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Fuel Economy...
by
eightyonerabbit
on 30 Jan, 2008 23:24
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okay, everyone knows that these things are capable of almost infinite mpg's, but i think we should have a thread about the most mpg's uve ever gotten... best ive gotten so far is 48mpg, but i think i might beat that with this tank of diesel... :wink:
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#1
by
Clankin-Rabbit
on 30 Jan, 2008 23:39
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Not to bust off topic here...but its slightly related to fuel economy
to my understanding...84' was the only year VW put the 4-speed in the rabbits correct? A 4-speed would be the best, economically based tranny for getting the best MPG out of a tank of diesel over a 5-speed right?
I'm getting one hopefully this weekend..and hoping its got the 4-speed. A manual, naturally aspirated, extremely slow diesel in a small car will be a complete blast to drive....I totally can't wait. :lol: It will be my first diesel and VW.
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#2
by
burn_your_money
on 30 Jan, 2008 23:42
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#3
by
burn_your_money
on 30 Jan, 2008 23:43
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VW used 4 speed all through out the mk1 chassis 74-84 I think
It depends what kind of driving you are doing and the gearing of the engine in the 4 vs 5 debate
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#4
by
Baselyne
on 31 Jan, 2008 05:37
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5th gear lower RPM's
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#5
by
burn_your_money
on 31 Jan, 2008 07:58
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I think as far as 020s go the 4A 4 speed has the lowest overall final output
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#6
by
ldeikis
on 31 Jan, 2008 16:31
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I think as far as 020s go the 4A 4 speed has the lowest overall final output
How much of a difference in final drive is significant? IE, comparing a 5 speed FF to the 4 speed 4A:
FF .71 * 3.89 = 2.762
4A .70 X 3.94 = 2.758
Is that difference significant? If you work that out, it's less than 1 mph difference at the wheels, no? I pulled the numbers from
http://www.brokevw.com/020ratios.html and
http://www.scirocco.org/gears/ and just plugged them into their calculator.
No doubt the 4A IS lower, but what does a .004 difference really mean?
Luke (getting wintertime 41mpg overall with a N/A 1.6 rabbit through aforementioned FF)
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#7
by
burn_your_money
on 31 Jan, 2008 16:57
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The 4 speed weighs less, has less rotating mass and also has less resistance
I'm glad they finally added the 4A to the list
You can make a custom lower one, and also the dodge omnis (I think) used VW tranny (4 speed) that was even lower IIRC
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#8
by
eightyonerabbit
on 31 Jan, 2008 16:59
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i have an FK with a .71 5th gear... i had a GP in it, but i needed better gearing... i think i lost about 1mpg, but its not that noticable...
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#9
by
Turbinepowered
on 01 Feb, 2008 07:56
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I think as far as 020s go the 4A 4 speed has the lowest overall final output
How much of a difference in final drive is significant? IE, comparing a 5 speed FF to the 4 speed 4A:
FF .71 * 3.89 = 2.762
4A .70 X 3.94 = 2.758
Is that difference significant? If you work that out, it's less than 1 mph difference at the wheels, no? I pulled the numbers from http://www.brokevw.com/020ratios.html and http://www.scirocco.org/gears/ and just plugged them into their calculator.
No doubt the 4A IS lower, but what does a .004 difference really mean?
If you put the final drive from the FF into the 4A you'd have 2.723...
an improvement of .039 instead of .004...
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#10
by
silvertdi
on 01 Feb, 2008 23:16
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Best I've gotten was 59.6 mpg on a 800 mile trip. I kept it at 62 mph for nearly the entire trip. Mine's an '81 with a GP 4 speed. It even had a head gasket that was letting go. Perhaps it was burning some antifreeze.
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#11
by
greenbert
on 02 Feb, 2008 19:31
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My ecodiesel gets about 40-42 mpg, and from what I learned the ecodiesel trans has the highest final drive.
Btw, whats an ASF trans?
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#12
by
estimatd
on 02 Feb, 2008 21:15
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I am a bit naive when it comes to trans codes and gear ratios, so I'm sorry I didn't follow with most of this thread, could someone help me out with this. I have an 81 NA with a 4spd, from what you guys are saying, it would be better to stick with the 4spd, considering I'm looking for the best mpg's? The trans needs either to be rebuilt or replaced and I considered replacing it with a 5spd, thinking that the 5th gear would improve hwy mpg's while giving it a bit more pep down low. Is that wrong to assume? Also, I'm totally open to mixing and matching gears and final drives as I have someone to help me build the right setup, but is the difference negligible??
Thanks and sorry for being slow with the tranny logic! :oops:
-Charlie
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#13
by
eightyonerabbit
on 02 Feb, 2008 22:27
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I am a bit naive when it comes to trans codes and gear ratios, so I'm sorry I didn't follow with most of this thread, could someone help me out with this. I have an 81 NA with a 4spd, from what you guys are saying, it would be better to stick with the 4spd, considering I'm looking for the best mpg's? The trans needs either to be rebuilt or replaced and I considered replacing it with a 5spd, thinking that the 5th gear would improve hwy mpg's while giving it a bit more pep down low. Is that wrong to assume? Also, I'm totally open to mixing and matching gears and final drives as I have someone to help me build the right setup, but is the difference negligible??
Thanks and sorry for being slow with the tranny logic! :oops:
-Charlie
well depending on your gear ratios now, u probably wont gain any fuel economy on the highway... if you have the GP tranny which is what was in my car (81 N/A), then u have a 3.89 final drive with a .71 4th gear which is about the best that you could hope for as far as highway mileage... i picked the FK tranny with the 5th gear swap so that my highway mileage would be the same, but my gearing down low would be so close that i would get instant torque as soon as i shift... basically, if you want about 2 less miles per gallon, then do the 5 speed swap with a .71 5th gear, but if you want the same MPG that you have now, just rebuild your tranny or get a GP or an FF...
sorry for dragging this post on, but i jsut couldnt help myself... i like to hear myself type... :lol:
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#14
by
estimatd
on 02 Feb, 2008 23:56
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ok thanks for the info, to keep it easy and since I'm used to driving with the 4spd, I'll probably just take your advice and rebuild it. Basically my fuel economy sucks right now which is why I considered swapping to a 5spd, but I think there are a few other problems that need to be addressed which would help get the mpg's up. I really think this new diesel is destroying my IP so I'll probably need to get that rebuilt soon too :x
thanks again.
-Charlie