BamaDan

when talking about the way an engine 'runs' (lean or rich), you are referring to the fuel in the air/fuel mixture. generally, a gas engine will run somewhere around 14.7 parts air to every 1 part fuel. kinda like 3 cups flour to 1 teaspoon of salt when making cookies or something.. dont know if that cooking part is anywhere near accurate..

so an engine running 'lean' would have a higher air-fuel ratio (AFR) than 14.7:1 -- this means you have more air. 16 parts air to 1 part fuel. like when a butcher talks about a 'lean' cut have less fat and more meat(:
an engine running 'rich' would have more fuel than air. 12:1, maybe.

so when you install a more efficient intake, its better at taking in air. that means more air, but your car's computer doesnt know that, so it injects the same amount of fuel as when you had less air.
when you tune your engine's computer, you adjust settings to bring you back to a 14.7:1 air-fuel ratio.

i know that was a little longwinded. hope it made some sense..

elroyjetson_1978

The few people I've seen post on here about them have all said they are only so so at best. They do supposedly free up on the 4.0L only about 5-7 hp not sure if at wheels or crank. 5-7 hp isn't alot and will barily be noticable unless you have a sensitive butt dyno.

phunnyguy

thanks that makes more sense..... what would a car running rich or lean feel like to drive???...just crurious.....

BamaDan

probably just plain weak.. too far in either direction and it'd probably be rough, or you may not get the engine to crank up at all.
i'm no expert, but thats what i've known to be true(:

themac5150

You can get the intake and get 87 octane tunes. I got mine from Bama, 87 performance, 93 torque(my fav), and 93 performance(I may get the 93 race tune to replace this one). You can get a milage tune from other venders for the intake. I had been running the 87 tune for quite along time. I've put the 93 torque in recently, it's got more ***** down low than the rest of them. The 93 torq is usually the one that stayed in it, but I stopped to fill up the car, grabbed the premium nozzle and got half filled before I realized it was only 92 octane. Loaded the 87 tune before I left(the tuner stays in the car, I put it in a shaving kit bag). Running too rich wastes gas, fouls the plugs, the car runs dirty, more emissions, can mess up the emissions parts. Running too lean, can melt the plugs and other things in the combustion chamber. Neither one is good. I wouldn't waste my money on the pulley. Get the intake and tune, and don't look back. On the installation side, the difficulty of the intake and tune is hardly anything.

05MustangSally

Car running lean is usually noticed by running rough and idles at high rpms on some occasions.