V2Rocket

Anybody played with this?
Search mostly comes up with people dialing in the cams to WSM specs.

Advancing the cam does wonders on the 8v 944...so I am curious if anybody had tried it on the 944S/S2.

I have an adjustable cam gear for the 16v engine so I know it's been done, but would like to know real results.

951Dreams

I don't KNOW, just using my shade tree engineering degree to talk out my rear. But I can imagine no reason it should be any different with DOHC. The principals are the same, moving the valve timing should move your power band just like in the 8V SOHC. And unless your racing at 5500+ RPM all day long (or dive on the autobahn) , it should be nothing but goodness.

But I'm wrong more than I'm right, so grain of salt.

Mongo

928s have factory adjustable cam gears but you need a proper degreeing tool if you are doing it with the valve covers on (i.e. Porken's 32v'r tool). Expect results similar to other 944s though - advancing introduces more torque sooner, while retarding may shift the powerband too high to actually gain any benefits.

thomasmryan

many moons ago, one design project was a spring/weight cam timing system for chain driven small block motors that retarded the cam at 7200rpm crank speed. much like the centrifugal weights on a mechanical distributor.

are you thinking outside the box?

V2Rocket

No, I actually have an adjustable cam gear for the 944 16v head, I don't know who the MFR is but it's the same design as the adj. cam gear I have on my 8v engine too. Nice piece, easy to adjust.

Whenever I get the 16v head on my engine, I'll play with it.

Mongo

What are your goals with cam timing?

V2Rocket

I ran for a while with the cam 2 degrees advanced on my NA and it kicked ***.
Just the 2* advance was worth +4whp/+7wtq by itself on the dyno.
Guessing there will be similar results with the 16v head, but the S profile is kind of hot as-is.

Mongo

You cannot advance further than 2 degrees and expect any gains on stock cam profiles. There is significant power loss thereafter. See Ken Porken's thread in the 928 forum.

V2Rocket

The 944 cam specs are very different than the 928 ones...
I don't discount the testing done, but so far this is uncharted territory in 944-land from what I've found.

My early NA put down 121whp with stock DME/AFM, 126whp with the MAF conversion, and 130whp with the MAF+2* advanced camshaft.

Further tuning got to 135whp. All numbers SAE corrected, done on the same dyno.

Mongo

The only way to confirm this is to do it on the dyno. Keep in mind that longer durations yield more power in higher RPMs as your keeping valves open longer. Depending on where you are focusing to optimize your powerband, most 944 engines are not 'high-revving' and were designed to have the torque balanced with HP. If you are seeking to build a higher revving 16v engine later, you may also want to consider upgrading the cams (i.e. webcam) and more durable valvetrain components.

Mongo

Follow these basic guidelines about advancing and retarding:

Advance
begins intake event sooner
opens intake valve sooner
builds more low-end torque
decreases piston-to-intake-valve clearance
increases piston-to-exhaust-valve clearance

Retard
delays intake event
opens intake valve later
builds more high-end power
increases piston-to-intake-valve clearance
decreases piston-to-exhaust-valve clearance


Heed my warning though. This is not the first rodeo I have done when it comes to fudging around with timing (did it on SBCs and LS).

V2Rocket

6000rpm tops, or wherever cams make peak power, I don't care about high RPM.
Going to see about cutting pistons to non-interference too, if I can.

Mongo

Depends on the depth of the piston and what is deemed safe.

No mad scientist work now.

ramius665

Don't care about the adjustable timing gear, but you changed your screen name?!?

V2Rocket

many moons ago