78-79 CIS Questions...
12-01-2007, 03:08 AM
#31
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You are getting some pretty good advice on the CIS cars. This is the car Porsche intended to build. They then got caught up in smog laws, an energy crisis and gas guzzler taxes. As always you will pay for performance. The CIS car even when well tuned will turn in about 13 MPG under the best of conditions. Maybe you will do 17 MPG on a long high speed trip, but around town you will be in the single digits. So figure 12-13 MPG avearge. But then if you wanted economy buy a Prius.
The suspension on the early cars needs a couple of up grades. The ball joints are aluminum and need changing to steel. It is surprising how many older cars I see still running the aluminum joints. There are no adjusters on the front shocks for height. The front brakes are under capacity for the weight of the car. You can find front suspensions off 84-86 cars that will bolt up. You will need the spindles. The conversion will give you the shock adjusters as well. These conversions sell cheap ($100-150) and there are plenty around as most want to change out to the S4 suspension. The S brakes are more than adequate for the CIS car.
The transmission has weak syncros, but it has a lower geared differential. You can convert to the later trans with the better syncos but you will end up killing the performance. A rebuild on the trans will last a very long time if you drive it carefully and keep the clutch in good shape. The lower differential gives a very nice jump and combined with the gearing gives a very smooth flow to the car and shifting. The CIS car is probably the best balanced driving 928 you will find until you get to the GT or GTS cars. Between the CIS cars and the GT / GTS cars Porsche was compromising at each turn to add features and meet government regulations. The CIS car is the only 928 choice for a libertarian or Ron Paul supporter.
There are some other minor upgrades like the clutch arm, adding an idler to the timing belt and issues with the alternator. The recent discussion on the Delco looks like a nice solution, although by changing brackets you can up grade to a later model alternator with higher amps.
The 78 has a separate battery box - not sure the advantage, but it is not part of the body and isolates any battery fumes to the outside.
As far as sun roof the older manual seats will give you more head room. The power seats are higher to allow room for the motor. The manual sport seats made for the 80-83 sports package are lower as well and work well to give more head room in the sun roof cars. Personally I like the sun roof. On my 85 I set the seats back a notch and there is now plenty of head room. This is not possible on the 78 as the seat mountings are not the same. The seats actually set up on a couple of rails. In theory the rails could be lowered. I have not tried this.
I am not sure what you saw on the exhaust system, but Porsche tried a number of variations. Personally I think they got it right the first time since I like the deep and quiet sound. The 78 to 84 has a single cat going to a single exhaust pipe with a middle muffler and a big punkin in the rear. Most of the rear mufflers have been replaced with Ansa or Flowmaster rear mufflers.
The 85-85 and Euro S cars have dual exhausts all the way back with the pipes parallel all the way back. The US models have dual cats. The 86.5 changed the batrery box to a smaller unit to allow the exhaust to split and route down the right side of the car and then cross quickly over to the dual pipe punkin. Most people replace the last muffler with a straight pipe. The middle mufflers are bigger on this set up and more heat shields are needed. Personally I do not see the advantage. More over these exhaust systems are frequently finding the road. The pipes are bigger giving a better flow.
What people are discovering is a disadvantage of a dual exhaust all the way back. A cross over pipe actually reduces back pressure and improves flow over the separate dual set up. Since the early cars had a single cat and a larger single pipe perhaps the older single system has the advantage while not being as sexy.
Overall for driving you will find a CIS car very competitve with an S4 or even GTS until you get to a straight out haul and then you will be eating dust. But in tight turns I give the CIS car the advantage every time and if you end up with a 300 HP Euro S even the straights will not cost you much.
One other modification you can make is to put 85-86 exhaust headers on the older engine. These are the same as the S4 headers but with the two bolt pattern. You will need to make a short adapter, but other than that they are a bolt up and will greatly inprove the flow.
Hope this helps. The black car in eBay looks good, but has been hacked away at a bit. Look at the covers on the back of the rear seats. It is very hard to find an unmolested CIS car, but you are better with one that has not been messed with and do the work your self to keep it stock. The one in Washington looks by and far like the better car.
Dan the Pod Guy with two 78s and one 83 Euro.
The suspension on the early cars needs a couple of up grades. The ball joints are aluminum and need changing to steel. It is surprising how many older cars I see still running the aluminum joints. There are no adjusters on the front shocks for height. The front brakes are under capacity for the weight of the car. You can find front suspensions off 84-86 cars that will bolt up. You will need the spindles. The conversion will give you the shock adjusters as well. These conversions sell cheap ($100-150) and there are plenty around as most want to change out to the S4 suspension. The S brakes are more than adequate for the CIS car.
The transmission has weak syncros, but it has a lower geared differential. You can convert to the later trans with the better syncos but you will end up killing the performance. A rebuild on the trans will last a very long time if you drive it carefully and keep the clutch in good shape. The lower differential gives a very nice jump and combined with the gearing gives a very smooth flow to the car and shifting. The CIS car is probably the best balanced driving 928 you will find until you get to the GT or GTS cars. Between the CIS cars and the GT / GTS cars Porsche was compromising at each turn to add features and meet government regulations. The CIS car is the only 928 choice for a libertarian or Ron Paul supporter.
There are some other minor upgrades like the clutch arm, adding an idler to the timing belt and issues with the alternator. The recent discussion on the Delco looks like a nice solution, although by changing brackets you can up grade to a later model alternator with higher amps.
The 78 has a separate battery box - not sure the advantage, but it is not part of the body and isolates any battery fumes to the outside.
As far as sun roof the older manual seats will give you more head room. The power seats are higher to allow room for the motor. The manual sport seats made for the 80-83 sports package are lower as well and work well to give more head room in the sun roof cars. Personally I like the sun roof. On my 85 I set the seats back a notch and there is now plenty of head room. This is not possible on the 78 as the seat mountings are not the same. The seats actually set up on a couple of rails. In theory the rails could be lowered. I have not tried this.
I am not sure what you saw on the exhaust system, but Porsche tried a number of variations. Personally I think they got it right the first time since I like the deep and quiet sound. The 78 to 84 has a single cat going to a single exhaust pipe with a middle muffler and a big punkin in the rear. Most of the rear mufflers have been replaced with Ansa or Flowmaster rear mufflers.
The 85-85 and Euro S cars have dual exhausts all the way back with the pipes parallel all the way back. The US models have dual cats. The 86.5 changed the batrery box to a smaller unit to allow the exhaust to split and route down the right side of the car and then cross quickly over to the dual pipe punkin. Most people replace the last muffler with a straight pipe. The middle mufflers are bigger on this set up and more heat shields are needed. Personally I do not see the advantage. More over these exhaust systems are frequently finding the road. The pipes are bigger giving a better flow.
What people are discovering is a disadvantage of a dual exhaust all the way back. A cross over pipe actually reduces back pressure and improves flow over the separate dual set up. Since the early cars had a single cat and a larger single pipe perhaps the older single system has the advantage while not being as sexy.
Overall for driving you will find a CIS car very competitve with an S4 or even GTS until you get to a straight out haul and then you will be eating dust. But in tight turns I give the CIS car the advantage every time and if you end up with a 300 HP Euro S even the straights will not cost you much.
One other modification you can make is to put 85-86 exhaust headers on the older engine. These are the same as the S4 headers but with the two bolt pattern. You will need to make a short adapter, but other than that they are a bolt up and will greatly inprove the flow.
Hope this helps. The black car in eBay looks good, but has been hacked away at a bit. Look at the covers on the back of the rear seats. It is very hard to find an unmolested CIS car, but you are better with one that has not been messed with and do the work your self to keep it stock. The one in Washington looks by and far like the better car.
Dan the Pod Guy with two 78s and one 83 Euro.
12-01-2007, 08:05 AM
#33
Drifting
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Thanks for all the info Podguy. I'll have to look into the front suspension upgrade. I have the steel ball joints but I have a front ride height problem and I would better braking.
12-01-2007, 08:47 PM
#35
Drifting
You are getting some pretty good advice on the CIS cars. This is the car Porsche intended to build. They then got caught up in smog laws, an energy crisis and gas guzzler taxes. As always you will pay for performance. The CIS car even when well tuned will turn in about 13 MPG under the best of conditions. Maybe you will do 17 MPG on a long high speed trip, but around town you will be in the single digits. So figure 12-13 MPG avearge. But then if you wanted economy buy a Prius.
12-01-2007, 09:07 PM
#37
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Ansa muffler?
12-01-2007, 11:32 PM
#38
Rest in Peace
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I am a old time carb/CIS/AFC guy, and given the choice between cis/afc or LH I will take the LH every time.
To me it is giant step backwards if you ever plan to do any mods.
Once you learn the modern electronic fuel injection there is no going back.
YMMV.
EDIT: I have owned and worked on more than a few CIS cars, if you give them clean fuel, don't let them sit, they will run almost forever.
I had a 240 Volvo with over 600,000 miles and never did a thing to the fuel system other than fuel filters and I hit the plug on the WUR one time to make it a bit richer on cold start.
Greg
To me it is giant step backwards if you ever plan to do any mods.
Once you learn the modern electronic fuel injection there is no going back.
YMMV.
EDIT: I have owned and worked on more than a few CIS cars, if you give them clean fuel, don't let them sit, they will run almost forever.
I had a 240 Volvo with over 600,000 miles and never did a thing to the fuel system other than fuel filters and I hit the plug on the WUR one time to make it a bit richer on cold start.
Greg
12-02-2007, 09:22 PM
#43
Race Car
Green car- whats hanging under the dash by the footrest?
Bright window trim on drivers quarter- ew. But are those 8" headlights?
No protective strip- nice.
Tough to tell, but looks like dash may be leather and OK.
Quality of paint will be an interesting datapoint. Ditto maintenance records and cleanliness/rattiness of engine compartment.
Borla exhaust, by the looks.
I've had an '85 with sunroof, don't miss sunroof in my rabid euro at all.
Bright window trim on drivers quarter- ew. But are those 8" headlights?
No protective strip- nice.
Tough to tell, but looks like dash may be leather and OK.
Quality of paint will be an interesting datapoint. Ditto maintenance records and cleanliness/rattiness of engine compartment.
Borla exhaust, by the looks.
I've had an '85 with sunroof, don't miss sunroof in my rabid euro at all.
12-03-2007, 02:14 AM
#44
Official Rennlist
Borat Impersonator
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Borat Impersonator
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The green car looks like it has an ansa system, the exhaust tips on the ansa face the rear, while the borla tips face out like the stock tips do
