wanting_ back_a_ss

Ok. I have a 99 z28 It ran 13:10 bone stock. I did all the free mods. Put on a Flowmaster exhaust, slp air lid, and slp mass air flow sensor. This and the summer temps it now runs 13:20's to 13:30's usually. I figured my air/fuel ratio was meesed up and I know I need a tune and planning on a EFI Live at exotic performance plus soon.

My question is, I needed some new tires cause my back ones were shot. They were 245/50/zr16. I ordered a set of Mickey Thompson Et Street radials and they are 255/50/zr16. I ran my car today at Muncie Dragway and the best time I could get was a 13:65 now. It feels like a dog coming out of the hole. My 60 foot went from 202 to 205 or worse. Its an automatic by the way and I stall it up to about 1300 rpm not to mention I lost about 4-5 mph

black00ssFL

iTrader: (24)

Going at things a little backwards. You are losing mph and bogging off the line cause of the drag radials. Should have gotten a stall with the tires....then you would be flying out of the hole. The flowmaster exhaust isn't doing much for you except a better sound. The mass air sensor is screwing up your computer. And, the lid MIGHT give you a tenth. Add all that and the fact the DA is probably a good 1000 or more than when you ran 13.1 and you have a loss of about half a second.

Put street tires back on or get a stall. Get a better catback and/or full exhaust with longtubes. Take the mass air off and sell it on ebay towards getting the stall or exhaust. Then run in similar weather to the 13.1 and you'll be seeing 12's easy. I don't think people realize how much the DA affects your times.

I ran my car for the first time last august. Best I could muster in Florida heat and humidity was 13.7 with only a lid. No mods, but running in november netted me a 13.4. then I got exhaust and stall....13.1. Then Came LS6 intake and hptuners to lock up the converter in 3rd gear....in feb. ran 12.6. Wait til it's cooler and do the mods I explained above and you'll see 12's.

1meantransam

iTrader: (8)

hmm didn't happen to me untell i did LTs and LS6 and i went back to bone stock auto times, time for a tune for me. sounds like you don't have enough ***** for the radials, get DRs and you will hook up better but not bog as much, get them once you got some power going through there. a stall would also help alot, launching at 1300 is going to bog it with those tires, GOOD LUCK!!!

King Nothing

iTrader: (9)

better tires, get rid of slowmaster, full catback and a stall. also what gears do you have? i'm assuming 2.73 since your tires were 245

BRAKE

iTrader: (14)

All the F-bodies with 16" rims had 245's (6-speeds and the 3.23 cars).

I agree get a good catback and a stall and drop about 7/10ths.

socmguy

iTrader: (18)

chuck that slowmaster crap in the trash. didn't you search the forums before you bought that thing? It doesn't flow worth a crap. Also, what everyone else said about the stall/gears/tires. You'll cut everything down quite a bit. Get everything done by the fall while the tracks are still open and see the improvement!

lilbuddy1587

iTrader: (1)

Flowmaster isnt helping matters, but waht kind of free mods did you do? You can chuck that SLP MAF too. That MAF is garbage and is proven to hinder performance unless tuned for. Even then, I've heard its a nightmare.

Strahley

iTrader: (4)

1) Get rid of that Flowmaster. Go with true duals or a cutout or something
2) Sell the SLP MAF and put your stock one back on
3) Use money from the SLP MAF to help buy a converter
4) Weight reduction
5) New gears if you can swing it (3.73s would be great)
6) Tear it up at the track

5_02ls1

iTrader: (20)

do gears 1st i couldnt imagine my stall on the 2.73s...leave the flowmaster alone ang get a 25 dollar cutout to remove at the track.....the stock maf isnt a restriction till you reach 450 hp..so sell the slp unit.....id do gears that with a lid was my 1st mod and it really woke up the car.....

sixvi6-camaro

iTrader: (9)

I had the same thing happen to me when I was on 2.73 gears. Ons treet tires I went 13.2's or better with a couple 1.9 60's then I borrowed a set of MT Drag radials and the car was a slug out of the hole after that getting 2.1 60's or worse. with a stock stall, especially stock stall and 2.73's, you actually benefit from a little wheels spin to get the car into the powerband quickly but its a fine line.. too much and you spin hard and loose time.. not enough spinning and the car just bogs and chugs along out of he powerband through the first 30feet.

what these guys were saying is true though.. flowmaster is a tiny little gain in power if any gain at all.. SLP MAF is a tiny 1-2 hp gain at best or a big hp loss at the worst (it depends on how it its effecting the tune.) so loose the SLP MAF or get it tuned for the SLP MAF. Then work on LT headers, Stall, and gears to give those sticky tires a workout!

wanting_ back_a_ss

I tried to but back on the stock MAF and the car barely ran. It would idle from 200 to 500 rpm and at 40 mph the exhaust was cracking and popping real bad. The free mods I did were port the TB. Tb bypass coolant line. cut out from under the air lid. I have 3:73 gears sitting in the garage waiting to be put on. I need a tune. What kind would be best? I dont want to get a stall and put a whole bunch into it cause Im trading it in August ond odering a new camaro for 09.

black00ssFL

iTrader: (24)

Find another mass air. Sounds like your stocker is bad. If you're planning on trading it don't mod it. Put everything back to just about stock and just have fun with the car until then. You'll get more money and more potential buyers by having a stock car.

wanting_ back_a_ss

Ok Thanks for everyone's input I appericiate it

NC98Z

iTrader: (1)

I would clean the old maf before I chuncked it. I mean it was working before right? A can of Maf cleaner isn't $5.00 at NAPA. After you clean it put it back on and before you go trying it out take the pos off the battery and when ever you feel froggy (some wait a couple of mins,some turn the key to on) hook it back up and see how it runs. That way it can learn from scratch. The other MAF has probally got the A/F screwed up. The cpu in your car isn't any different than the one in your home. When all else fails its power cycle time!

ChocoTaco369

This is killing you. The stock MAF is good for 500 hp. Why did you change it? ANY aftermarket MAF is bad unless tuned for, and I don't think you can even tune an SLP MAF. They're the worst. Put the stock back on and sell the SLP MAF. You'll run a lot better.