Here is a cool link to a calculator for 0-60 speeds based on weight and HP

[FinallyGotOne]

http://www.060calculator.com/

So according to specs the orginal SC from 79 weighed 2558 pounds and had 180HP at the flywheel. some say 188 tho. After I removed the front and back bumpers and bumper shocks and brackets, and went to the Cup wheels I'm betting I losyt at least 100 pounds possibly 125+.

One of the books I havce says 0-60 speedis 7 sec. The Standard HP calc puts it at at 180 6.4 / 6.2 at 188 and after the reduction of weight about 6.14.

So now I assume there is a bit more HP by removing emission air pump.
How much do you all think?
And then going to the 74 heat exchangers and muffler another bit more?
How much more HP would all this work out to?>

My guess is maybe 200 HP total. Which gets the 0-60 speed to 5.9.

Does this sound about right or not?

I assume chain tensioners and shortshift kit really does not figure into these calcs anywhere.

So if I can get my car to 2450 pounds with me in it I can get down to a 5.5 sec 0-60 speed.


But I have heard that the 74 could add about 15 more horses alone?

okay thoughts please... since I'm autocrossing I want to make sure i am as quick as feasibly possible.

By the way, My understanding is that my original wheels were 16 inch fuchs? What is the weight of those? My 17 inch alloy cups may with thinner profile tires may actually be lighter than I think. I need to go weigh in someplace.

Oh yeah there is further weightreduction by removing the air pump, so it seems you increase HP by taking it off, then further increase quickness by reduction of the weight. make sense?

[cgarr]

4.26 Wow, I'm on a diet now!!

[deathpunk dan]

It actually seems pretty accurate. I entered approx curb weights and bhp figures for a bunch of cars I've owned or am familiar with, and the #s are surprisingly realistic/close. Maybe a 10th or 2 optimistic, but close overall.

good stuff. Most interesting when you start playing around with curb weight by 1 or 2 hundred lbs in either direction, and 10-30 hp in either direction...

[FinallyGotOne]

I just did some calculating and it appears that by removing the sc bumpers and bumper shocks and replacing with fiberglas that is a weigh treduction of about 164 pounds.
This was more than I suspected.
The air pump should be aanother 20 pounds i think. So 184 pounds lighter? seems a lot.
wonder if the 74 exhaust is any lighter than a 79?
I am thinking my tires are lighter than stock ones, as they are Falken ZIEX 255/40Z 17 in back. But I really am not sure if there is any difference there.?

[bhyde]

http://www.060calculator.com/

Just in case you wanted to know the formula, it’s:

[Weight/HP * DriveType * TrannyType * 0.875] ^ .75

Where :
DriveType = 1.0 for FWD, 0.90 for RWD, 0.85 for AWD.
TrannyType = 1.0 for manual, 1.1 for automatic.

Looks like he took a bunch of published times and just did a curve-fit to the data.

[spuggy]

Heh. If I ever actually tried for 0-60 in 3.25 seconds, I'm sure there'd be a trail of little bits of 915 tinkling gently on the road behind me as I coasted away without power...

Also, I wonder how much difference it actually makes in real life having the weight over the driving wheels?

[scarceller]

I just took the specs from the 84 Carrera M491 (WideBody optioned, non-turbo) car and the calculator is spot on!

Weight=2712
HP=200

Calculator says 5.9 seconds

Specs say 5.9 seconds.

[scarceller]

Here's the specs for the 84 Widebody optioned Carrera non-turbo:


Hard to read but here is what the specs read.
Weight=2712
HP=200
0-60=5.9seconds

[DW SD]

275 rwhp ~ 323 flywheel HP ('95 3.6 w/ bigger cams and chip, backdated flat tappet lifters).
2180 (corner balance weight w/ 1/4 tank of fuel) + 200 lb driver = 2380 curb.

Calculator says 3.75 seconds. I don't buy it. But, I baby first gear. I'm not naturally skeptical.

Doug

[911pcars]

IMHO, all the above numbers are optimistic. E.g. backdating to '74 heat exchangers isn't going to net 20 hp. The items described above don't weigh that much. Your car isn't that light, your engine doesn't make as much power as you think. The test cars in magazine reviews are "prepped" for better performance (not off the showroom), etc. Performance is incremental at best when deleting weighty items.

However, 0-60 times will decrease without the driver's weight inside the car; moreso if it's obvious the left side of the driver seat bolster is lower than the right side or the vehicle leans to the left, but not when parked.

Sherwood

[lin7310948]

585 chp with 2250 punds say my 71 coupe should do it in 2.3 seconds!!! so somewhere in these calculations other things have to be reckoned with!!

[teenerted1]

Horsepower
(at the flywheel):204 at the wheels so add the 15% loss =@234hp
Curb Weight:2171lbs
Drive Type: RWD
Transmission: Manual


Power / Weight Ratio: 0.10778443113772455
0-60 mph: 4.44396772735055 seconds

yea right.
like they know what my gear ratios are, or my tire size is, or that i hit my rev limiter at @55mph in second gear.

[DougM]

Don't you need to add your own weight in there ? The car doesn't drive itself?

[911pcars]

Originally Posted by DougM

Don't you need to add your own weight in there ? The car doesn't drive itself?

You do what they do in thoroughbred racing, they hire jockeys, or, since my racing budget can't afford a jockey-type, a munchkin-type instead. I hope I haven't offended any munchkins.

Sherwood

[willtel]

3.8 to 60!

Sweet! If only I could shift that fast.

[equality72521]

Man, if I had 1,000,000HP and 1600 lbs I could hit 60mph in .0068seconds.

[GothingNC]

It gives the VW thing a 0-60 time of 12.66 seconds

48 HP / 1950 lbs

Road & Track had 19 seconds at the time.

[FinallyGotOne]

[74 heat exchangers isn't going to net 20 hp. The items described above don't weigh that much. Your car isn't that light, your engine doesn't make as much power as you think. The test cars in magazine reviews are "prepped" for better performance (not off the showroom), etc. Performance is incremental at best when deleting weighty items.]

According to a web site which breaks out all the parts, the items do weigh that much. I can tell you the bumpers are freaking heavy! and with the shocks and rubber componets, I bet they are definitely within that weight. The SC bumpers are heavy for sure.
The weight of the car stock is in several publications and on line sites just at 2550.
I have not weighed it, but I believe that is about right. I did not think I said 20 HP with teh '74 heat ex and exhaust, I thought i gave it 15? My 79 is supposed to start at 188 HP. And the only real way to make these cars fasyter is by losing their weight. This is a mostly agreed upon statement? So what are you thinking the weight, HP and best way to increase quickness is?

[javadog]

There is absolutely no way that you'll save 164 pounds by replacing the stock bumpers with fiberglass. Don't believe everything you read. The parts don't weigh near that much and, yes, I've weighed them myself.

Most 911s sold in this country were heavily optioned and weighed a bit more than 2550 pounds. Add fuel and a driver when you do your calculations, too.

Likewise, your car was rated at 172 SAE hp. The rating on the ROW SC was 180 DIN hp. Later versions of the ROW SC were rated at 188 DIN hp, then 204 DIN hp. Deleting the air pump frees up less horsepower than a good tune-up. The gain from early heat exchangers is much less than 15-20 hp at peak power revs, although that amount of gain is close to what you get at lower revs. Peak power readings are less important than the entire area under the power curve. Take a look at the power curves of a US SC or Carrera and compare it to it's ROW cousin. Peak power isn't that different but the ROW car makes much more power on either side of it's peak.

The wheels and tires you have on your car are heavier than the stock ones, too.

JR

[FinallyGotOne]

Link to HP per another estimate.

http://www.eastwesteuroauto.com/Porsche.html#911%20SC

911 SC


Exhaust System: Replacing the stock 3.0 exhaust system with an earlier Porsche system (1974 or earlier) The earlier system can improve horsepower by 17-22 hp.

also, check this out, something I figured was that I had less rubber on a bigger rim vs the smaller rim, but my width incresed so my tires are actually heavier. I should refigure because I bet I added about 5 pounds per corner with bigger rims/tires.

I really need to just go weigh this thing. Ok. that's my plan, I'll weigh and post