Sorry if this has already been asked, couldnt find it. And if u know where it is please feel free to point me in the right direction.... but is anyone running the 3.917 final gear with F/I. If so how is that working out for you?

 

it's usually a bad idea for FI

I run it with my vortech setup and it's been great since it adds gear torque and brings the revs higher so I get into the boost faster. It wasn't until I started making a lot more power that it has possibly started making me rethink it. I can't fully use 1st or 2nd gear. If I was on the 3.5, I could probably fully use 2nd gear

 

Ive asked this question myself a few times, I currently have a 3.9FD and will be going with a TN setup most likely. The problem I have been told is traction, hopefully with 285 DRs I can hook it up enough to use the shorter gears and hopefully run better traps. The problem is we barely get into 4th gear in the 1/4mile, and at many tracks ive been to 5&6 are useless. So adding a single turbo should alleviate the need for more power to push me through 4th gear and run better traps

 

Don't waste your time or money.

 

why do you say this, any evidence or experiance roast... Back the opinion up bud.

I think on a low power SC system a 3.9 FD would be very usable, a HKS kit and 3.9 would be great.

I am still thinking I can run faster times with less power with my FD.

 

Because it's a step backwards. If your goal is to increase power, shortening your gears would be the last thing on your mind unless the gears were already way too tall in the first place(old school muscle cars for instance). With our stock 6mt, first gear is already as short as you would ever want it to be(not considering adding 100hp)... and having a close ratio 6mt there are not many good reasons that I can think of why you would want shorter gears..... I guess unless you like wasting gas, don't like traction in low gears, like having to shift sooner/more often... etc. BTW, your final drive affects your trap speed about as much as having a bowel movement before or after a race.

I don't know... call me crazy.

 

MI 35th happens to be right - on your typical out of the box FI setups - be it a TN single, APS single, Vortech, ATI, it works wonderfully well. Once you eclipse that 400 whp level, the standard ring and pinion, or the 3.3 swap is the better overall choice

All comes down to your goals with the car, and what you (realistically) use it for

 

I didn't say he was wrong or that it wouldn't "work". I was just supporting my opinion, since he asked me to, by pointing out the reasons why I would take more power rather than shorter gears. Definitely just my opinion though. If you can prove my opinion illogical or irrational, please do.

 

you are certainly entitled to it, no one faulted you for having an opinion. All I did was state what I've experienced first hand

 

Yes, as Z1 was saying my goal is a stock low boost setup get me around 380rwhp.

I think that with the right Tire setup I will have more usable power for the rev-up motor.
IMO...


Z1 what is your experiance with the FI and 3.9FD.

 

well i have the TN set up... not too shy from 400rwhp. i wanna up the power too. so would 1st and 2nd be too short for me? ive jus heard many ppl said there 1/4 and 0-60 drops a good amount. and those r the times i like to focus on.

 

I'm in the process of getting things started to eventually go FI and I have the 3.917 coupled with the Quaife. The main thing for me, is I have the 5AT so my 1st and 2nd gear are taller than the 6MT. Will make it a bit easier for me to launch.

I'm aiming for 380-400 with a CSC, so it should combine the best aspects of both setups. The 3.917 will give me a solid, fast launch until boost builds, then the power won't be so ridiculous that I'll be overpowering my ability to grip.

 

I am running the 3.9 with a 5AT and yes to your questions but I am under 400whp so that might help.

 

like u said tho 5AT is longer then my 6MT... so with my set up with my 1st and 2nd go to hell? in about a year or less hopefully shes gonna be jus a weekend rider, so daily driving isnt too much of a concern, but i dont wanna be overwhelmed by the **** neither.

 

I just blew my diff at the track, what are my upgrade options for a 6mt.
I have DSS level 5 and over 700whp, thanks for the help.

 

We've got the Cusco RS LSD in stock, ready to go (1.5 way, adjustable to 2 way, and adjustable lockup as well) - price would be $998 shipped to Puerto Rick (~3 day transit time)

Adam