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3.9 diff gears 

 

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 Post subject: 3.9 diff gears
Posted: Tue Nov 28, 2006 9:21 pm 
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Hey guys..

Im buying an EF II XR8 MANUAL... it has 3.9 diff gears... i was just wondering, what will it rev at 100km/h... and what sort of top speed would it have?...

Do these diff gears affect the fuel consumption much?

Does it make a noticable difference in Acceleration?

Any information would be greatly appreciated...

And if anyone wants to go to the bother of typing a s**t - What are the top speeds of each gear with 3.9 diff gears....

Thanks

 

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Posted: Tue Nov 28, 2006 9:40 pm 
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Obviously it will rev higher at 100km/h but you won't use much more in fuel. That depends more on how often you keep your foot to the pan. Will be a difference in acceleration in comparison to say 3.23 or even 3.45. The engine will feel like it revs a lot quicker..

 

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Posted: Wed Nov 29, 2006 12:13 am 
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have a look at this, I made it to calc where my 3.7's would rev at 100kph.

 

 

Attachments:
Diff ratio calculator.xls [44 KiB]
Downloaded 147 times

 

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Posted: Wed Nov 29, 2006 12:22 am 
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Im pretty sure there was a thread on this topic (cant remember if its this site!?) any ways it did make a difference in rpm by about 400 at roughly 110 km/hr (3.45 vs 3.9)

Still its the best bang for your buck if its the first mod you do to your car as the behaviour and pick up changes for the better. You will feel more pick up with 4.11's but you'll end up spending more time shifting and revving it out than the 3.9's.

 

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 Post subject: 3.23 VS 3.9
Posted: Wed Nov 29, 2006 9:26 pm 
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Well my mate has 3.9's & I have 3.23 & before his motor had new lifters off the lights he would get a little bit of a jump on me but from 90km onwards I would catch him & beat him but now he has had the TOP END rebuilt he has got a better jump then me but in the end the 3.23 will WINDOUT & more get up & go past 100Km when you want to PLANT IT.

 

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Posted: Wed Nov 29, 2006 10:48 pm 
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I have 3.9's in mine AUTO fairy, it does about 2800 rpm at 110. I did notice a big difference in consuption with the auto around town, and lost about 100k range when on a long trip. EG last year for the Geelong AFD, i drove from Sydney to Melbourne, and used $300 of fuel at 1.40 a litre for the drive down.
Brett

 

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Posted: Thu Nov 30, 2006 12:30 am 
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Ill take you up on the challenge Ben, I very strongly doubt that you would beat my car to the limiter, although both dont have one :lol: By 70kph, Ive got 2 carlengths on my mrs XR6T, keeping in mind that i can launch a lot harder due to the manual

 

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 Post subject: Re: 3.9 diff gears
Posted: Sat Dec 02, 2006 6:13 pm 
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orloxsis wrote:
Hey guys..

Im buying an EF II XR8 MANUAL... it has 3.9 diff gears... i was just wondering, what will it rev at 100km/h... and what sort of top speed would it have?...

Do these diff gears affect the fuel consumption much?

Does it make a noticable difference in Acceleration?

Any information would be greatly appreciated...

And if anyone wants to go to the bother of typing a s**t - What are the top speeds of each gear with 3.9 diff gears....

Thanks


Well I don't have 3.9 but 3.73s in my XR8 and mine sits at 2200 @ 100 in 5th, guessing your 3.9s would add a couple of hundreds to that.

top speed - depends on whats done to the motor.

yes they affect fuel consumption - more so because u drive it harder as its more fun, but yes there is a slight increase over standard, on a side note, i found a good exhaust and tune helped peg mine back to 'normal'

make a great difference in acceleration - punchier in all gears, worthwhile change.

only other thing i can mention is check your speedo, mine was out 14km so i had to get the speedo and odometer recalibrated.

hope that helps

 

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