Why going for "Every Last Ounce" isn't always a good idea...

Gearheads have a tendency to never be satisfied, to always be looking for the next edge in performance. Sometimes that's a good thing, but sometimes it can bite you in the ass. Here's a few examples. # 1. "Air Gap" intake manifolds. NASCAR racers discovered that by raising the plenum and allowing air to flow under the runners, that they gained 10-15 hp on the top end because of the cooler fuel charge. Edelbrock, Holley and other companies began selling these "Air-Gap" manifolds to the public. In sunny California or at Daytona, this works fine. Whether or not you can actually feel a 10-15 hp gain in the average street car remains open for debate. However, in many northern or Rocky Mountain states people that ran out and bought these intakes were furious in the fall,winter and spring. Their cars would not start and idle properly, sometimes taking 20 minutes or more to warm up, and many wouldn't run at all because of carburator Icing! The buff magazines were deluged with angry letters, and Summit, Jeg's, and other retailers of speed parts were getting angry letters and emails from people demanding refunds, saying they re-installed their old intake so the car would start properly! That 15 hp wasn't looking that good now!  # 2. "We shall Overcam". As we all know-"bigger" isn't always better. Especially on a street machine with an automatic transmission,when it comes to cam selection, it's better to err on the side of caution. Here's a perfect example, and thankfully my friend didn't take the advice of the "expert" at Summitt. He had a '78 T/A with the W72 400, a TH350, and 3.23:1 gears. He installed the Edelbrock Performer package-heads, cam, intake and headers. According to Edelbrock this combo makes 387 hp and 439 lbs of torque and makes 15 inches of vacuum at idle. I believe it. This T/A would literally spin it's tires as long as you wanted to stay on the throttle, idled smooth, and had more power than you'd ever need. He was escatatic. Then some idiot salesman told him he should "upgrade" to the Performer RPM cam and intake because that combo made 422 hp and 441 lbs of torque. He asked me what I thought. I told him absolutely, positively do not change a thing on his car!!  Here's why-1st off-why spend a bunch of money and time to gain 35 hp and 2 lbs of torque? Honestly-all other things being equal-and especially with street tires-not slicks or drag radials-is a car with 422 hp going to be noticably quicker than one with 387 hp?  And-the "Performer RPM" cam is an exact replica of the factory RAIV cam-which was only available with 3.90:1 or 4.33:1 gears for a reason! It barely makes 10 inches of vacuum at idle, and your giving up quite a bit of low-end and mid-range torque for top-end rush. To take full advantage of it, he'd need to swap his 3.23:1 gears for some 4.10s and he'd probably need a 2,500 rpm torque converter as well. Which would ruin the car's wonderful drivability. The motor buzzing at 3,500 rpm on the freeway at 70 mph is not pleasant. Luckily-he took my advice and is still very happy with his car's performance-with roughy 400 hp-it blows the doors off  95% of the stoplight challengers he encounters, it idles smooth, cruises effortlessly on the freeway and purrs like a kitten until you hit the loud pedal. He doesn't need that "last ounce" of performance at the expense of a LOT of good drivabilty. Motor Trend made this point in an ultra-exotic sports car comparo recently. They said they loved the Aston-Martin V12 Vantage for it's all around feel and great performance up to "8 or 9 / 10ths ". What they meant was-yes, the Nissan GTR, the Corvette Z06, the Porsche 911 Turbo were faster around the Nurburging and Willow Springs raceway. But 99 out of 100 people who buy them are never going to push the cars to that absolute limit. Hence-the 8 or 9 tenths comment. When is Joe Average going to run a Z06 or GTR or 911 Turbo absolutely flat-out?  The same goes for your musclecar. If all your doing is drag racing it, then by all means do everything you can to get every last tenth shaved off your time. But if your going to drive the car at all, it might behoove you to leave a tenth or two on the table in the interest of a pleasant Sunday drive or Wednesday night cruise!!  Mastermind