Factor in the Whole Combination before you throw parts at it....

I've seen it so many times-people read an article in one of the buff magazines about an intake manifold, cam, torque converter, etc that makes the most power in a dyno test or offers the biggest improvement in 1/4 mile e.t. ,they go out and buy it for their car, and are severely disappointed because they didn't get the same results the magazine did, or worse yet-the car ran better stock. The reason for this is people don't take into account the intended purpose of the engine build, or the whole combination. Here's a couple perfect examples. A guy I know read in a magazine that the Edelbrock Victor Jr intake and 750 Holley Double-Pumper made the most power and torque on a dyno test of a small-block Chevy. He goes to his local speed shop, and buys this combo for his '79 Camaro and is furious when it doesn't run as good as it did stock. Here's what he missed. The magazine test mule was an 11:1 compression 406 with Trick Flow Aluminum heads,a Comp Cams 280H Magnum cam and 1 3/4 inch headers. The Victor Jr-which is basically a NASCAR manifold designed to make power from 3,500-8,000 rpm-may have knocked 25-30lbs ft of torque off at idle-but with 450+ lbs ft on tap from the 406, that didn't hurt. And from 3,000-7,000 it REALLY rocked-adding 40+ hp on the top end compared to the nearest competitor. When he put it on his 8.5:1 stock 350 that had maybe 280 lbs ft of torque AT THE PEAK, it killed the bottom-end. And since the stock 350 with a "smog" cam-was all done in by 5,000 rpm-the Victor Jr-which doesn't even START to make power until almost 4,000-didn't help the top-end either. The car ran better with the stock iron intake and a Q-Jet!!  Now here's an opposite scenario. Pontiac builders have long said that it's hard to improve on the '67-74 factory intakes. That back in the '70's aftermarket ones even showed a loss at some speeds, and that only the Edelbrock Torker showed a 20 hp gain, above 4,000 rpm. In the intervening years Edelbrock has come out with the Performer RPM-which out performs the Torker at all rpm levels. Anyhow-a buddy with a '66 GTO put a Ram Air IV cam and a Torker intake on his car, and his 1/4 mile time dropped by more than 1/2 a second. He was esctatic. How did that happen? Well, for one thing-his car has a 10.75:1 compression 389, a 4-speed and 3.90:1 gears. ( In 1969-70 The RAIV was only available with 3.90:1 or 4.33:1 gears ). Secondly-at the drags he revs the car to 3,500-4,000 rpm and drops the clutch hard, and then powershifts at 6,000 rpm. Shifting at 6,000 rpm-he's going to hit 2nd ( and subsequent gears ) about 4,400 rpm. Right in the thick of the Torker intakes and the RAIV cam's 3,500-6,500 rpm power / torque peak. Now if he put this combo on an 8:1 400 in a '77 T/A with an automatic and 2.56:1 gears, it would have absolutley KILLED the performance, running worse than stock. See what I'm saying?  Here's the rule of thumb. Larger engines can take more "cam" than smaller ones, because they have more torque to spare. For example-the old L79 "350hp 327" cam for small-block Chevys-that was only used with a 4-speed and 3.70:1 or 4.11:1 gears in Corvettes and a few Novas and Chevelles-would absolutely kill a 305. It would work pretty good in a 350 with a 4-speed and 3.42:1 gears or an automatic with a 2,500 rpm converter, and it would be really sweet in a 383 / 400 even with a stock torque converter. Manual transmission cars can take more "cam" because idle speed isn't as important, and the driver can launch at whatever rpm he desires by manipulating the clutch. This applies to other things besides intakes and cams. Heads for instance. Here's a couple good examples. Years ago, Car Craft built identical 454 Chevy engines-same compression, cam, intake,exhaust,etc-except for one thing-one had "standard" oval-port heads, and one had "Hi-Performance" rectangular port heads. Here's the shocker-on the dyno-the rectangular port heads did not show a noticeable gain until 6,300 rpm!!  Now in your street / strip machine-or even a race car-how often are you going to be above 6,300 rpm??  A few years ago Hot Rod did a hop-up article on the GMPP "ZZ4" crate engine. If you don't know-the "ZZ4" was a 350 that was pretty hopped up to begin with-aluminum heads and intake, roller cam, 10:1 cmpression, etc. It had 355 hp and 418 lbs ft of torque. What made it such an awesome street engine was it made over 350 lbs ft from 1,800-5,200 rpm. Anyhow they experimented with hotter cams, dual and single-plane intakes, different carbs, etc. The last thing they did was add a set of Trick Flow aluminum heads, which cost $1,400!!. Here's the kicker-the "Antiquated" stock L98 heads were within 5 hp and 5 lbs ft of torque at every rpm up to 4,600!! Now how often are you going to be above 4,700 rpm in most driving conditions?  Granted, the Trick Flows did offer a 40 hp gain-at 6,100 rpm!! Now on an all-out race car-that might be worth it. But think of this-for $1,400 you could buy a well thought out nitrous system, a higher stall-speed torque converter, stiffer rear end gears, etc. that would give you a better gain than 40 peak hp at 6,000 rpm!!  Here's why I balk at "Gotta Haves" when people are people are talking about building a small-block Chevy or Ford. The "Gotta Haves" I'm talking about are usually forged pistons, shot-peened rods, 4-bolt mains, screw in studs, etc etc. This is all well and good if your building a NASCAR engine that has to go 7,800 rpm for 500 miles at Daytona. But for a street machine? People will say what if you want to run a blower or nitrous? To that I say-If you have that much money and need to go that fast, why aren't you building a 454 instead of a 350, or a 460 instead of a 302?  Anyhow it's better to err on the side of caution, especially if the car is a street machine. Mastermind