ColorChange

I am planning on buying a 996 and tracking it with heavy mods (suspension, roll bar, enginge tune, DOT comp tires ...). What I am concerned with is accelration nonlinearity when you are coming through a corner.

OK, threshold breaking, turn-in with some trail braking, apporaching apex - squeeze the throttle, continuing through turn further squeeze until floored hopefully well before trackout. In a typical turn like this, is there any upset to the car? Or, does the inital squeeze begin the spool up of the turbos and there is no noticable lag? I understand during shifting that I will feel the lag (0 throttle shift, floored - lag - bye bye).

Thanks,

Tim

racer63

There is pretty noticeable lag in the stock 996TT. To make matters worse, you can't left foot brake due to the quirks of the electronic throttle control. I think that your best bet is a very late apex, making the exit relatively straighter, and allowing you to apply full throttle as quickly as possible. That should reduce the chances of upsetting the chasis when the turbos do kick in.

Disclaimer: I have not tracked my 996TT. This is just an educated guess from 8 years of road racing and several months of driving a 996TT on the street.

As an aside, if you plan on doing track events regularly, I'd recommend the EVO stage 4GT ball bearing turbos. They have virtually no lag and are much easier to apply throttle progressively. For reliability purposes, you might want to run lower boost levels than the standard stage 4 package (1.2 bar and about 640 HP). I'd have the ECU tuned to put out around 500 HP for a track car - similar to what Porsche is willing to run in a stock 2004 GT2. You'd have the power of the GT2/X50, better spool up, and lower cost.

Also, EVO has a chipswitch that allows you to switch between programs. So, you could have both a track setting (500 HP) and a street setting (640 HP).

Greg A

I hope you have that reversed.

Greg A

Trojan Man

I am by no means a racing expert, but I have taken an instructor out to the track with me, and I was always taught that Porsches (rear engine) are late apex cars.

This statement would be consistent with what Racer63 said.

As far as upsetting the car is concerned - I have Techart coilovers and an Upsolute chip - I cannot upset the car at all unless I am very sloppy in a turn. If you are smooth, there is very little you can do to upset a Turbo.

ColorChange

OK, thanks guys. This forum is awesome. I won a Lamborghini Countach and there forum has 1 racer. Ughh.

OK, what I am talking about maybe isn't so much lag but boost upset. I have felt the wham (and associated woooosh) when the turbos come on hard. If the turbos suddenly jump in when you are squeezing the throttle in a heavy drift towards track out, I have serious concerns about busting the rear end loose and playing high speed tilt-a-whirl (assuming you miss the wall).

I'm used to big tourque and a heavy rear-end, but my Countach has a very responsive and linear thrust.

Tim

KPV

Colorchange,
I understand your concern exactly. Most turbo cars, and particularly older, less sophisticated, types had to be driven in such a manner that you became comfortable with the amount of lag inherent in the system and worked with it. In other words, timing was everything. You would tend to plant your foot a little earlier in anticipation of the boost and turn exit. This way, as the turbos spool up and deliver the power you have incrementally traveled around the turn and are ready for the onslaught of hp and tq. You basically need to balance the lag, turn timing and corner exit tangent point so that the punch occurs at just the right moment. I practiced this extensively with my 944 turbo at the track eventually being able to get a nice four wheel drift going on dry pavement. It can be a little unnerving for the faint of heart. That car was a dog below 2500rpm but felt like a sledge hammer was hitting you in the back as the boost came on above that.

There are a lot of variables in high performance driving. In a turn, you are asking a lot of the outer tires since they are taking the majority of the vehicle's weight as well as lateral forces from cornering. These all contribute to add stress to the tire contact patches. Throw in a little sudden power and you can quickly exceed the precious contact patch's ability to adhere. You need to be really cogniscent of this in motorcycling. The result there is a feeling of rear tire greasiness.....but I digress.

Of course, with practice, you can time the boost onslaught earlier and earlier in the turn as long as you can handle the results. It takes practice.

ypshan

I find it much easier to control the turbo thrust on the track than during an autocross. (Remember I am a novice.)

There seem to be enough of pedal travel that I can keep the tire squeal consistent on the track by throttle steering the car. (I have an X50 TT so the turbo boost is more noticeable than the stock TT and the flat power peak is narrower.) However, during autocrosses, I often feel that the turbo kicks in too suddenly for me to make any fine adjustment. Maybe the autocrosses afford me much less time to do anything than the track. My believe is that if I can control the throttle well in autocrosses, I should be able to track the car without any problem.

racer63

Actually, I had the order the way I intended. I wouldn't want to run 1.2 psi at the track. Lap after lap, 20 minutes at a time, four sessions a day. I just don't think it's wise.

On the other hand, using 1.2 bar for an occassional run from 0-to-something somewhat prudent isn't nearly as risky (from a reliability standpoint).

ColorChange

Thanks again guys, I didn't win a Countach, I own a Countach. Sorry

I am pulling the trigger today on the car (new 2003 turbo).

I intend on doing a complete tune-up. My thoughts are to go after the suspension this winter (everything roll bar, adj. sway bars, camber plates, PSS9 coilovers, lowered ...). Then I will track the car and get comfortable with the car.

Next winter, I attack the engine for big low-end fat flat torque (screw horsepower).

Makes sense? I think I will get most of the GT-2 performance for much less cost.

Tim

KPV

Tim,
Can you post a pic of your Lambo? I have always liked them.
Your plans for the car sound spot on. I have a lot of respect for those that upgrade the car's ability to handle additional power before adding the additional power. Upgrading the suspension first makes a lot of sense and learning the car before adding power makes even more sense. What are the specs on the new turbo?

ColorChange

Here is a shot.

Tim

Eric in Chicago

ColorChange, nice shot. Looks like turn 3 at Gingerman.
You should come by Road America next weekend with the Countach and have a few cold ones with the Turtles. Drop me a line if you want some more info

MM951

What year is that Countach?

LSM

Tim,

Where are you buying the car from? I live in Chicago.

-Lou

ColorChange

Eric:
Yes, turn 3. Spun the car on 3 my first time there (but kept it on the track). Late brake, the drop unweighted the car, sent me in too fast, big slide as I turned it in, thought I had the slide caught and got on the throttle a little too abruptly and ... oops, a little throttle induced oversteer.

I was planning to track my Countach with the Badger BMW group at RA in Sptember, but when I broke my spinlde at Gingerman, I lost confidence in the Lambo and bought a new 996T.

I would still love to meet everyone at RA but I won't have my car track ready or the driver ready for a place like RA. I don't think RA is a great first tracking place for a new car! Secondly, I have two young kids so time away is not easy, and when I take it, I definitely want to drive. Next year.

Mike:
1983 5000S with weber 45DCOE carbs. I have done a ton of upgrade work on it: Ansa fomula 1 exhaust, racing clutch, new synchro's, triple cut valve job, new springs, additional brake ducting, 6-piston Wilwood brakes, data acquisition system, .... I hate to be selling it.

Lou:
I'm getting my car out of Rusnak in Pasadena. I should have it by Friday. I have to go pick up my Lambo from Ohio this week also.

Now, how do you break in a new Turbo? I will be asking a whole lot of questios and want to thank you guys for your responses.

Tim