Final Drive and Power gains
06-28-2006, 08:52 AM
#21
Originally Posted by 350Zteve
In my experience, you always LOSE some rwhp when you go to a shorter ring and pinion setup because of the increased friction. In the Camaro and Mustang world it was typical to lose 7 or 8 whp when changing out to 3.73 or 4.10 gears. Yes the car is faster overall due to the gearing change, but on a dyno you will actual drop a few ponies. Don't let this discourage you, your car is quicker with the shorter gears.
06-28-2006, 01:02 PM
#22
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How much quicker?
So how much quicker are the 3.9 gears in the 6MT than stock? Anyone observed 0-60 or 1/4 mile time/speed improvements...or is it all just seat of the pants?
Thanks
Thanks
06-28-2006, 01:27 PM
#23
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Seat of the pants for now, but the car really DOES feel faster.
Also, FWIW, I did manage to pull awa from a few stock 6MTs already, and my car is 5AT with the 6MT pumpkin...
Also, FWIW, I did manage to pull awa from a few stock 6MTs already, and my car is 5AT with the 6MT pumpkin...
06-28-2006, 03:57 PM
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Originally Posted by 97supratt
If you want to check out the difference, just look at wrx's vs sti's. The sti's have such shorter gearing which gets them awesome 1/4 mile et's.
06-28-2006, 04:04 PM
#26
Originally Posted by 97supratt
Dont you also gain some torque? The car will definitely be quicker because of the shorter gears and the rpm staying inside the powerband. +1 for shorter gears
06-28-2006, 05:36 PM
#27
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Originally Posted by 350Zteve
I can't remember. I know on my 2000 Camaro SS, I lost about 6rwhp going to the 3.73 gears, but the car sure hauled ***.
Like mentioned earlier, getting locked into the auto-forum mentality that dyno #'s are everything is expensive and not practical...
06-28-2006, 06:38 PM
#28
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I guess it is possible that you could loose a tiny bit of whp doing the swap, as you have changed a component in the drivetrain, but I could also see you being just as likely to gain a tiny bit. Change could go either way IMO, depending on fitment, etc. I think any loss seen on a dyno would probably be due to running pre-swap at 1:1 and post swaps at a different ratio. Some dynos seem to handle different ratios OK, but most will give you the best numbers 1:1.
06-29-2006, 09:35 AM
#29
I would tend to agree with steve that if anything you stand to lose a minute amount of power due to more friction.
also, 1:1 (5th) at the tranny is still being multiplied by the FD...
Gearing is not a power adder, simply a torque multiplier. If you don't know the difference between hp and torque (a lot of people don't), now would be a good time to learn.
also, 1:1 (5th) at the tranny is still being multiplied by the FD...
Gearing is not a power adder, simply a torque multiplier. If you don't know the difference between hp and torque (a lot of people don't), now would be a good time to learn.
06-29-2006, 11:15 AM
#30
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So has anyone measured the difference in acceleration with the 3.9s over stock? We have seat of the pants testimonials but has anyone done the quarter after a 3.9 instal?
06-29-2006, 04:00 PM
#32
Originally Posted by sentry65
people with a great launch with drag radials have said it helped .1-.2 sec faster, with a 2mph trap speed increase.
06-29-2006, 04:45 PM
#33
well maybe it's possible, just passing along what I've read
people with 5AT's switching their 3.36 to a 3.54 FD have claimed .5 sec and that's only a 6% difference in gearing vs the 3.9's 10%. I think that's partly cause the 5AT's gearing is so much taller than the 6MT's
people with 5AT's switching their 3.36 to a 3.54 FD have claimed .5 sec and that's only a 6% difference in gearing vs the 3.9's 10%. I think that's partly cause the 5AT's gearing is so much taller than the 6MT's
06-29-2006, 09:30 PM
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***Nominated for post of the year***
I laughed, I cried, I walked away a better man...
I laughed, I cried, I walked away a better man...
Originally Posted by Oleg
Unfortunately this is the usual my350z.com FI project progress:
1)Read the forums
2)Get obsessed with dyno numbers more then the butt dyno feel
3)Go for over 400whp on stock internals, b/c that's what all the cool guys have. Come on, 400 is the holy grail. Even 10whp less is not cool. Same mentality that makes you feel that something for $9.95 is a better deal the $10.
4)Blow up the motor. At this stage most of us run out of money. At this point there is a fork ith the path
5a)Throw in forged internals
6a)Well, not that you're build, don't be a wimp and go for 500-600 whp, like the cool guys
7a)End up with something unstreetable and nearly undrivable, but be everyone's hero.
But who cares, each of your update threads gets over a 1000 views and 5 pages of replies in less then 3 days. Not to mention that your tuner will absolutely love you and blow so much sunshine up your ***, you'll start believing it yourself (I know from experience. I dropped almost 7G in a month at one shop, the owner test drove my car, I drove back and he kept on telling me that I am such a great driver and should be playing with a ton on power
).
OR
5b)Put the car in the driveway
6b)Wait for god know how long to get the $$ together. The more you wait the hight # goals you dream up
7b)Proceed to 5a
1)Read the forums
2)Get obsessed with dyno numbers more then the butt dyno feel
3)Go for over 400whp on stock internals, b/c that's what all the cool guys have. Come on, 400 is the holy grail. Even 10whp less is not cool. Same mentality that makes you feel that something for $9.95 is a better deal the $10.
4)Blow up the motor. At this stage most of us run out of money. At this point there is a fork ith the path
5a)Throw in forged internals
6a)Well, not that you're build, don't be a wimp and go for 500-600 whp, like the cool guys
7a)End up with something unstreetable and nearly undrivable, but be everyone's hero.
But who cares, each of your update threads gets over a 1000 views and 5 pages of replies in less then 3 days. Not to mention that your tuner will absolutely love you and blow so much sunshine up your ***, you'll start believing it yourself (I know from experience. I dropped almost 7G in a month at one shop, the owner test drove my car, I drove back and he kept on telling me that I am such a great driver and should be playing with a ton on power
).OR
5b)Put the car in the driveway
6b)Wait for god know how long to get the $$ together. The more you wait the hight # goals you dream up
7b)Proceed to 5a
06-30-2006, 05:09 AM
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Originally Posted by sentry65
well maybe it's possible, just passing along what I've read
people with 5AT's switching their 3.36 to a 3.54 FD have claimed .5 sec and that's only a 6% difference in gearing vs the 3.9's 10%. I think that's partly cause the 5AT's gearing is so much taller than the 6MT's
people with 5AT's switching their 3.36 to a 3.54 FD have claimed .5 sec and that's only a 6% difference in gearing vs the 3.9's 10%. I think that's partly cause the 5AT's gearing is so much taller than the 6MT's
That was me.
06-30-2006, 09:10 PM
#36
Originally Posted by sentry65
well maybe it's possible, just passing along what I've read
people with 5AT's switching their 3.36 to a 3.54 FD have claimed .5 sec and that's only a 6% difference in gearing vs the 3.9's 10%. I think that's partly cause the 5AT's gearing is so much taller than the 6MT's
people with 5AT's switching their 3.36 to a 3.54 FD have claimed .5 sec and that's only a 6% difference in gearing vs the 3.9's 10%. I think that's partly cause the 5AT's gearing is so much taller than the 6MT's
Current plan is to drop the car off at AAM on the 8th. Leave it for 2-3 weeks depending on my work schedule and how things go there. I'll pick it up and it'll have a reflashed ECU, 3.917 diff and a Quaife.
I'm optimistically hoping for a .75 gain. That would put me running 14.00. We'll see what happens. I'll still be happy with .30-.50.
07-01-2006, 03:13 AM
#38
well the interesting thing is that with the 5AT and 3.9 FD, the multiplied gear ratios would be roughly just about even overall with the stock 6MT transmission down the 1/4 mile. It'd be more aggressive up to about 90mph, then as soon as you shift into 4th gear, you'll lose 12.9% gear ratio over where the 6MT will be. The stock 6MT will have an easier time going 91-160mph than the 5AT would even with the 3.9 FD
6MT with 3.538 FD muliplied
3.794 x 3.538 = 13.423 .... top speed@6600 = 39 mph
2.324 x 3.538 = 8.222 .... top speed@6600 = 64 mph
1.624 x 3.538 = 5.745 .... top speed@6600 = 91 mph
1.271 x 3.538 = 4.497 .... top speed@6600 = 116 mph
1.00 x 3.538 = 3.538 .... top speed@6600 = 148 mph
.794 x 3.538 = 2.809 .... top speed@6600 = 186 mph
5AT with 3.917 FD multiplied compared to 6MT
3.54 x 3.917 = 13.866 = 3.3% shorter .... top speed@6600 = 38 mph
2.264 x 3.917 = 8.868 = 7.8% shorter .... top speed@6600 = 59 mph
1.471 x 3.917 = 5.762 = .2% shorter.... top speed@6600 = 91 mph
1.00 x 3.917 = 3.917 = 12.9% taller .... top speed@6600 = 134 mph
.834 x 3.917 = 3.267 = 7.8% taller .... top speed@6600 = 160 mph
no 6th gear
5AT with stock 3.357 FD muliplied compared to 6MT - for reference
3.54 x 3.357 = 11.884 = 11.5% taller .... top speed@6600 = 44 mph
2.264 x 3.357 = 7.600 = 7.6% taller .... top speed@6600 = 69 mph
1.471 x 3.357 = 4.938 = 14.1 % taller .... top speed@6600 = 106 mph
1.00 x 3.357 = 3.357 = 25.3% taller .... top speed@6600 = 156 mph
.834 x 3.357 = 2.800 = 20.9% taller .... top speed@6600 = 187 mph
no 6th gear
in a lot of ways the 5AT's wider stock gear ratios are suited better for turbos and the closer ratio 6MT are suited more for centrifugal superchargers. In the same way a car with only 4 gears can work ok with a V8, but would be terrible with say a honda VTEC engine. It's just too bad the 5AT completely drops the ball as soon as you hit 4th gear with it being way too tall for what it should be.
I'd prefer the 4th gear to have a ratio more like 1.13 instead of 1.00. People get some really fast times though with the 5AT. For the sake of performance, I'm actually really suprised the 300hp REV UP engine does not have a more aggressive final drive ratio, but I guess Nissan was concerned more about highway gas mileage, so that's actually not so suprising
6MT with 3.538 FD muliplied
3.794 x 3.538 = 13.423 .... top speed@6600 = 39 mph
2.324 x 3.538 = 8.222 .... top speed@6600 = 64 mph
1.624 x 3.538 = 5.745 .... top speed@6600 = 91 mph
1.271 x 3.538 = 4.497 .... top speed@6600 = 116 mph
1.00 x 3.538 = 3.538 .... top speed@6600 = 148 mph
.794 x 3.538 = 2.809 .... top speed@6600 = 186 mph
5AT with 3.917 FD multiplied compared to 6MT
3.54 x 3.917 = 13.866 = 3.3% shorter .... top speed@6600 = 38 mph
2.264 x 3.917 = 8.868 = 7.8% shorter .... top speed@6600 = 59 mph
1.471 x 3.917 = 5.762 = .2% shorter.... top speed@6600 = 91 mph
1.00 x 3.917 = 3.917 = 12.9% taller .... top speed@6600 = 134 mph
.834 x 3.917 = 3.267 = 7.8% taller .... top speed@6600 = 160 mph
no 6th gear
5AT with stock 3.357 FD muliplied compared to 6MT - for reference
3.54 x 3.357 = 11.884 = 11.5% taller .... top speed@6600 = 44 mph
2.264 x 3.357 = 7.600 = 7.6% taller .... top speed@6600 = 69 mph
1.471 x 3.357 = 4.938 = 14.1 % taller .... top speed@6600 = 106 mph
1.00 x 3.357 = 3.357 = 25.3% taller .... top speed@6600 = 156 mph
.834 x 3.357 = 2.800 = 20.9% taller .... top speed@6600 = 187 mph
no 6th gear
in a lot of ways the 5AT's wider stock gear ratios are suited better for turbos and the closer ratio 6MT are suited more for centrifugal superchargers. In the same way a car with only 4 gears can work ok with a V8, but would be terrible with say a honda VTEC engine. It's just too bad the 5AT completely drops the ball as soon as you hit 4th gear with it being way too tall for what it should be.
I'd prefer the 4th gear to have a ratio more like 1.13 instead of 1.00. People get some really fast times though with the 5AT. For the sake of performance, I'm actually really suprised the 300hp REV UP engine does not have a more aggressive final drive ratio, but I guess Nissan was concerned more about highway gas mileage, so that's actually not so suprising
Last edited by sentry65; 07-01-2006 at 03:51 AM.
07-02-2006, 03:01 PM
#40
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Originally Posted by sentry65
well the interesting thing is that with the 5AT and 3.9 FD, the multiplied gear ratios would be roughly just about even overall with the stock 6MT transmission down the 1/4 mile. It'd be more aggressive up to about 90mph, then as soon as you shift into 4th gear, you'll lose 12.9% gear ratio over where the 6MT will be. The stock 6MT will have an easier time going 91-160mph than the 5AT would even with the 3.9 FD
6MT with 3.538 FD muliplied
3.794 x 3.538 = 13.423 .... top speed@6600 = 39 mph
2.324 x 3.538 = 8.222 .... top speed@6600 = 64 mph
1.624 x 3.538 = 5.745 .... top speed@6600 = 91 mph
1.271 x 3.538 = 4.497 .... top speed@6600 = 116 mph
1.00 x 3.538 = 3.538 .... top speed@6600 = 148 mph
.794 x 3.538 = 2.809 .... top speed@6600 = 186 mph
5AT with 3.917 FD multiplied compared to 6MT
3.54 x 3.917 = 13.866 = 3.3% shorter .... top speed@6600 = 38 mph
2.264 x 3.917 = 8.868 = 7.8% shorter .... top speed@6600 = 59 mph
1.471 x 3.917 = 5.762 = .2% shorter.... top speed@6600 = 91 mph
1.00 x 3.917 = 3.917 = 12.9% taller .... top speed@6600 = 134 mph
.834 x 3.917 = 3.267 = 7.8% taller .... top speed@6600 = 160 mph
no 6th gear
5AT with stock 3.357 FD muliplied compared to 6MT - for reference
3.54 x 3.357 = 11.884 = 11.5% taller .... top speed@6600 = 44 mph
2.264 x 3.357 = 7.600 = 7.6% taller .... top speed@6600 = 69 mph
1.471 x 3.357 = 4.938 = 14.1 % taller .... top speed@6600 = 106 mph
1.00 x 3.357 = 3.357 = 25.3% taller .... top speed@6600 = 156 mph
.834 x 3.357 = 2.800 = 20.9% taller .... top speed@6600 = 187 mph
no 6th gear
in a lot of ways the 5AT's wider stock gear ratios are suited better for turbos and the closer ratio 6MT are suited more for centrifugal superchargers. In the same way a car with only 4 gears can work ok with a V8, but would be terrible with say a honda VTEC engine. It's just too bad the 5AT completely drops the ball as soon as you hit 4th gear with it being way too tall for what it should be.
I'd prefer the 4th gear to have a ratio more like 1.13 instead of 1.00. People get some really fast times though with the 5AT. For the sake of performance, I'm actually really suprised the 300hp REV UP engine does not have a more aggressive final drive ratio, but I guess Nissan was concerned more about highway gas mileage, so that's actually not so suprising
6MT with 3.538 FD muliplied
3.794 x 3.538 = 13.423 .... top speed@6600 = 39 mph
2.324 x 3.538 = 8.222 .... top speed@6600 = 64 mph
1.624 x 3.538 = 5.745 .... top speed@6600 = 91 mph
1.271 x 3.538 = 4.497 .... top speed@6600 = 116 mph
1.00 x 3.538 = 3.538 .... top speed@6600 = 148 mph
.794 x 3.538 = 2.809 .... top speed@6600 = 186 mph
5AT with 3.917 FD multiplied compared to 6MT
3.54 x 3.917 = 13.866 = 3.3% shorter .... top speed@6600 = 38 mph
2.264 x 3.917 = 8.868 = 7.8% shorter .... top speed@6600 = 59 mph
1.471 x 3.917 = 5.762 = .2% shorter.... top speed@6600 = 91 mph
1.00 x 3.917 = 3.917 = 12.9% taller .... top speed@6600 = 134 mph
.834 x 3.917 = 3.267 = 7.8% taller .... top speed@6600 = 160 mph
no 6th gear
5AT with stock 3.357 FD muliplied compared to 6MT - for reference
3.54 x 3.357 = 11.884 = 11.5% taller .... top speed@6600 = 44 mph
2.264 x 3.357 = 7.600 = 7.6% taller .... top speed@6600 = 69 mph
1.471 x 3.357 = 4.938 = 14.1 % taller .... top speed@6600 = 106 mph
1.00 x 3.357 = 3.357 = 25.3% taller .... top speed@6600 = 156 mph
.834 x 3.357 = 2.800 = 20.9% taller .... top speed@6600 = 187 mph
no 6th gear
in a lot of ways the 5AT's wider stock gear ratios are suited better for turbos and the closer ratio 6MT are suited more for centrifugal superchargers. In the same way a car with only 4 gears can work ok with a V8, but would be terrible with say a honda VTEC engine. It's just too bad the 5AT completely drops the ball as soon as you hit 4th gear with it being way too tall for what it should be.
I'd prefer the 4th gear to have a ratio more like 1.13 instead of 1.00. People get some really fast times though with the 5AT. For the sake of performance, I'm actually really suprised the 300hp REV UP engine does not have a more aggressive final drive ratio, but I guess Nissan was concerned more about highway gas mileage, so that's actually not so suprising