Euro951

I noticed my 86 951 has no real harmonic balancer. It is pretty much just a balanced front crank pulley. I have a 87 944s engine which appears to have a harmonic balancer on the front. The crankshaft pulley is two parts , is heavier and has rubber isolation in between. Does anyone know the advantages of using later pulley's on earlier cars? Or does the heavier pulley/balancer just slow down the rotating assembley? I would assume that Porsche felt the 944 S model needed a better balanced rotating assembley because of the increased RPM capability of the 16 valve engine. Maybe they also knew of some bad harmonics at higher RPMs ?

JohnKoaWood

I'm not Chris White, but I do believe you are correct somewhat...

16V motors have their own set of harmonics due to the second camshaft, and different crank stucture..

The 8V motors use only the balance shafts for harmonics management, but the 16V motors needed something more.. on 16V 944's Porsche used a harmonic wheel on the nose of the crank, on the 968 they used a dual mass flywheel..

This is a consideration of anyone putting a 3L crank in a 2.5 L block, either the nose pulley or the dual mass flywheel needs to be carried over as well... but you get a 2.8 liter displacement from the 88mm stroke..

Chris White

You need to turn on the spot light that shows a 951 silhouette in the sky for immediate response...

Very interesting, I never thought to look at the 944S to see if it had a harmonic balancer, I would have guessed that it didn’t.
So that means that Porsche added the harmonic balancer based on the 16v head not the displacement as originally thought. (I don’t think there is one on the 2.7)
The 16v engines only rev slightly more than the 8v. Its also hard to believe that the 16v valve train adds to the bottom end harmonics. (BTW - the 944s and the 951 have the same crank)
It won’t hurt to add a harmonic balancer to a 2.5, it may help but I have not seen any longer term examples torn down to check for wear.

RajDatta

I know for a fact that a 968 turbo S with it's 2 valve head used a harmonic balancer . So much for the 16 valve theory, lol...
Raj

George D

We added one to my 3.0 8V 968 motor. Figured the factory had a reason.

George

Darwantae951

Used they are going for over $300...

RajDatta

I have one if anyone is interested.

Euro951

I will try to post some pictures of both for reference.

PorscheDude1

I have an S2 harmonic balancer as well.
Removed from an S2 with 62k on the clock.
$150 shipped in the lower 48.

Voith

Is 2.5 944S and 3.0 S2 harmonic damper the same unit or are these two differernt parts?

blade7

I'm guessing it didn't come with a DMF ? I haven't compared the pulley on my 2.7 engine with a 2.5 version but it's not the same as the one on my S2 crank.

Chris White

The only engine that got the harmonic balancer was the S2 engine (and according to Raj the 968 turbo). Porsche's theory is that the 3.0 engines needed the harmonic balancer because of the longer throw crank would have more flex than the short 2.5 crank. The 968 engine do not have the front mount harmonic balancer because Porsche went to a dual mass flywheel which acts as a harmonic balancer.
The purpose of the harmonic balancer is to dampen the crank flex due to the harmonics of the power cycle, each cylinders power stroke will flex that crank throw slightly and at certain rpms the crank can 'ring' like a bell. The harmonic damper is there to reduce the ringing. with out it you may get metal fatigue over a very long term.

Voith

Lart is selling 2.5 harmonic dampener here..

http://www.ebay.com/itm/Porsche-944S...1560dc&vxp=mtr

Is this really rubber lined or not, and would it work or do I have to find 3.0 dampner for 3.0 engine?

Btw Chris, do you happen to have any piston oil squirters for sale, suitable for 2.7 block retrofit?

Chris White

That does look like a harmonic damper. I have not looked at the 2.5 16v pulleys very closely before -not many of them out there!
I don't have any squirters here, I usually order them for each project.

blade7

Jeez, $250 will get the crank as well here.