G-tech fun. What's a 0-60 on 81 SC?
 

I just got an early x-mas present to myself today. A G-tech pro. The older model that is.

I went out and had some fun on a dead end road in my stock US spec 81SC. The best I could get without raping the clutch and transmission was 6.6 seconds for 0-60. That is wiith a rather slow upshift on the 915. What do you think? What's the factory number and what is a contemporary test number for an 81 SC? I sure feel that I could get down to 6s if I was able to power shift and did a clutch drop at 4krpm. :D The LSD helps already not to spin tires much when getting on it from the dead stop.

I also did HP numbers. Got anything from 155-171 at the rear wheels assuming 3k pounds total weight with me in there and quite a few interior pieces and one seat missing ... The distribution seemed to have it's maximum around 160-165. That actually makes pretty good sense, coming from what? 185 at the crank?

The road was too short for 1/4 mile times, I'll do those another time.

Now the next present to myself should be SSI and a nice sport muffler. Then I could see if I can see a mighty 10-15% increase in umph and start trying to G-tech race my american muscle car!

Cheers, George

Interesting - I always wondered what my '81 Coupe was capable of as well. Unfortunately I've never done any kind of testing like that but at least now I've got some kind of benchmark.

Thanks.

Ha! I got a G-tech Pro as an early gift to myself too!

6.6 Seconds is pretty good for an 81SC. I'll have to wait until spring for my runs, or I could go for it sans the front end :D

HP numbers are no good until you really know the weight and the loss. But it'll be good for relative changes in HP.

The G-tech is a great toy. It won't tell you a whole lot, I agree. But it is great to measure before and after modifications or if you are fine tuning a car. Absolute numbers need to be taken with a grain of salt, which is true for most chassis dynos too, BTW.

George

0-60 = 6 seconds for an '83.

0-60 = 5.5 for a '78.

Both are Road and Track as I recall.

Darn, they must have had some test cars that they didn't own! :D Of course, my valve adjustment and a tuneup are way due, but I can't see breaking below 6s without major abuse of the driveline. I will have to test again after fine tuning the mill ...

George

Turbo it and you'll get 5.0 with that 3.0 SC. The "driveline" will, be fine but you might want the Sachs Power clutch but not until the stock one fails. My stock clutch lasted 20 years. 18 years WITH the turbo.

5.5 for a stock 78 SC huh... wow! thats quick.. I would say mine is faster than that then.. as I have SSI's and Sport Exhaust and Nothing inside thecar and or onthe outside really for that matter, i'll have to borrow on of these G-techs and post my munbers..

great to hear..
5.5 out of a 78SC.

How much Hp did a U.S spec SC have to get 5.5 seconds? Euro (204Hp) models are quoted as 5.7 by most road test articles.

I've been meaning to get a stopwatch and see what happens. Most of you know that we dyno'd some SCs recently here and most of us made about 174 lb/ft of torque at the wheels, which is about 205 at the flywheel. And with the 20/21 cams, my torque curve is deliciously flat. So, I think the factory-specified 7.0 seconds is a joke. Like others have said, balky shifting is probably the thing that holds us back the most. If our clutches and trannies were up to the task, I think six seconds flat is very very achievable. First gear is over in a flash, ending at 40 mph. Second gear gets that last 20 mph pretty quickly too.

And with a Cool Collar, perhaps we could get close to the 917 numbers. I think they got to 100 mph in something like 3.4 seconds.

I did some Net research and came up with 6.7 second 0-60 timing.
If you did 6.6, that sounds pretty good.
I can't believe a 78SC can do 0-60 in 5.5 seconds without a bit of help.
By the way, the "official" Porsche stats of 7.0 seconds was for 0-62 mph (100 kph), which is probably about 6.8 seconds 0-60, buth they seem to notoriously underestimate anyway.
- Bill

Well, of course, 0-60 times involve a tremendous amount of variables. I had a G-tech, and received so many different readings, that I gave it up for a good old fashioned St. Moritz chronograph. That said, I timed my car very, very conservatively from 0 to 60, and received 6.1. What I mean by "conservative" is I started out at 1,500 RPM in second gear, and accelerated to 60.

I just don't think the 0-60 time is all that important - though it is a fun stat. And SUPERMAN is correct about the transmission et al playing a major factor in how fast the car accelerates.

Everyone at TRE estimates my car should accelerate to 60 in the low 5s, but I'm not willing to blow my clutch or break my transmission in the process.

dd74 -
What kind of car do you have? I enjoy 0-60 stats.

Side question: My speedometer is a bit fast - I think I'm probably closer to 50 than 60 when the speedometer says 60. Would the G-Tech (or similar device) also reflect an inaccurate reading in this case?

I also wonder if this is a common thing to have a fast speedometer on a 911?

Eric, I think Carston has one, and so do I. You can borry it any time. As long as I can get a ride in your 959 someday.

I used to read (and practically memorize) all the car mags from the late 70s and early 80s.

As I recall, most mags here in the US got 60 in 6.2 to 6.7 for the SC.

Here's the post for the article of the 1978 Road & Track test where they got 0-60 in 5.5.

http://forums.pelicanparts.com/porsche-911-technical-forum/125228-1978-911-sc-c-d-road-test-scan.html

I've seen a few statistics for the 204hp RoW SCs that said 0-100kph (62mph) in 5.7 sec.

'74 911 with an '83 engine. 7.31 r/p. 2,340 pounds w/ 1/4 tank of fuel.

I really like the way the SC feels in the turns.

As far as I can remember a Euro 180HP SC will do 0-62 mph in 6,8 secs. The 204HP 81-83 Euro SC should be 6,5 secs. Still according to road tests of the time the 204 cars have been measured to 6,2 & 5,9. Probably depends....if the driver has to pay for clutch etc. then the times will be slower ;)

I know the 77 Carrera 3.0 suppose to do 0 - 62 at 6.1 according to all my books. I would be surprised if the 3.0 SC's did it faster Weight difference and less hp for SC (US). I read the 3.2 (U.S.) was down around 5.5. I doubt that too. Anyways, who cares. They are all beautiful cars.

I should get a stopwatch so I can objectively measure whether performance upgrades actually make the car faster. But I would not choose 0-60 as the measure. I'd choose something like 80 to 110 in fourth gear. Or 60-95 in third. Something that will isolate the engine's performance, away from clutch, tranny and tire variables.

I believe the reason the early SC is faster than the later one might be attributed to larger intakes and head-bore size, giving it a slight edge at the top end. And possibly a lighter car overall.

Did anyone notice that the early SC was also a Targa, which is always heavier than a coupe?

Was there a notable weight increase between the early SC and later SC?

And if so, where did it occur? Was it in the body? The chassis, etc? Anyone know?

If you are running different sized tires than originally equipped with, your speedometer may be noticably off. My 74 911 came with 185 70's, I am currently running 195 60's which have over 5% less circumference than the 70's which will make the speedometer fast by approx. 5%.

The G tech will also measure sideways G force if you go to a skid pad! Unfortunately, there is no skidpad looking piece of road that I could use here. I doubt it would be long until the cops showed up if I chose any school or other public parking lot. :) I will have to wait until the next AX school and take the G-tech to the skidpad. I will report what I can do. Would be neat to get numbers to compare between street tires and stickies.

George

Yep. The extra weight on the later cars was all bolt on stuff. Power windows, a/c etc.

I am unsure about the 'more power' of the earlier 3.0? Where do you get that info? The later engine had higher compression and dropped the air pump. The bentley manual lists "engine specs."as follows:

78-79 930/04 930/06 comp.=8.5:1, hp= 172@5500, torque=189@4200
1980 930/07 comp.=8.5:1, hp= 172@5500, torque=189@4200
81-83 930/16 comp.=9.3:1, hp= 180@5500, torque=189@4200

I think if there is a difference in power, it is marginal. As far as I am concerned, higher compression is always better and there is a few other reasons to prefer the 81-83....

George

Well, one of the "few other reasons" to like the later SC engine, particularly the '83 is it had the same block as the turbo though I don't know if it was the 3.0 turbo or 3.3. My guess is it's the 3.3 turbo, since they were contemporaries of each other at that time. Nonetheless, it was a stronger block, I believe.

George - you're correct about the horsepower, so all things being relatively equal, it seems the lightness of the early SC over the later is the reason for the difference in acceleration to 60 mph. But then, we're only talking about a half second, and also a measurement of the car that, in all honesty, is not its strongest suit.

There's a 2.7 porting thread going on right now, that has some good insight into the 3.0 from John (jluetjen). It's a good read if you/anyone is interested.

During the 80s I remember reading an article in Car and Driver that explained the various steps they took to control for variables like temperature etc. I don't remember the details except that after that I was more likely to belive that a Car and Driver figure was repeatable and defensible. I also remember that Motor Trend tended to have wildly varying numbers. There are so many variables to account for. Air temp, tire temp, alignment, tire compound, how agressive is the launch, how fast is the shift...

I guess my point is, I would put too much stock in published acceleration or handling numbers. I also wouldn't put too much stock in G Tech numbers (though I bought one for myself, and one as a gift). Can't wait to try mine out! (I got .78gs braking on the freeway offramp yesterday)

If you search on G Tech on Yahoo...the first site that pops up advertises them for something like $49. Think this is the real thing?

The basic model sells for that price indeed. I think it became so affordable after the new models are out. The basic model has been around in that form for at least 5 years.

Cheers, George