92 fleetwood performance

[jayHunt]

I need help figureing what intake filters are the best and if its worth the hundred to do so. are there any relativly cheap ways to boost mpg or hp

[jayHunt]

should I add a cold air intake will it screw with anything if i do. I cant find oval shaped intake pipes. what other possible performance modifications are there

[barczy01]

Really nothing you can do just make it reliable transportation. Tune-up would help.

[Cadillac Jim]

The cheapest way to improve gas mileage is to go to 32-32 psi cold in the tires and develop a light foot, and brake gently and early whenever possible.

Another way is to run premium gas, but you need to watch how much it costs. You will get 1-2 mpg that way if your PCM advances the spark to match using the knock sensor, but sometimes premium gas is priced proportionately higher. Shop around because the prices of premium gas vary a lot more than the prices of regular or intermediate. You might end up breaking even with the cost of gas per mile but your fuel injectors and throttle body will be cleaner and there will be a small improvement in performance.

Check your tire wear. If the tires aren't wearing evenly, you might get an alignment. Poor alignment can cost you gas mileage as well as tire wear.

If you are under 45 mph, consider turning off the A/C and opening the windows. Above 45 mph, you will get better gas mileage closing the windows and using the A/C. See Myth Busters; they had two or three episodes on that.

Consider running synthetic oil. I don't know if 5W-30 Mobil 1 is OK for the 4.9 year-round bit Cadillac recommended it for my 1997 ETC year-round. That will get you about 0.5 mpg.

I doubt that an aftermarket air cleaner will help your fuel economy. I would recommend an AC/Delco replacement, but keep it fresh by changing it according to your owners' manual. Most people neglect their air cleaner elements. The aftermarket "cold air" intakes may or may not help performance but they probably will not have any effect on normal driving or fuel economy.

[KHE]

GM has tested all different types of air filters. They test everything that is out there. In the end, the standard paper element gave the best results (fuel economy and performance). If you think about it, if it were that easy to increase the fuel economy, GM would install K&N or whatever filter as standard equipment.

K&N filters actually let more particlate matter reach the enging vs. a standard paper filter.

The 4.9 and the Northstar engines take in "cold air" from the front of the car anyway so what is to be gained from some aftermarket intake??? GM tests the intakes for water intrusion so that the engine won't hydrolock. I can't say the same for any aftermarket company.

The 4.9 engine is a great engine that delivers good performance but it is not a Northstar. When GM began researching how to increase the performance of the 4.9, they realized they needed a dual overhead cam engine and that is how the Northstar was born.

[rockfangd]

I dont recommend cold air intakes. Doesnt help anything other than maybe sounding good.

[rockfangd]

There is basically duplicate thread to this one. Other one should be removed to avoid duplicate posts.

[Bruce Nunnally]

Merged these two threads

[rockfangd]

thanks

[Cadillac Jim]

You might consider a low restriction exhaust. While you are at it you might consider a low-restriction cat. With both you may get something like 5% more torque and hp and a noticeable improvement in fuel economy. The "Super Turbo" mufflers will give your car a sporty sound without a noisy result; Cadillac dealers installed these on new cars in the 1990's.

It's a bit out-there, but the Allante used a special fuel injection on the 4.5 that might improve performance on the 4.9 if it fits. And if you can find one.

High performance tires will improve the handling over "touring" tires, and can make a dramatic improvement in steering feel. They will likely have lower rolling resistance too, which will give you a tiny improvement in fuel economy.