rd.cullen

Question to a local expert in Vancouver: ' What changes do I need to make to the 996TT when moving up the HP curve via ECU tuning? Will this improve Autocross times? What changes are possible to reduce understeer?'

Here's what I got back.

For your 996TT to reach approx 500hp the only thing really required is an ECU tune.

As far as other complimentary upgrades go, you raise a very good question. It depends on how you use the car. A very good all around complimentary upgrade is to install an IPD intake plenum. They will add noticeable gains in the midrange with a slight increase at the top end. Changing the muffler can also increase power by an additional 20-25 but comes with increase sound levels and tone changes which are very subjective, and something you notice/hear every time you drive. If the car will be street driven only, there is no requirement to upgrade brakes or suspension to handle the additional power. The reason being that, despite having extra power, you are likely to not change your driving behavior in terms of corner speed and what you consider a safe speed on a given road. Now, if you are looking to improve the handling and braking then there are upgrades available.

For suspension: All suspension upgrades come with tradeoffs. For the street , the simple upgrade is a set of lowering springs. These will lower the car, increase the spring rate and improve the handling and overall responsiveness of the car. The trade offs are slightly harsher ride and reduced ground clearance. Next up would be sway bars. These have really no downsides besides very slightly increasing ride stiffness over uneven pavement. They do allow you to tune the behavior of the car because they are adjustable. They will also provide much "flatter" cornering and improve overall grip.

For brakes: What issue do the current brakes have? Lack of brake torque? Overheating on track? etc... The best brakes for the street on our 996TT are the stock brakes. Even on track they are excellent as well. We only want to address brakes when there is an issue with them. Most braking systems have ample brake torque. The issues arise from heat management. The rotor is a heat sink. Once large enough to provide enough brake torque its main job is to dissipate heat generated by friction. So, if you are getting a soft pedal after repeated hard stops or track use, then we want to change to high performance fluid first. If that does not cure the issue we would look at bigger rotors, different pads. Bigger rotors do a much better job of getting rid of heat, which lower pad and fluid temps allowing them to work in the environment they were designed for. They can provide and increase in brake torque, but this is not an issue with the 996TT. Many brake upgrade exist, but my favorite is for all but an all out racecar is made by Girodisc. It is a larger upgraded 2 piece rotor (aluminum hat with iron rotor) and utilizes the stock caliper. Again, these are a great upgrade, but likely not required. To recap, for brakes we first want to ensure we have the best fluid for heat, then if issues persist, address the ways to shed excess heat (increased cooling, larger rotors).

The 996TT is a fantastic car. I consider it the most undervalued Porsche available, period. I do feel strongly that the market will start to appreciate it the same way the market moved the value of the 996 GT3.

For autocross an ECU tune would certainly help, as well as a Plenum as it helps fill in the midrange. Boost will come on a bit stronger at the bottom end with the tune as well. To make the car under steer less we address the alignment. A set of adjustable sway bars allows shifting some roll stiffness to the rear which will help with turn in and help the car rotate. However, I would start with an alignment and see if you think it needs more help after that.

In the end it all comes down to what is important to you as an individual and your budget for vehicle enjoyment. A lightly modified 996TT can be and extremely fun and reliable car. Performance can exceed all but the latest supercars.

Thanks Jeff - what you don't know is probably not worth knowing on the topic of Porsche performance! You may have just made this upgrade possible for me.




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Kevin

Yes. A tune will allow the turbochargers to spool up sooner and longer thru the RPM curve. If you can spool the turbochargers sooner, that removes lag and yields more boost. More boost equals more engine torque.

I would look at the header porting thread vs installing a plenum. In your application you want the velocity thru the intake runners to produce more low end power vs at the top end.

Feel free to contact me..

"02996ttx50

i use my car as a X btw an auto X'r and a hill climber ( think pikes peak driving condition/style ) and have to agree with their comments re the IPD plenum. make sure you don't fall for the "bigger is better" for your intended usage as those looking to make BIG power ( over 700rwhp ) are better served by using the larger 74mm and gt3 TB while i ( happily ) chose to stay with IPD's 68mm plenum and it helps to provide significantly more mid range torque just where i need it in mid range of the power band. i also have very quick hitting hybrid turbo's ( 16/24's ) w/ a 1.2 tune, free flow catless kline exhaust and other complementary bolt on's but my car is setup exactly for the usage you describe. i'm about 575+ rwhp, running rwd with a wavetrac tbd lsd also. a "must have" have for any auto x or hill climbing since so much of hill climbs require power equally delivered to BOTH rear wheels simultaneously to the ground which is antithetical to most all "off camber" situations.. the wheelspin running open differential is a time killer. so stay awd which would suck for auto x i would think? or convert to rwd and get an lsd!

per kevins comments.. agree. i also have ported headers along with the ipd plenum. the plenum though is a serious mod for his intended usage and i can guarantee he'll feel it when and where he needs it. mid range wot. also per kevins thread on ported headers. mine also were done by speed gallery in NoHo CA as noted in post #6 in kevin's very ancient ( 12 year old post!! wow...) yet STILL valuable header thread that has somehow been resurrected to first page in here today.

Mtrboatvr6

I second a proper alignment and suspension for AutoX. The best thing you can do in my opinion for AutoX are mods that inspire confidence in the car. I find a great set of tires, well setup suspension, and good brakes (which the turbo already has plenty of for AutoX) will help you feel more comfortable with the cars limits, and thus make you faster. Power is the last thing you really need to be fast at AutoX. I would be more interested in the wuicker spool a chip would provide than just the horsepower. Kevins tunes do both, so its a no brainer.

Just remember the nut behind the wheel is the most important thing in AutoX!

BioBanker

Im in Vancouver with a tuned 996TT. Great car. Give me a shout if you want. Happy to help you with your process.