Why Car / engine / trans / axle ratios have to be custom tailored...Everything isn't a small-block Chevy!

Whenever I talk to someone about what cam, carb and intake, torque converter, rear end gears etc to use for a street machine or drag racer or hobby stock or Super Stock circle track car-they almost always argue with me and quote some magazine article or the Holley carb catalog, or B&M trans catalog, or Lunati cams catalog, etc. What their not grasping is, for about the last 50 years-the default test mule for any aftermarket performance part has been a small-block Chevy. For example-torque converter stall speed. When you read in a B&M or TCI or Summit Racing catalog that their selling a 3,000 rpm stall converter, if you read the fine print or send away for the test results or tech sheet-you will see that their test engine had 230 lbs ft of Torque! A 165 hp carburated LG4 305 Chevy in an '84 Camaro has 240 lbs ft of torque. And that's "peak" torque-i.e.-the maximum the engine made throughout the rpm range-and the "peak" reading probably came at 4,000 rpm or more.  So yes, in that car-or even say a '77 Z/28 Camaro with a 170 hp LM1 / L48 350 that has 280 lbs ft of  "peak" torque, the converter will stall roughly about 2,800-3,200 rpm. But what if you put that same "3,000 rpm" converter behind a 455 Pontiac in a '71 GTO that has a peak rating of 480 lbs ft of torque at 2,700 rpm? It would stall much higher and the car would actually be slower off the line than it would be with a stock converter because it would just blow the tires away, even with drag radials. "Hi-stall" converters came into vogue as a crutch to compensate for a small engine, or a peaky,overcammed big one that doesn't have enough torque to launch the car properly. If the engine has enough torque to launch the car properly, you don't need a high-stall converter. For example- the ZZ4 Chevy engine in my Cutlass is rated at 355 hp at 5,400 rpm and 405 lbs ft of torque at 3,500 rpm. What makes this engine so awesome despite it's modest numbers-it's GM's best-selling crate engine in history-is the torque curve. If you read the dyno sheet that comes with the engine-yes the 405 lb torque peak is at 3,500 rpm; however it makes more than 350 lbs ft of torque from 1,800-5,200 rpm!! That kind of broad, flat torque curve, is what makes for exciting street performance and wins races at the drags. If my car had a stock converter that stalled at 1,700 rpm and 3.08:1 gears instead of it's "Holeshot" and 4.10s, it would still smoke the tires from a light and probably only be 3 or 4 tenths slower in the 1/4. That's because with 350 lbs of torque right off idle-the engine has the torque to launch the car without mechanical advantage. And conversely-if I installed a 3 grand converter as opposed to a 2,000 rpm one, the car wouldn't go any faster because it would spin the tires excessively on take off.  The same applies to other things-cams for instance. For small-block Chevy enthusiasts the old standby "hot" street cam has always been the "350 hp" 327 Corvette hydraulic cam. Now, this cam would absolutely ruin a 283 or a 305. It works pretty good in a 327 with a 4-speed, better in any 350, and is really sweet in a 383 / 400 even with an automatic. Why? because larger engines can tolerate more "cam" without ill effects. In installing a high-performance camshaft in any engine-you almost always are losing low-end torque in exchange for an increase in mid-range and top-end power. Well in this case-a 283 or 305 doesn't have a lot of bottom-end torque to start with, so losing any at all kills the performance. It was fine in a 327 'Vette with a stick and 3.70:1 or 4.11:1 gears-the mechanical advantage of the 4-speed and stiff gears masked the engine's lack of torque and lumpy idle by getting the rpm's up quickly. The 350 or 400 small-block made enough torque to start with that the cam smoothed out all through the range-it even had a good enough idle to use an automatic with a stock converter. To further illustrate this-the "Hot" "350 hp" small-block Chevy cam has 222 degrees duration ( at .050 lift ) and .447 valve lift. A stock 327 / 350 "300hp" cam has 194/ 204 duration ( at .050 ) and .383 / 410 vale lift . By contrast the cam that comes stock in a 400 Pontiac in a 200 hp '75 Catalina has 212 / 225 duration and .410 lift. The cam that came stock in my 8.5:1 250 hp 1973 455 Hurst Olds-the vaunted "W30" was long gone-this engine was also used in Vista Cruiser wagons and Delta 88's and 98s-has 231 duration ( at .050 ) and .474 valve lift! Yet in a heavy car or station wagon with 2.73:1 gears both of these cams idle at 600 rpm and will pull a trailer up Donner pass at 70 mph! The reason is a 400 Pontiac or a 455 Olds has substantially more torque than a small-block Chevy and can use a bigger cam even in a milder application. Manual transmission cars can tolerate more "cam" than automatics becuase idle quality isn't as important-the driver can launch at any rpm he wants by manipulating the clutch. The same goes for induction. Yes, most magazines recommend a dual-plane intake like the Edelbrock Performer and a vacuum-secondary 600 cfm Holley or Edelbrock carb for the "average" street engine. This of course being an 8.5:1 compression 305 or 350 Chevy, a 302 or 351 Ford or a 318 or 360 Dodge in heavy cars and trucks or suv's with lazy cams and automatic transmissions and high ( low numeric ) gearing. On those applications they are absolutely right-you need a carb and intake that will build low-speed and mid-range torque. A single-plane Torker II or Victor Jr intake and a 750 Double-Pumper Holley or 800 cfm Edelbrock would absolutely ruin any of those applications. They'd actually run WORSE than stock rather than better. However, on a 10:1 compression 350 Chevy or 340 / 360 Mopar with a hot cam, a 4-speed and 3.55:1 or stiffer gearing it would really rock-pulling hard from about 2,800-7,000 rpm!. And a single-plane would work even on a mild 440 Mopar or 454 Chevy- because the loss of bottome-end torque may actually help the car launch better because of less wheelspin, and the increase in mid-range and top-end rush. So just remember that the "General Rule" is based on testing of a small-block Chevy. And that means a "basic" small-block Chevy-an 8.2:1 compression 350 that makes about 200 hp and 280 lbs ft of torque-not an 11:1 370 hp LT-1, or a 450 hp 383 stroker. So take these "General guidelines" with a grain of salt-especially if your building a 460 Ford or 440 Dodge, or 455 Pontiac, Buick or Olds! Mastermind