RSR vs IROC
 

can those in the know tell me as much as possible the differences in these 2 car iterations that Porsche made. Even the yrs made, colors offered...

Thanks alot as I am trying to see which way I want to go on an SC.

Thanks! Bob

An IROC is a RSR built to the specs of the series of that name.

They share the same serial # sequence and most if not all major components

thanks Bill. Can you recommend any good places to go read up on the specifics of both, specs on engines, mechanicals, photos, yrs produced...ya de ya da

Bill, would it be more economical (less $$) to make an "RSR appearing tub" and put in a stock or slightly modded 3.6?? Would you go with coil overs?? Would you use 930 floating brake set up or something different?? I would like A/C in the car but to not tax the engine, thus 3.6?? Would you use an SC tub as a starting place or go the "zuffenhaus c2 to RSR" that is what Keith is doing in NC??

Basically, I am wondering what is the least expensive way to have a RSR looking car, A/C, perform like a RSR did, and have some modern comforts so you can drive it on a 95 degree day w/ 70% humidity, and the car still cranks!! 95% street... 5% de
Thanks! Bob (Bill, is this similar to what you have built before??)

my comparison on the engine is the 3.6 as described above vs. building a 3.0 RSR which I am told will run $15-20k... and if I tweak the 3.6 slightly, I can get it to ~ 300hp way less expensively and maybe a more reliable engine??
Bob

The IROC was essentially the same bodywork as a '74 Carrera RS (9 &11 x 15" wheels), whereas the '74 RSR had much larger "ducted" flares (10.5 & 14 or 15" wheels). The confusion arises because the '73 RSR (long hood + ducktail) had essentailly the same flares as the '74 RS.

That's how I understand it too. IROC had '74 3.0 RS body with '74 3.0 RSR engine, suspension, brakes, etc.

I've been trying to find THIS book by John Starkey, as I hear it does an excellent job chronicling R's, RS's and RSR's.

I may have found the author and have emailed him emailed him about getting a copy. If I have success, I'll let you know.

- Skip

The RSR can be divided into 2 groups the 2.8ltr '73 longhoods and the 3.0ltr '74 G body cars (short hood). The '73 2.8 ltr were MFI high butterfly, 9&11x15 Fuchs. The '74 RSRs were 3.0ltr MFI slidevalve, the IROC cars also ran 9&11x15" Fuchs. The RSRs had the wider flairs and 12&14x15 centerlock mag wheels. In later years the cars came with BBS 3 peice wheels.

early RSR (note oil door, first RSR were built on 72 tubs)
http://forums.pelicanparts.com/uploa...1188078756.jpg

9x15 and 11x15
http://forums.pelicanparts.com/uploa...1188078814.jpghttp://forums.pelicanparts.com/uploa...1188078832.jpg

'74 RSR
http://forums.pelicanparts.com/uploa...1188078888.jpg

12x15 and 14x15
http://forums.pelicanparts.com/uploa...1188078934.jpghttp://forums.pelicanparts.com/uploa...1188078949.jpg

I just got a responce from John Starkey...
- Skip

The '73 IROC cars were officially Carrera RSR 3.0 and were the same as the '73 RSR w/ 9 &11" flares, 917 brakes etc. except that they had the the later '74 up style f/g bumpers(this was the first intro of the '74-89 style bumper cap.
the chassis #s were 911.460.****

15 IROC RSRs were supplied in this configuration to Roger Penske for the series

The original cars had the '73 ducktail, but they were soon changed to the more efficient later whaletails.


engines were 316 ± 3hp, high butterfly injection identical to the other RSRs campained at the time

the 53 '74 3.0RS's were a derivative of this car, the RS was a homologation special, and had a detuned 230hp version of the RSR engine. Bodies and other running gear were identical.

the '74 RSR did indeed have the wider 10.5" & 14" fenders w/ centerlock wheels

these '74 RSRs had 330hp@8000 initially lter bumped to 345hp

A much more informative book is Starkeys "From R to GT3R'

Starkey

Matteos car is an IROC replica, yes, it wil be a lot cheaper and streetable w/ 3.6 power. A true RSR engine is not streetable.

as to the tub you have 3 choices
'73 and earlier
'74 -89
'89 -94 964

each has plus/minus depending on what you want to do.

If you want a 6 spd start w/ a 964 tub

if you want rust protection 'late 911 is best

if you want lightest weight '73 and earlier.

it isn't cheap to get 300hp form a 3.6 either

the 3.6 does have the advantage of very streetable torque, this is what you really want.

to be absolutly correct it is the otyher way around, the IROCs came first, then the 3.0RS

'the 74 RSR did have the bigger vented fenders

the '74 RS looks like an SC/Carrera

Again IROC was first, 3.0 RS followed and did use the same bodywork and running gear, but the IROC had the 300hp 3 liter introduced in late '73 for the '74 season ,'73RSR engine not the more powerfull '74 RSRS engine

Bill is as usual correct. The IROC was between the 2.8RSR and the 3.0RSR with attributes of both. The 3.0ltr with the high butterfly, the 5 stud hubs with the g bumpers, early flares.
As time went on many of the cars were updated and when looking at photos from the day you will see many of these cars with this evolution taking place not to mention the team developed changes.

the chronology starting w/ '73
2.8RSR
3.0RSR
IROC
3.0RS
'74 3.0 RSR

after that it all went downhill when the turbos took over;)

Try Reading The Mucho Articles That Have Been Written On The Subject .

Thanks Bill and others!! Great info here to read up on.

So to wrap up, I will read Starkys book and the new one coming out in 6 mos... in the interum, can you guys give me an overview of what is needed and the costs to make a 3.6 put out 300hp and are we talking f/w or wheels when the hp # is generally thrown about. I know that ~10-20 hp is lost through the drive train in getting to the wheels. I just want to understand the answers correctly.
Bob

Bob

check out a book called "the Porsche 911 and derivatives by Michael Cotton" It has a series of "factory photographs illustrating the stages of the development from the normal 911 2.7 through to the turocharged 2.1 Carrera. Shows a shot of the car and a shot of the different components used on that car. Cars include Carrera RS, RS3.0, RSR3.0, and the turbos. I think I bought this book in the early 80's. The IROC cars look like they are based on on the competition RS3.0 cars.

[QUOTE=skipdup;3445410]That's how I understand it too. IROC had '74 3.0 RS body with '74 3.0 RSR engine, suspension, brakes, etc.

I've been trying to find THIS book by John Starkey, as I hear it does an excellent job chronicling R's, RS's and RSR's.

If you are after this book let me know I can still get my hands on it. I know there was about three copies left.

Michael

Walko, I am also interested in a copy. Can you obtain one for me?
(and still looking for the German Carrera RS book, as well)