Hurst

I have an '87 IROC with a 305 TPI automatic. The motor has about 26 thousand on the rebuild and the transmission has about 12 thousand on the rebuild. I am not sure exactly what was done to the motor on the rebuild or what it was rebuilt with.

I have done the following mods:
new high flow cat by Catco
Flowmasters from the converter back
Hypertech streetrunner chip
K & N air filters

I just recently had a tune-up with new plugs and a new O2 sensor. I run Mobile 1 oil. The MAF sensor is under a year old.

I was at the dragstrip and was very disappointed with my et's. Below are some numbers from my time slips.......
reaction .642
60' 2.246
et 16.183
mph 83.415

reaction .515
60' 2.303
et 16.312
mph 82.467

reaction .602
60' 2.314
et 16.233
mph 83.653
I ran a boat load of 16.3's

After combing through the posts on this site, I have THE SLOWEST IROC!!! Why?????

Any suggestions to start troubleshooting???
Thank you very much!

Blucamaro

What was your 8th mile time's,just wondering cause the way my car is running and not hookin up right now i probably would run that in the quarter(and I have a 350)....

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http://community.webshots.com/user/blucamaro

Hurst

Hi,
My other times are
reaction: .642
I1: 2.246
I2: 6.698
I3: 10.346
I4: 13.391
et: 16.183
mph 82.659

reaction: .602
I1: 2.314
I2: 6.779
I3: 10.413
I4: 13.449
et: 16.233
I hope this helps!!

AlkyIROC

Go and get the car weighed (with you in it). IROC's are heavy. Estimating a 3700 pound car, you have about 170 rear wheel HP. Those 60 foot times should give you at least mid 15's.

There could be many things slowing you down. Check the timing, run premium fuel, leave everything you don't need at home (spare tire, jack, etc). If you can, get a scan tool and see what the engine is doing. You may have spark knock and the computer is retarding the timing. How hot is the engine? You'll get less performance running a 195 thermostat than you will with a 160 or a 180.

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Follow my racing progress on Stephen's racing page
and check out the race car

87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block

Best ET on a time slip: 11.242 altitude corrected to 10.69
Best MPH on a time slip: 121.52 altitude corrected to 127.76
Altitude corrected rear wheel HP based on power to weight ratio: 504.5
Best 60 foot: 1.546

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

[This message has been edited by Stephen 87 IROC (edited May 18, 2001).]

Hurst

Thanks! I will check into that. What is spark knock. Would I hear it or see other symtpoms????

smokin87iroc

my iroc only weighs 3500 lbs with me in it (about 200 lbs) so 3300 lbs for my car alone. i have headers and no cat but other than that its normal. i run a 14.48 @ 95 at 1200 ft in humid oklahoma.
Andrew

Thor

Do you shift yourself or leave it in OD? Your '60 times are really slow. Are you spinning off the line? My '60 times usually are around 1.95 and I never leave under full throttle. I also run 14.22 with a basically stock motor.

IROC5.7TPI

By the looks of the 60' times, I'd say hes blowing the tires away. If not, he needs to look at a possible clogged fuel filter.

Somethings wrong if his car is THAT slow.

I run a 1.9x 60' and get bottom 14's all day with a personal best of 13.98 @ 100mph. Motor all internally stock.



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Mike L.

"If it feels good - stay in it "

1987 IROC Z TPI 350 A4 3.27 Borg-Warner.

Mods: 2300-2500 Stall Converter, Shift Kit(GM parts), TPI Specialties Stage 3 PROM, Modified Airbox w/ K&N's, Relocated MAT sensor, Gutted MAF, Accel 8mm Wires, bypassed TB coolant, Flowmaster 3 chamber single 3" in/out muffler, airfoil, Random Tech Hi-Flow Converter (soon to go byebye!). ALL STOCK otherwise.
http://www.MichaelLasiuta.home.att.net

**BOYCOTT LAPEER DRAGWAY**

5.0GTA

well, it looks to me like he's running lean up top. I was having a lean condition at the track one time and my SES light kept comin on, i ran it anyways and left it in full auto and ran a 16.1, when i shifted it manually i got a 15.8, needless to say I got a full tuneup and replaced my fuel filter and ran a 15.3 the next week. Theres no way this guy is meltin the tires off the line..its an automatic people, and i seriously doubt a stock 305 TPI auto is gonna smoke them gatorbacks off the line. Just replace your fuel filter, get a tune-up, and shift it manually around 5100 and you'll be fine

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1988 Pontiac GTA 5.0 TPI
*FOR SALE* $4,000 obo
Mods: K&N Filter, Hypertech Air Foil, Hypertech Perf. Chip, 2.5in Flowmaster Muffler, Catco Hi-flow Cat

Maryland Int. Speedway Bracket Racing Trophy Winner

Best ET-15.32@88mph 2.077 60-ft.

Kills
94 Probe GT, 95 Mustang GT, 96 Impala SS, 85 Thunderbird 5.0, 95 Accord V6, 98 Integra VTEC, 70 Chevelle Malibu, CRX

1979 Pontiac Firebird
301/2-bbl automatic
Dog slow, flowmaster true duals
Best ET-break out the hour glass

Crusader

iTrader: (1)

Well it must be tune up/fuel filter time for me then. I was just at the track yesterday. Oh and by the way I DID smoke my tires OFF THE LINE for almost ALL of 1st gear in my 305/auto.

Best slip of the night:

R/T .987
60' 2.366
330 6.619
1/8 10.147
mph 69.10
1000 13.242
1/4 15.840
mph 86.99

best MPH of the night was 87.59
best 60' was 2.204

new87

About my stock times but my 60's ran 2.1's. Now you see my times in the sig.

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87 Z28 305 TPI, Auto, LT-1 cam (@.50 418/430, 194/199, LSA 111), roller timing set, 2.73, Gutted air boxes, K & N fillters, Dyno Max 3" cat back, 8.8 mm spirals, air foil, BFG Drag radials, and 170* Stat.
Old Best 15.414 @ 87.47.
new best 15.006 @ 89.55.
w/ drag radails 14.72 @ 92.1

“Fallen But Not Forgotten”

5.0GTA

well god d@mn, you need new tires then. What kind of gears do you have? I cant even smoke them in my 305/auto GTA w/3.27's! oh, and try to torque it up before you launch. Hold the brake, press the gas until 1500rpm's, then let go of brake and floor it. WOrks everytime for me and i get a slight chirp off the line, but no spinning at all. I almost pulled a sub-2 second 60ft.

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1988 Pontiac GTA 5.0 TPI
*FOR SALE* $4,000 obo
Mods: K&N Filter, Hypertech Air Foil, Hypertech Perf. Chip, 2.5in Flowmaster Muffler, Catco Hi-flow Cat

Maryland Int. Speedway Bracket Racing Trophy Winner

Best ET-15.32@88mph 2.077 60-ft.

Kills
94 Probe GT, 95 Mustang GT, 96 Impala SS, 85 Thunderbird 5.0, 95 Accord V6, 98 Integra VTEC, 70 Chevelle Malibu, CRX

1979 Pontiac Firebird
301/2-bbl automatic
Dog slow, flowmaster true duals
Best ET-break out the hour glass

tach'n_8000

Crusader,

What kind of tires are you running? Are they all-season tires?


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95 GS-R
5spd

modded? yeah it has some

Crusader

iTrader: (1)

I know the tires aren't great. They are Vison GTH 4's (think thats it)that were on the car when I bought it. I have 3.27's and couldn't rev it up at all with out spinning the **** outta them upon take off. Not to mention I was powerbreaking @ about 2 grand.

Jess

new87

Time for drag tires.