Offset Cam Key/Adjustable Cam Gear?

[OK-944]

While I really have no complaints about the current performance of my ‘87NA - it would be nice, given my style of “spirited” driving…which generally means whenever I get the rpm’s up into the 4K range (I know, pretty lame for some folks here!) - it would be nice if my car could have just a tad more low-end torque. While my car can really start to come alive at above 3.5Krpm’s or so…its on those rare occasions when I get it up to 4K and above that it really starts to fly.

With the above in mind…I came very close to installing an offset cam key when I did my rebuild awhile back - my understanding being that by doing so I might realize a bit more oomph on the low end while sacrificing a bit on the high end…which actually sounds like it might be just right for my driving style.

But I chickened out on the offset key as this seemed a bit too risky, given that the effective thickness of this key is reduced by either half or a bit more…depending on which particular offset is chosen. But I still find the idea of this slight change in cam timing intriguing.

Another approach, which to my thinking might be a bit safer…would be to go with something like an adjustable cam gear assembly such as is offered by Lindsey Racing, which is a bit pricy but seems like a nice product, and which would also allow for a bit more fine-tuning than would a fixed offset key.

At any rate…is there anyone here who has possibly done one of the above modifications (or are thinking about this) to an eight valve NA, who could comment on changes in performance? Alternately…are there any published charts illustrating the specific torque-band shift resulting from this modification? Thanks!

[v2rocket_aka944]

I have done both - the adjustable key and then a gear.

The key is actually an OEM Mercedes Benz part that happens to fit the 944 - so it should be solid enough not to break. I never worried about it as there really isn't that much load on the key (the cam bolt torque locks the gear down against the camshaft; the key is really just for alignment)

Absolutely 100% you should get a key/gear and advance the camshaft 4 degrees. There is a big gain in low end power, throttle response and general driving pleasure, without any actual tradeoff at the top end - the 944 cam is too mild to have much top end anyways.

Below is a dyno graph of mine from years past - the ONLY change between the two runs is advancing the stock cam by 2 degrees. 4 degrees should be even better but I never dyno'd that. Blue is stock cam position, red line is advanced cam. This is on an early model 944 with the 05R cam.

[OK-944]

Thanks for the info! Sounds like a 4 degree cam gear shift may be in my future...but I do wonder why Porsche did not choose this (cam timing) from the get-go.

[v2rocket_aka944]

Emissions, most likely.
A lot of cars in the 70s-80s had their cam timing severely retarded by the manufactures to clean up emissions. To the point where if you just set the cam timing advanced 4 degrees or so the engine really wakes up - this is of course true on the 944 but does wonders on domestic smogged-down V8s and similar old engines.