Total performance plan

After a year of reading everything I could find and talking to anyone with an opinion (i.e., everyone), I think I have come up with a comprehensive performance plan. What do you think?

The best way to get performance out of my 79 SC is to learn how to drive. I intend to take lessons and run periodically at the local tracks to refine my skills.

The second best way is to reduce the weight of the car. Here I am stuck. I plan to drive the car to work and I am old enough to appreciate the creature comforts. Being in Colorado it is also important to have both A/C and heat because you often may need both in one day.

Driving around town and on the track has prompted me to look at the transmission. I will keep first gear, add new ratios for second and third, use the original third gear as forth, and add a slightly lower fifth gear so the jump from "fourth" to fifth will not be so dramatic. This will better allow me to match my RPMs given 95% of my driving habits (I'll continue to save my pennies for a 550 Maranello to race on the freeways). While the transmission is apart, I'll add a limited slip which will also help in those unexpected snow storms.

The engine will receive only slight modifications. Internally, along with a total rebuild with upgraded bolts, I plan to install the European 9.8:1 p/c. I doubt any of the fancy machine work would produced justifiable results. I will also update to the Carrera tensioners. External modifications will be limited to the exhaust as I already have the European fuel distributor. I will "backdate" to a pair of new SSIs (because they look nicer than the original steel) with a dual in/dual out banana muffler. This leaves open the possibility of Webers and cams once I no longer have to pass emissions but as a semi-daily driver, I may just keep the CIS. I am replacing the oil loop with an actual cooler as well.

Anything I missed? Anyone have the winning lottery numbers?

Rich

I also have a ROW SC, and I'm curious as to the advantages of the European fuel distributor. What's different about it?
Also, what's the cost of replacing the differential with a limited slip version?

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Bill Krause
'79 911SC Euro

Rich,

If you are going into the transaxle, how about changing the ring & pinion to a 7:31 (4.429:1) and a limited slip? Because of the post-'76 (coarse spline) output flanges, you have the option of Quaife as well as ZF.

Revised ratio spacing is probably not needed with the 7:31.

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Warren Hall
1973 911S Targa

I'd agree with Warren (again). The more I look at it, the more it looks like the stock SC gears would be PERFECT if you used the 7:31 ring and pinion. the limited slip thing is also (I have heard) a worthwhile upgrade.

Hopefully the european fueld distributor will be 'richness curved' properly for the engine modification you plan. If you''re going to upgrade pistons and cylinders, a special (like "s") cam is thinkable. Your engine can be made to produce around 300 reliable horses if you're willing to take it apart and install upgrades. But, you may need Webers.

Finally, you did not mention an important aspect which is suspension and traction. Tires are the most significant performance parts on your car, and upgraded susppension stuff can keep those tires connected to the road. Keeping that connection is more difficult at higher horsepowers.

Good luck. You're certainly on the right 'track' (pun intended). Your thinking seems crystal clear to me.

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'83 SC

I'm sorry (you don't know how sorry) but you cannot get 300 HP from a 3.0L SC motor. Normally aspirated with cams, headers, webers, and snake oil will get you 250 nearly undrivable HP if you're lucky. I have many freinds who have tried with dyno sheets to back it up. The 930 Turbo 3.3L only put out 300hp in euro form, 265 US. SOK whipplecharged 3.0L only puts out 260 at the rear wheels. I have heard this claim before, It probably originated from an aftermarket vendor.

One step at a time; I am still learning about suspension upgrades.

300 hp? You can talk hp all you want but it is torque that drives the car.

The problem with S cams is the overlap. My understanding is that the SC cams are about as "radical" as you can get without confusing the CIS system. In four years my car will not have to pass the emission tests. At that time I may consider a Weber and cam combination.

If I were to replace the R/P, what would happen to the speedometer and highway RPMs? The setup I am considering would still allow me to cruise at highway speeds without reving the engine. Also, the purpose of the gear changes to to make them closer in ratio. It seems that lowering the final drive would make first gear worthless and I would still have three widely spaced gears before the cruising gear. Wouldn't it be best to have four usable, close ratios gears?

Rich

Hi Guys, first, the speedo in your SC is electronic so I can be recalibriated easly.
Second, If you are going to the expense of changing P/C's think about pistons that have enough valve clearnce so that when you do remove the CIS and put cams in you won't be handicapped in picking a cam that will not give you the full benefit of the carbs. Third, if you are going to the expense of new P/C's think about going to 3.2 maybe use after market pistons and have your cylinders bored and sleaved. Jerry Woods and Dick Elrude are the two people I know that do that. I am sure that there are a whole bunch more that can sleave cylinders, fourth, wait until you get the motor done before you start changing the gear box around. Get the motor crankin' first then see what you want for gears, maybe the torque curve will be different and the new gears won't make you happy. Fifth, I have been told the "factory" limited slip is the one to get, that comes from my friends who do this for a living.

Randy Jones
1971 911

"Speed costs money, how fast do you wanna go?" I know you've heard this before, Porsche takes it to an obscene level. You can spend $7G or so to coax ~250HP out of your motor. Everything you mentioned in the opening post is sound, it becomes an issue of how you use the car and how much money you are willing to throw at it. You know that CIS will limit what you can do to the motor, but you may not like carbs for daily use. This will be a deviding line in the progression of modifications. Obviously you don't want to mess with the trans until the engine mods are done and you are comfortable with them.

[This message has been edited by RarlyL8 (edited 09-15-2000).]

Well, perhaps Superman has been busted exaggerating. I was looking at graphs on p. 151 and 152 of Bruce Anderson's book. they show a horsepower of 250 for a 3.0-based 3.2 liter, and 330 for a more highly modified one. Perhaps undriveable, but there is no mention of turbocharging.

these guys are making a good point though. Real high performance can get expensive, and hard to drive. the Bruce Anerson book is the one to read according to consensus.

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'83 SC

Big S - You are right, you can get 300 HP from an inlarged 3.0L, but it is no longer street worthy. You also have to remember that pump gas is all you can use. These are the rules. Ever see the "quickest street car" competitions? What these guys are calling a street car is definitely not my definition of one. A grey area gone bad.

This is a very interesting subject (for me at least)out of all my friends the want i will like to use ;1- 1995 M3 fully street, a/c power everything, Turbo, NOS,ect,ect top speed 190mph,2- 1998 Porsche Twin Turbo,fully street ,daily driver,top speed 215+ mph,My point is that with enough money and little brains you can do wonders.hook up with the right people and have fun,as much as your wallet can handle.

I suppose deciding whether a particular level of performance is streetable or not would depend upon both the driver and gearing ...

AND, whether the appropriate tolerance for high revs was willingly accepted or forced by 'eyes bigger than one's stomach' syndrome.

In my opinion, a 915 with 7:37 ring & pinion would make a 906, RSR, GE-80, or GE-100 cammed engine tolerable ... with significant grin factor, too!

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Warren Hall
1973 911S Targa

Like I said on another thread recently, these cars of ours can be hot-rodded to the point where they are scary (a technical, racing term). Even the more moderate and typical engine upgrades make these things strong enough to be quite dangerous, and exciting, cars. and reliable too.

Again, I believe an ordinary Sc tranny with the 7:31 ring and pinion would be very useable for a combination of track and street. Combined with the SSI exhaust you'd have some pretty fun power. I think the suspension is what comes next. Bigger torsion bars would make handling more serious and them perhaps the most imortant thing of all - bigass wheels and tires.

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'83 SC