Can you identify this cylinder head?
#17
Well that girdle holding the cams isn't normal, at least I don't recall it being but I've only glanced at a couple of 16v heads. I don't see the variocam computer stuff either...
#19
Rennlist Member
Well, it doesn't have a vario-cam solenoid installed... I'm curious about what all the dowel pins are for on the intake ports. I know those don't exist on either an S2 or 968 head.
Your cams have removable sprockets, that's different. I also see that your tensioner isn't hydraulically actuated. Presumably with the new cam girdles and a fixed tensioner, you're aiming for every high RPM. I also see the turbo oil port on the balance shaft cover, but it looks "home made", making me think it wasn't originally a turbo block.
Your cams have removable sprockets, that's different. I also see that your tensioner isn't hydraulically actuated. Presumably with the new cam girdles and a fixed tensioner, you're aiming for every high RPM. I also see the turbo oil port on the balance shaft cover, but it looks "home made", making me think it wasn't originally a turbo block.
#20
Rennlist Member
Thread Starter
Ah, Van. You're my man so far. You're clearly familiar with the Porsche 4V head, and you're picking up detail. A few hints: The chain sprockets are removable, but they're also adjustable. So their real purpose is to be able to adjust both intake and exhaust cam timing. You also picked out the mechanical tensioner and the girdles. Moderately high RPM (8000), but the real purpose is to stabilize the valve train with very aggressive cam profiles. You also caught the oil bung on the (empty) balance shaft cover. It's not a turbo feed, it's simply the source of oil pressure for data acquisition. Keep going; you're good.
Think a little more about the dowels.... what are they typically used for?
Think a little more about the dowels.... what are they typically used for?
#22
Rennlist Member
Well, dowel pins are used for alignment, so I suppose you're doing individual throttle bodies/manifolds (or at least 3 separate ones, since the middle two shares a stud) and you want to keep alignment for the porting you've done.
Hmm... longer cams? The S2 doesn't have that bearing journal after the #4 lobes, does it? I assume that's for additional support, too. I actually don't know that much about the 16v heads - do they all have those bearing surfaces on the back, or did you have to put those in? If they have them, why didn't Porsche take advantage of it and make the cams longer?
Hmm... longer cams? The S2 doesn't have that bearing journal after the #4 lobes, does it? I assume that's for additional support, too. I actually don't know that much about the 16v heads - do they all have those bearing surfaces on the back, or did you have to put those in? If they have them, why didn't Porsche take advantage of it and make the cams longer?
Last edited by Van; 08-17-2011 at 08:39 AM. Reason: Updated 'cause I figured out the long cams...
#27
Nordschleife Master
Perhaps the oil jets for the chain are throwing eveyone off, or the reliefs cut for cam clearance?
It is NOT an S head (wrong casting number), only 1 stud/bolt for fastening the forward coolant passage..
Its an S2 head (no 3rd moutning boss near the chain tensioner, to the rear, unless it was machined off).
Do I also spy port matching (for the ITB setup)?
Looks very nice... but will it run?
It is NOT an S head (wrong casting number), only 1 stud/bolt for fastening the forward coolant passage..
Its an S2 head (no 3rd moutning boss near the chain tensioner, to the rear, unless it was machined off).
Do I also spy port matching (for the ITB setup)?
Looks very nice... but will it run?
#29
Rennlist Member
Thread Starter
First, excuse my ignorance but what's 'iirc' and what's 'FIFY'. I feel illiterate.
Good eye, JohnKoaWood, you picked up some detail. Oh BTW, it's not a S2 head. What doya mean 'will it run'? I certainly hope so; too expensive for a lamp like Spencer's.
Good eye, JohnKoaWood, you picked up some detail. Oh BTW, it's not a S2 head. What doya mean 'will it run'? I certainly hope so; too expensive for a lamp like Spencer's.
#30
Nordschleife Master
FIFY = Fixed it For You
NOT an S2 head... then an S head with plenty of work done.. I guess you like heavy breathing..
Big valves, ITB, high reving... that should prove to be one hell of a 2.5 (2.8?? PLEASE tell me this is a 2.8) race motor.. If left at 2.5L I am guessing that it is being prepped for a class limited by displacement?