hi all,
I need a bit of assistance please.
I'm looking at a bit of R&D into fitting VVL to a Cosworth engine, but I need some information about the 911 996 tt hydraulic vvl lifters/followers.
If I could get some dimensions and a bit more tech on how they work that would be great.

 

It is not a variable lift lifter. it is either on the low lift cam lobe or the high lift one.

 

here is a pic of the cam. Top one with 3 lobes

 

996tt intake lifter. 996tt exhaust lifter. 997gt3/cup lifter.

 

Thanks Tim for the explanation and pictures. I know the basics just wanted to get as much info as i can.
Its the dimensions that I would like. Any chance you could measure the height & Diameter of the vvl lifter.
That would be much appreciated.

 

diameter is 32.94mm
height from top to bottom 28.72mm uncompressed
compressed 28.60
bottom to where the valve stem seats 1.92mm uncompressed.
compressed.2.53mm

 

Oh subtract the valve stem seat heights from the over all height to get valve tip to cam lobe height.

 

just what I was after thank you.
You wouldn't know where I can find a much more detailed description of how it works would you ???
thanks a bunch

 

Works off oil psi. The solenoid between the spark plugs controls it. There are two oil ports on the lifter one for the hydraulic bucket and one to lock the high lift.

Both ports (red tubes)



Backside.



oil galley for hydro bucket.



oil galley for high lift.



oil dump port when off high lift.



Oil supply to solenoid.

 

Great info. I was not aware of the location of the oil passages... I am adding a small animation to complete Tim explanation....

 

Once again excellent thank you.

 

Hi JP, thanks matey, I have that as well. Its the dimensions and internal operation at blue print level I need. So as to compare the space for the followers in the Cosworth head.How are you any how??
frank

 

Hello Frank, I am fine, hope you are in top shape!!! Happy to see you are having a new project. Isn't it a very good information you got from Tim!!! Always post valuable information and sometimes I don't understand what he's talking about but I am trying hard!!!!!

 

LOL



He's a good guy.

I think I'm on a hiding to nothing with this project. getting followers and a cam made is the easier of the problems. Getting the oil supply galleries into an already existing head is another trick all together.

It means I will only be able to see about 550 bhp with usable low speed torque. As cams for the 650+ I was going for make the car very hard to drive /cruise and even harder/ impossible to pass emissions. A duel lift cam would have solved the problem. low lift for emission testing and cruising and very high lift for big power.

Its been a very very long time since I had en Escort RS Cosworth and if its a case of me forgetting how bad they drive I will sell it. I fancy either a 996 GT2 or a very cheep manual 6tt and do it up slowly.

As top my problem it cant be solved without an operation and there isnt a doctor in the UK that will take the risk as it can be a very very tricky operation. However the good news is my brain isn't getting starved of O2 when I sleep

 

Ouch, scary!!!! Wish you all the best Frank. It is a good thing that you stay busy thinking about other project