I will be changing my '92 Grand Marquis in the next few years. I will be considering either another Grand Marquis, Lesabre, or a Park Avenue.

If I get a supercharged Park Avenue, will it hurt the drivetrain if I use 87 octane, or does that just hurt performance? The main reason I'd get a Park Avenue is to get something with slightly better economy and is cheaper to run. My Grand Marquis isn't bad at 20 mpg city/hwy, and is very easy to maintain. Running premium will probably eat up any cost savings.

The low octane may not have an effect on performance, but the engine needs the higher octane to reduce knock retard. I believe.

Moved to General for better visibility.

Hm, I'm confused now.

As far as I knew, retarding the timing will hurt performance. However, because the computer usually enriches the mixture at WOT in N/A applications, I'm going to guess that the performance will be hurt mostly at part throttle acceleration and cruising. Of course, my only knowledge of superchargers is that it compresses the air to get more air flowing through the engine, thereby increasing power.

Basically, I won't mind getting something with a supercharger on it as long as it doesn't knock itself to death on 87 octane.

Using 87 octane in a supercharged engine seems to lower the mileage a bit. So in the end, the cost per mile comes out to be about the same. Adding 2 miles per gallon off sets the $0.20 per gallon.

couldnt have said it better myself..

OK, that makes sense to me.

New question:

Is economy hurt more in city driving or highway driving? More on cruising or accelerations? This answer could affect my choices.

If I had to guess, city driving would be effected more. More bang per gallon means less fuel needed to get going.

I have 99 Park Ave and a 98 SSEi. So i can compare them for you. Don't consider buying the supercharged engine with the intent of putting 87 octane in it. I have tried it and have found that 87 octane takes all the fun out of having a supercharger. It just doesn't run the same. You won't get the performance, the computer won't let it knock hard but it will detune it so you don't get near the acceleration. In my case I have documented several times that 89 octane gets 2 mpg less than 91 or 93 gets in the supercharged engine. My SSEi gets 25 or 26 on highway trips
l drive alot of highway miles and my Park Ave reads 27 mpg on the DIC, I have seen the Dic read 29 mpg on long trips. The non supercharged engine does a real nice job, plenty of pep and outstanding gas mileage.
The biggest diference between these two cars is when you stand on the gas and throw it into a turn the SSEi says gimme more lets go! and the Park says whoa big fella! take it easy.