german-motorsport

please state your 1/4 mile times!
Any official GM data how much abuse they take?

AlkyIROC

When I was still using one, I ran high 11's at 117 mph on 26" tall slicks and 3.27 gears.

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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 (times are for the current engine)

Best ET on a time slip: 11.447 altitude corrected to 10.99
Best MPH on a time slip: 119.42 altitude corrected to 124.86
Altitude corrected rear wheel HP: 493
Best 60 foot: 1.586

Racing at 3500 feet elevation with a typical race day over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

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

ZZ42Fast

iTrader: (2)

Stephen, when you say when I had one you worry me You didn't blow it up did ya?

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'86 Iroc ZZ4
Best Run 13.8 @ 100mph

88 427 Camaro

I've been running 1.7x at 12.1x with no problems (3.27 ratio). I recently installed a 3.73 ratio and may even try a 4.10 in one of my 9 bolts to see how works. Just don't use a trans brake or a manual trans (with slicks) and it should work well into the 11's.

Miles

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88 427 Camaro
12.18 @ 113mph 1.75 60ft
Currently installing 3.73's into my 9 bolt (YES, it is a 9 bolt & YES they are 3.73's, not 3.70. I currently have 4.10 gear sets and new series 3 carriers in stock for 9 bolts )
www.koolmeister.com

Acceld Z

Notice both of these gentlemen run big blocks which are more violent (TORQUE) than small blocks

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92Z28
89GTA

AlkyIROC

I never used mine with the big block. I was running a very strong 383 that blew up last year. I changed the diff just before the SBC blew up. There was nothing wrong with it. I even still have the complete 9 bolt diff with disk brakes sitting in my shed. The reason I changed it is the lack of performance parts at the time for the 9 bolt. I needed some good aftermarket axles. I wanted a solid diff cover to add strength. And mainly I needed deeper gears. My current 10 bolt has 4.10 gears and this winter a ford 9" goes in with 4.56 gears with a spool.

Those high 11's at 117 mph were with the 3.27 geared 9 bolt on 26" slicks. I was pulling 1.7's 60 foot times. The combination I was running either needed 3.90 gears (no such luck) or going to 28" tall tires and 4.10 gears which I did with the diff swap. That way I was topped out at the red line at the end of the 1/4 mile. With the old combination by the time I hit the end of the 1/4 mile I was only doing about 5500 rpm but was shifting at 6500. There was more in the engine but gearing was my limiting factor. Unfortunatly I never did get to see what the potential of the 383 was since it blew up before I was able to get a good full pass with the new diff. The diff and new gearing wasn't the cause. I threw a rod and disintigrated a piston. Only the heads and intake were salvagable.

Fastcamaro87

i had a 9-bolt with 3.45 gears until i broke one of the teeth off the pinion gear still driveable noisy as hell tho, so far i have only heard about the gears being weak. when i get some money together i am going to put some 3.73`s or 3.70 in it, but so far the 10-bolt is doing fine.good thing i had an extra rear...

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87 IROC-z 305 TPI
Borg Warner T-5 fresh rebuild
10-bolt 3.73 Richmond gears rebuilt GM posi,
Ported Plenum and Runners Homemade AFPR
ACCEL 8.8 wires, High output coil,and cap & rotor
Bosch platinum + 4 plugs
Ram Air w/ K&N filters,
MAF sensor screens removed, TB coolant bypass
Polyurethane tranny and torque arm mounts
Dynomax catback w/custom tips
K&N oil filter,Mobil 1 synth, Futura GLS Super Sport tires 265/50/15 rear and 235/60/15 front mounted on 86 monte carlo SS rims ,

400 sbc and a 6 spd in the works