At this point im unsure how far I am going to mod the Z but i always wonderd this. Would putting in the 3.9 final drive help or hurt a basic bolt on z? The mods that I know I am going to have will be header, test pipe, Mrev and spacer, exhaust, reflash and clutch and flywheel. So you guys think that the 3.9 would benifit it?
Thanks

 

3.9 is a great choice for a non turbo Z. If you have any plans to put boost to the Z stay away from the 3.9, you wouldn't be able to use 1st gear very effectively once boosted...

 

Yea I dont have any plans to go f/i. I just wanted to see if i would benifit it even with only basic bolt ons if i did it.

 

...

 

JTG: I'm interested in the Central20 gearing as well. From the research I've done I would put it in the "Best Bang for the Buck" list. I'm all about making useable street power and this seems like a good investment. However if you plan on making around 400+whp, as mentioned, its no good.

 

Yea I have no intentions of making 400whp. Im staying n/a for sure, lot less stress. My mods are going to be exactly wat i said in the first post. Right now I have top speed exhaust, test pipes, mrev and plenum spacer, jwt intake, and a reflash. If I add the 3.9 final drive with just these mods should it be an effective and great upgrade?

 

From research I've done you will notice a difference! Also consider a diff. Since you will have everthing open might as well upgrade the diff. I'm looking at getting the Central20 3.9 gear w/ Quaife diff and Nismo Diff cooler.

 

The last ? I have then is with the 3.9, will it shorten my top end power at all? And does it help with 1/4 mile times at all or is it more for the street?

 

Modifications have no relationship to the drive ratio. You can change the rear gear if you are stock or 600HP.

 

It won't "shorten/ lower" your top-end power but you'll have a slower top speed. However you will get to the new top speed quicker. You'll have quicker 1/4 times with a slower trap. From my understanding. Go here: http://www.350z tech.com/zwiki/Part:Final_Drive_Gear_Sets PLace a "-" where the space is.

 

your top speed on a 287hp engine will be lowered from 184 to 167mph with the 3.9 FD

on the 300hp engine with 7000 rpm redline, it'll lower it from 198 to like 176mph

 

It is, without a doubt, 100% the best mod for the money on a NA Z. Period. Nothing comes close to the driving experience you get with an upgraded rear end.

(And I only went from the 3.3 to the 3.5! and it was huge!)

 

Are we talking about a Z here or a Z06 vette?

 

a 350Z

the gearing and engine's redline can't help it that the ECU has a speed limiter or that the engine isn't powerful enough to actually get to that speed

otherwise top speed with or without the 3.9 gears on an otherwise stock Z is always going to be 160mph since that's where the ECU cuts you off at 5650 rpms in 6th gear

 

The Z has a surprising ammount of Top End, It is electronically limited though. As for 198, I have NEVER seen one do it? I guess it is possible if you drop it out of a plane..

 

you'd need FI to hit 198mph with something like 600 hp

a couple guys with FI Z's (287hp engine, 6600 rpm redline) have taken their Z up to around 193mph with the 3.357 final drive

if you had a 300hp engine with a 7000 rpm redline and the 3.357 final drive, your top speed would max out at 208mph
you'd just need a buttload of power to make it there

 

Table of max speeds

Gear : 3.5 @6850 --- 3.9 @6850 --- 3.9 @7200
1st : 38.9 --- 35.1 --- 36.9
2nd : 63.5 --- 57.3 --- 60.3
3rd : 90.8 --- 82.0 --- 86.2
4th : 116.1 --- 104.8 --- 110.2
5th : 147.1 --- 132.9 --- 139.7
6th : 185.6 --- 167.6 --- 176.5

 

Power will not change. Top speed in all gears will decrease. Use this calculator to see the difference in RPM and speed:http://www.wallaceracing.com/gear-speed.php.

 

yeah I'm always telling people to go to this site:
http://www.f-body.org/gears/

I mean, it's a freaking sticky in this forum
https://my350z.com/forum/engine-and-drivetrain/145369-gear-ratio-calculator.html

 

Sounds great. Im really interested in this now. I realy dont care about the top speed being cut down ha cuz i never plan to go 160+mph anyway. I just want the quicker kick in the *** and quicker accel to say 140 to be quicker and it sounds like thats wat it would do. So my final ? would i see a great benifit by doing it with only the mods in my sig + the mrev and the spacer? Thanks again for all the info guys