cleanandquick06

iTrader: (3)

someone with 3.9 fd, please tell me what you now top out at? im guessing in the 145mphish range? dont flame me, its just a guess, thats why im asking. i searched and didnt come up with shiit

sentry65

iTrader: (11)

it's 158-166 depending on your tire diameter - assuming this is for a manual Z. The normal theoretical top speed in a stock manual 350Z is 184mph if the ECU would let you rev 6th gear all the way out


http://www.f-body.org/gears/

Oleg

iTrader: (1)

Find out how many % shorter your final drive is going to be and that's how many % you are losing off of each gear.
How's that exhaust anyway?

sentry65

iTrader: (11)

yeah but it doesn't work that way for 6th gear because the stock top speed is way higher than the ECU will let you with the 160mph limiter

Jason@Performance

iTrader: (11)

i worked out the math in a thread...

I did this for the AT guys....


Ok here are my calculations on the gears:


1st - 3.540
2nd - 2.264
3rd - 1.471
4th - 1.000
5th - 0.834


Stock Tire Size 245/45/18 = Revs Per Mile = 756

FD = 3.3
FD = 3.538
FD = 3.700
FD = 3.917


Formula:

RPM / FD Gear Size / Tire RPM x 60 = Speed in MPH


RPM:

3000 RPM in 4th Gear:

3.3 @ 3000 RPM = 72.15 MPH
3.538 @ 3000 RPM = 67.29 MPH
3.700 @ 3000 RPM = 64.35 MPH
3.917 @ 3000 RPM = 60.78 MPH

3.3 @ 6000 RPM = 144.30 MPH
3.538 @ 6000 RPM = 134.59 MPH
3.700 @ 6000 RPM = 128.70 MPH
3.917 @ 6000 RPM = 121.57 MPH

Forumla for other gears:

RPM / (FD Gear Size x Tranny Gear Size) / Tire RPM x 60 = Speed in MPH


3000 RPM in 5th Gear:

3.3 @ 3000 RPM = 86.51 MPH
3.538 @ 3000 RPM = 80.71 MPH
3.700 @ 3000 RPM = 77.17 MPH
3.917 @ 3000 RPM = 72.90 MPH

3.3 @ 6000 RPM = 173.02 MPH
3.538 @ 6000 RPM = 161.42 MPH
3.700 @ 6000 RPM = 154.35 MPH
3.917 @ 6000 RPM = 144.21 MPH


6200 RPM in 1st Gear:

3.3 @ 6200 RPM = 42.12 MPH
3.538 @ 6200 RPM = 39.30 MPH
3.700 @ 6200 RPM = 37.56 MPH
3.917 @ 6200 RPM = 35.48 MPH




The 3.7 gear set works with any rear end that will work with the 3.5 or 3.9 gear set...

So, basicly all you need is a 3.5 6MT pumpkin w/ VLSD or can be used with any Aftermarket LSD that works with the 3.5 gear set...

THe 3.70 gear set is: $480 for the gear set alone... You will also need the same pinion nut, pinion seal, spacer housing, bearing, etc etc just like with the 3.5 gear set...

to date ive done half a dozen of the 3.7 gear sets into auto's...

sentry65

iTrader: (11)

yeah I agree with jason's data



I still say this website is your friend
http://www.f-body.org/gears/

cleanandquick06

iTrader: (3)

so if i did a 3.9 i owuldnt even notice a difference in the top speed cause of the limiter anyways? i would just be at a high rpm when it hit?

cleanandquick06

iTrader: (3)

so if i did a 3.9 i owuldnt even notice a difference in the top speed cause of the limiter anyways? i would just be at a high rpm when it hit?

sentry65

iTrader: (11)

exactly and in fact in some ways that would be safer on the engine cause you'll reach 160mph way sooner than before which means the engine won't have to work as long and hard to get you to 160, though the car would reach 160 just under redline instead of 5600

cleanandquick06

iTrader: (3)

that will be awesome since i have the rev up anyways, thanx guys

sentry65

iTrader: (11)

if you have the rev up engine with the 3.9 FD, your top speed will be close to 175mph give or take depending on your tire diameter

the normal top speed with 3.5 final drive is more like 195 give or take. It's 198mph with the stock tire sizes

it doesn't matter though cause the car probably doesn't even have enough power on it's own to even get to 175 unless you have a lot more power than stock

99atlantic

iTrader: (1)

I think you're going to end up being disappointed w/ 3.9s......4.10s were just 'meh' in my books; next time I do gearing it's atleast 4.56s

bhk1004

iTrader: (6)

seeing as how quickly we already finish out first, and modded how quickly second is gone, I honestly doubt first or second will ever be useable street gears if u go abover 3.9, unless ur able to rev to 8k or more.

sentry65

iTrader: (11)

who makes a 4.1 FD for our diff?

Oleg

iTrader: (1)

How do you think the 6MT final drive would affect a TN ST?
First gear is a waste either way, and having to keep higher revs would actually keep the turbo spooled even during cruising, no?

sentry65

iTrader: (11)

you don't really drive at higher revs if you don't want to except for 6th gear

around town, if you start feeling like the rpms are too high, you upshift the same as you normally would. It'd get you into the higher rpms faster. You're going to want a killer tire setup though - like drag radials or competition tires to maintain traction when the TN kit hits peak tq etc

I know one guy that loves it, but most hate the 3.9 with their turbo kit

ReavTek

iTrader: (1)

A 6MT is a 3.5? I want to eventually hit 180mph, should I just move up to a 3.7 instead of a 3.9? Who makes a 3.7?

Jason@Performance

iTrader: (11)

we have a factory nissan 3.7 final drive gear avaialble...

cleanandquick06

iTrader: (3)

how much is the 3.7

Jason@Performance

iTrader: (11)

its around $570 for the gear, pinion bearings, pinion nut, spacer housing...

but i have to check for sure...