mannys6speed

My car is stock besides a cold air intake and a flowmaster. I wanted to know what long tube headers give good hp gain and are not too expensive. I also wanted to put a x pipe with two super 44 flowmasters, is there any way of passing smog without catalytic converters. in nevada

DANOZ28

im happy with the clearance of my jet hots (same as hooker). you'll need a tune to get the rwhp advertised. air/fuel ratio should be around 13:1. ps you may want to checkout true duals if your trying to run twin mufflers & an X pipe. ps2 coated pacesetters use to be lowcost longtubes.

94Zee28

There are plenty to choose from and the HP gain should be pretty similar with all of them except maybe some SLP tuned headers getting more HP (not sure though). Here is a starting point.

1998-2002 LS1 F-Body Headers & Accessories from Thunder Racing

alex-z28

I have never heard of this before. Why would you need tune with headers.

DANOZ28

if your A/F ratio was correct before you added headers then probably not. in my experience when you add performance parts the engine can run leaner. im no mechanic. i first got a mail order tune & was disappointed with my dyno #s, then had a speed shop doug rippy motorsports tune it and the car woke up! goodluck! ps from the factory the a/f ratio is like 14.5:1 (way too lean)

WhiteKnight2001

If you don't get a tune after adding some air intake and exhaust parts, ESPECIALLY headers, your car will run too lean, and you'll be missing out on maximum performance. you might pick up 20WHP where with a tune you could get 30WHP.

DANOZ28

another example grannatelli advertises 10 rwhp for their mass airflow sensor. i believe the way they achieve this is tune the engine to aprox 12.5:1 a/f ratio (too rich) then add their 85mm sensor without a screen which leans out the engine to aprox 13:1 (the sweet spot) resulting in more rwhp.

alex-z28

Thanks guys.

I am looking at getting some headers myself and I made a thread asking about modding 93 f-bodies and do I need a tune after headers and no one said anything that I would or that my car would run lean after headers.

Damn, just another thing I have to do now, it never stops.

Cam Camaro Z-28

I'm no trained Tuner, but one of my best friends is and Develops the Pulling-in Tuning Devices for one of the large National Companies.
What I do know from his teaching is that nearly any modification you make to the engine from Air Intake changes to Internal engine component upgrades to even exhaust will require at least tweeks to your computer tune. With this exhaust modification including the headers and deleteing the Catalytic Converter the car will have a reduction in exhaust back pressure therefore allowing for increased performance. Now think about the function of the O2 sensor and its positioning on a factory car. The O2 sensor is after the factory exhaust manifolds but before the Catalytic Converter. The O2 reads the Air/Fuel ratio in the exiting exhaust and sends that information to the computer to make adjustments. The back pressure at that point in the exhaust is much higher if you have a Cat, than if you remove the Cat. Also, if the exhaust Pipe diameter increases ( ie. 2.75' to 3.50") than the back pressure could decrease. Why is this important? The O2 is sending the air/fuel ratio reading back to the computer. Less back pressure will cause leaner exhaust headings.

Bottom line is do the mods and get your ride tuned before you run to lean or too rich and break something.

WhiteKnight2001

Yeah, it's just not a good idea to go with that big of a modification and not tune the car for it. The guy in the post above me says to tune for exhaust kits or intake lids, but that's pretty minor stuff, can't say that would matter too much.

DANOZ28

the only thing i'll add is IF you had a tune & your a/f ratio was 13:1 then you added headers while the a/f would change, it wouldnt be "critical" to immediately get a retune unless you wanted max hp. you might be leaving a few on the table. the only thing i've added since my tune was the 80mm tb & the instructions said if i let it idle for 10-15 min the computer would re-learn the fuel curve. not sure if thats true or false.