THE 3.0 Liter Turbo Thread
05-07-2005, 05:54 PM
#136
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Tom, its too long for me to remember as well. We are going back over 1 year. The 968 oil filter housing is different. It uses o'rings to seal the oil lines to the cooler compared to the 951, which uses threaded fittings. I think the OPRV is still the same though.
I am not sure if the housing themselves are interchangeable anymore.
Raj
I am not sure if the housing themselves are interchangeable anymore.
Raj
05-09-2005, 06:50 AM
#137
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Originally Posted by Pauerman
It's pretty clear (to me) that d993 is not seeing the point about turbocharging a 8V vs 16V. This is not an issue of "monkey-see, monkey-do" - it's a matter guys here on Rennlist who have built or are looking to build these engines "correctly." The mantallity of "use a thicker head gasket - it'll work" vs "use the proper parts for the job" is what's being debated.
Some tuners use shorter rods, some have probably looked into a thicker head gasket to drop the CR, but at the end of the day, to maintain the combution chamber characteristics that the Porsche engineers designed you've got to use the "proper" 104mm turbo pistons - 16V or 8V. It's clear that "minor" details like squish area are not of a conern to you.
For the 8V 3L application, the 951 parts needed are much more readily available and are more cost effective than many of the custom parts (intake, exhaust/crossover) needed for a 16V application.
As already stated, if a thicker head gasket is all that is req'd then everyone in the 944/968 community would have done it already.
d993, you talk as though the thicker head gasket route is a far better, more cost effective option for turbocharging a 16V engine compared to the 8V - correct piston, modified 951 or 2.7 head option.
Obviously, you haven't spent a red cent on your thicker head gasket idea and can't back up what you are saying. In my opinion, what you fail to recognize is that even with a thicker head gasket 16V application, the 8V option is still a more cost effective option and it's built with the "correct" parts.
Some tuners use shorter rods, some have probably looked into a thicker head gasket to drop the CR, but at the end of the day, to maintain the combution chamber characteristics that the Porsche engineers designed you've got to use the "proper" 104mm turbo pistons - 16V or 8V. It's clear that "minor" details like squish area are not of a conern to you.
For the 8V 3L application, the 951 parts needed are much more readily available and are more cost effective than many of the custom parts (intake, exhaust/crossover) needed for a 16V application.
As already stated, if a thicker head gasket is all that is req'd then everyone in the 944/968 community would have done it already.
d993, you talk as though the thicker head gasket route is a far better, more cost effective option for turbocharging a 16V engine compared to the 8V - correct piston, modified 951 or 2.7 head option.
Obviously, you haven't spent a red cent on your thicker head gasket idea and can't back up what you are saying. In my opinion, what you fail to recognize is that even with a thicker head gasket 16V application, the 8V option is still a more cost effective option and it's built with the "correct" parts.
"Use the proper parts"..............again, downgrade to upgrade. I'm sure you'd get an extra 40 HP to the wheels on a n/a 968 with a 2.75" exhaust (as long as you compare it with a 1" exhaust pipe!!!)
"For the 8V 3L application..........yes, it of course it makes a lot more sense, since your objective is SOHC 8V!
Nice!
You make a lot of sense.............So now we should start buying those (non-BB) $450 turbochargers from you for..........uh......... $900.......... correct?
05-09-2005, 07:10 AM
#138
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Originally Posted by TurboCab
Does any one here experienced problems with a thicker head gasket? Because if no one has experienced problems, how can we disregard the idea without testing it? I made a 968 16V turbo conversion myself. I decided to take the shorter rod way to lower the compression, and I remember a lot of people talking about the squish area. I have run up to 20 psi of boost without the most remote sign of detonation on street gas. I suspect that the pentroof design of the 16V head diminish the tendency to knock. The bottom line is that we can assume some things based on theory, but the thruth is that all the theory in the world cant susbstitute testing. I'm not saying that messing with the squish area is the right way, but that there are some ways that may not seem correctly but that can yield very good results.
By using the 16V from my 968 I saved the cost of buying a 2.7 8V, but incurred on the expense of a new intake manifold and the modification of the 968 exhaust header flanges to fit the 951 crossover pipe. That made the 16V conversion a little more expensive. Going with the 8V will save you some money and the problem about the fabrication of the intake manifold and exhaust header modification. By using the 16V head I do not need to mess with the timiming belt and sprockets. How much reliable will be the 16V head over the years to come have to be seen.
But hey, Porsche did not made the 2.7 head for turbocharging either!
By using the 16V from my 968 I saved the cost of buying a 2.7 8V, but incurred on the expense of a new intake manifold and the modification of the 968 exhaust header flanges to fit the 951 crossover pipe. That made the 16V conversion a little more expensive. Going with the 8V will save you some money and the problem about the fabrication of the intake manifold and exhaust header modification. By using the 16V head I do not need to mess with the timiming belt and sprockets. How much reliable will be the 16V head over the years to come have to be seen.
But hey, Porsche did not made the 2.7 head for turbocharging either!
Hey, to the guys who insist on MORE WORK, and MORE $$$ to turbocharge a 968.................. Be my guest.
05-09-2005, 01:28 PM
#139
Hitsquad Ninja
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i'm in the process of a 3.1 L turbo, and am using the 2.7 head from my 89 n/a. the work involved in using a 16v head is not worth the time, the effort, and the money. especially with having to customize a dual cam setup because that internal cam chain tensioner is a pos, and a BIG no no with an expensive engine like a 3.1 turbo. an 8v head will give you all the hp and torque one could ever even imagine. i back up my knowledge with experience as well, and if anyone needs further evidence talk to the guys at the RUF dealership here in Dallas. 900 hp 3.1L 951 with a 968 tranny (30 psi). i guess it's more of a "958" 
05-16-2005, 05:12 AM
#140
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I'd like to add a data point if I may to the debate over 8V vs 16V head on a 3L turbo.
Recently, I spent some time with my mechanic, and wandering 'round his shop, I found a 968 race car under a cover. I persuaded him to let me take a closer look, and found it was turboed using the original 16V head (with the VarioCam disabled for some reason).
The owner had experienced a LOT of trouble with what was described as "localised boiling" in the head around the exhaust valve area. As it was described to me, the water jacket is quite small in that area due to the space taken up by the 4 valves. The net result was that the ability of the cooling system to conduct away the extra heat induced by the turbo setup was insufficient. The cooling system had multiple "swirl pots" added to try and get the bubbles out, and was still causing problems two years into development.
Note that this was a RACE car, and the lesson might not apply to a street car, but the mechanic thought the cooling system would have worked better using an 8V head with its larger water galleries.
_________
Steve Aitken
'89 944 S2
Recently, I spent some time with my mechanic, and wandering 'round his shop, I found a 968 race car under a cover. I persuaded him to let me take a closer look, and found it was turboed using the original 16V head (with the VarioCam disabled for some reason).
The owner had experienced a LOT of trouble with what was described as "localised boiling" in the head around the exhaust valve area. As it was described to me, the water jacket is quite small in that area due to the space taken up by the 4 valves. The net result was that the ability of the cooling system to conduct away the extra heat induced by the turbo setup was insufficient. The cooling system had multiple "swirl pots" added to try and get the bubbles out, and was still causing problems two years into development.
Note that this was a RACE car, and the lesson might not apply to a street car, but the mechanic thought the cooling system would have worked better using an 8V head with its larger water galleries.
_________
Steve Aitken
'89 944 S2
06-02-2005, 07:25 AM
#143
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The water pumps are different for the 2.5 and 2.7 L blocks, so you have to use the correct one. The impeller is moderately larger for the 2.7 L blocks. Both pumps have the port for the turbo thermostat: in fact this is the only location to drain coolant from a 2.7 L block because there is no drain plug for the coolant passage in the block.
06-02-2005, 03:41 PM
#144
Rennlist Member
As long as the 968 waterpump has a port of the thermostat, I see no problems there. Thanks.
As for the OPRV and Oil Thermostat housing. It appears from PET that the 968 uses a late one-piece 944 turbo OPRV. The oil thermostat housing is a different part, howver. Does anyone know if a 944 turbo oil thermostat housing can be used on a 968 block? The big metal gasket and OPRV are both interchangable between the late 944 turbo and 968 (same parts), so I am guessing the hoping are interchangeable as well. Anyone know for sure? (I'd like to use the 944 turbo housing, so I can use my factory 944 turbo oil cooler lines.)
As for the OPRV and Oil Thermostat housing. It appears from PET that the 968 uses a late one-piece 944 turbo OPRV. The oil thermostat housing is a different part, howver. Does anyone know if a 944 turbo oil thermostat housing can be used on a 968 block? The big metal gasket and OPRV are both interchangable between the late 944 turbo and 968 (same parts), so I am guessing the hoping are interchangeable as well. Anyone know for sure? (I'd like to use the 944 turbo housing, so I can use my factory 944 turbo oil cooler lines.)
06-02-2005, 07:20 PM
#146
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D993
Have you put any thought into the fact that if you use a "thick headgasket" you will be changing the distance from the center line of the crank to the center line of the cam.This will change your cam timming,even with an adjustable cam gear you will have a hard time to get it right.
Yes it will change the squelsh area of the chamber with a thick gasket/spacer that I could live with but you are now adding 2 gaskets into the combustion area and this is were your detonation will become a problem. Look at the 951 headgasket failures they love to eat their way through the edge of the gasket.
John on Long Island
Have you put any thought into the fact that if you use a "thick headgasket" you will be changing the distance from the center line of the crank to the center line of the cam.This will change your cam timming,even with an adjustable cam gear you will have a hard time to get it right.
Yes it will change the squelsh area of the chamber with a thick gasket/spacer that I could live with but you are now adding 2 gaskets into the combustion area and this is were your detonation will become a problem. Look at the 951 headgasket failures they love to eat their way through the edge of the gasket.
John on Long Island
06-02-2005, 09:15 PM
#147
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Originally Posted by 968TurboS
A 968 oil cooler is bigger than a 944 turbo oil cooler. Not sure why you would prefer to use a 944 turbo unit.
Raj
Raj
In other words, I was hoping to use the cooler and lines already in my car. Does the 968 cooler mount in the same location as the 951? I'd consider it if it could be mounted without duct-tape and bailing wire.
06-03-2005, 09:22 AM
#148
Rennlist Member
I think the fact you are doing this on a 951, it makes sense to stick to a 951 oil housing. I was thinking a 968 body which has mods to mount the cooler. I need to keep reminding myself that the motor will go in a 951.
Raj
Raj
06-11-2005, 09:56 PM
#149
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Originally Posted by JPBNY
D993
Have you put any thought into the fact that if you use a "thick headgasket" you will be changing the distance from the center line of the crank to the center line of the cam.This will change your cam timming,even with an adjustable cam gear you will have a hard time to get it right.
Yes it will change the squelsh area of the chamber with a thick gasket/spacer that I could live with but you are now adding 2 gaskets into the combustion area and this is were your detonation will become a problem. Look at the 951 headgasket failures they love to eat their way through the edge of the gasket.
John on Long Island
Have you put any thought into the fact that if you use a "thick headgasket" you will be changing the distance from the center line of the crank to the center line of the cam.This will change your cam timming,even with an adjustable cam gear you will have a hard time to get it right.
Yes it will change the squelsh area of the chamber with a thick gasket/spacer that I could live with but you are now adding 2 gaskets into the combustion area and this is were your detonation will become a problem. Look at the 951 headgasket failures they love to eat their way through the edge of the gasket.
John on Long Island
You're right, the timing issue will come up, but it can be compensated for.
Also, I was suggesting a single "multi-layered" SS head gasket (about 3mm), NOT multiple stock head gaskets, which would make it hard to seal properly for long-term use.
06-11-2005, 10:04 PM
#150
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Originally Posted by 968TurboS
A 968 oil cooler is bigger than a 944 turbo oil cooler. Not sure why you would prefer to use a 944 turbo unit.
Raj
Raj
Obviously it's not a direct bolt-in, but there's nothing wrong with increasing the oil capacity with a drastic improvment in cooling. With that much cooling ability, it also allows for the use of thinner oil (5W30), which means higher efficiency for the engine.
IMO, it's a better set-up than the "dual" oil coolers that some do on their high-HP 951's.