HUG WEDGE WORLD TECH 4 TECH INFORMATION ABOUT TRADE-OFFS $0.00
WEDGE WORLD NEWS
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World of Mopar wedge engines
Issue #4 Trade-offs
(the facts of life)
We get many calls (too many) from potential customers who do not realize or understand that everything they change in or on their engine causes a “trade-off” somewhere else. There ain’t no free rides. A trade-off means whatever change you make to improve the performance in one area will compromise the performance in another area.
An engine is a “team” of parts that must work well together, or it won’t provide the power it should (or the team won’t win many games)! Factory engines are built to please the general public, normally not car guys. They are generally a good combination of power, mileage, smooth running, low maintenance, and long life (at least past warranty).
You must understand the engine is an air pump, and it is full of restrictions to air flow. When you make changes to allow more air to pass through the engine, you can make more power – but there are trade-offs!
Trade-off example: Going from a restrictive stock exhaust system to a less restrictive (air flow wise) header system. This allows the engine to flow more air, hence, more power; but there are trade-offs with this change. For example, the headers have more power, but there is more heat under the hood and more noise. The engine does not like hot air; it will reduce some power. Racers use hood scoops to cool this underhood air temperature. Bottom line is the header increased the power but brought with it some problems. You must decide if you can live with the trade-offs.
One of the biggest problem areas of trade-offs is the camshaft (see Wedge World #3). Camshafts come in sizes. The sizes are, or should be, listed as the duration @ .050 in. Read Wedge World “Cam Size” – AGAIN!
Let me list a few of the things people want and what they trade-off (and don’t want to trade) to get what they want.
§ A cam or engine that has pick a number (high horsepower) that gets good mileage. (What do you think creates that power? Burning a lot of gas!
§ A rough (race cam idle) with plenty of vacuum for my brakes.
· An engine that has a rough idle is struggling to run, hence it has low vacuum.(getting your distributor re-curved can help this situation)
§ An engine that “Looks” stock, cast iron exhaust, cast iron intake manifold, cast iron heads, stock distributor, and has 650+HP. “Yeah- we could sell dozens of these”
Yes, that is possible, that is why all the Pro-Stock cars keep these components on their engines, DUH! If you want your engine to look stock, guess what it will probably run like?
You should decide what your budget is before you go to the engine shop or call a parts supplier. This is the best way to approach and engine build-up. If you start with what power you want, “you” may have problems breathing when the shop quotes your price. You will save you and your shop both time and frustration if you start with a realistic budget figure.
When you build up an engine you WILL make trade-offs (plus $$$). There is no way around it. Now, as far as performance goes, if you want power at 6500 RPM you trade-off lower RPM cruising, gas mileage, noise, vacuum, and money.
How about mechanical (solid) cams vs hydraulic cams? The mechanical cam will require rocker arm (valve) adjustment on a regular basis. The hydraulic cam can run for long intervals between adjustments. A hydraulic cam will have more life in a street car than a mechanical cam. If the cams have exactly the same specs, the mechanical cam will produce a little more power(your looking at maybe 3%), again, a trade-off.
Now wait just a minute, is there nothing you can do to improve the performance of your street rod without a trade-off? I’m glad you asked! Yes there is! Changing the advance curve in your distributor and a good set of spark plug wires carefully separated and a cap+rotor with copper terminals will help at all rpm and you don’t trade off power anywhere. And it may even increase the mileage – if you keep your foot out of it.
So when you decide you want to build up your engine, what do you want to trade off? | 
