heinrich

Some components are IMHO way overengineered, and that would be why we can get away with supercharging a 20yo car without changing its compression ratio, and how we can get away with turbocharging a '78. Also why we can get away with taking a 150k mile car onto the track and thrashing it, and why Mark A and Mark K can thrash their cars as they do and walk away, no real service requirements, to face another day ... same engine, same gearbox, same tub, same same same. I think the most amazing is the use of alusil.

But some parts pale by comparison.....
LH
rear body (rust)
radiator and oil coolers
electrical gremlins
the fuse box spaghetti
sunroofs
cracking dashes/pods
vacuum system
rear quarter buckling
bellypans
hvac system
heavy seats
seat switches
window switches
etc

So what do you think. Is the car overengineered for a sportscar, or are some features just so far behind that they make the rest look good?

Big Dave

I'm biased of course, but the whole concept of an interference engine seems to be a bad idea.

I don't think we can fault aspects of the car that are problems only after 10+ years (warpage, dash cracks, gremlins due to corrosion over time, etc.).

Bill Ball

The dash cracks seem pretty peculiar to Porsche. My brother's 924 dash cracked around all the vents when relatively new. These cars do seem more susceptible to interior heat warpage and cracks than other cars. I'm not sure the vacuum system and HVAC is any more troublesome than others. The heavy seats sure are nice and hold up very well (my 135K mile seats look almost as good new) - no broken springs like in my MBZ. The switches, although perhaps common issues, are probably not more troublesome than any other car of the same vintage and they do respond to a little cleaning in most cases. The sunroof doesn't strike me as a troublespot. Agreed on the relays for relays and central panel spaghetti and the high failure rate LH brain. The LH FI is nice otherwise and remarkably efficient for a honkin' V8. My issue with the belly pans is the attachment - crazy number of screws and the front tabs are a pain. Idea is good, execution is not user friendly. There are a number of areas where users service access was not considered, like the front marker lights - having to remove the wheel and wheel well liner to get the the bulb is unfortunate. Rust is typical to low for the vintage. Not a problem except in the rust belt. If you take some care to clean water-trapping debris from under the hatch glass frame, the rust potential is greatly reduced.

Bill51sdr

The T-belt tensioner is total overkill with too many componets that can wear out, resulting in a catastrophic failure. There are plenty of other belt driven OHC V-8's out there with similar architecture that do not have these problems. Water pump as well... have a look at a Lexus V-8 sometime and it will look very familiar. Could be they've learned fom Porsche's experience, but who knows???

heinrich

Bill what can we learn from them? Pics?

Bill51sdr

Sorry, no pic's at this time, but I do recall that the T-belts were probably 25% wider than the 928, and if I recall correctly the tensioner was a MUCH simpler design... the belt in that engine is probably equal in length, but the add'l width must be beneficial in dispersing some of the load on the bushings/bearings of the accessories being driven by it. I believe that at this time, Kalifornya was also mandating that manufacturers increase the T-belt change interval to 90K miles and this may have been Toyota's response to this. Not much we can do or learn from this as we are stuck with what we have.

sublimate

Are you asking about the early cars or the later ones? I think the 928 was obviously way ahead of the times when it came out in '78, even despite the underpowered US early cars. Think about the features it had compared to the competition back then. But when Porsche realized that it would never be accepted as a 911 replacement (the New Coke syndrome) they put as little development into the 928 as possible. As great as the GTS is, it's nowhere near as great when compared to other cars of the mid-90's as the early cars where when compared to their peers. Now if they had put money in it and made it lighter with more aluminum/carbon fibre and added a twin turbo...

So anyways, I'm voting for "way ahead" as the car was engineered in the mid-70's.

hacker-pschorr

There are not very many DOHC or (or OHC) motors that are NOT interference. Every honda (even my 51hp CRX) was an interference design.

VW is one of the few non-interference 4-valve engines I know of that have a higher compression retio (over 9.5:1) Their valves are offset in a weird way to prevent this.

I'd be willing to bet the LS series Chevy engines are interference - but use a chain instead of a belt.

mark kibort

20 years old, still able to beat most all producton cars on the track in simular prep. at 13 years old, it would have been a top 10 World Challenge SpeedVision GT car! Just think of how fast it would have been if it was raced in the late 80s instead of the late 90s and early 2000s. FAR ahead of its time. In fact, try and find ANY 1995ish cars that compete with the 928, and Im only talking about 1987 S4s . if you start to find some competition, you can always fall back to the argument using the GTS. Now, thats a supercar from todays standards.
so, ahead of its time?? You bet. aside from normal gremlins in the street functionalities, its way way ahead of its time. I have to think of what porsche would be offering today in performance if the 928 was still produced today. a GTS like car with 550hp, stronger , lighter components , and a big price tag.

mk

heinrich

Good points. I was actually intending to ask as of today ...... but not a problem, valid points! I agree.

worf928

H-P, which VeeDub engine are you talking about? The original AFAIK 1.8l 16v engine - Scirocco and GTI circa 1986 - is an interference design. Don't know about the later longer-stroke 2.0l or the current 20v.

Nicole

Well, Just for comparison, my '95 Saab V6 engine is interference as well, and when the timing belt no longer moved the valves... Well, you get the idea. No difference to the 928.

Coincidentially, I'm experiencing vacuum leaks in the AC in both cars at the moment - actually, it's worse in the Saab. THere must be a big leak under the dasy, because it sounds like a big respirator hidden somewhere.

I am more forgiving when it comes to the 928 because it has been designed lmost 20 years before the Saab - even though my 928 is not an early one, Porsche did not have the money to upgrade some of the "peripherals" during the course of production.

Overall, I think the 928 is still a very modern car tocay - 30 years after it had been designed.

How many of you were not even born when they engineered the 928?

Thaddeus

A quote from my website:

"Porsche seems to approach every design problem with a clean sheet of paper. Although they sometimes blow it in concept or execution (we're all human), they tend to introduce new automotive technology decades before the mainstream manufacturers."

Sierra Shark

Couldn't agree more. The 928 was far ahead of its time. Perhaps too much so for the market. Could Porsche have done better? With 20/20 hindsight everything could have been done better. Once your committed to several hundred million dollars worth of tooling certian things will remain the same or with very little change. Believe me, after 14 years as senior design and manufacturing engineer in the aerospace business, I have designed and worked on systems for military aircraft and weapon systems that are 10 times less complicated than some of the systems on the 928. Especially on the electrical end. But you've just gotta admire Porsche for the effort. No other car manufactuer put as much time or effort into their designs for that era of cars. Even the so called supercars of that time period are crude by comparison. What would a current model 928 be like? Think Carrera GT with engine up front. Oh baby!

hacker-pschorr

I can't find it but I have a VW ad from 85ish about the Scirocco. In the ad it shows the head of the 16V 1.8 and states its a non-interference head design. I've know enough VW mechanics on both sides to question that theory - but per VW back in the day, that was their story.

The 16V us 928 motor is also a non-interference, some have bent valve's in these motors. Carbon buildup is the common story as to why this happens on these cars - so I guess over the years enough VW's suffered the same fate to convince them this motor was an interference design. I'll keep looking, if I find the ad I'll scan it in.