SL500 - variable valve timing

[simonshearer]

I have a 1997 SL500; I'm trying to learn as much as possible about the design and function of the variable valve timing on the intake cam. I had a leaky cam adjust solenoid (magnet) and dealing with that started me thinking about it's function. Rather than make assumptions, I thought I would ask for advice from the experts on this forum!

It appears to me that there is no adjustment on the exhaust cam so all cam phasing is achieved on the intake.

I did a search on "variable valve timing" but found very little discussion about it on the SL board.

When I look on the EPS at the individual parts, it looks to me like this is a magnetically controlled (vane?) phaser using an armature as an electro-mechanical camshaft position actuator. Am I on the right track? Using the exploded parts view isn't a good way to determine physical operation; I am therefore a bit clueless - that might be obvious!

Can anyone help educate me on the signal this solenoid receives, from where, and with what result? How does the electromagnet phase the cam? Does it advance it for low end torque performance? How many degrees? Etc.

Any help would be appreciated. Thanks.

[ctaylor738]

Here is what Alldata has to say:

With the engine running both camshaft timing adjusters hydraulically/mechanically rotate the intake camshafts relative to the driving camshaft sprocket by 20° of crankshaft angle in the advanced position and back to the retarded position. The adjustment is controlled electromagnetically through the engine control unit.
The adjustment time of about 1 second is dependent on the engine oil pressure at the camshaft adjusters and the temperature or viscosity of the oil.
The camshaft position indicator on the camshaft sprocket (13) sends the camshaft rpm signal from the camshaft position sensor as an input parameter for the ignition control unit. The angle of rotation for the camshaft advancement is limited by circumferential stops between the camshaft sprocket (13) and the flanged hub (15).

Alldata goes on to say that the intake camshaft is:

retarded up to 1000-2000 RPM for better idle
advanced up to 4700 for increase torque
retarded above 4700 for "volumetric efficiency."

[Strife]

You should see the cam timing on a 2011 Ford 5.0. It's really amazing.

http://www.hotrod.com/techarticles/engine/hrdp_1004_2011_mustang_engine/index.html

(The site might work only with Internet Exploder only).

The geek in me would like to see the source code for the cam phasing.

A show I like that is occasionally on The Speed Channel, "Two Guys Garage", had a GREAT tech session on this engine.

A lot of car builders are looking hard at this engine because it would be darned near impossible to build a street drivable "old school" engine with this kind of power, certainly not with any kind of durability, comfort, emissions, or efficiency.

[simonshearer]

Originally Posted by ctaylor738

Here is what Alldata has to say:

With the engine running both camshaft timing adjusters hydraulically/mechanically rotate the intake camshafts relative to the driving camshaft sprocket by 20° of crankshaft angle in the advanced position and back to the retarded position. The adjustment is controlled electromagnetically through the engine control unit.
The adjustment time of about 1 second is dependent on the engine oil pressure at the camshaft adjusters and the temperature or viscosity of the oil.
The camshaft position indicator on the camshaft sprocket (13) sends the camshaft rpm signal from the camshaft position sensor as an input parameter for the ignition control unit. The angle of rotation for the camshaft advancement is limited by circumferential stops between the camshaft sprocket (13) and the flanged hub (15).

Alldata goes on to say that the intake camshaft is:

retarded up to 1000-2000 RPM for better idle
advanced up to 4700 for increase torque
retarded above 4700 for "volumetric efficiency."

Thanks Chuck. Not sure why I didn't think of ALLDATA. I asked a shop-owning buddy to print off all 13 pages of that same section on engine timing and valves. Gives you a great perspective on just how sophisticated that engine is; and perhaps why it's a little pricey. Anyway, it was extremely helpful. I would post it all but I don't want to violate any copyrights!

[simonshearer]

Originally Posted by Strife

You should see the cam timing on a 2011 Ford 5.0. It's really amazing.

http://www.hotrod.com/techarticles/engine/hrdp_1004_2011_mustang_engine/index.html

(The site might work only with Internet Exploder only).

The geek in me would like to see the source code for the cam phasing.

A show I like that is occasionally on The Speed Channel, "Two Guys Garage", had a GREAT tech session on this engine.

A lot of car builders are looking hard at this engine because it would be darned near impossible to build a street drivable "old school" engine with this kind of power, certainly not with any kind of durability, comfort, emissions, or efficiency.

Thanks Strife. Wonderful article. Ford's done a great job with Mustang styling over the last few iterations, and this article provides a really interesting perspective on how their engine designers are using cam phasing to squeeze out incredible performance with lower emissions and smaller displacement, at a reasonable cost. Probably not going to rush to buy one... just stuck on our marque I guess!