Engine rebuild 964 RS
09-29-2017, 04:54 PM
#1
Rennlist Member
Thread Starter
Engine rebuild 964 RS
My engine is in the workshop for a total rebuild. The cylinders are oval and out of tolerance. I need 6 new cylinder/pistons.
I can buy the cylinder/piston each with RS number or a kit with all six cylinder/Pistons But then it seems its the same for c2/c4/RS.
Anyone know what to choose? Someone must have rebuild an RS engine with new cylinders without choosen 3.8l
jonas
I can buy the cylinder/piston each with RS number or a kit with all six cylinder/Pistons But then it seems its the same for c2/c4/RS.
Anyone know what to choose? Someone must have rebuild an RS engine with new cylinders without choosen 3.8l
jonas
09-30-2017, 04:57 PM
#2
Burning Brakes
Carrera and RS pistons and barrels are the same item.
I would speak with Langcourt Cylinder Technology in England 44 1934 612226 as they will probably be able to help with your original barrels and pistons.
I would speak with Langcourt Cylinder Technology in England 44 1934 612226 as they will probably be able to help with your original barrels and pistons.
10-01-2017, 05:29 AM
#3
Rennlist Member
Thread Starter
not exactly the same, the RS Pistons is always 644-648g, the c2/C4 Can be 644-652g, 660-6xxg etc.
10-01-2017, 06:57 AM
#4
Burning Brakes
Yes the weights group can be slightly different but if you replace with new then you get what are available now. It would make no discerable difference to how the engine runs and you could easily lighten whatever piston was received.
Give Langcourt a call
Give Langcourt a call
10-01-2017, 07:45 AM
#5
Rennlist Member
Thread Starter
So if I could buy 6xc2 cylinders/Pistons for 3000€ or 6xrs cylinders/pistons for 4000€ I should buy the first one?
10-01-2017, 03:11 PM
#7
Burning Brakes
I would think they will both be identical despite what is shown that advert. As I said the weight difference is marginal and make no difference. Langcourt will almost certainly be able to renew your originals at far less cost.
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10-02-2017, 03:34 PM
#8
Racer
My engine is in the workshop for a total rebuild. The cylinders are oval and out of tolerance. I need 6 new cylinder/pistons.
I can buy the cylinder/piston each with RS number or a kit with all six cylinder/Pistons But then it seems its the same for c2/c4/RS.
Anyone know what to choose? Someone must have rebuild an RS engine with new cylinders without choosen 3.8l
jonas
I can buy the cylinder/piston each with RS number or a kit with all six cylinder/Pistons But then it seems its the same for c2/c4/RS.
Anyone know what to choose? Someone must have rebuild an RS engine with new cylinders without choosen 3.8l
jonas
Are you using a workshop in Sweden?
//Patrik
10-02-2017, 05:57 PM
#10
I had always assumed it was the cylinder distorting that made them go oval. When I used to use langcourts for all my mtocross bike cylinders if they were out of shape they were junk as the nickosil coating would only do just that, re coat the existing out of shape bore. Have I got this wrong or is the nickosil wear sufficient to make the cylinder oval?
10-04-2017, 09:41 AM
#11
Rennlist Member
Thread Starter
I had always assumed it was the cylinder distorting that made them go oval. When I used to use langcourts for all my mtocross bike cylinders if they were out of shape they were junk as the nickosil coating would only do just that, re coat the existing out of shape bore. Have I got this wrong or is the nickosil wear sufficient to make the cylinder oval?
jonas
10-04-2017, 09:08 PM
#12
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You should definitely replace the complete piston and cylinder set. I have seen many 964RS engines fail due to fatigue breaks of the piston, so even if the pistons are not visibly or measurably worn, the material will have changed composition due to the years of high rpm track-day use our RS engines have enjoyed and will hence be a ticking time-bomb if retained with refurbished original cylinders. Don't believe me? Look at the photos of the RS piston and cylinder below. This came from a 30,000 mile 964RS that had been used exclusively for track days around the 'Ring and Spa, from what I recall the owner had visited both over 100 times before it let go flat out at Fuchsröhre (Foxhole). Luckily for the owner whilst the case was too far damaged to rebuild as a 3.6, we did manage a small weld repair and successfully bore it out to 109mm for a 3.8 conversion.
To replace you have two choices:
a) buy a brand new set of 964 P&C's from Porsche
b) fit a brand new set of 993 P&C's from Porsche, plus a set of 9m RSR rods to run them on the standard crank.
So, what's the advantage in b)? Inertia. The 993 pistons weigh 10% less (approx. 592g against the 964 at 660g) and the RSR rod weighs 576g vs stock 964 at 666g. That represents a 1kg saving in reciprocating weight (the equivalence of circa 6kg of rotating mass from the flywheel) with a corresponding reduction in friction from the lower moving masses and of course reduced bearing loads.
Incidentally, we use these rods in all 9m 964 3.8 engine conversions to run the 993RS piston on the 964 crank. For reference the 993RS piston is around 624g.
To replace you have two choices:
a) buy a brand new set of 964 P&C's from Porsche
b) fit a brand new set of 993 P&C's from Porsche, plus a set of 9m RSR rods to run them on the standard crank.
So, what's the advantage in b)? Inertia. The 993 pistons weigh 10% less (approx. 592g against the 964 at 660g) and the RSR rod weighs 576g vs stock 964 at 666g. That represents a 1kg saving in reciprocating weight (the equivalence of circa 6kg of rotating mass from the flywheel) with a corresponding reduction in friction from the lower moving masses and of course reduced bearing loads.
Incidentally, we use these rods in all 9m 964 3.8 engine conversions to run the 993RS piston on the 964 crank. For reference the 993RS piston is around 624g.
10-07-2017, 09:47 AM
#13
Rennlist Member
Thread Starter
You should definitely replace the complete piston and cylinder set. I have seen many 964RS engines fail due to fatigue breaks of the piston, so even if the pistons are not visibly or measurably worn, the material will have changed composition due to the years of high rpm track-day use our RS engines have enjoyed and will hence be a ticking time-bomb if retained with refurbished original cylinders. Don't believe me? Look at the photos of the RS piston and cylinder below. This came from a 30,000 mile 964RS that had been used exclusively for track days around the 'Ring and Spa, from what I recall the owner had visited both over 100 times before it let go flat out at Fuchsröhre (Foxhole). Luckily for the owner whilst the case was too far damaged to rebuild as a 3.6, we did manage a small weld repair and successfully bore it out to 109mm for a 3.8 conversion.
To replace you have two choices:
a) buy a brand new set of 964 P&C's from Porsche
b) fit a brand new set of 993 P&C's from Porsche, plus a set of 9m RSR rods to run them on the standard crank.
So, what's the advantage in b)? Inertia. The 993 pistons weigh 10% less (approx. 592g against the 964 at 660g) and the RSR rod weighs 576g vs stock 964 at 666g. That represents a 1kg saving in reciprocating weight (the equivalence of circa 6kg of rotating mass from the flywheel) with a corresponding reduction in friction from the lower moving masses and of course reduced bearing loads.
Incidentally, we use these rods in all 9m 964 3.8 engine conversions to run the 993RS piston on the 964 crank. For reference the 993RS piston is around 624g.
To replace you have two choices:
a) buy a brand new set of 964 P&C's from Porsche
b) fit a brand new set of 993 P&C's from Porsche, plus a set of 9m RSR rods to run them on the standard crank.
So, what's the advantage in b)? Inertia. The 993 pistons weigh 10% less (approx. 592g against the 964 at 660g) and the RSR rod weighs 576g vs stock 964 at 666g. That represents a 1kg saving in reciprocating weight (the equivalence of circa 6kg of rotating mass from the flywheel) with a corresponding reduction in friction from the lower moving masses and of course reduced bearing loads.
Incidentally, we use these rods in all 9m 964 3.8 engine conversions to run the 993RS piston on the 964 crank. For reference the 993RS piston is around 624g.
I bought a new set from porsche!
best regards
jonas
10-10-2017, 12:35 PM
#15
Rennlist Member
Better call Colin
