Rob Edwards

For sale is a set of four S3 cams taken from a 1986 Auto motor. Mileage unknown but these cams are in excellent condition. No pitting whatsoever on the nose of the lobes, all the teeth are present and accounted for.

Buy these and have them modified to run in S4 heads- voila, inexpensive GT cams. (Ok, the S3 intakes are ground 8 degrees retarded vs. GT intakes, but lift and duration are identical between S3 and GT, intake and exhaust.



Discussion of the mod to run S3 cams in S4 heads:

https://rennlist.com/forums/928-foru...ance-gain.html


Video of cams' condition:




Asking $300 for these cams, shipped anywhere in the Continental U.S.

Temekun

pm sent

Ducman82

I should have charged Brendan more.....

Ketchmi

I bought every set Mason could come up with just to have for a rainy day...call it an investment. Now I just need to find somebody like Elgin to modify them since they won't anymore.

Strosek Ultra

When I did the cams for Tuomo he sent me one cam which I identified as a used GTS intake camshaft. When checking out the cam profile the duration (212,5 @ 1mm) did not come up the same as specified by Porsche (228 @ 1mm). Anyone else who know anything about this? What else camshafts do have a lift of 9,5mm? It make sense the GTS cam should have less duration than the S3/GT cams as the lift is less. Has Porsche given incorrect specifications for the GTS cam? All other 928 cams I have checked are in compliance with the specs by Porsche. Here is the cam diagram I made.

Åke

BC

ptuomov

Just to close the loop on those GTS cores that Ake spoke about, here are the casting and stamped identifiers.







I picked GTS cores for this, because I had an orphan intake set from a GTS. The fact that they are GTS cams had no other significance.

Should it turn out that these were in fact GTS cams, it'll be a somewhat interesting question to ponder whether Porsche's spec or Ake's measurement are correct. Food for though: GTS peak power at 5700 rpm and peak torque at 4250 rpm, versus S4 6000/3000 and GT 6200/4150.

Since then, these cams, whatever they were, have decided to let it go and not be the perfect girly cams anymore. Ake used his method to fabricate an adjustable center sprocket for them and changed the max lift to about 11.2mm and the 0.05" duration to 227 degrees. The idea is to optimize the overlap with these cams for John's turbo system.

atb

Louie had come across a similar situation when he put GT cams into a GTS. At one point I had put in a Public Disclosure Act request for the documentation that Porsche submitted to get the GTS approved by the EPA for importation. I seem to recall that the cam spec was different than what was published in the tech spec booklet / WSM. Sorry, don't have that documentation readily available any longer.

Rob Edwards

First off, the set of stock S3 cams are sold. Thank you!

Second, I have a couple of sets of cams here that I could rig up in a head and try to figure out how to 'degree' them- I have the right dial indicator and holder, I think all I need is a degree wheel that would work on a camshaft.

These are stock S3 (left), S4 (middle), and GTS (right). Tragically I've got no spare set of GT cams just sitting here.




/Not on topic, here is the comparison of the modded S3 cams (left) vs. the stock set (right). BC and I did a 'group buy' on the mods done by Todd Tremel.



Here's the modded 5-8 S3 exhaust cam next to a stock S4 5-8 exhaust cam.

Rob Edwards

Just for posterity:

Casting numbers:

Both sets of S3 cams I have are the same casting #'s:





S4, GT, and GTS cams all use the same castings:
S4:


GT 5-8 intake:

GT 5-8 exhaust:


GTS:

End markings:

S3:
1-4:

5-8:
[img] https://webfiles.uci.edu/redwards/pu...%206-22-14.jpg [/img]

S4:
1-4:

5-8:


GT:
5-8 exhaust:

5-8 intake:

1-4 intake:

1-4 exhaust:


GTS 5-8:

GTS 1-4:

SteveG

This is a great thread on cams. I try to gather info from context, but sometimes that is difficult and I get wrong impressions. For those of us getting up to speed, so to speak, what is the significance of casting numbers on shaft and the end stamp? I assume it goes beyond authenticity of factory part. TIA.

ptuomov

I believe the casting numbers identify the cast core and the end stampings identify the profile that was ground on the core.

Vilhuer

Did those cores come from me? If yes they were from early ROW GTS engine which had never been open after it left factory. If lift was 9.5mm like it should also duration should be same it was when new. If its not as factory documents say it wouldn't be large surprise.

End stamping is last 5 digits of part number.

Rob Edwards

Yes, for all intents and purposes you can tell a 32V cam by looking at the last two stamped digits on the end:

S3: '04'
S4: '00'
GT: '01'
GTS: '03'

If the first 3 digits are odd, it's a cam for the 1-4 cylinders, if even then it's for the 5-8 cylinders.

ptuomov

Your GTS cams were in better shape than these, but these also looked very much untouched after they left the factory.

This episode will probably motivate me to pull the trigger on the camshaft lobe measurement equipment.

What he said.