IcemanG17

Whats really crazy is it still is a "street" car...with AC no less....... converting this monster into a full racer would drop a few hundred pounds easy......granted 16V are slightly lighter, but casper was 2632lbs with 1/4 tank.....sure a fuel cell, dry sump and 32V screamer would add some weight....the lightest I ever saw was Petty's at 2590 nearly empty (also 4.5L 16V)......I want to say Anderson's shark was around low 2600lbs with a dry sump.......

Whats silly is if the owner's friends want 1 or 5.....since all the cars Doc mentioned are easily in the $200-400K or more club......I do remember many years ago Anderson put down a lap time on par with the GT3 Cups of its day, but were talking like 2006 if I remember correctly (good luck).

If I had that kind of change....I will build an S4....Just like Tim Dey did when he built the Beast that went 209.9mph.....different game, same dedicated build......also in theory street legal, minus the AC (did have cool suit + cool air).......

GTS 5 speeds are just too rare

GregBBRD

3330 lbs, here.
With, 1/2 tank of fuel, oil, and water.
3504 with the driver in the car.

IcemanG17

Doc
3500lbs on track.....and you mentioned the brakes (HUGE) boiled the fluid.....so the driver clearly knows what he is doing.....you must have some serious tire under there.....I know they are slicks, I'm guessing 305 all around.....maybe more....

I ran 275 slicks all around at 2850lbs at 265whp and barely got them up to temp!

GregBBRD

The brakes are not huge...stock GTS calipers with 330mm discs, up front. (He wanted to be able to run his stock 17" wheels, but I'm trying to get him to use all 18", so we can put bigger brakes on it,
240/640/18 up front, on a 9" wheel.
280/650/18 on the rear, on an 11" wheel.
That's just about as much front tire as I can get under the stock front fender
Front tire wear has been an issue.
I think the rear tires are actually gaining tread....they are virtually new, after ~599 miles.
The strange thing is that we have been "hurting" the left front, when at Thermal, all the cars "hurt" the right front.
That raises some eyebrows, trackside.

Still sorting.
Had it brought back to the shop last Thursday and have been making some changes...

The transmission cooler on a GTS is plumbed through the radiator and then to a stand alone cooler in front of the radiator.
On a 90 degree day, after some really long run sessions, the water temp was 238 and the transmission was 240.
And while it is difficult to know which one of those is driving up the other, I decided that the transmission cooler probably ran through the radiator to "warm up" the gear oil, in cold weather.
And wasn't such a great idea for a track car....
So we moved the transmission cooler to the rear of the car and are using two fans to keep it cool. (Setrab Fan Pack.)
Plus that, I'm on a mission to move some weight to the rear of the car...and every 20 lbs that switches ends, helps.

Did a bump steer and camber curve, with some surprising results. (Had not done this, to date.) Camber looks great....very linear (as one would expect with a double wishbone design.) Toe changes with the car as low as it can get was...too severe.
We've had some rubbing on the right inner fender panel (at the top) and the very corner of the oil tank and we've had to raise the car to 135mm front ride height to combat this.
Turns out that this tire doesn't hit the oil tank until that front corner height is under 75mm....that's really low!

So we "stood" on the spring rate (again) and installed a slightly longer bump stop to limit the suspension travel (90mm sounds about right....if we start at 130mm or so.
Fabricated some tasty new tie rods to be able to adjust the front "bump steer"....something I've never needed on a stock 928!
At`150mm front ride height (about the lowest we will set up a street car) and the limited shock travel, toe changes are very minimal.

We made some changes to the exhaust system.....removed the rear muffler (still have two.)

Not unexpected, because of the huge amount of stuff we "invented" for this car, some of those things need some refinement....there's a whole bunch of uncharted territory, in this car!

With the above items and about 20 other "small" details which bothered me changed, it's just about ready to go back for more testing.

IcemanG17

Doc
Standard Yokohama slick sizes. I ran some of those "used" of course and liked them, just wanted more grip in front especially brakes!!!! Casper ran standard GTS brakes. I found the 18x10x65mm standard Porsche wheel with a 275 in front only needed a touch of fender rolling. I do have a set of 17" Fiske wheels that came with Casper. Those were 295/35-17 front and 315/35-17 rear on a hoosier A6. I think they are the old Devek spec wheels. Not sure of the offsets, but the tires cleared without any fender rolling. The rims in my avatar are the 18x10-65mm with Pirelli 275/645 slicks

karl ruiter

The next one will be 1/4 as hard and the same money.

GregBBRD

If only I'd kept patterns for all of the stuff....
At least I don't have to invent the basic concepts, again.

GregBBRD

I've got some really interesting data and thoughts about bump steer.
New thread or buried on page 17/18 of this one?
Anyone really interested, or is the stuff I'm doing too evolved for anyone to care?

Rob Edwards

I think a standalone bump steer thread would be good- applicable to anyone who's ever thought of dropping their front ride height for the look of it.

Zirconocene

I'm not driving at the level to really worry about bump steer, but I would love to learn about it, how you're thinking about it, and what solutions look like for the car. I vote for a new thread.

Cheers

Speedtoys

@Zirconocene

https://rennlist.com/forums/928-foru...l#post18129473

808c2s

I am interested, and I vote for a new thread on this ??

IcemanG17

Bump steer.......in all the race 928's I built or was involved with, never really had an issue. Casper would bottom out in some of the high G corners with mid corner bumps and it never really upset the car? As my pace increased, I kept increasing the spring rates (especially in front) and re-valving the front shocks to compensate. I must admit Turn 8 at Thunderhill around 100mph at 1.5-6 G and bottoming out (look at avatar) is kinda freaky.....

Watching an extremely fast BMW M3 (national champion GTS3 car) he would take T8 dead flat....like a miata but SO much faster....however he is an extremely skilled driver with top of the line aero and the car is built to the limit of the rules.....he also happened to be 9 seconds per lap faster than Casper.....despite my slight power/weight advantage

Speedtoys

^^There is one.

808c2s

Oh, missed that...thanks!