JS99Z

I just had my car dyno tuned last week. It is a 99 Z28 A4. On my print out it says my air fuel ratio is almost 13.2:1. The tuner said that would be ok but I don't really trust him. Isn't that too lean? Where should it be at? I was told I need to be between 12.2-12.4:1 to be safe. I was also told if I run the car hard with the a/f at 13.2:1 I could blow the engine is this true?

I don't know If you need to know my mods to answer my questions but here they are: comp cams 224/224 581/581 112LSA, comp cams 1.75 rocker arms, total valvetrain upgrade, LS6 intake no egr, Slp longtubes w/high flow cats, Loudmouth, TCI SSF 3500 stall convertor, Lid, Bellows.

I guess what I'm asking is where should my a/f ratio be at for an LS1 with these mods and still be safe?

Thanks

MasterEvilAce

13.2:1 would be running rich... and I think that would give you slightly more power
14.7:1 is IDEAL (stoichiometric) [spelling]
anything higher would be LEAN (more parts AIR to one part GAS)

I'm pretty sure that's correct. I don't think it would harm your engine at all, but it would definitely not get the best gas mileage that you could have.

mebanditws6

You want the engine to be slightly rich to curb detonation. If it blows out black smoke though at WOT, you're a little too rich though. Does it do this?

Jason

JS99Z

No I haven't seen any black smoke at WOT.

95TealLT1

You are lean, not rich. You need to be at 12.8 to 12.9. The lower the number the more fuel is being delivered by the injectors. You can probably gain 5 to 10 hp with dyno tuning.

Good Luck,

Al

MasterEvilAce

... Why would that be? Whatever happend to 14.7?????

JS99Z

13.2:1 was after dyno tuning. The tuner said he was having trouble getting fuel. Are my injectors or my fuel pump to small (both stock) for my set up?The car has only 16,000 miles so I wouldn't think my fuel pump is shot already?

taner

ok...for idle and part throttle cruising 14.7 is ok! that will help you with fuel economy. 13.2 is not that far off for wide open throttle. mine is tuned for about 12.6 - 12.9(WOT), in that range. i use my prtable wideband and my dfi, with a friend to drive the car while i tune it. a little rich is ok in my book.
still 13.2 isn't that far lean for wide open throttle. as long as you aren't using a power adder ontop, then i would think that is ok.

just my .02.

AL SS590 M6

I agree with Tanner 13.2-1 is OK for NA. I don't understand why they had problems getting fuel. Although 99s do have the smallest injectors of all the LS1s. Cna you get to auto tap to check your inj. pulse widths?