Hi Guys,

Can anyone shed any light regarding the cam control on the M120 engine? Which method is used ? And how can I trigger it? .... My ECU has an RPM set output but I have absolutely no idea how?

...... I actually read somewhere that the SL600 (m120) had no variable valve timing and I was very happy in that knowledge until further developments.

......just to follow up on other posts, the kit car will be ready in late April.

Thanks Guys

Stuart

I don't know the exact details but its not exactly variable. The exhaust cam only advances a fixed amount at ~2100 RPM then retards back to base at some higher RPM. So its basically an on off switch triggered at set RPM values.

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John Roncallo

Do we know what that's for? Is it performance related or again because of antipollution system? If the latter and emissions are not an issue, can the thing just be left unplugged?

Yes thats right, its cam phasing on the intake +20 degrees. On the M119 I believe they use a hydro-mechanical set up? Is that the same on the M120.

So I would need to hydraulically activate the (VVT) via a pump which is annoying as I`ve ditched the tandom pump.... but I`m sure I can rig something up.

OFF <2100 rpm is for smooth idling,
ON 2100>4700 for increased torque
OFF at 4700 for volumetric efficiency

It is a simple on/off. 12vlts and ground.

Is that to a pump or do you mean straight to the cam gear? The reason I ask is that some systems are elctro magnetic....well I`m told that

You can see the connector plugs on the central intake cam shafts on the picture below, I`m hopeing that the connectors are the magic items I need to connect to a 12v supply.

Any ideas what the sensor/connector on the far left hand is?

Exhaust? Do you mean the intake cam?

I thought it was exhaust based on my 54 year old half dead brain cells. But looking at the picture it must be intake.

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John Roncallo

Anyone ever try leaving it on for increased torque at all times. How would it run in the 1/4 mile with a bypass switch in the cockpit??

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John Roncallo

The megasquirt guys at DIYAutotune have a controller specifically for variable cams now. I'd like to see someone mess with it, and even adapt the adjuster mechanism it to work on both cams. It isn't automatic but I think you can basically set the table for it like a fuel map. Curious if it could make an old engine as efficient as a new one.

So the advance is hydraulic off of oil pressure. It has a plunger in front that is pulled by the solenoids when activated. The solenoids are 12vlts and grounded for activation. You can just run them with a switch, but you do not want them over the mid 5000 rpm range. It will cost you hp. I have done a fair bit of dyno runs with them on and off and different combinations of switch points. I have mine turn off at just under 5250 rpm.