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#1 |
72 GMC
Join Date: Feb 2008
Location: Wells, Maine
Posts: 534
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TH350 vs 200R4
On the highway, what is the MPG and RMP difference
for each tranny running behind a stock 350 ? Thanks |
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#2 |
72 GMC
Join Date: Feb 2008
Location: Wells, Maine
Posts: 534
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Re: TH350 vs 200R4
that's "RPM", not "RMP" !
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#3 |
Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: TH350 vs 200R4
the final drive ratio of a 2004R is 0.71// multiply your present RPM by 0.71 to get what the RPM will be. divide for mpg
__________________
71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY Last edited by cdowns; 05-25-2010 at 07:35 PM. |
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#4 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: TH350 vs 200R4
there are too many variables to answer either question.
What gear ratio do you have in the diff, ans what size tires do you have. What is your cruise speed? Adding an overdrive can actually HURT the MPG on the freeway if you have tall gears out back. |
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#5 |
Registered User
Join Date: Mar 2003
Location: San Francisco, CA USA
Posts: 2,454
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Re: TH350 vs 200R4
The rpm drop will be a little better than the O/D ratio because the 200-4R has a converter lockup. Even a "tight" converter still slips at highway speed.
Ray |
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#6 |
Registered User
Join Date: Apr 2010
Location: Boise, ID
Posts: 1,280
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Re: TH350 vs 200R4
I am interested in this as well since I have a powerglide and want to switch. So which one is overall better? Stronger? More efficient? (sorry, not trying to hijack your thread)
Last edited by ubtripn; 05-25-2010 at 09:31 AM. |
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#7 |
Cops, ha, catch me if you can!
Join Date: Jun 2009
Location: Santa Barbara, CA.
Posts: 271
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Re: TH350 vs 200R4
I currently have the th350 and I am looking at going with the 200-4r. With my set-up now; 3.73 gears and a 26" tire(275 60 15) at 60 I am pushing about 2800-2900RPM, with the swap to the 200-4r evryting else the same, my RPM will drop to 2395 (thats at 70MPH). Thats a good drop in RPM and I believe it will increase my MPG on the highway to about 12 or so.
__________________
72 C-10 Stepper 350/TH350 3.73 in the back Edelbrock intake and Carb Hooker Comp Headers 275/60R15 on Rallies ![]() ![]() |
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#8 |
sharp as a marble
![]() Join Date: Jan 2007
Location: atlantic beach,florida
Posts: 1,082
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Re: TH350 vs 200R4
Find an RPM calculator on the web. The inputs to this formula will be : tire size, gear ratio, and MPH. I am a big fan of the 200r4, because of the spread in the gear ratio's of the transmission. 700r4 has a very low 1st gear.
I will tell you that to get a 200 to shift firm in all gears can be some work. UNLESS you get the BRF calibration. I have done several of these, and it usually takes dropping the pan a time or two to get what I like in firm, but not too harsh shifts. The final drive ratio in a 200 is .67 |
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#9 | |
Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: TH350 vs 200R4
Quote:
http://fbperformance.com/viewtrans.a...nsmissionID=27
__________________
71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY Last edited by cdowns; 05-25-2010 at 08:14 PM. |
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#10 |
Cops, ha, catch me if you can!
Join Date: Jun 2009
Location: Santa Barbara, CA.
Posts: 271
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Re: TH350 vs 200R4
Gear ratios of the 200-4R are: 2.74 first, 1.57 second, 1.00 third,
.67 fourth. You will find different answers depending on the website you’re looking at
__________________
72 C-10 Stepper 350/TH350 3.73 in the back Edelbrock intake and Carb Hooker Comp Headers 275/60R15 on Rallies ![]() ![]() |
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#11 |
Registered User
Join Date: May 2009
Location: Eliot, Maine
Posts: 1,314
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Re: TH350 vs 200R4
my dad's suburbans with stock size tires:
'72 2wd w/ th350, 305 swap, q-jet and 3.73 gears: 15mpg highway (60mph) '84 2wd w/ 700-r4, 350 q-jet and 3.73 gears: 18mph highway '87 2wd w/ 700-r4, 350 tbi and 3.73 gears: 18mpg highway you guys need to remember that trucks have poor aerodynamics and weigh more yet everyone is driving faster and faster each day. mpg's drop off drastically over 60mph as drag increases exponentially. even with optimal highway gearing, most vehicles get best fuel mileage around 50mph. keep it to 60-65 so you aren't contributing unduly to all the anti-truck/tree hugging/poor mpg hype! Last edited by capev86; 05-25-2010 at 09:08 PM. |
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#12 |
Cops, ha, catch me if you can!
Join Date: Jun 2009
Location: Santa Barbara, CA.
Posts: 271
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Re: TH350 vs 200R4
I really don't care about milage, right now I get about 8.5-9MPG and that dose not bother me. All I really want is to be able to drive on the freeway (60 or so) and not be pushing 2900RPM. The mileage increase would be nice, but if I don't see an increase I would not care.
__________________
72 C-10 Stepper 350/TH350 3.73 in the back Edelbrock intake and Carb Hooker Comp Headers 275/60R15 on Rallies ![]() ![]() |
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#13 |
Registered User
Join Date: May 2009
Location: Eliot, Maine
Posts: 1,314
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Re: TH350 vs 200R4
you are nuts....
i think less than 10mpg sucks....even back 12 years ago when gas was still a buck a gallon. my 72 burb gets 10-11 with a 307, 3 on the tree (more efficient than an auto) and 4.57 rear gears. i'm swapping a 4.10 third member into the ho52 rear and hoping to get my mileage up to 14 or so. 50 bucks for gas every 200 miles makes it really tough to enjoy driving my truck. guess i'll have to save up a bit for the big camping trip coming in a couple months. i'll be back down to 8-10 pulling the family camper! |
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