performance & mileage
 

I'm was looking at picking up some heads, roller rockers and an intake and all at once give my car a nice upgrade in power. However, this is my daily driver and I frequently have to drive pretty far. My concern is how badly different upgrades are going to hurt my fuel economy. I realize some mods are gas guzzlers (e.g. steep rear end) but a friend of mine suggested intake stuff may actually leave fuel economy almost stock. I'm open to other ideas of course as well. So my question is what performance upgrades can I do that leave fuel mileage alone - or, better yet - increase it?

It is not unusual for an 89-93 5.0 to get 25+ MPH on the freeway. City driving is always going to be poor.

My car was at one time a 25+ car. It was before I bought it but it was a good performer. I know it had a 70mm TB, 1.7 rockers, Flowmaster cat-back, and gt-40 heads and intake. The stock cam was retained.

Now I can't be sure the heads and intake made the high mileage combo but the stock cam is the largest helper. Note that the gt-40 heads are not that aggressive. They have smaller valves and ports (than a standard performance head) and are good for mild power and good economy. The intake valves are 1.84" compared to 2.02" for the standard trickflow/afr/edelbrock etc.

Since you want a daily driver, you are correct the gears would not help much. You could leave off the 1.7 rockers and get more economy and extend valvetrain life.

Mike

My car was a 25+ car also with the GT-40 heads and intake, B-cam, and other bolts ons. However, it has dropped off recently and I can't figure out why:confused: . I don't think my engine is getting tired or anything. I may have a bad sensor or something.

You can get pretty good mileage even with some add-ons to your car, although as stated before, city driving seems to always be poor.