sleeper

Does anyone have timeslips from before they changed their rear gear to after? (without other mods)

I want to see what kind of 60 foot time (and 1/4 mile) gain you get when changing from a 3.27 to a 3.43 or a 3.73

AlkyIROC

No 2 cars are the same. Just because someone gained .3 won't mean you will. It all depends on how the car is set up and what kind of modifications have been done to the engine.

When I had 3.27 gears then best ratio for my setup would have been 3.90. Since that wasn't available I went to 4.10 and changed tires from 26" tall to 28" tall to get the same effect.

Also going from 3.27 to 3.70 (9 bolt ratios available in north america) will increase your rpm at highway speeds. You can also have too much and spin the tires resulting in slower ET.

I raced for 2 years with 3.27 gears and only changed diffs because of the lack of performance parts available for the 9 bolt.

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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

sleeper

I realised what you said when I wrote the post. I'm only looking for a general idea here. Besides the engine plenty of other factors could change the results... that's why I'm more interested in 60 foot times... they would be a better indicator of wheel slip.

My end result here is to find out if getting the optimum rear end for my car is worth the cash (or if it's a waste of $500 to get .2 of a second and lot's of wheel hop)

MeanGreen 305

I upgraded to 3:42's from 2:73's and gained .3 overall. But, I also added the Hotchkiss rear suspension package and the Spohn adjustable torque arm.

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Always looking to go faster....383 is soon on the way!!!!!!

Willie

iTrader: (1)

The first mods on my other stock '87 305 TPI automatic were gears and exhaust. I went from 3.23's to 3.42's and a dual-cat with 3-inch catback exhaust. I gained 0.3 seconds. I do not know which mod contributed the most gain. It's all outlined on my webpage.

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Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
Former Paxton (6-psig): 12.57 @ 111 mph.
Former Paxton (6-psig) & former 50-hp nitrous: 12.04 @ 114 mph.
Current ATI D1SC (Initially 10-psig): Projecting high 11's.
Future ATI D1SC (15-psig): Gotta catch them pesky 26-psig boosted TTA's!!

http://willie.camaro-firebird.org/

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.