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Dr. Gear Head

A sometimes close examination of cars, drivers and roads : Q&A

July 30, 1998

Question: I have driven sports cars most of my life. I like the handling and the fact that I can control the car. I have recently become one of the many who drive a sport-utility vehicle. I arrived at this with two ideas in mind:

1. We usually drive family and friends when we go out, and it is easier to park one car than four.

2. We do take the occasional road trip and like the comfort of not having to worry too much about weather.

I like driving the SUV except for the fact that it does not handle the way I would like it to. I realize that it is a taller, longer and heavier vehicle, but it should have some handling. While turning, I experience a great deal of body roll. I also experience drifting while in a long curve and find myself having to work the wheel a little harder than I expect. The vehicle does have factory sway bars, and the shocks are in good shape. Is there any thing that you can recommend?

J.M., Covina

Answer: There are a number of things to suggest, but you might not be happy with the results. Few improvements in suspension performance come without some kind of ride penalty.

Aftermarket sway bars that are stiffer would reduce body roll, as would harder sway-bar bushings. The latter might make the ride noticeably harsher; the former probably won't have much noticeable effect unless the bars are a lot bigger in diameter.

If off-road ground clearance isn't important, you could investigate aftermarket springs that lower the vehicle. The lower center of gravity would help some. Stiffer springs won't have much effect on body roll, but the suspension will handle bumpy roads better and be less likely to drift in sweeping corners.

The same can be said about aftermarket shocks, and a good adjustable shock coupled with stiffer sway bars might be the best approach from the standpoint of increased performance without a severe ride penalty.

More About Octane

Q: My 1962 E-Type Jaguar requires minimum 100-octane fuel. Is there any place in Orange County where one can buy 100-octane gasoline? I have tried the supermarket "octane boosters," but they are expensive and don't seem to be effective. Do you have an opinion about these products?

G.R., via the Internet

A: I can't say that octane boosters are a substitute for higher-octane fuel, nor have I seen any tests to back up manufacturers' claims. Results of a recent test show that it's quite expensive to boost octane using additives. And, depending on what chemicals are used to boost octane, the additive could damage rubber bushings and gaskets in the carbs.

As for your E-Type, if it's normally aspirated and properly tuned, we can't see a need for 100-octane fuel.

According to John Sethian, technical chairman of the Nation's Capital Jaguar Owners club, the official Jaguar manual calls for 98 octane fuel based on the research method. That equates, Sethian says, to about 93-94 pump octane. While premium gas in California is mostly 92 pump octane, you should be able to use this fuel without knocking, by retarding the ignition timing slightly. He doesn't recommend using aviation fuel.

Take care, however, to test your new ignition timing when it isn't 100 degrees out. If your engine still knocks, you could have carbon buildup or another mechanical problem that affects timing.

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Q: Could someone please explain the difference between the octane levels? My sister-in-law has a Corvette and claims it runs better on the lowest-octane gas. I have a '68 Mustang and like the higher levels. Also, why in the world is gasoline priced with 9/10ths after the large number? Why not 7/10ths or 3/10ths?

C.M., Northridge

A: Basically, octane describes motor fuel's resistance to detonation. It's quite conceivable that your sister-in-law's Corvette runs fine on regular gas depending on what year Vette she has. The '68 Mustang's need for premium isn't too surprising offhand, given its age, but if Ford says it should run on regular, the need for premium could mean that something is out of adjustment or that you have a more serious problem, such as carbon buildup.

As for pricing gasoline at $1.349 instead of $1.343 or $1.347, I always wondered why it wasn't simply priced at $1.35. But a very informal poll of two colleagues suggests that it's a leftover marketing technique--gasoline priced at $1.349 a gallon sounds cheaper than gas priced at $1.35.

If you read last month's Under the Hood about octane and it wasn't enough, check out the gasoline FAQ on the Web at http://www.cs.ruu.nl/wais/html/na-dir/autos/gasoline-faq/.html. This behemoth contains details that delve well into the scientific aspects of motor fuel.

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Q: Since the appearance of the first Highway 1, I drove into the Rocky Mountain area and discovered that regular gasoline is 85 octane. The middle grade is 87 octane. My car normally uses 87 and, to play it safe, that is what I filled up with. I think the high altitude is a factor in 85 octane. Would it have been OK to use the lower octane?

M.H., La Palma

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