Mongo

I'm still in the process of gathering information about the OB 928s as part of my research and pursuit of finding a great daily driver 928. I'm looking at 81-84 OB 928's. Of course, there's that difference between not just the transmission, but the engines as well (4.5 vs 4.7).

I would prefer an automatic since I don't want to be shifting back and fourth and dragging a clutch in stop and go traffic.

How is the acceleration of the '81-'82 928 autos compared to the '83-'84 autos?
I'm not looking for neck-snapping performance, but something that has good pickup.

What is gas mileage like with a 3-speed auto versus a 4-speed auto?

drnick

andy, i can only comment on euro performance. i had a 4.7 euro S2 with 4spd and it was a very good car - i think this is probably equivalent to the usa 86.5 in many respects, so its not quite the 4spd you are referring to. the reason im chiming in is because lately ive been driving an old 79 euro 3spd auto and its a hoot! dont overlook the early 4.5 litre cars, not sure what the difference is between the euro 4.5 and usa 4.5 though.

Mongo

about 80 HP, that's the difference

drnick

seriously, i thought all the 4.5 litre cars made about 240 bhp at the crank?? do you mean the usa 4.5 made only 160?

Mongo

No it made 220. When I said the 80 HP difference, I was comparing it to the 928S.

Bill51sdr

You've got a "great daily driver" 928. It just sits in the garage not being driven, and we all know the problems these cars become once they acheive Garage Queen status. Drive and maintain the S4 you have Andy.

Mongo

It's not my responsibility anymore, hence why I'm looking for one of my own to drive daily...

Bill51sdr

This situation seems to change month to month...

jpitman2

Last long cruise I did I got 25mpg (imp) or 20mpg (us), but around town its TERRIBLE! Probably half that..
jp 83 Euro S AT 51k

Podguy

I think on a comparative basis you will find a US 80 to 82 auto to be a dog. The injection was detuned for gas mileage. These are probably the worst models Porsche ever created. They also came with 85 MPH speedometers reflecting the 55 stay alive thinking at the time.

I question the 80 HP increase from a 4.5 to a 4.7. 928 Specialists shows the US 4.7 at 234 HP vs. 219 for the 4.5. When I went to school that was a difference of 15HP. Now with new math it might be higher. Note the 5.0 US 85 only had 288HP.

https://www.928gt.com/default1.htm

But then DR and Wally could be wrong. It has happened before but too few times to count.

The 83-84 US auto has a higher final drive. So while you get a little more horse power and an extra gear the advantage is robbed by the higher final drive and the tendancy of the transmission to alway shift up to fourth gear. Again this was done for gas mileage and not drivability. In the Mid 1980s the US government was on a binge of crippling good cars.

Since the final drive is so high around town you will have to keep the transmission out of drive to get any response. This kills expected gas mileage - although on the road cruising at 70-85 you will see mileage go up substancially.

The next step is the 85 US model. The extra horse power is needed for the automatic. I set up the transmission throttle cable, set the valve timing correctly and the car really performs. Just a light touch of the throttle and the trans kicks down. Rotten on gas mileage, but the car is fun to drive. I get about 14-16 MPG .

If you are going for an automatic then I would recommend at least an 85 and probably an 87. The 87 has 316HP which is enough to pull the taller gearing, get good gas mileage and be fun to drive. The best combination outside of a GTS is the 89 US which has the lower final drive making the car much more responsive. The people I know who have upgraded the final gears in an older four speed auto are quite happy with the better performance. Yes the final drive gearing can be changed on an automatic.

This analysis is a bit flawed if you throw in the Euro cars. The 80-83 Euro S is 300 HP and the 84-86 is 310 HP - the most Porsche squeezed out of the 16 valve engine. The final drive is also lower. Both of the S cars are 4.7 liter non interference engines. This means when the timing belt breaks you will not crash the valves.

If you can find a nice 80-86 Euro automatic you are probably getting the best of all worlds. The 80-83 Euro is a mechanical CIS system which will give you a lot of performance, but at the cost of less gas mileage.

Hope this helps

Dan the Pod Guy

largecar379

US 4.5L CIS/K-JET was 219 hp 245 torque
US 4.5L L-jet was 220 hp 265 torque

Euro 4.5L was 229 hp 250 torque 77-79
Euro 4.5L was 229 hp 271 torque 80-82

both Euro's above CIS/K-JET

the hp difference (80 hp) he's talking about is with the 300hp 4.7L Euro's

again, read..read..read.

the info is out there for the taking.

---Russ

928ntslow

I'll give you my take on this. Though i haven 85 US 4 spd, it sits in my garage waiting for parts and time to get it road worthy. That being said, I had an 82 US 4.5 3 spd. I did some upgrades to the engine just in bolt on stuff like Euro intakes and throttle body along with a rising rate fuel pressure regulator and MSDS headers with a Y and Borla exhaust to finish it off. This helped a tad in the HP area and some better performance. I did pull the tranny and have the torque converter stall speed increased. The car was nothing short of a blast to drive, be it mild mannered to and fro or tearing up the canyons of southern California. The transmission was robust and I swear that if you take care of these things, you just can't kill them. NEVER had any issues and with a kick down bypass, and manual shifting, it was ALWAYS fun. Gas mileage wasn't noticeable enough for me to care. I sold it and sorry it is gone, BUT, I did take Dan's (the Pod Guy) advice and got myself a Euro 3 spd. I bought it to donate to my convertible project. Although I just got it last week, I have been sorting out some issues the PO never took care of. I actually finished enough to the work today to take it out for a quick test drive. Wow! This one is better than my US version. It is an 82 4.7 (CIS) 3 spd. Throttle response is instantaneous and I think it has to do with the mechanical injection. No problem breaking the tires free from a standing start. I can tell I am going to love this thing. I don't knw how it will do on gas mileage, but from what I understand, the car may require premium gas due to the compression ratio.

Also, when I used to run the canyons, the 4 speeds had no advantage even though we all manually shifted the auto boxes. As a matter of fact, I did have a couple of 4 spd owners ask me how I could pull away from them when they had the throttle to the floor. Personally, I love the 3 spd gearing.

Not sure if this helps any,but take it for what its worth.

rhys

I don't know what '82 US AT you're referencing, but mine certainly doesn't have an 85mph speedo (mine's 160mph) and, if detuned for gas mileage, dramatically failed at that. If properly driven, i.e., manually shifting the auto, if a dog, it is one quick dog.

Mongo

Isn't it bad to manually shift an auto though?

928ntslow

Apparently not for the 928's. They are built incredibly well. I haven't heard of anyone yet tearing up a 928 auto due to manually shifting. it's just too much damn fun toggling between the gears. It's absolutely necessary when driving in the twisties! Add kick down by-pass and hang on!