is this too lean?

[99-SS-Conv]

If I get a bigger intake manifold and bigger trottlebody will that be running too lean and if so can I get a tune to even it out?

[Mr. Luos]

No. It shouldn't go lean. If anything, it should richen up. ECU adjusts for the flow.

Yes to tune. Probably not going to be a big gain though with an intake and exhaust.

[SSpdDmon]

What's done to the car already? The stock tune comes fairly rich from the factory and Mr. Luos is partly right about the PCM's ability to adjust. But, the PCM can only adjust for part throttle - not so much at wide-open throttle. At WOT, the PCM only hopes it's producing the AFR's commanded based on what it sees happening at part throttle. The only sure way to see if you're running lean is to get your hands on a wideband O2 sensor.

[tblu92]

HI--Unless you have done other mods to your engine--a bigger manifold and T-body won't really make Horsepower--maybe 2-3 at WOT--but it will make it a dog at part throtte and out of the hole .your engine isn't pumpning enough air and the bigger manifold and T-body will slow down the air speed horribly to produce less torque..Air speed makes torque--A good use for some thing like that would be a larger C.I engine or a huge cam or trick hiflowing heads--then you would need the big stuff to supply enough air---Otherwise I would say--get something else--Long tube headers are good for 20-30 HP-Air box--cat-back exhaust--1.85 rockers---next level would be heads/cam---turbo-supercharger-NOS---bigger motor C.I.

[SSpdDmon]

HI--Unless you have done other mods to your engine--a bigger manifold and T-body won't really make Horsepower--maybe 2-3 at WOT--but it will make it a dog at part throtte and out of the hole .your engine isn't pumpning enough air and the bigger manifold and T-body will slow down the air speed horribly to produce less torque..Air speed makes torque--A good use for some thing like that would be a larger C.I engine or a huge cam or trick hiflowing heads--then you would need the big stuff to supply enough air---Otherwise I would say--get something else--Long tube headers are good for 20-30 HP-Air box--cat-back exhaust--1.85 rockers---next level would be heads/cam---turbo-supercharger-NOS---bigger motor C.I.

He should see closer to 10~15rwhp from a bigger tb/manifold. Even more if it gets tuned and dialed in. Maybe not so much as a result of the tb...but the manifold, yes. He's got a '99, so bigger manifold means LS6 intake. Although, a FAST LSX intake would be overkill.

[tblu92]

YES i agree a LS6 manifold will net you betwen 10 & 15 RWHP--He said Bigger which threw me a curve--the LS6 is not neccesarily bigger-just better designed-- so by bigger I thought he meant ported out or sometning fabricated---