well I'm well over 400 dynojet whp (450-460+) and I'll let you guys know as soon as I can rev my car to redline again, but a month ago I was breaking traction with the 3.9 FD in 2nd gear in 50-60 degree weather with the car and tires fully warmed up

Now that it isn't so cold outside and I had all that bushing work done on the rear end of my car, it really has made a difference in how the rear end stays planted. It feels noticably more stable than before, however I can't test it on my car yet until I fix the fuel issues and fully rev it


eliminating any rubber bushings will kill wheelhop. The bushings are like springs which once the tires dig into the ground, the stock rubber bushings want to bounce the tires back off the ground and you get wheel hop instead of the tires just planting


to help traction, I'm running:
-295 pirelli corsa competition tires (for now, will probably try something new - mine BTW are over 2 years old so they're not as sticky as if they were new)
-nismo LSD
-solid motor mounts
-solid differencial mounts
-JIC camber and traction rods with way stiffer bushings
-GT spec lateral bar - I've heard some people say it has increased their straight line traction, possibly by preventing the independent rear suspension from spreading apart as much as before
-I relocated the battery to the very rear of the car
-my rear sway bar is on the softest setting which helps with rear weight transfer, and on a smaller level helps prevents lifting up one wheel while the other goes down since they're not on such a tight leash
-heim joint end links for rear sway bar
-another thing that can be done is adjust the rear camber to be around maybe -1 or -1.5 degrees instead of -2 or more


If I can get 1st gear to hook then that's great, otherwise I'll not be suprised if it doesn't since the 1st gear ratio is WAY short, but at this point I have confidence that 2nd gear will hook on my car

That's a lot of things to do that most people won't do. I pretty much agree though that if you're not willing to do those things, then the 3.9 final drive probably isn't a good idea for over 400whp. Still, I'm not giving up without a fight. Even if I need to try 315's on the rear

 

School keeps me busy, but I try to make it out to the Tuesday and Wednesday meets when I can. If you are ever gonna head out to one of them let me know, I will come out and take you for a spin.

 

but that is for over 400whp right...would you think the 350-380whp would be good, but that is good to know, if your 1st and 2nd is like riding on ice, I could only imagine 3rd gear, with the 3.91!!!!

 

I understand, what school/major are you??

Where are the meets at?? Ill head out Tuesdays, Weds I have a class till 945pm

 

3rd gear is weaker than 2nd gear. It isn't multiplying as much gear torque to the ground and the tires are also covering more distance since they're turning more at higher mph so they get more surface area for traction

3rd gear will always have better traction than 2nd

 

This is good stuff here!! First hand expierence. I definitely be in touch with you, did you do the install yourself, if so, how hard?? Ive looked up info about here, it does not seem all that hard. I am a moderately good mechanic, installed my last motor, but horrible at wiring!!

 

I have a local shop do my work. That stuff is beyond my abilities and I just don't have the free time to attempt it, especially without a lift

 

USF/Biology. Tuesday night meets are at the Sonic on Bearss. Check the TR local events section for more info.

 

Ill have to stop by one time.

 

RUnning lower [350-380 ] WHP , would more than likely be perfect for you . You have to remember to , that running higher gears . Your rpms at highway cruising is going to be higher also . And you'll get lower MPG

 

Just shoot me a pm when you plan to attend, Ill make sure to show up.

 

Its not backpressure that you need(that is a common misconception). What you need is to keep the exhaust velocity at a high rate. The reason to not go w/ a 3" exhaust is becuase the exhaust velocity in the lower part of the rpm range would be sacrificed due to the volume of the exhasut pipe being to big. Ideally w/ a aftermarket exhaust you want to gain a increase in moving a larger volume of exhaust gases while maintaining a sufficient exhaust velocity.

 

I'll chime in briefly, as we've been using the 3.9 gears on S/C'd cars for a long time here - a match made in heaven, especially with the Vortech, which makes it power in the upper rpm ranges.

As far as the exhaust - at the typical Vortex power levels, it won't matter if you run a true dual or a single 3 inch unit + Y pipe, so get which ever exhuast meets your looks/sound/budget criteria

 

A internal Combustion engine is an air breathing monster,,,The more air (mass)an engine intakes the greater the power it can produce...Of course there are limits in that the additional air will not provide a linear increase in power.. High RPM introduces inefficiency's in piston vs exhaust dynamics...

The size of the exhaust can only reduce air flow (mass) if it's too small..A large exhaust will reduce velocity but not air mass...The important factor in mass air flow is the Delta P. The pressure differential between the exhaust manifold and ambient ( exhaust tip)..Greater delta P's result in greater mass air flow..