EGhatch33

i wanna put a new final drive into my z6 but dont know what to choose between a 4.785 and a 4.928? i want it to be a daily driver... so decent gas mileage. is the 4.9 a little too much for daily?

Nova_Dust

I am using 4.785. Gas mileage so far went from 15km per liter to about 11km per liter.

But the pick up is so nice. Highway is a little annoying, 100km at 3500 RPM, where before it was 2500.

Hope that helps.

EGhatch33

so a 4.9 would pretty much kill my mileage?

SkankyEJ7

i didnt think they made those fd for dseries engines

EGhatch33

i know they do a friend of mine had one in his eg..

BlueIntegraBoy

iTrader: (5)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98ekhx &raquo;</TD></TR><TR><TD CLASS="quote">i didnt think they made those fd for dseries engines
</TD></TR></TABLE>

http://www.srr.com.tw/english/e_transmission.asp

EGhatch33

hey thanks man

EGhatch33

anybody out there have experience w/ a 4.9 in their sohc?

GBRacing

Yes I did but it's in a road race car. No highway. I'll be running the car for the first time this weekend. I'll let you know then.

EGhatch33

alright cool. what kind of mileage do u think you'll get? i'm trying to build a fast daily driver

Nova_Dust

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EGhatch33 &raquo;</TD></TR><TR><TD CLASS="quote">so a 4.9 would pretty much kill my mileage?</TD></TR></TABLE>

4.7 is already at the limit, let alone 4.9 (for a DD that is). But, I don't have 4.9 so I cannot speak it with confidence however, If you all do is local driving not exceeding 80km an hour, you could get away with 4.7 or 4.9, you will just be in 5th gear all the time. The moment you bring your car onto highway, you will travel slower than transport trucks IF, you want to save some gas. Or you can choose to rev at 4000 and doing 110km/hr just try to keep up with other grocery getters.

My change sort of came in a good timing. My previous job was all highway driving and 6 weeks ago, I switched job and it is now all local, so I can still travel at a slower speed and try not to rev pass 3000. For one, it is loud for others (urethane engine mounts) and second, to save gas and if I leave early for work, there is no need to speed. But with some decent torque and that tranny, sometimes, I had to step on it - great passing power on highway.

B18C5-EH2

I'd say the 4.929 would be fine bro.

What's the D series 5th gear ratio? It's .750 if it's a Si tranny, and what, .702 if it's a DX/LX/CX/VX or EX, right?

Dude I ran a 4.929FD with a .787 GS-R 5th gear in my old Type R tranny on the freeway all the time.

The 4.929Fd is fine man - those 5th gears in the D trannies are nothing as short as the B series man, and people run 4.9s all day in their B series. Hell some people even run the short-*** ITR/B16A .848 5th gear with the ATS 4.929FD!!!

BTW:

If you're getting serious enough to swap final drives then you'll probably be serious enough to go with a good Uberdata/Crome tune, right? If so then just have someone highway tune it and lean it out at your normal cruising highway rpm at 60-80mph. That's how I've gotten killer mpg on my B18C5.

Nova_Dust

I guess you are right. But I guess it was a big jump for me and I truly felt the difference in mileage.

Bense

think about it like this

i know i'm going to get flamed so much for this by people that don't know **** about gearing.

if your car is 127hp with a 4.25 final drive

lets see here, 4.7 divided by 4.25 = 1.1058824

a 4.7 final drive it will feel like 140.44706 hp!
a 4.9 final drive will feel like 146.42353hp!

remember guys, d16s have a 89mm stroke, d15s have a 84.5mm stroke

b18c's have a 87.2mm stroke, and b16s have a 77mm stroke. just because the b16s 5th gear is incredibly short, the stroke of the b16 is incredibly short, so it's not like having a 89mm stroke bounding around at 4450rpm at 80mph



i'm a gear *****

DOES ANYONE KNOW WHERE ONE CAN STILL FIND A SRR FINAL DRIVE FOR D-SERIES

superdupervtec

if your car is 127hp with a 4.25 final drive

lets see here, 4.7 divided by 4.25 = 1.1058824

a 4.7 final drive it will feel like 140.44706 hp!
a 4.9 final drive will feel like 146.42353hp!

That's in a near 1:1 ratio, you might gain 6hp in 4th although it still is not a direct drive and is still a torque multiplication gear.

I think you don't know **** about gears.

Stroke and rods and all that **** your talking about means nothing, it comes down to acceleration, the lower your final drive ratio the better you accel with a trade off of top speed.

Why don't you try first gear and see what you get

I will do it for you

Sir gear ratio

4.7 x 3.23 x 127 =1927.98
4.9 x 3.23 x 127 =2010.02


So in first you gained 83 hp from the 4.7 to 4.9

Now also did you think to add overall tire diameter, because I'm running a 4.7 and with the tire I'm running the overall ratio is a 4.9.

you have to keep in mind the tire sizes as well and with a 4.9 and 15 inch tires if you build a decent engine you will find traction issues on street tires.




Modified by superdupervtec at 7:58 PM 11/21/2005

Bense

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by superdupervtec &raquo;</TD></TR><TR><TD CLASS="quote">That's in a near 1:1 ratio, you might gain 6hp in 4th although it still is not a direct drive and is still a torque multiplication gear.

I think you don't know **** about gears.

Stroke and rods and all that **** your talking about means nothing, it comes down to acceleration, the lower your final drive ratio the better you accel with a trade off of top speed.

Why don't you try first gear and see what you get

I will do it for you

Sir gear ratio

4.7 x 3.23 x 127 =1927.98
4.9 x 3.23 x 127 =2010.02


So in first you gained 83 hp from the 4.7 to 4.9

Now also did you think to add overall tire diameter, because I'm running a 4.7 and with the tire I'm running the overall ratio is a 4.9.

you have to keep in mind the tire sizes as well and with a 4.9 and 15 inch tires if you build a decent engine you will find traction issues on street tires.


Modified by superdupervtec at 7:58 PM 11/21/2005</TD></TR></TABLE>


dumbass, i don't think you understand. think about the gsr's 5th gear at 80mph, 4050rpm and then the b16s 5th gear at 80mph, 4450

now, both motors are nearly identical, however the gsr has about 10mm increased stroke.

WONDER WHY IT HAS TALLER GEARS