Sunday, September 19, 2010

Low Power Grin Factor

Between the KLR and ZRX and experience with the Fiat 500, this has been an interesting summer of contrasts. For years, Bob and I have been discussing the question of how big and heavy a vehicle you really need to move you around the world. But that's a bigger question that I'll leave for a later time.

This summer, I've been interested in the intoxication of power versus the everyday fun of driving/riding. Most people I talk to believe that fast cars and motorcycles are exciting and the most fun to own. I'm not so sure. I believe that a slightly underpowered vehicle that you drive/ride hard all the time is a lot more fun on a fun/mile basis than a really powerful vehicle.

Lets take my two motorcycles. The ZRX has about 130 HP and weighs 400 pounds or 635 pounds with me and my gear. That means about 5 #/HP or really bloody fast for a street vehicle. But this bike better be upright and pointed in a straight line when the rider goes for the throttle. Even then, if you don't want a ticket, that big twist on the throttle can only last a few seconds before its shift, shift, shift, and slow down to somewhere near the speed limit.

The KLR has 45 HP, weighs a few pounds less, and ends up with about 13 #/HP. That's not slow, but it is slow enough to need full throttle and frequent shifting. That said, I can twist the throttle while leaned over in a corner and run through the gears ending up only a little too fast.

The difference between these two descriptions is key to the problem. The reality is that the faster the car, the smaller the weight/HP, the more the engineers need to compromise the turning behavior to keep it stable. That means a less tossable, less capable cornering vehicle that has to wait for the straight to go fast. For me, the lower power vehicle that turns well and can be driven/ridden flat out all the time improves the percentage of time spent with a grin on my face.

How does that add up with cars. The picture above is a composite of the Dave's AREX engine and a internet stock photo of a Fiat 500. Dave's supercharged engine is about 600 HP at about 2600 pounds or 4.7 #/HP with me in the driver's seat. My AREX is only 475 HP at 2500 pounds, so 5.7 #/HP. The Fiat is roughly 20#/HP (a guess as the HP and weight for the US car aren't published).

Even though the AREX is a pretty good handling car with massive 335/35 tires out back, the same problem as the ZRX exists. The car has to have more built in understeer so that the wheels don't spin when the throttle is opened and the car goes better when you wait for the strait.

The Fiat on the other hand is hugely tossable, is a blast to shift, and drive flat out all the time. As a person who likes to be an active part of driving/riding, I think I'll stick to the lower powered vehicles in the future.

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