Let's all agree this is speculation--despite deeply stuck ideas, none of us have talked to designers, planners and costs analysis folks at Toyota, Honda, or Isuzu.
I can understand why vehicle manufacturers would use smaller tailpipe, if it has only a small effect on HP. 2 lbs less metal per vehicle, times millions of vehicles...times the current price of steel. 5 cents per narrow tailpipe, vs a 1 hp or 1/10th MPG loss (Reported vehicle MPH is rounded to the nearest integer anyway), pretty soon you've saved a lot of money. Ford celebrated saving 5 cents on their ashtray design about 4 years ago.
ò Belief 1. I believe that cam timing wasn't chosen at random on vehicles, but for an overall balance of many factors, including power and reliability.
ò Belief 2. When you're machining millions of cams, a slight change in the lobe shape is inconsequentional in cost (from what I know about metalworking 100k+ runs of housings and frames at my job).
Who do I put blind trust in: a team of Toyota/Honda (and Isuzu) engineers with decades of experience who mass-produce millions of the USA's most reliable vehicles and proudly display their HP/Torque numbers, or some guys (including me) with no engine design or engine reliablity experience guessing on a web board.
I'm not saying professional engineers can't screw up and someone else can come along later and re-design better. I'm just having a hard time believing some small shop can out-design Honda-Toyota-GM-Ford-Chevy-Isuzu, and in 10 years time, the auto manufacturers can't copy the idea. Getting a small HP increase must come at the cost of something else--even if it's just a slight drop in *projected* engine life, fuel efficiency, rougher running, etc.
As for the "There's a cam company out there, so it must be true" arguement...that's the classic example of circular, self-reinforcing logic. there's MAF resistors out there (that work--with a cost). There's turbos and superchargers that work--with a cost. There's intake "tornados" and magic magnets that have all been out there longer than Crane and people buy them--so they must be true, too. There's even pills out there that will make me lose weight and make my...uh...well, that's just spam. Nowhere on Cranes website does it say "More power with absolutly zero negatives or drawbacks-guaranteed." Unfortunatly, their help line isn't 1-800 or I'd call.
You may *want* a free lunch, but it's very rare to find a working perpetual motion machine. If anyone wants to call a major automotive systems engineer or even a cam design shop and get facts, I'd be willing to listen.
