Year Differences in 3.2 Carreras

[tshore]

Reading the G50 vs. 915 poll, I read the following post:


I like the 95 lbs savings of a 3.2/915 Carrera. If I was to turbo it, a G50/3.2 would be a must.

I think of the 915/3.2 as the poor man's Club Sport. Add 15" Fuchs and take the spair, tools, jack and rear seats out and you can have a 150+lb advantage over a stock G50/3.2.

The 86/915 is a special car with lower seat tracks (more room for helmet) and stiffer sways and rear springs.

The 87-88 may have P&C's that are not the best for adding a turbo. The 84-86 &89 has the better P&C's and comes with 8" rear rims from the factory. The later car has a better factory chip for HP to over come the added weight."


Also, there was a post in that thread that stated that the G-50 cars had the engines further back than the 915 cars...



Specific questions:

1. What is weight difference between complete G-50 and 915 setups, including the hydraulic 5-50 clutch and stock flywheel?

2. What are the chassis differences between g-50 and 915 cars? I have seen diagrams showing additional door beams in '87 cars, which also show the rear of the chassis was changed a bit to accomodate the additional size of the G-50.

3. Are there differences in pistons and cylanders between the years?

4. I understand the DME chip was changed from '86 to '87, resulting in a 10hp gain, but I've also read that the number of pins in the chip was increased mid-way through the '86 model year. Is that correct, and did the hp gain coincide with the chip change, or the model year change?

5. Is there a difference in seat rail height?

6. What I think know: The seats changed in '85, the vent system changed in '86, the sway bar diamater changed in '86, the headlights (US) and rear reflector changed in '87, as well as the G-50 change. Is this true?

[Peter Zimmermann]

Originally Posted by tshore

Specific questions:
1. What is weight difference between complete G-50 and 915 setups, including the hydraulic 5-50 clutch and stock flywheel?

Here is a copy of a post I made last year - it'll take care of your #1...

Originally Posted by Peter Zimmermann
Let's look at this a little closer. The weight of a filled 915 RoW version 915/67 with cooler is approximately 60 kg (132 lbs). The cooler weighs almost nothing (I can testify to this because I've cleaned a number of them), so let's call the USA 915/68 at 130 lbs. The weight of a filled RoW G 50 version 950/00 is 66 kg (146 lbs), which is virtually identical to the USA version 950/01. So we have a weight difference between the two transmissions of 16 pounds.

The 915 flywheel weighs 12 lbs, and so does the G 50 flywheel, so that's even.

The stock 915 clutch weighs 18 lbs, the G 50 clutch weighs 29 lbs. So, in total, the G 50 package is approximately 27 lbs heavier, which was offset (in 1986) by an increase in rear torsion bar size from 24.1mm to 25mm. Something else comes into play here that contributes to the 915 car "feeling quicker" to some drivers. Back in the day of Hemi-Cudas, 427 Vettes, etc., the ticket to really quick quarter mile times was having a "short", 4.11 rear end (final drive) ratio, or an even shorter 4.56 ratio. Of course, the big compromise with a short ratio was having to run at much higher revs at freeway speeds. Cars with a taller, aka longer, 3.00, or 3.30 rear end (ring & pinion ratio) just wouldn't come out of the hole as quick, and the race was usually over in 2nd gear. In 1974, 911s were fitted with a 7:31 ring & pinion, which is a final drive ratio of 4.43 (remember, the bigger the number the shorter the ratio). Later SCs and early Carreras w/915s had an 8:31 (3.88) final drive ratio, BUT, G 50s are fitted with a 9:31 (3.44) final drive ratio. Yes, the factory fitted all new, "shorter" ratios to 1st-5th to try and make up for it, but, while striving for better mileage and reliability, couldn't overcome that "longer" ring and pinion, which can make, combined with the extra pounds, a G 50 car feel more sluggish than a 915 car. A lightweight clutch will help the G 50 car, but on a road course there should be very little difference between the two because the rpm drop between second and third, between third and fourth, and between fourth and fifth, is very similar when comparing a 915 to a G 50. Yes, the 915, in some situations, will "feel" quicker, but can it generate quicker lap times on a road racing course? I doubt it.

[tshore]

Thanks...just to clarify, was the torsion size increase in '86 was carried over in '87-'89? Any idea how much the weight difference was? I would think pretty small...

BTW, I enjoyed your book, which I have almost now memorized, and which I purchased *after* I bought my '86...

[88-diamondblue]

I have tried weight reduction and have not noticed enough difference to do more right now. If I were racing and had times to verify the improvement that would be different. My car has an 3.4, SW chip, pre-muff and modified suspension and 17" Rota's.

I have driven both the 915 and G50. The g50 is a better trans, saying that I would not let that stop me from buying a 915 equipped car. I didn't feel that much difference and you will never mistake a G50 for Honda or BMW shifters. Plenty of feel and feed back and less chance of the "money shift"

Porsche used both Mahle and KS P & C's in the engines from at least the SC's through the 89 Carrera. It is a crap shoot as to which you will get.

In the later years Porsche used a more aggressive chip to improve both power and drive ability. Get an SW chip for the best experience

Not sure of the seat rail issue and in my 88 I have no problems with helmet clearance but I can see if you are taller than 6' it could start to be an issue.

[vanwyk4257]

1985 Carreras had seat rails that were about 20mm higher IIRC. I had an 85 coupe for a while and my helmet would bump the headliner occasionally with the stock seats, but I'm 6'3"+. I have a SW chip, euro premuffler and M&K muffler on my '87 and it feels much quicker than my '85 did with the same setup, so I don't think the G50 feels sluggish at all.

[Por_sha911]

Originally Posted by tshore

4. I understand the DME chip was changed from '86 to '87, resulting in a 10hp gain, but I've also read that the number of pins in the chip was increased mid-way through the '86 model year. Is that correct, and did the hp gain coincide with the chip change, or the model year change?

Mid year `87 the chip was changed from 24 to 28 pin but there is no HP change. In `88 the HP bumped up slightly. Consider a Steve Wong chip (sold by our host) to get more out of the same car (especially if you have made mods to the car).

Keep in mind that the 915/G50 differences are about how the clutch feels and how the car drives. I prefer the G50 with a replacement Sachs spring centered clutch: easy to shift, plenty tough.

[Quicksilver]

The 86 and earlier cars had the upper rear brake light at the top of the rear window. In 87 they moved it to the bottom.

[dw1]

I have an '87 with the rear brake light mounted high, so if the change was made in '87, the move to the bottom of the window was definitely a mid-year change. I understand that the cars equipped with a rear wiper may have been the first to have the CHMSL (center high mount stop lamp) moved.

There is a well documented HP increase, starting with the '87 cars. I don't know how much of it is attributable to the 2K vs. 4K chip in the DME and how much is the actual programs in the chips. Sources conflict, but for US-spec cars, the hp difference is usually documented as 14 hp.

Drop a message to Steve Wong, as I'm sure he knows the DME details.

[Talewinds]

My 88' has a high mounted light and no tail. A quick browse of the E-bay shows a number of post 87' cars with high mounted brake lights. This topic has been discussed before here on Pelican, and the bottom line is that there appears to be no consistancy with where/ which style center brake light was used.....

[Zeke]

Mine is high.

[MOMO3.2]

This was a ridiculous post (from the "915 VS G50" thread) on sooooo many levels, I don't even know where to start.

I like the 95 lbs savings of a 3.2/915 Carrera. If I was to turbo it, a G50/3.2 would be a must.

I think of the 915/3.2 as the poor man's Club Sport. Add 15" Fuchs and take the spair, tools, jack and rear seats out and you can have a 150+lb advantage over a stock G50/3.2.

The 86/915 is a special car with lower seat tracks (more room for helmet) and stiffer sways and rear springs.

The 87-88 may have P&C's that are not the best for adding a turbo. The 84-86 &89 has the better P&C's and comes with 8" rear rims from the factory. The later car has a better factory chip for HP to over come the added weight."

Thank you Perter Z for posting the facts!

Mike

[911st]

I suspect that part of the 95 lbs spec difference between the 916 and G50 cars might be with the standard rims. The 15" Fuchs were so light and were the base rim for a long time. They were about 20 lbs less some of the later rims.

Some of the weight difference might be in other things that came along with the G50's like the need for an added hydraulics. The G50 the rear suspension has more metal in it as the sway bar has a few small extra bends and the torsion tube was lengthened. There may have also been a few other additions here and there as Porsche seems to keep adding amenities.

10 extra pounds in a clutch is going to make a motor feel smother but slow throttle response down a bunch for less of a lively feel.

Some years had some type of added motor dampening or isolation device and I do not know what years but it had to add weight out back.

Thus, the G50 transmission bare might be close to a 915 but the other supporting changes that were made to make the car nicer to sell the the Doctors and such back then may have added about 75 lbs or so.

The chips are not a big deal unless you are restricted in some way or do not wish to change the chip. The later chips had a little better programming that pulled some more pony's. But they are a match once a SW chip is added.

Mostly it comes down to finding the best condition car you can in the colors and options you want.

For performance it would be tough to beat a euro 915 Carrrea with LSD, sunroof delete, non electric sport seats, and 15" rims with the right tires for an added gearing advantage. For Sunday drives a G50 with all the trimmings.

They are all great cars and condition is what is most important. Most have a lot of deferred maintenance that most do not think of. The windshield can be pitted, dash pulling up, suspension bushings sagging from time, leaks at the motor. Need of a valve adjustment and service. Old rubber brake lines that are starting to swell... Low miles is not going to keep all this from being an issue.