'82 Porsche 911 Turbo 3.3 Tips?

The '82 911 is probably one of my all-time favorite cars in real life. I would LOVE to find one of these for purchase, but they are still far too expensive.

I’ve tried several times to figure out how to tune this car for C and B class. However, I can’t seem to figure out how to get past these issues when tuning the car:

For C class
Upgraded brakes, suspension and rollbars to race. I think the tires remained stock, but I widened the back tire.

Problems:

  1. Lift-off oversteer entering turns
  2. Understeering existing turns (I can visibly see the front of the car lifting upwards when I put power down, so I know it is reduced friction)

If I can slow down enough before taking the turn, I’m usually able to take the turn – but I lose valuable time by slowing down first.

For B class, the same problems but I have also upgraded the tires and reduced the overall weight of the car.

For both tunes (numbers are approx, I’m at work and can’t get the exact numbers right now):
Front camber is around 2 - 2.2
Rear camber is around 1.2 - 1.8

Front toe in is 0.1
Rear tow out is 0.2

Caster is between 5.4 and 5.8

Front anti-roll bars around 14-18
Rear anti-roll bars around 21-23

Front springs around 530-580
Rear springs around 580-620

Ride height is right in the middle

Front rebound around 8.1 - 8.7
Rear rebound around 9.2 - 9.5

Front bounce around 5.2 - 5.5
Rear bounce around 6.2 - 6.8

Anything that sticks out from those numbers?

Drop camber around half, drop rear springs 50-100lbs, drop rear rebound and bump around 1.5.

But most important what are your Diff settings?

In most RWD cars, I tend to remain around 45-50% acceleration and 25-35% deceleration. If the car seems to have a lot of power, I’ll drop as low as 30% acceleration / 10% deceleration.

However, I will admit that this area of the tuning setup is the most mystic to me. I don’t truly understand what it means (and how it affects handling) when I set the acceleration diff to 50% vs. setting it to 80% or 30%. I’ll also admit I’ve not done a tremendous amount of research on the subject either. I’ve just started understanding camber, caster and toe and how they play into handling – and I’ve far from mastered it.

Best thing to do is just experiment with the DECL at various incremental levels until it feels good for you. A lot depends on your particular throttle technique.

Besides tuning, it’s your driving. You have to adjust your imputs. Roll on and off braking and throttle.

.
Lower camber as fifty suggested. I’d drop the bump (F/R) to half those numbers as a starting point. Rear Toe to -0.1 Also, as fifty asked, the Diff is VERY important.

PRKid
.

Move caster to max
Your bump needs to be way lower.
Move your differential decel up to reduce lift oversteer on entry.
Move your differential accel up to reduce exit understeer.

This might not be the best for you, but it should get you at a good starting ponit.
PI B600
STK tires 245/45R16, 285/40R16
STK Eng and DRV
Sport Camshaft
STK turbo
Race Block
Full Race suspension with STK rims
Race Clutch
STK Trans
STK Driveline
STK DIFF
Race Brakes
STK Aero

29.5 Psi FR & RR
4.55 Gearing
-1.3
-1.2
-0.1
+0.0
4.8
19.02
31.2
690.4
782.2
7.6
7.5
7.5
7.7
4.7
5.5
49%
104 (or whatever you like)
60 30
Rear end is under control !

Thanks! I’ll play with the numbers tonight when I get home from work.

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Rule of thumb is to stay away from clutch, cams. I also try to stay away from expensive transmission in B/Cclass.
What is stk, stock?

I would harden the rear springs lots. And also raise the rear diff decal lots.

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Use stock clutch and get something more important for those points.

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Ok, got the back end under more control by dropping the accel/decel and softening the rear springs as suggested. Also dialed down the camber. My C class tune still loves to drift, but the B class is much more stable than it was.

Are you sure lowering decel/accel solved the problem?

Lowering decel → increase lift-off oversteer corner entry
Lowering accel → increase on-throttle understeer corner exit

These were the exact isssues you wanted to be fixed. Lowering decel/accel actually emphases them.