140mph check it out
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Joined: Sep 2002
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140mph check it out
just thought yall would like to know my
70' f250 pickup did 100mph at 3000rpms on 10-11-02
its a far cry from 140 but its a start!
it only toped out at 80mph at 3200rpms the first
week i had it, but thx to some good tips so far
my project is rolling along
THX AGAIN
70' f250 pickup did 100mph at 3000rpms on 10-11-02
its a far cry from 140 but its a start!
it only toped out at 80mph at 3200rpms the first
week i had it, but thx to some good tips so far
my project is rolling along
THX AGAIN
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Joined: May 2002
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From: Rimbey Canada
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Junior User
Joined: Sep 2002
Posts: 72
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From: Nashville USA
140mph check it out
In order to go a higher speed at a lower RPM, you would have to change the rear end gear (ie change from 3.73 to 3.08) or the transmission (go to overdrive tranny) or the tire diameter (increase tire diameter). Merely doing tune-up type maintenance will not do this.
John
John
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Elder User
Joined: May 2002
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140mph check it out
Unless it was in passing gear on the slower run, or something was slipping badly... or the tach was acting up, or he switched tire diameters... Or there was a typo...
But you're right.
The math just doesn't quite work out as the statement is written.
1972 F250 Custom Sport Camper Special 4x2 360 2v C6 3.73
Some day hope to shorten to a 104" wheelbase as part of a Broncification project
My FTE Website -- http://www.clubfte.com/users/mlf72f250/index.html
My Galleries -- https://www.ford-trucks.com/user_gallery/displaygallery.php?userid=1108
But you're right.
The math just doesn't quite work out as the statement is written.
1972 F250 Custom Sport Camper Special 4x2 360 2v C6 3.73
Some day hope to shorten to a 104" wheelbase as part of a Broncification project
My FTE Website -- http://www.clubfte.com/users/mlf72f250/index.html
My Galleries -- https://www.ford-trucks.com/user_gallery/displaygallery.php?userid=1108
Elder User
Joined: May 2002
Posts: 799
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140mph check it out
With a 3.00:1 rear end, 30" OD tires, no tranny slippage, and the engine at 3000 rpm, the speed would be around 90mph.
How are your specs different from these?
I'll run a few numbers if you'd like.
--Matt
1972 F250 Custom Sport Camper Special 4x2 360 2v C6 3.73
Some day hope to shorten to a 104" wheelbase as part of a Broncification project
My FTE Website -- http://www.clubfte.com/users/mlf72f250/index.html
My Galleries -- https://www.ford-trucks.com/user_gallery/displaygallery.php?userid=1108
How are your specs different from these?
I'll run a few numbers if you'd like.
--Matt
1972 F250 Custom Sport Camper Special 4x2 360 2v C6 3.73
Some day hope to shorten to a 104" wheelbase as part of a Broncification project
My FTE Website -- http://www.clubfte.com/users/mlf72f250/index.html
My Galleries -- https://www.ford-trucks.com/user_gallery/displaygallery.php?userid=1108
Elder User
Joined: Aug 2001
Posts: 962
Likes: 2
From: Collierville, TN
140mph check it out
>you guys dont deserve to drive fords
>think about it !
We are thinking about it, and it's plain that one of five things is happening:
1. you changed your final drive ratio but left that important fact out;
2. you were smoking dope and hallucinating when you made your speed runs;
3. your 100 mph speed was clocked by pushing your truck off a cliff;
4. you mistyped your initial post, and achieved 100 mph at 4000 rpm and not 3000 rpm; or
5. you're just a liar.
It is simple math. First of all, you can't get to 100 mph at only 3000 rpm with a stock driveline. The lowest gear ratio available from Ford was 3.25:1, which only yields 26 mph per thousand rpms with standard tires and a manual trans (no torque converter slippage). With a C6 auto and standard tires (235/75R15, about 29" high), you'd barely be going 70 mph at 3000 rpm. To get to your claimed 100 mph at 3000 rpm, you'd need a rear end ratio of about 2.50:1 or tires that are 38 inches tall! So which is it?
Second, you claim to have initially topped out at 80 mph with the engine turning at 3200 rpm. That part is believeable. With 29-30" tall tires, a C6 and a 3.25:1 rear end, 80 mph is about what you would see at 3200 rpm. Unfortunately, you claim that a basic engine tune-up got you an additional 20 mph. The only way that could happen is if the tune-up generated more power, which allowed the stronger engine to push to a higher rpm. Assuming the same tires and final drive ratio, your claimed increase in top speed of 25% (80 mph to 100 mph) would require the engine to be turning 25% faster, i.e., 4000 rpm instead of 3200 rpm. You simply can't go faster on fewer rpms without changing the final drive ratio, the tire size, or both.
>think about it !
We are thinking about it, and it's plain that one of five things is happening:
1. you changed your final drive ratio but left that important fact out;
2. you were smoking dope and hallucinating when you made your speed runs;
3. your 100 mph speed was clocked by pushing your truck off a cliff;
4. you mistyped your initial post, and achieved 100 mph at 4000 rpm and not 3000 rpm; or
5. you're just a liar.
It is simple math. First of all, you can't get to 100 mph at only 3000 rpm with a stock driveline. The lowest gear ratio available from Ford was 3.25:1, which only yields 26 mph per thousand rpms with standard tires and a manual trans (no torque converter slippage). With a C6 auto and standard tires (235/75R15, about 29" high), you'd barely be going 70 mph at 3000 rpm. To get to your claimed 100 mph at 3000 rpm, you'd need a rear end ratio of about 2.50:1 or tires that are 38 inches tall! So which is it?
Second, you claim to have initially topped out at 80 mph with the engine turning at 3200 rpm. That part is believeable. With 29-30" tall tires, a C6 and a 3.25:1 rear end, 80 mph is about what you would see at 3200 rpm. Unfortunately, you claim that a basic engine tune-up got you an additional 20 mph. The only way that could happen is if the tune-up generated more power, which allowed the stronger engine to push to a higher rpm. Assuming the same tires and final drive ratio, your claimed increase in top speed of 25% (80 mph to 100 mph) would require the engine to be turning 25% faster, i.e., 4000 rpm instead of 3200 rpm. You simply can't go faster on fewer rpms without changing the final drive ratio, the tire size, or both.
Junior User
Joined: Aug 2010
Posts: 58
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From: hughesville
stupid people are like slinkys ABSOLUTLY USELESS UNLESS PUSHED DOWN A SET OF STAIRS!!!!.....this guy had to of been toking something cause my 72 with a 351modified c4 trans and god only knows what gears in a 9'' rear with 235/75/r15 tires and only motor mods are open air filter, edelbrock intake with a holly 550 4bbl, with dual exaughst from manifolds to daytona turbo mufflers i run about 3900-4100 rpms at 100mph+ the poor thing screems and goes chugalug chugalug