Weight difference between 2.4 and 3.6

RS-GT · 02-05-2005, 05:16 PM

Does someone ever weight a 2.4 and a 993 3.6 ?

Wil Ferch · 02-05-2005, 05:28 PM

Engine alone?

Not much difference...Bill Verburg may have the numbers...I'm going to guess 2.4 is low 400 lbs ( say 400-440) and 3.6 not much more...maybe only 50 lbs more.

Wil

pwd72s · 02-05-2005, 06:40 PM

Cars altogether? I don't have a clue. All I know is that my '72S has an official curb weight of 2,440 pounds, Yankee delivery model.

randywebb · 02-05-2005, 07:03 PM

the engine wts. are in the tech spec books and in various other books - if that is what you want

also see my spreadsheet at Thom's web site, rennlist.com

Bill Verburg · Bill Verburg's Garage

kg  lbs     models             Source



182 400   2.4L E, S, RS   1972-73 Tech. Spec. book



183 403   2.4L T 1972-73   Tech. Spec. book



200 440   2.7L 1975-1977    Aichle - 911 Engines



190 419   78-83 930/09,19,10   78-81 78-81 & 82-83 Tech Spec. book



200 441   78-83 930/03-08,13-17   78-81 & 82-83 Tech Spec. book



190 462   3.0L 1980-82   Aichle - 911 Engines



219 483   84-87 930/20,26   84-87 Tech Spec. book



220 485   84-87 930/21,25   84-87 Tech Spec. book



219 482 3.2L 1987 - 1988   Aichle - 911 Engines



238 524   964 89-94 M64/01,02 ROW &US   964 Tech Spec. book



226 497   M64/03 RS   964 Tech Spec. book



275 605   M30/69 3.3L   964 Tech Spec. book



276 608   M64/50 3.6L   964 Tech Spec. book



232 510   M64/05-08   993 Tech Spec. book



221 487   M64/20   993RS v-ram w/o ZMS 993 Tech Spec. book



230 507   M64/20   993RS v-ram w/ ZMS 993 Tech Spec. book

Previously posted here

Grady Clay · 02-06-2005, 02:08 PM

Bill,

Thank you.

I will speculate that it is relatively easy to get a 2.4 (2.8 for that matter) down to 375#. With some effort (and expense) down to 350#. What does an original 2.8RSR engine weigh with all the Titanium parts and FG tin?

Light weight = fast.

The other rules are:
Reduce the weight at the rear of the 911.
Reduce the un-sprung weight.
Lower the center of gravity.

Best,
Grady

Porschekid962 · Porschekid962's Garage

Grady it seems your on the right track but dont forget the polar moment of inertia. CoG is important but so is the polar movement. Unsrpung weight is one of the hardest things to cut down on. A bit OT but when F1 cars started running RFCC rotors and pads ala gordon murray some teams experimented with caliper placement. They put the caliper at the bottom of the rotor to lower the CoG. Some even experimented with composite metal matrix caliper construction to lower unspring weight. I forget what F1 teams fill their tyres up with but I know its not O2, doubt its helium though.

As far as the motor you can always lower it an inch or so like in the 935's and push it forward a bit. The more you can center weight within the planview of the car the better off you will be. Happy hunting.

Grady Clay · 02-06-2005, 04:57 PM

Absolutely, I was just trying to not be too complicated. These subjects have been extensively discussed. Someone interested should search the Forum.

You are exactly correct; the moment of inertia around the CG is very important. I think this is the reason for the ’69-’73 dual batteries. That gives a greater moment about the longitudinal axis. I think that is particularly significant on a lightweight 911. It is far easier to reduce the weight of the car than the un-sprung weight. The dual batteries location increases the moment with minimal increase in weight. Of course it moves the CG forward for more equal weight distribution and adds to the moment around the vertical axis. This is an attempt to compensate for the “mass in the ass” of a 911.

The mass distribution (moment) around the vertical axis effects the “twitchiness” of the 911. For a given wheel base if a greater proportion of the mass is close to the CG, the 911 is more reactive and possibly less stable.

The height of the CG off the ground is critically important. F1 goes to extreme effort to pare every gram off the weight of the car, particularly up high, to get as much underweight as possible. They then ballast with a large steel plate under the chassis. The purpose is to get CG low.

I recall a Christophorus technical article where Porsche built a variable CG 911. It was built on a very lightweight ’69-’71 911. It had a large lead weight on a vertical track through the CG in the horizontal plane. They had re-routed the controls so the weight could go down through the tunnel and out the bottom of the pan and all the way up to just under the roof. I recall that a 2” vertical change in the 911’s CG was the same difference on a skid pad between 165-78x15 street tires and the Dunlop race tires of the day. A big, big deal!

Best,
Grady

CBRacerX · CBRacerX's Garage

F1 teams, and any competant SCCA racer will use nitrogent o fill the tires. Little expansion, since the gas is completely dry.

Chris

911pcars · 02-06-2005, 05:22 PM

I once read a tech article on the MB SLK race car in the old German Touring Car series of about 6-8 years ago, before they placed limits on modifications.

These cars were as or more technically advanced than the then current F1 cars. They wered turbocharged, had throttle by wire systems, traction control, radio-controlled suspension/traction settings, max power settings for each corner of the race track...... and a sliding weight along the vehicle axis to change F-R weight distribution for whatever purpose they desired.

I think other manufacturers refused to race in the series unless the rules were changed (or something like that).

Sherwood

Porschekid962 · Porschekid962's Garage

Race teams go to extreme lengths to place weight at the lowest and most central point in a car's chassis. Grady it's funny this came up as I have been rereading my McLaren F1 book, Driving Ambition and Competition Car Suspension by Alan Staniforth. Aero affects are discussed briefly but focuses and unsprung weight and polar moments along with CdA and CoD. Gordon Murray said the whole reason behind going to RFCC brake systems was to reduce unsprung weight, they didnt know how much better they were than steel.

Today the "plank" that is run under all F1 cars is impregnated with tons of tungsten to act as ballast at the lowest point of the car. Seeing as all of these cars are built so underweight they get creative with where they put the weight now. Supposedly Ferrari has built their past few cars underweight that they almost ran out of places to stuff their ballast.

So is there a minimum weight in any of the POC PCA classes?

BTW a bit off topic but does anyone around here run an upside down 915 or know what is required to make a regular 915 an upside down 915?