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Old 12-31-2002, 04:20 PM
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Post What gears & tire size for racing

So lets say Im in the ballpark of 425 horse. The motor in 68 Chevelle with a turbo 400 ,Full Manual Valve Body , Stage 3 shift kit With 2800 Torque converter.

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Old 12-31-2002, 04:43 PM
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are you running 660 ft or 1320.
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Old 12-31-2002, 07:44 PM
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Try these guys, they can help.

www.pchotrod.com

Their program helped me with tire size and ring/pinion selection.

Using the computer software I have and assuming the following, your car could be expected to run the following times.

12.92 seconds at 106.8 mph

60 foot times are 1.86 seconds

3995 lb. weight with driver

425 hp.

450 ft/lb. torque (estimate)

5800 rpm redline (estimate)

POSI rear with 4.56 gear (guess)

Rear tires are 29" x 12" racing slick with alloy wheels (suggestion)

2800 rpm stall converter

Shifting at 5800 rpm (redline) (estimate based on guess)

3770 RPM at 70 mph

I think that the 425 hp estimate that was noted in another post may be a bit high.

What is the redline that you feel is safely obtained? This is one of the things that will really pull out the horsepower.

Will you run pump gas?

Classify the engine setup for me:

Hot Street
Street Strip
Mild Race
Full Race

[ December 31, 2002: Message edited by: 2quik ]</p>
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Old 12-31-2002, 08:30 PM
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Yea.
It depends on the track your on. 1/8th or 1/4. If its a mainly street car, Id go no higher than a set of 4.10's. I had 4.88's in my Chevelle and in town was fun, but cruising to get there was horrible! Let us know what your planning. HG
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Old 01-01-2003, 09:20 AM
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[quote]Originally posted by 2quik:
<strong>Try these guys, they can help.

www.pchotrod.com

Their program helped me with tire size and ring/pinion selection.

Using the computer software I have and assuming the following, your car could be expected to run the following times.

12.92 seconds at 106.8 mph

60 foot times are 1.86 seconds

3995 lb. weight with driver

425 hp.

450 ft/lb. torque (estimate)

5800 rpm redline (estimate)

POSI rear with 4.56 gear (guess)

Rear tires are 29" x 12" racing slick with alloy wheels (suggestion)

2800 rpm stall converter

Shifting at 5800 rpm (redline) (estimate based on guess)

3770 RPM at 70 mph

I think that the 425 hp estimate that was noted in another post may be a bit high.

What is the redline that you feel is safely obtained? This is one of the things that will really pull out the horsepower.

Will you run pump gas?

Classify the engine setup for me:

Hot Street
Street Strip
Mild Race
Full Race

[ December 31, 2002: Message edited by: 2quik ]</strong><hr></blockquote>
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Old 01-01-2003, 09:43 AM
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When I ran at the track it was friday nights and $5.00 race . But they didn't time yeah they just used lights at the end of track to show ya who won . I was shifting at 7000 rpm with a 4 speed , 12 bolt posi 3.73 gears
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Old 01-01-2003, 12:54 PM
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If your 1/4 mile racing. You want your car at redline at the end of the 1/4. Did you pay attention to what your rpm was when you crossed the finish mark? HG
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Old 01-01-2003, 01:42 PM
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No but when I shift in to forth gear I only had about 50 yards to the finish line
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Old 01-01-2003, 04:03 PM
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SHIFTING AT 7000 RPM IS OUT OF THE POWER CURVE OF A 355CU IN 5800 TO 6000 WOULD PICK UP THE MPH.
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Old 01-01-2003, 06:56 PM
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Are we still talking about the 1968 Chevelle with the TH400? If so, a TH400 does not have a 4th. gear.

Did the car have a different transmission at that time?

I can rework the numbers with the info provided if you like.
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Old 01-01-2003, 11:11 PM
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hey could you figure that out for me? i haev a 1970 chevelle with a 383 stroker, turbo 350 w/shift kit and 4.11 rear end. it should be around 400 hp. if you do, could you PM me? im new to this board but it seems pretty cool. later
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Old 01-02-2003, 07:49 AM
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I will need your rear tire size to start the process.
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Old 01-02-2003, 01:16 PM
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Repley to 2quik: Im thinking 4.33 gears , Tires 15" 28" tall 10" wide
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Old 01-02-2003, 03:24 PM
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12.67 seconds at 106.7 mph

60 foot times are 1.77 seconds

3995 lb. weight with driver

425 hp.

450 ft/lb. torque (estimate)

7000 rpm redline (Your info)

POSI rear with 4.33 gear

Rear tires are 28" x 10" racing slick with alloy wheels (Your info)

2800 rpm stall converter

Shifting at 7000 rpm (redline) (Your info)

3670 RPM at 70 mph

I think that the 425 hp estimate that was noted in another post may be a bit high.

Will you run pump gas?

Classify the engine setup for me:

Hot Street
Street Strip
Mild Race
Full Race

[ January 02, 2003: Message edited by: 2quik ]</p>
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Old 01-02-2003, 06:06 PM
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2quik I run 92 octane plus a can of N.O.S. octane booster. I don't drive the car on the streets every often .Im looking for best gear & tire comb to get the fastest time in the 1/4 mile with the turbo 400.
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