Ultimate ST thread

[HughH]

Raj
Nikolay posted this on another forum (i have cropped it as well to fit better on this board)
Zasada in rallye Bulgaria in 1972 in 911 230 0769 (before he crashed it)
I tried to email to you but it bounced back

regards

[JPP]

Hi all,
Great thread, new(er) to forum, quick S/T question:
What does the S/T designation stand for? After reading everything it appears that some folks say it was originally a factory internal designator for a combination of a lightened 'T' chassis with 'S' running gear for factory motorsports purposes. Later it is referred to as a lightened 'S' chassis sometimes fitted with steel or aluminimum or fiberglass or combinations of all three, panels plus other factory racing parts and the implication is the cars were used as 'test beds' for homologation purposes. Any clear definition anywhere on what the 'T' stands for?
Thanks,
JP

[Highfield]

I have a rust free 1973 narrow body car that I am theming on the ST cars - I know I should build based on an RS being a 73 car, but I preferred the ST.

There are a couple of narrow body cars featured here, and my question is did they feature steel or fibreglass front bumpers ?

I note that some ST have standard (albeit in most cases widened to cater for the flared front fender) bumpers whilst others have them from the 'S'. Any reason for this ?

I also have the holes in my metal bumper from the 'S' mounting trim - on an ST, and if they used a metal bumper, would these have been welded up and the tape applied over them, or the tape applied straight over the holes. ?

At the rear, some have the quarter bumpers and no center chrome guards, whilst others have the one piece 'R' style bumper - the 'R' will be my choice and in fibreglass. Same question, if they kept quarter bumpers, where they metal with tape over or fibreglass ?

Ian

[letsrollbabe]

From the great Racing Sports Car web site:

http://www.racingsportscars.com/phot...973-02-04.html

We can see the benefit that the 73 RSR 2.8 L engine, plus suspension/brake changes had compared to the 72 STs of Kremer and Toad Hall with their 2.5 L engines. Here are the data from the 73 24 Hours of Daytona:

Penske Sunoco 73 RSR (911 360 307 R3) 2.8L class
Started 12th, DNF (piston failure), Qualifying time: 2:02.794

Brumos 73 RSR (911 360 328 R4) 2.8L class
Started 8th, WON, Qualifying time: 2:02.156

Kremer 72 ST 2.5 L class
Started 23rd, finished 6th overall, Qualifying time: 2:07.812

Toad Hall 72 ST 2.5 L class
Started 26th, finished 8th overall, Qualifying time: 2:08.503

From these numbers, the 300 hp (RSR) vs. 270 hp (ST) advantage plus the suspension improvements and bigger brakes resulted in an approximate 5+ seconds per lap. And the factory never looked back.

[Chuck Miller]

Gib,

I thought I read that the two 'Prototype' RSR's at Daytona had 'modified' 2.7 RS engines not the 2.8's......

I'll try to find it....

Cheers

[letsrollbabe]

Chuck:

I have never seen any documentation on a 'race' 2.7 engine that achieved higher than the 270 hp of the 2.5s. Looking at the lap times, the engine had to achieve significantly more output than the 270-275 hp that Kremer and Toad Hall had, to beat them by 5+ seconds per lap. My first thought was that the engines might have been the 3.0 L versions, but I think since these cars were built in Jan. 73, the 3.0 engines were not yet available.

I wanted to put this data on this thread to contrast the ST and RSR performance at a known venue to show a good comparison of how the evolution of engines, suspensions, and brakes gave the 911 a significant performance benefit in a very short period of time once the factory got interested in developing the 911 for track competition. The 917 was gone, and with new management, the 911 was now the only game in town.

Maybe the source you remember was using the reasoning that the 2.8 was a 'modified 2.7', as early references for the RSR called it a Carrera RS intended for track competition. Other references show that as early as July, 72 the Strahle prototype RSR (possibly 360 0002) raced in Austria with a 2.8 L engine, and both prototype rally cars at the Tour de Corse in Nov. 72 had 300 hp engines, which would have been the 2.8L engines.

[Flunder]

Chuck:

Maybe the source you remember was using the reasoning that the 2.8 was a 'modified 2.7', as early references for the RSR called it a Carrera RS intended for track competition. Other references show that as early as July, 72 the Strahle prototype RSR (possibly 360 0002) raced in Austria with a 2.8 L engine, and both prototype rally cars at the Tour de Corse in Nov. 72 had 300 hp engines, which would have been the 2.8L engines.

Gib: I think you are on the right track and my reasoning is as follows. I believe that upon introduction, the werks considered the race cars to be Carrera RS with option code M491, but referred to them as a Carrera RS for branding purposes. Remember, they were taken off the RS line and then converted to M491, so they did indeed start out as a Carrera RS.

It was Erwin Kremer who began referring to a Carrera RS with Option Code M491 as an RSR. So, the early race entries showing Carrera RS are most likely correctly identified as RSs, but with Option Code M491.

We know these as RSRs today, but they were not called that by the factory until Kremer's name for them gained popularity in the motoring press.

Would love to hear differing opinions.

Tom

[letsrollbabe]

Raj:

We are talking about Daytona. Both the RSRs and STs I listed were running 9+11 Fuchs, so the differences were the ducktails, larger brakes for the RSR and engines...not much else. The only way to have a 5+ sec lap better time would be a significantly stronger engine. Both RSRs were comparable in times, as were the STs.

Helmuth Bott is quoted as saying in the Carrera RS book: "We see this merely as a long distance test of our engine." They would have been interested in tesing the engine they planned to use for the race season in the RSRs...and that would have been the 2.8L engine.

[Flunder]

Gib: I would add to your list the RSR's raised spindle front struts from Bilstein. I think the factory tests on these showed significant improvements in lap times because they allowed a superior chassis set up. Tom

[letsrollbabe]

Tom/Raj:

Yes, those raised spindles probably contributed to the better times. It is interesting to compare the Kremer ST with the Toad Hall ST. Kremer had the better lap time by less than a second, although the car did not have the deep front air dam or hood mounted lights of the TH car (the pics above are from the 73 Daytona race). The front air dam on the TH car would have upset the balance (actually increased rear lift) without a rear spoiler, and those lights on the hood increased the Cd (drag co-efficient) rating I am sure, which probably explains why the Kremer car was a little faster.

The factory prepared RSRs had extra lighting mounted on the front bumper/ spoiler, which did not have a detrimental effect on Cd. Both cars had the extra 2" lip on the front spoiler, but not the Mary Stewart spoiler in the rear, so they were not getting the full benefit of aerodynamics that Porsche would discover later in the season (Targa Florio).

Raj, to your point I think, the factory worked on both the aero effects to get better speed and handling, and then took advantage of the experience with the turbo charged 917 to build a 2.14 turbo 911 race car ('74) developing 450/500 hp when rules allowed a 1.4 multiplier for forced air engines in the Championship of Makes rules coming in 75/76. The factory worked on weight reduction, aero effects, and more HP to keep the 911 derived cars competitive throughout the 70s. It was a great period for Porsche and established them as a world class competitor...continuing to today.