I just purchase an '03 G35 with the automatic transmission and while I love how it runs at higher RPM's, I was wondering what can be done to improve the launch from stop or if it is even normal that it dogs down.

 

Ever since I bought my car I have thought the same and I have come up with three ways you can most definitely fix the problem...with some downsides though.

1) Install a shorter final drive ( like 4.08 for example ). While the power output of the engine will stay the same, 1st gear will be considerably shorter ( along with all the other gears ). This means that the engine will get out of it's weak spot quicker due to this fact. Think that if going from 2K rpm to 4K rpm took you 1 second...now it'll take you .5 ( I made up the numbers just in case ). The downfall is that your 5th gear will be at a higher rpm at cruising speed. For example, if before you were at 60mph at 2000rpm..now you will be at 2500rpm for the same 60mph ( numbers are also made up, just an example ). This makes fuel economy plumit a little.

2) Higher stall torque converter. If the stock converter stalls at 2K ( by braking and accelerating at the same time before launching ), this means the engine has to crawl from 2K to 4K ( a whole 2K rpms ) to make any real power after that. By adding a conver that stalls at 3K for example...then the car only has to deal with crawling from 3K to 4K instead of 2K to 4K. This makes it far easier to simply jump into the powerband. The downside is that fuel economy will also suffer because the converter slips more and the car will feel a bit more sluggish at stop lights ( not much unless you get a 4K stall converter or something hardocre like that ).

3) Do BOTH! You'll have the launch of a V8 and the fuel economy of a V8 as well...lol. This would be the ultimate drag setup if you find tires sticky enough.

 

turn traction control off

 

That's another thing I didn't think of...have you turned TC off? I mean, not that it makes a huge difference anyways...are cars a weak down low as it is...the VDC just makes it worse.

 

+1

Of course, mods that add power will also be beneficial.

 

where do u get a higher stall torque converter??

 

Oh, and I forgot...add nitrous. That'll make dieselish torque.

 

Thanks for the advice! The stall converter had crossed my mind. I may have to do that. I am not much of a gearhead, nor do I have time to be one, so anything that gets to involved I will have to have done at a shop. Nitrous sounds great, but I would like my car to last more than this summer! LOL Any performance tips that you have, esp. those that are relatively inexspensive and easy to do, would be greatly appreciated.

 

Try this:

1) Foot on brake, VDC off
2) Selector in neutral
3) Rev the motor to 4500rpms or so, you should feel the brake pedal drop a bit (1/4" to 1/2"). Keep your foot on the brake.
4) Place back into gear
5) With foot on brake, floor the accelerator. Release brake 1 second later. You should come off the line at around 2500-2700rpms.

Keep in mind it's the summer. All cars are quite a bit doggier when the air is less dense with O2 and the motor is baking hot.

 

Yeah it was 92 and humid yesterday so I am sure that had something to do with it. I will try your tip when it cools down a little and see what she does. Thanks

 

Any suggestions on what brand/setup to use for the intake system?

 

Each 11F of temperature reduce engine power by 1% minimum due to reduced air density.

Most after market products affect high rpm power, at low rpms so little restriction that they offer little improvement especially below 3,000 rpm.

 

Yep and many times, the improved flow hurts low and mid range power which is very detrimental to acceleration from a stop or low rpms. In drag racing, the faster you are in the first 200' has a major impact on elapsed time.

 

Yup, which is why I'm afraid to put an exhaust larger than the one I already have ( Mine is 2.5" mandrel with two inline straight through mufflers ). I see people with 3" exhaust on a N/A VQ and wonder if it actually helps but i'm afraid to spend the money just to find out it makes my car even slower from a stop.

 

When I first red this I completely missed your 5th step and was about to cuss you out haaaard. I thought you were telling him to do a neutral drop hahaha.