Hello,

I just got my car back from the shop. (Z Car Garage in San Jose) They installed the 3.9 final drive into my Z. While I haven't had too much driving time, the shop did some tests pre-3.9 and post 3.9. They used a g-tec meter. Main thing was to see any gains. Here is what they got.

Stock..
0-60
5.81
5.84
5.90

1/4 mile
14.47@104.9
14.49@104.3

w/3.9 drive installed
0-60
5.70
5.80
5.90

1/4 mile
14.08@106.6

I really like the 3rd gear pull the car has now! Can't wait to drive it more!

 

how much did it cost for u to install it?

 

Took a nice bite out of the 1/4 mile time.

 

Wow, 14.4 in a stock Z? What kinda 60' are you running?

 

If you want to see that 0-60 time drop (not that 0-60 means that much) get the rev limiter raised with the l-spec reflash. But Damn!! that is a nice chunk out of the 1/4 time. by the way what were the 60 ft times on those launches?? with that trap speed you should be mid-low 13's

 

How much for the drive and install?

 

I will be getting this done next week I cant wait! IMO best bang for your buck speed improvement, plus its stealth

$875.00 for parts
$650.00 for labor

Total = $1525.00 for 1/2 sec drop in quarter mile times, cant really get much better than that in the Z for $1500

 

You have to be a bit careful when looking at G-Tech results. They are not generally perfectly accurate, however they are very consistent. This means the numbers they give you might not really correlate to the real world, however, they are great for comparing differences before and after an upgrade. If they are using a G-tech Comp model, then doing a really good set of calibrations can make the results much closer to the real world.

In this example, the G-tech shows that he got a .4 second drop in the 1/4 mile. So, even if the actual numbers themselves are off by a lot compared to what he'd get at a real drag strip, the .4 sec drop is probably right.

Anyway, just thought I'd toss that in. I love my G-techs, but you have to be careful about how you evaluate the results.

 

you should get a dyno! then we can see the gains!

 

Man this FD is a really nice mod. The price is just so steep. Gotta start saving.

 

Final drive is a sweet mod. I only went up to the 3.53 and ran 1/2 a second quicker in the 1/4.

 

a joke?

 

ummm. what gains? he changed his rear end gear...

 

yah it was a joke... anytime someone does a mod... people think that the dyno will prove all. the dyno is god on this forum, its sad that alot of people dont realize how many variables go into the results of the dyno, and hence the results can vary greatly

 

Actually, you can "see" the gains from final drive ratio change. If you map the old dyno over the new dyno plot using mph instead of rpms the results are quite impressive. I did this with my 3.5 to 3.9.

 

SJ when you have time can I get a ride in your z? as a passenger of course. I want to see how much of a difference the gear makes.

 

Hit me up via PM. I'm sure we can set something up.

As far as the g-tec testing goes, it was just to see if there was any difference. Nothing more. The installer has a strip he calls "central raceway" where he does the testing. So, the road was the same and the weather was similar. Like I mentioned, it was mainly for testing purposes. There is a noticeable difference though. The more I drive the car, the more I like it!!

 

Yeah, dont use a G-tech, the dont work. Trust me. I have one. Go to the damn track.

 

I was under the impression that you don't "Gain" hp/tq but it just shifts the torque curve. Is this correct or did you actually see a gain?