Ultimate 3.6 spec help

02m2 · 09-29-2011, 09:44 AM

Newbie to 911's and about to start on a 72 RSR build. Car will be a spirited street machine with no track time in its future. Want great reliability and torque.
My initial thoughts are a 3.6 w/ g50/6 speed CR with LSD. Individual Tb's. I need some help advice and spec's for the ultimate build that will get me in the mid to high 300's achieving my driving goals. Budget not a significant concern.
All advice appreciated.

boba · 09-29-2011, 04:58 PM

Welcome to the Porsche world, you will find lots of very knowledgeable people willing to help here.

You did not give a lot of detail about your project so I will reply with info on the two paths based on the chassis you can start with, a 89 or earlier car or a 964 chassis. Both can get you to where you have indicated you would like to be. If you are going to start with and early pre '89 tub there will be a lot of surgery to fit the package that you interested in. If you start with a 964 the chassis will be ready for the drive train but will need cosmetic surgery to achieve the look you would like. As it turns out there are two well documented threads, one of each approach done by the same shop.

The first is a IROC RSR built on a early tub with 3.9 and G50/31 six speed.

3.9 RSR project --- my Carrera reborn

The second is a '72 RSR built on a 964 tub.

zuffenhaus C2 to '72 RSR project...

These two threads will cover most of the questions you have asked with the exception of the close ratio G50 6 speed, and for that I can tell you that I am in the process of having the same shop do that for my '94 C2. In fact they just received the donor '95 993 gearbox w/LSD and it will be re-geared with a tall first, stock second, short 3ed, 4th, 5th and stock 5th in the sixth gear slot.

This should get you started.

02m2 · 09-30-2011, 08:07 AM

Quote:

Originally Posted by boba

Welcome to the Porsche world, you will find lots of very knowledgeable people willing to help here.

You did not give a lot of detail about your project so I will reply with info on the two paths based on the chassis you can start with, a 89 or earlier car or a 964 chassis. Both can get you to where you have indicated you would like to be. If you are going to start with and early pre '89 tub there will be a lot of surgery to fit the package that you interested in. If you start with a 964 the chassis will be ready for the drive train but will need cosmetic surgery to achieve the look you would like. As it turns out there are two well documented threads, one of each approach done by the same shop.

The first is a IROC RSR built on a early tub with 3.9 and G50/31 six speed.

3.9 RSR project --- my Carrera reborn

The second is a '72 RSR built on a 964 tub.

zuffenhaus C2 to '72 RSR project...

These two threads will cover most of the questions you have asked with the exception of the close ratio G50 6 speed, and for that I can tell you that I am in the process of having the same shop do that for my '94 C2. In fact they just received the donor '95 993 gearbox w/LSD and it will be re-geared with a tall first, stock second, short 3ed, 4th, 5th and stock 5th in the sixth gear slot.

This should get you started.

Thanks for the info. I got a 72 911 roller. TRE Motorsports will be doing the build for me. It will be a spirted street car with some creature comforts so that I will actually like to drive it a little. This is my first 911 project but have a number of builds either underway or completed. I am looking forward to a lot of help from the forum.
Marc

PFM · 09-30-2011, 01:53 PM

If Dave B at TRE is involved it will be fun to drive...

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by 02m2

Newbie to 911's and about to start on a 72 RSR build. Car will be a spirited street machine with no track time in its future. Want great reliability and torque.
My initial thoughts are a 3.6 w/ g50/6 speed CR with LSD. Individual Tb's. I need some help advice and spec's for the ultimate build that will get me in the mid to high 300's achieving my driving goals. Budget not a significant concern.
All advice appreciated.

For a street car where torque is king, start w/ a 993 or a 964 bottom end w/ 993 top end, w/ ITBs use a Gt3 plenum to enhance lower speed torque and don't go too crazy w/ the cams, rev limit will be limited to <7k by the crank/rods and oiling. alternatively emulate what they put in the Singers, ie a 993 engine w/ GT3 crank/rods and oiling itbs and a 8k redline, but you will want much lower gearing w/ that setup.

Keep tire sizes low to say under 25.5" OD which means something like a 315/30 x18 rear max on an 11 -11.5" wheel.

the stock 6 speed ratios can vary from great to awful, careful selection of the box and or gearing is going to be critical. I'd look for a late 997 GT3RS transmission or maybe an early 996 GT3. If using a stock 993 plan on spending a lot of money to regear it

02m2 · 10-03-2011, 09:24 AM

Quote:

Originally Posted by Bill Verburg

For a street car where torque is king, start w/ a 993 or a 964 bottom end w/ 993 top end, w/ ITBs use a Gt3 plenum to enhance lower speed torque and don't go too crazy w/ the cams, rev limit will be limited to <7k by the crank/rods and oiling. alternatively emulate what they put in the Singers, ie a 993 engine w/ GT3 crank/rods and oiling itbs and a 8k redline, but you will want much lower gearing w/ that setup.

Keep tire sizes low to say under 25.5" OD which means something like a 315/30 x18 rear max on an 11 -11.5" wheel.

the stock 6 speed ratios can vary from great to awful, careful selection of the box and or gearing is going to be critical. I'd look for a late 997 GT3RS transmission or maybe an early 996 GT3. If using a stock 993 plan on spending a lot of money to regear it

Thanks Bill !!