with the Foxbodies. PartĮ7TE Cylinder Heads - What you need to know Factory port volume was 127cc intake and 44cc on the exhaust side with an average air flow of 125 CFM between 0.100" and 0.500" lift. They featured a 1.782" intake valve and a 1.46" exhaust valve, with a combustion chamber size ranging between 60.6-63.6 cc. ![]() Iron is also somewhat difficult to work with.Į7TE cylinder heads came equipped on all 5.0L Foxbody Mustangs between the years of 1987-1993. Alas, it is also just as easy to hamper performance as it is enhance it if you are a beginner. With some dedication and careful work, you can port it yourself. At the end of the day, it isn't logical to spend $500 for someone to port these iron heads for a measly 30HP. Unless you do it yourself, you will have to pay a professional to do it for you. 30HP is nothing to sniff at, except porting is very expensive. Porting these E7 heads, even an A job, may yield a 30HP gain. Remove unnecessary casting material, smoothing out imperfections, and polishing the chambers are all part of the process. Porting heads involve using a rotary tool (dremel) and a burr to restructure the passageways to optimize air flow through the cylinder head.
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