964 vs 993, a systems analysis

[kurquhart]

Originally Posted by strokher racing

Damn for what I am doing I think I will spend my 1600 elsewhere. 9 pounds is not enough to justify it to me

It is not as much about weight (which is nice), but more about bump steer. If you are going to aggressively lower your car toward (or beyond) RS ride height, the RS/GT2 uprights are about the only way to correct the resulting bump steer.

[Tom W]

I wasted plenty of time and money to try and reduce the bump steer using the 964 (original stock) uprights on my car. Once I switched to the EVO uprights (and full monoballs) the issue was solved. Yes, it's a bunch of money, but for a track only car where class rules permit it, it's a great change.

[strokher racing]

Yes I agree with all that. My car is more geared for drag racing so not worth it in my case.

[Bill Verburg]

964 wheels(mainstream) from the top Design 90, 928 Gullydeckel 16s, Cup narrow spoke, Cup1(akaDesign92)

the Cup 1, aka Design 92 was also available inthe folllowing sizes



993 wheels(mainstream)














In addition to the mainstream wheels there were some specials
964 Cup 1 magnesium, 7 & 9 x17, both ET55 8x17ET52

[Bill Verburg]

964T Speedlines 8x18 Et 52 10x18 ET61




993RS Speedlines 8x18 ET52 10x18ET65

[KobaltBlau]

Originally Posted by Bill Verburg

It seems that the serious track setups eliminate or at least reduce the Weissach effect on both 964 and 993. I don't think it's even part of the 996 or 997 design, but I don't know enough about thoose cars to say for sure.

I agree that serious track setups eliminate or reduce the "Weissach effect" but I do believe that the 996 multilink rear uses a very similar concept to the 993 to create this effect and that serious 996 track setups similarly eliminate or reduce the effect. I do realize this is a 964/993 thread, however

[Bill Verburg]

The question of using 996 GT3 gear box has come up, the g96 thru 2000 can be used in a 964 or 993, 2001 up changed to a cable shift mechanism to use those the sfifter would also need to be changed

here's a comparison of the transmissions.

[Cobalt]

Bill,

This might help a little.

The pictures of the 3.6T speedlines are actually an aftermarket wheel. Here are a few pics of factory speedlines. these are both polished and painted center versions.








If this is too many pictures just tell me what to eliminate

[Bill Verburg]

Originally Posted by Cobalt

Bill,

This might help a little.

The pictures of the 3.6T speedlines are actually an aftermarket wheel. Here are a few pics of factory speedlines. these are both polished and painted center versions.


If this is too many pictures just tell me what to eliminate

The ones in post #46? I thought they looked hinkey, and the brakes under them are wrong too.
If so I'll just relable them

all pics are welcome, the more the better documented all this is.

[Cobalt]

Originally Posted by Bill Verburg

The ones in post #46? I thought they looked hinkey, and the brakes under them are wrong too.
If so I'll just relable them

all pics are welcome, the more the better documented all this is.

Yes # 46 I believe they are made by a company called Kerscher. You can tell because the 3.6T speedlines have much more curvature to them.

[Steven Alarcon]

I do have question.....I understand that the 3.6 964 Turbo 18" Speedline Wheel
is the same as the 92 964 Cup Car Wheel. The rear 3.6 964 Turbo 18" Speedline
Wheel is a 18 x 10 / 61 mm offset and the 92 964 Cup Car Wheel is a 18 x 9.5 /
47 mm off set. Can I purchase the 3.6 Turbo rear wheel and downsize the
inner rim halve to make it fit my 92 964 Cup Car ??? I understand that the
18 x 9.5 is unavialble. Here are some pictures of a customers 18" Wheels.

[Cobalt]

Originally Posted by Steven Alarcon

I do have question.....I understand that the 3.6 964 Turbo 18" Speedline Wheel
is the same as the 92 964 Cup Car Wheel. The rear 3.6 964 Turbo 18" Speedline
Wheel is a 18 x 10 / 61 mm offset and the 92 964 Cup Car Wheel is a 18 x 9.5 /
47 mm off set. Can I purchase the 3.6 Turbo rear wheel and downsize the
inner rim halve to make it fit my 92 964 Cup Car ??? I understand that the
18 x 9.5 is unavialble. Here are some pictures of a customers 18" Wheels.

Yes it can be done.

PM sent.

[Bill Verburg]

964 & 993 road test performance data is summarized Here

[Bill Verburg]

Originally Posted by Steven Alarcon

I do have question.....I understand that the 3.6 964 Turbo 18" Speedline Wheel
is the same as the 92 964 Cup Car Wheel. The rear 3.6 964 Turbo 18" Speedline
Wheel is a 18 x 10 / 61 mm offset and the 92 964 Cup Car Wheel is a 18 x 9.5 /
47 mm off set. Can I purchase the 3.6 Turbo rear wheel and downsize the
inner rim halve to make it fit my 92 964 Cup Car ??? I understand that the
18 x 9.5 is unavialble.

Jim Dorociak
805-498-7261
jdorociak@gmail.com

Has done a lot of work refurbishing and modifying outer/inner combinations of the various Speedline wheel sets

[Cobalt]

Originally Posted by Bill Verburg

964 & 993 road test performance data is summarized Here

Bill,

I understand these are a compilation of different magazine tests of the time and that there are numerous factors that come to play. However, can any of these numbers really be the truth. There are variations and exaggerations that I don't think could be achieved by some of these cars even if they were treated in a brutal fashion with a full drop of the clutch from very high rpms.

Car & Driver IMO had always reported ridiculous numbers that most factories wished their cars would perform at but know they are not capable of. I would love to find the RSA that C&D claimed did a 4.6s 0-60 time and although I would love to believe my turbo is capable of 4.0 seconds flat in stock form but I think I would be needing a new clutch and tranny after 4 or 5 launches like that. With the mods it is far easier to obtain but still not what these cars were meant to do.

I find Auto car and top gear #'s to be the most realistic with Car & Driver in a world of it's own.

[tommott]

I am a bit surprised to read that the 993 has a higher drag coeff. than the 964. Granted I had just gotten my license when the 993 came out, but I could have sworn that I read the revised bodywork of the 993 was more for aerodynamic purposes as opposed to aesthetics. Was this a case of the original intent to be one thing but through development, ie the addition of the picnic handle, you end up with a production vehicle that has gone array from the original intent?

[ilko]

The 993 had wider hips due to the redesigned rear suspension. That's what made it less aerodynamic.

[Cupcar]

Originally Posted by tommott

I am a bit surprised to read that the 993 has a higher drag coeff. than the 964. Granted I had just gotten my license when the 993 came out, but I could have sworn that I read the revised bodywork of the 993 was more for aerodynamic purposes as opposed to aesthetics. Was this a case of the original intent to be one thing but through development, ie the addition of the picnic handle, you end up with a production vehicle that has gone array from the original intent?

Aero lift coefficients front and rear are greater than 964 as well.

[Bill Verburg]

Originally Posted by Cupcar

Aero lift coefficients front and rear are greater than 964 as well.

That depends, here are the #s I posted back in #4. They are only good at stock ride height w/ stock suspension settings and stock wheels. Your results will likely be different.


As Ilko mentioned the rear fenders are much wider on a 993, makes lots of room for wheels, tires and mufflers but not so good for aero. I'll add that the front fenders are also wider, again great for fitting big wheels and tires not so good for aero.

JMO, aero isn't all that important in and of itself, I prefer a balance of aero and pleasing looks. A 996 aero wise has it all over 964 and 993 but is just too plain for my tastes.

[Cupcar]

Originally Posted by Bill Verburg

That depends, here are the #s I posted back in #4. They are only good at stock ride height w/ stock suspension settings and stock wheels. Your results will likely be different.


As Ilko mentioned the rear fenders are much wider on a 993, makes lots of room for wheels, tires and mufflers but not so good for aero. I'll add that the front fenders are also wider, again great for fitting big wheels and tires not so good for aero.

JMO, aero isn't all that important in and of itself, I prefer a balance of aero and pleasing looks. A 996 aero wise has it all over 964 and 993 but is just too plain for my tastes.

Cool data, here are some things I think are interesting:

In pounds then the 993 RS has 40 pounds of lift at the front 0 at the rear.

The 993 RS Clubsport has 0 pounds lift at the front increasing to 40 pounds of lift at the front when the rear wing angle is increased to nine degrees.

The 993 RS Clubsport has rear downforce increase from 26 pounds at zero rear wing angle to 160 pounds at nine degrees angle

So, the RS Clubsport front lift goes up as rear downforce goes up.

Frere in his book states the 993 has a higher rear lift number than the 964 because "the exhaust system makes it impossible to raise the (engine) underpan at the car's rear end" (as the 964 does).

So, an interesting data point would be that of a 964 Carrera Cup car which would be a 964 without the engine underpan which would presumably add to lift at the rear as Frere states.

Data for the RS America whould be interesting since this adds the bigger wing to the 964, perhaps generating downforce at both ends, not just the front.