All,

Recently I've been contemplating running my 66 912 in FSP with SCCA. I've run stock class Mini's and a CSP CRX nationally over the past few years with some good success. the 912 idea came about as I tend to lean towards oddball cars for competition (call me a glutton for punishment) as it forces excellence in driving.

Now, I came up with a few questions that I hope a few of you may be able to answer or give an opinion on:

1. What sort of power output can be expected from the 912 engines taking into account the SP prep rules? This means intake/exhaust manifolds can be redone, aftermarket fuel injection (electromotive or something similar). No cams, valve modifications, or piston changes. Also what about the reliability of the stock crank (I have heard the stock cranks tend to crack under high stress conditions, that combined with their rarity makes me wonder about OEM replacments and their availability) and other stock parts?

2. What sort of rim/wheel combinations fit on the car? Since this is somewhat of an experiment I would rather not cut/flare the fenders since the car is in decent condition. What are the limitations for tire fitment on the car? Is it strut placement, trailing arm interference, fender clearance? Also, since technically almost any wheel is fitable, it just depends on how far it sticks out, at what width's do the tires start to extend beyond the bodywork and increase track/overall width.

3. Suspension design. I must admit I am not very well versed with the 911/912 suspension (my other cars are primarily double wishbone). Are their any SWB specific problems or advantages as far as suspension geometry goes? Odd toe curves under compression, flat camber change curves, ultra low/high RC's, bump steer issues?

It's been a LONG while since I posted so this is also a bit of a welcome back post.

Again, thanks for the time and thoughts.

Ian

 

Ian,

I don't have time too get too detailed right now but I've auto-x my 67' 912 for 9 years very successfully in CSP. My stock crank has about 500,000 miles on it still on std bearings and turns 6000 rpm all day. You need to re-post this in the 912 thread. you'll get more return posts. I'll get back to you when I have more time sorry.

Brgds, Peter

 

It's good to hear that you have had no issues with the crank. I'm guessing that with good maintenance that the crank should be good to go but I didn't have a specific confirmation of it.

I have the motor apart right now so part of my dilemma is whether to remove the big bore kit the previous owner had in the car or whether to just leave it as is and not compete with the car.

Also, any reason you are not running the car in FSP? SCCA has the 912 and 912E specifically classed in FSP. There is a Porsche 1600 catchall in CSP but the specific classing in FSP overrules that.

Thx

Ian

 

To be honest, it has been some time since I have run SCCA solo events so i can't comment on the difference between the classes. However, if you go the 912 page there is a recent thread about wheel/tire size, this is also restricted if I remember. I run 14x5.5 fuchs with 195/60/14 rubber it's generally agreed that the ideal wheel is the 15x6 fuch with a 205/50 tire. But check out that thread some folks have success with a 15x7 fuch. My susp is not trick, stock sway bar in the front, no sway bar in the back, mild comp alignment and lowered with a capital 'L' konis on a 4 corners and stock rubber bushings all around. I do experience a fair amount of bump steer but it doesn't phase me enough to counter act it. The only thing I would like to experiment with is a larger front bar to curb the little body roll there is. It handles very well and the balance is its best quality but if you get into a situation where it changes direction rapidly you rarely will recover. I have read that the SWB 912 cars actually benefits from no rear bar as the 'soft' rear end helps traction especially since there's less wgt back there compared to a 911. I am not aware of any odd geometry issues since this is not a swing axle car everything is well composed under load. At DE events in yellow, I can maintain the same corner speeds as any 2wd 993.

Just have your crank magnafluxed for stress cracks and your journals measured for proper bearing fitment. Have you considered a light wgt SCAT crank?? check out shasta design for p/c and crank options not cheap but bullet proof. Pick-up the 912 guide while your there. Everything you wanted to know is in there.

The biggest improvements I made to my 912 was weber carbs (32mm venturi / 135 main jets), bosch 050 dist with pertronix optical trigger and a crane cams cd ignition and ps92 coil huge difference in drivability and performance.

Brgds, Peter

 

"2. What sort of rim/wheel combinations fit on the car? Since this is somewhat of an experiment I would rather not cut/flare the fenders since the car is in decent condition. What are the limitations for tire fitment on the car? Is it strut placement, trailing arm interference, fender clearance? Also, since technically almost any wheel is fitable, it just depends on how far it sticks out, at what width's do the tires start to extend beyond the bodywork and increase track/overall width."

Ian,

I've got a set of 5.5x14in fuchs that I am going to post here soon. If you are interested, let me know. I have 2 sets, 1 for street and one for track but I restored the old steelies and I'm going to use them on the street from now on.

Brgds, Peter