Never drive faster than your guardian angel can fly! So....if you are going to be a Porsche guy, you better have a fast f'n angel.

 

dang it my nine year old again.....I do want to help but she wants a chart and graff paper explanation ....i'll be back...

 

You should be able to redline it in top gear. I've only had mine up to 130, but it's gets there pretty quickly.

 

a second closer look tells me just under 5,000 and just over 120....the plot thickens

what was the maximum rpm's at 100 miles per hour? it could be that the tires are oversized, the air filter is dirty, the cat is clogged, timing or a million other things. I hate to think you are missing out on the best part of the car.....speed that you do not need. my money is on the cable first, fuel delivery second, and third is air flow.

 

just put 2 and 2 together...the car is overheating and wont go fast. it is time for a good shop and a good lawyer back in the city by the bay....

 

Factory literature for the top speed of an '83 SC is 225 km (139.7 mph). The wide body conversion will definitely trim some off the top, but not more than 10 mph. Douglas made a very good point, if the cat is plugged the car will run "good," but it just won't go...

 

gearing in my (Euro) SC could be similar --
4th gear 1000rpm indicated = 20mph indicated, 6000 = 120 (indicated)
5th gear 1000rpm indicated = 25mph indicated, 5000 = 125 (indicated)
engine is a lightly tuned 993, and the car will not reach 6000 in fifth on any of the tracks I drive. Fifth may be too high because shifting from 4th to 5th at 6800 does not result in any significant gain in speed. Seems like the wall of air occurs about 140.

 

Alan: What you're feeling is correct, your Euro trans (915/62) has a longer 5th than the USA trans (915/63). The 915/62 has a 28/22 5th, the 915/63 has a 28/23 5th. About the only track that I've been on where your car should pull 6K in 5th is the big track at Willow. And then, the car has to be perfect because it will happen in turn 8 (the front straight is uphill and unless you come out of 9 with a serious head of steam you probably won't see more than about 5500-5700 rpm).

 

I had a european 1978 911SC Targa- the owner's manual said it would do 140mph- I once hit a little over 140 (225 KM) just about redline (didn't really look that closely as I was watching the road- which was 4 open lanes with no traffic (and many years ago), but it was definitely getting close to redline). I believe the top was reached about at redline- I attributed the fact that I had a couple more MPH to go as it was still accelerating when I let up (i.e. it would have topped out say at indicated 145 or whatever) to speedometer error. I had the top in place by the way... The 1978 european motor was rated at 180hp/195 ft lbs of torque. I believe later 911SC euros had somewhere around 204 hp. I don't know if the 5th gear was any different...I think my car did 2,600 at 60mph.

I have a period road test home of a US '83 cabriolet that had top speed of around 128 if I remember correctly...even with your cabriolet and wide body, the car should go over 125 if not over 130

 

Not sure about speedo accuracy or exactly how my car was setup when rebuilt by the previous owner, but I've red-lined my 2.7 in 5th gear and the speedo needle went well past the 150 MPH mark when doing so. My tires were a smaller diameter than stock (14" 60 series), so the actual speed was probably under 140 MPH.

Note: This is neither a confession nor a plead of guilty to any traffic violations that may or may not have been committed. All similarities to self or others are purely coincidental. e pluribus unum, sancto sancto, hakuna ma-tata, ahem, amen.

 

My 1979 SC Targa with horrible compression in one of the cylinders (85% leakdown) would peak at 135mph. I was not in a financial position to rebuild, so dealt with it. Besides, anything above 120mph was an adrenaline rush.

IMHO, my SC loved to be run between 95 and 115mph. The car was just so smooth at those speeds....

My $0.02,
-B

 

From some literature that I have.:

The European performance numbers were :-
Power Torque 0-62mph Top Speed
204 bhp 195 lbs-ft 5.7 secs 148 mph

 

I still have the acceleration info from my 1978 owners manual memorized: 0-100 KM (62MPH) 7.0 seconds

The actual magazine road tests were typically faster on the 0-100KM or 0-60MPH times, more in the low to mid 6 second ranges.

 

I could pull 140 with the stock engine (before my engine swap). 1978 SC....

 

Porsche routinely uses top speed numbers as exactly how fast the car is moving when red line in top gear is reached. If they discover that a particular engine will not reach red line in top gear, they change that gear's ratio. For example, sometime in 1985 Porsche offered to its home market an option called M 298. That option consisted of an engine fitted with catalyst and oxygen sensor, a lower compression ratio (9.5:1), and made 207 DIN horsepower, compared to the rompin'-stompin' 231 DIN of the non-cat RoW cars. When they ran the 207 hp car up to top speed it was discovered that the 207 hp engine couldn't pull all the way to red line, so Porsche had to change the ratios for both 4th and 5th speeds. The 231 hp motor got transmission 915/72, but the European M 298 market got USA's 915/73! The 915/72 trans was built with a 29/28 4th and a 38/29 5th. The 915/73 trans had a 26/26 4th and a 38/30 5th, both gears were shorter than those used in their powerful non-cat 231 hp brother. It sure would be interesting to know how many Germans bought M 298 cars...