Power to Weight

T Freeland

This is something too many kit cars screw up on, in my opinion. Valkyries need not be concerned in this department, they are adequately powered. Avengers, on the other hand, are not. Consider this, you have a car that looks like 200 M.P.H. just sitting in the driveway. Some punk comes along side in his tricked out Honda and goads you into a race. You are not worried, after all, you have a 2180 V.W. with dual webers and an extractor exhaust, in a sleek light bodied car with great traction. The light turns green, and buy the time you cross the intersection, he's 3 car lengths ahead! What happened, oh, I know, you weren't really racing, you are a mature adult and would never do anything illegal. I know, I wouldn't either!

What really happened is that the kid is a spoiled brat and mom and dad give him $500 a month to spend on his hobby of fixing up the rice burner. What you didn't realize, is that beside spending his money on clear taillights and a bolt-on spoiler that looks like it was made from materials from Home Depot, he's got Nitrous Oxide and a Turbocharger. You guys with the stock V.W. motors, well how do I say this. Your car is like these ladies on Sunset Blvd. who are gorgeous to look at, but when they speak to you, their voice is abnormally low.

We have a responsibility. If your car looks fast, it should be fast, or else don't step on the gas and let everyone know what a slug a V.W. is, even if rebodied.

Take a look at this table. You'll see various cars, their power to weight ratios, and how they perform. Cars with equal power to weight ratios, perform similarly.

To sum up, if you want to accelerate hard, you must lower your weight or increase your power, or both. If you have an Avenger with a veedub motor, your car weighs probably around 1600 lbs. Let's say your motor is putting out 72 H.P. Take the power (72), divide by the weight (1600), and your PWR equals .045 horsepower per pound. This is the equal of the mighty Ford Escort. Not acceptable.

I bought an engine on eBay in Feb. 2002 for $300. It is a 2.8 liter V6 from a Fiero, complete with the port fuel injection and all the accessories. By the time I am done with this car, I expect it will weigh in at about 1825 lbs. The stock engine puts out 140 H.P. - .076 PWR, almost the equal of a twin turbo Mitsubishi 3000 GT. Not bad. A used turbo ($100) should net me about 250 crankshaft horsepower, mildly boosted. This would yield a PWR of .136, the same as the dodge viper. Not too shabby. Will the car perform as well? Probably not. In my favor, is a mid-engine placement, so traction should be good. However, I weigh almost 300lbs., which reduces the true PWR considerably. Also, turbo horsepower takes a little while to happen, while the Dodge is instantly on tap. I'll might add Nitrous to speed things up a little. I don't think I'll encounter too many other cars I'll have to worry about. Especially since it's all for show, I'm too mature to race. But hey, when your engine shows beneath a glass window, shouldn't it look as fast as the car does? fieromotor.jpg (28664 bytes)

Some of you have asked why my own car isn't in the gallery. It will be, but I have a lot of  tweaking to do first. Now, go out and increase your power to weight ratio.

Update 10-18-03 Though I am not quick at getting my projects finished, sometimes procrastination works in your favor. I recently bought a 4.9 liter aluminum V-8 (you really NEED a V-8 in these cars to really look and sound right). Nice thing about this motor os it has 295 ft/lbs of torque stock (plenty for a sub 2000 lb. car) and I can turbo it for more. The bigger engine can be turboed more moderately (hence greater reliability) to achieve in power in excess of my needs. The bonus is that the motor is no heavier that the 2.8 liter 6 cyl, that the car has now. Now, I could end up with near Valkyrie acceleration, but with greater stopping and cornering power, due to the lower weight.