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220lbs of “ballast” on top of the rear bumper (under the cover). The ballast adds 310lbs to the rear while taking 90lbs off the nose
Full tank of gas
non-power sports passenger seat, Recaro racing shell drivers.
No spare tire, heavy RV “House” battery in stock location.
No A/C, power steering converted to electric, pump mounted in rear of the car
Rear wheels are stock S4 slots widened to 10" with Micky Thompson 255 DOT drag slicks. Fronts are stock size
As documented in other threads, Todd has made other modifications to the car to lighten up the nose while moving weight to the back.
The goal is to lighten the car without changing the current weight bias.
This is the baseline:
As a comparison, we weighed my 87
S4 Automatic
Full tank of gas
Rear A/C
Stock except for the wheels and missing front spoiler / belly pans
25lb weight added to spare tire location to make up for missing spare
Full tool kit
1978 #277
1/2 tank of gas
Stock 5-speed, no sunroof, manual non-power seats
35lb weight added to passenger area to simulate the missing seat / rails
60lbs added to battery box to simulate battery and spare tire
S4 "manhole cover" wheels with 225's on all four
1980
Full tank of gas
Stock 5-speed, no sunroof, power leather seats
Factory roof rack attached
25lb weight added to spare tire location
Custom widened phone dial wheels,245F / 255R tires
1979 - Track car
Full tank of gas
5-speed, no sunroof
Roll bar, Recaro Pole Position seats with stock rails. 6-point harness, stock belts removed
Rear bumper bar removed, no rear seats, A/C & stereo removed
HVAC system still installed (blower, heater core etc..) however the head is blocked off, no coolant in heater core
Carrera III wheels with 235F / 265R tires
210lbs of ballest added to drivers seat / floor to simulate driver:
1986 VW Scirocco 16V
Stock except for wheels
1/2 tank of gas
Manual windows
Power steering & A/C
This is the only video of the turbo running down the strip that we have uploaded. He has since hit 9.5 @ 155mph at the same track:
Some interesting numbers there. Not sure I would want to go round any bends in a hurry onboard Turbo Todd's 928 but quite amazing to watch the video and soo how the front suspension was lifting off- never seen anything like that on a 928 before- clearly he realised his objectives as demonstrated by the time slips.
On your car I would say that is reasonably well balanced. On the earlier cars they clearly show a bias to the front and this may reflect the way these things so often have the "nose down *** in the air" attitude that I so dislike given my perception that it exaggerates the car's natural understeer characteristic.
I do not have a set of scales available over here so when trying to set mine up again recently the local Omani police were very obliging at their test centre. Their test rig only weighs one axle at a time but the numbers made sense. I ended up tweaking the load on the passenger side rear coilover to get a reasonable result that made an immediately noticeable difference.
I set my 928 up with a full tank of fuel and a driver sat in the car. It may still not be perfect but better than it was. I believe that corner balancing is critical to handling for those into such so for racers like Glen highly desirable that they carry out such.
Just wish I had a set of those Longacre scales but at $1000 or so a pop it is hard to justify such when there is plenty ongoing attrition to attend to. I tried to get the local agents to acquire a set given they are required to support the likes of the GT3 where corner balancing is critical to performance.
For corner balancing for best handling are not only supposed to have the weight of the driver in the driver's seat, BUT 1/2 tank of gas not a full tank.
When corner balanced 944 Turbo it was light on right front, left rear. Lengthened right front 1/32" and it evened out. That was the only change and it decreased lap times by 2 seconds on a 70 second autocross course. Before the corner balance you could feel the car rocking like a table with a short leg every time the weight changed in a turn. It was abrupt enough that it would break the tires loose before going smoothly into a 4 wheel drift.
For corner balancing for best handling are not only supposed to have the weight of the driver in the driver's seat, BUT 1/2 tank of gas not a full tank.
When corner balanced 944 Turbo it was light on right front, left rear. Lengthened right front 1/32" and it evened out. That was the only change and it decreased lap times by 2 seconds on a 70 second autocross course. Before the corner balance you could feel the car rocking like a table with a short leg every time the weight changed in a turn. It was abrupt enough that it would break the tires loose before going smoothly into a 4 wheel drift.
Tony weighed the '94 GTS with rear seat, A/C and spare tire, sunroof, rear wiper delete. Storage boxes and a sub added. Seats replaced with 997 GT3 sport seats. I don't know the gas level. Probably low.
There's a reason why GM is sinking so much money into the mid-engine Corvette program. They simply cannot compete anymore with a nose heavy (or even 50/50) car.
There's a reason why GM is sinking so much money into the mid-engine Corvette program. They simply cannot compete anymore with a nose heavy (or even 50/50) car.
I am mystified how Todd managed to get the weight distribution like that unless there is a pile of pre-cast in the rear hatch! For sure it must be an exciting ride and those drag numbers....
10-09-2016, 06:57 PM
Shop loaned us some corner scales, weighed a couple 928's including Todd's Twin Turbo
