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)

Walko, That would be great if you could check to see if you can get 1 of these books for me. If in fact you do find 1, please let me know what the cost would be. I presume the book is in english as I am unable to read any other language... well printed language that is ;-)
Thanks, Bob

I fellow PCA'er here owns a original IROC and has it on diplay on occasions at our Grand Prix.http://forums.pelicanparts.com/uploa...1188135777.jpghttp://forums.pelicanparts.com/uploa...1188135817.jpghttp://forums.pelicanparts.com/uploa...1188135840.jpghttp://forums.pelicanparts.com/uploa...1188135856.jpg

Great photos!! Have any head-on, rear-on, cockpit and engine photos??
Bob

None personally other then whats shown. There looks to be an original halfway down this page:

http://images.google.com/imgres?imgurl=http://www.flat6.com/images/project_iroc_05t.jpg&imgrefurl=http://www.flat6.com/projects.shtml&h=56&w=75&sz=3&hl=en&start=64&sig2= 60TeGAGKJzIF6VTqaANeqw&um=1&tbnid=0rONZZKGJxXpRM:& tbnh=53&tbnw=71&ei=0pTRRt74Ap7Uerb81aAJ&prev=/images%3Fq%3D1974%2Bporsche%2Biroc%26start%3D63%26 ndsp%3D21%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3D GGLD,GGLD:2004-32,GGLD:en%26sa%3DN

PM sent. Thanks!

911 Tweaks -

As someone who's been down a similar road, I'd suggest you decide on very clear goals before you start the project. If you want a street car with the look of an IROC, RSR 3.0 or RSR 2.8, but computer-controlled reliability and some creature comforts, then a 3.6 is a great way to go. Keep in mind, purists won't consider it a 'clone,' even, since it won't have an early motor in it.

Also keep in mind that you're describing something that could be done for as little as 40K or could easily add up to 140K. Your target of 300 hp is worth looking at. A stock Varioram 3.6 might cost you 7-8K and will come with 285 or so hp. To get that figure to 300+ hp could cost you an additional 8K. Is the last 15 hp worth it to you? To some guys, it is.

If you're starting with a stock SC, and you want a longhood body style, keep in mind that you'll be replacing just about everything, and that it's going to be a fairly expensive way to go. If money is an issue, you might want to think about selling the SC and then backdating a 964, or sourcing a cheap early tub (which is getting harder to do) and a Varioram 3.6 and a suspension. For an IROC or RSR 3.0, you'll still be replacing most of the SC panels. For what it's worth, the backdated 964 -- which will have bigger brakes, coil-overs and a much more rigid chassis -- will probably be cheaper.

And if you want to do it for less than 40K? There's really only one way, these days. Sit tight and wait for someone else's 3.6-in-an-early-car project to come up for sale. You can get the whole package for 30-50 cents on the dollar.

Thanks Jack, as you know, you are correct. It still is great hearing/confirming what one "thinks" to be true AND then to have it validated by someone with your experience. Thank you!!

Anyway, is there much gained if one was to add carbs, a more aggressive cam and maybe a different exhaust, to a stk 3.6?? Would it only be for minimal hp, like15-25 hp gained, and need to spend $4k on carbs, $1500 on exhaust, $600 on cams = $6-8K for 15 to 25 hp?? To me that is not worth it at all!

IS THIS STATEMENT ACCURATE, 15-25 HP FOR $6-8K??

To the tub subject...what in your opinion is most economical: a C2 with its coil overs, stiffer body, body needs backdating, it has 3.6 w A/C... OR an early long hood/SC and need 3.6, A/C, fewer body panels but most, needs beefed up suspension... I am too deep in the forest now and I cant see a single tree...HELP

maybe I need to do a spread sheet or can you share what you may of gone through or know of someone with a similar situation and how they noodled it out.

I see what you are saying in your most recent answer, and I believe you. However, that is going to be a needle in a hay stack, especially here on the east coast, no? Thus, any hopefully equal opportunity that may cost more in my "sweat equity" but same or very similar parts cost in the end?

So many options and areas to think of! Thanks for helping me cut through the fog.
Bob

you will barely be able to get a stock used 3.6 for $6-8k

Jack gave you some good advice

the major decisions are base engine, base trans, base supension and base brakes.

then where do you want to go w/ each of those categories. and what do you want when you are done.

that will determine where best to start. Any 911 from '64 to '94 can be made to look like an IROC or RSR but not all will perform like one(or better)

Bill, I was trying to explain the cost for the additional components to POSSIBLY make the 3.6 deliver 300 hp.
So, would spending the hypothetical $6-8k achieve the 15-25 additional hp? Even if it does, I cant see spending that kind of money for that minimal hp increase.

So, I will try to ask the question another way:

What tub + what engine will develope 300hp(as the RSR did) + what suspension + what other bits = "RSR w/300 hp in appearance and performance" = that is the most economical way to build such a 911?

I am willing to make some concessions, trade-offs, to have the look and performance. Maybe even better "performance" in some aspects. i.e. coil overs probably perform better than original RSR suspension and I could go either way...which either way is more $$ smart.

Bob

There is more to it also then just numbers. Torque is what you need for a track car. You can have two engines with similar horse power production and vastly different torque curves. A nice broad torque curve can do wonders for a cars performance compared to a peaky one.

This also needs some thought. I would seriously consider buying someone else's project. ;)

thanks Jack, Bill, Boba and all others.

I guess I need to continue my research, liking refinement and all the rest.

It is great that their are so many options and directions to achieve the same end result.

HOWEVER, I truley thought that my above back and forths with everyone would of resulted in my car objective having been defined.

Maybe I need to re asses this whole process as I already have A LOT OF $$ tied up in parts with "0" to show so far...other than lots of parts.

I will read the above books and see if this is worth it after all...

Thanks again all.
Bob

Bob- What about taking a 930 (or '91-'94 Turbo) and making an IROC replica?

You'd already have the fenders, brakes, target hp rating, etc...

Just thinking out loud...

- Skip

Skip, that is a great idea, but wont the price of a turbo roller be steep if for no other reason that it is a turbo body?
Then to possibly sell the turbo motor and get or build a 3.0RSR or put in a stock 3.6...sounds like a great idea...I have no clue what those #'s would work out for cost. I you can inform me I am all ears...

Presently, having just spoken w/ Keith Walters @ Zuffenhaus, I am leaning twd finding an 89-94 c2 964 coupe and backdate the bodywork. Keep the stk 3.6. If after it is complete the performance is less than desired, I can always add PMO's, exhaust, maybe some cam work... I am led to believe the power addition can be 40-60 hp and make the engine then look like an early car w/carbs.

I think an extensive spread sheet is in order w/ all items needed being factored in.

When I am done, I will post for all others to learn read and we all can then maybe have a more specific discussion (take the emotion out of the subject I have always said makes it easier to noodle it out)
Bob

Actually, I was thinking you could buy a 930, put on IROC front & rear bumpers, remove rocker covers, add an IROC tail, put some proper sized wheels on and call it a day.

Depending on the year you chose, the turbo motor would already make your target of 300hp, or more - stock. Why replace it? Unless you don't want a turbo. I know a lot of guys prefer N/A motors - for some strange reason. ;)

I guess you'd also have to do the suspension and interior (race seats, roll bar, etc). But, that'd happen with any car you start with, if you plan on track work.

I was just thinking a wide body (9&11 inch fenders) with 300hp sounds an awful lot like a 930.

If you started with an '89 or later, you'd get a 5-speed transmission.

I believe '91 and earlier would also give you non-torsion bar suspension, which might be preferable??? as well as the 5-speed. But, someone with more knowledge of the later turbo's would have to help with this, as my knowledge is limited.

Just throwing out ideas.

- Skip

I like the idea of starting w/ a 964 base. You have most of the basics for a really strong street car.

You also have lots of flexibility as far as engines, trans and suspension goes. A 6 speed, Cup suspension or brakes bolt right in.

Again Matteo's beautiful blue car is an example of an updated IROC clone done right. He could have saved some grief and expense by starting w/ the 964 tub.

now we are cooking guys!

Can you add to your previous great info regarding 964 tubs??...I know zip about 964s other than that they continued the air cooled 911, 3.6L engine, later yrs have better? varioram intake, BAnderson stated they have over 60% new parts vs. 84-89 911 generation. That is the extent to what I know.

Is there a ton of sh^t that will need to be removed from the 964 that the factory added to possibly make them more comfortable for intended era buyers??

Any one know what the tub weight of a 964 stripped vs. an SC tub stripped?? I believe Keith posted the weight of his zuffenhaus c2 to RSR but I cant find it and I cant recall what weight info he actually posted.

Anyway, I can see the ball starting to take shape so it can begin its roll! (I am so stupid with the poetic clichets crap... bear with me as maybe I am a legend in my own mind... ;-) ha ha)

Bob

What do you want to do with the car? Track it? Or just have it look fast on the street?

I think 964 is the way to go, but you don't want a roller, you want the whole car (maybe one with accident damage). Then backdate the parts you want, but the guts (engine, ac, abs, etc) are all there.

I AM LOVIN' IT ! Great idea nostatic. Now to find a great 964 that someone had all of their fenders beat in, some broken glass, f & r lid wrinkled, BUT the chassis is straight and the engine runs and has all important stuff there...then I will be all set.

Whats one of those going to cost? Where can this condition car be had AND looked at BEFORE I fork over the $$ so not to buy a POS??