[Diy_efi] Continuous VVT system

[Alexei Pavlov]

> > It's EFI but without cam sensor as it's 2s per
> > cylinder.
> 
> Ah, waste spark and bank fire injection.  In some
> ways, this offers extra flexibility, since you don't
> need to accomodate two cam position sensors, one for
> the VVT and one for the EFI.

No sir, bank fire but twin spark twin distributor ignition :-)

> 
> Check and see if the end of your camshaft could accept
> a drilling and tapping.  Some cams come with a tapped
> and drilled hole on the end already.  Fixing a trigger
> wheel of some type to the end of the crank would then
> become a matter of physical space.

Yes, there are, but only on the 'wrong' end. I have to remove
the engine head to modify it if I want to put a sensor on it.
So for a moment (on a prototype stage) I'm trying to work around.


> The magnets?  Yes, they are attached directly to the
> camshaft.  I can show you pictures straight out of
> some motorcycle service manuals I have lying about.
> Attaches with a cap-head screw onto the end of the
> (ferrous) crankshaft.  You don't need a very powerful
> magnet.
>

Ok, a good news. I'll think about that.
 
> > I would have to fix magnets on the camshaft, as the
> > front of the camshaft is 'unshifted' (the VVT device
> > is here).
> 
> Is there room at the rear?  I don't have a clear
> picture of the cylinder head layout, so let me know if
> that is a ridiculous question.  ;)

As already said no place for a moment. I must modify the head for that.


> > Another point is that magnets loose their
> > 'magnetism' when heated.
> 
> Not all of them, as is apparent from their use in cam
> position sensors by default.  It might require some
> research to locate ones suitable for the task.

yes

> 
> > The better would be to put sensors on the back of
> > the camshaft,
> 
> External to the cylinder head?  I gather so from your
> further comment on engine packaging.

yes, external.

> 
> > The Alfa Romeo engine without VVT should deliver
> > something like 90HP from a 2L engine. The VVT brings
> > the power at the 150 hp level on a 2s/cyl engine at
> > 6000RPM, not so bad !
> 
> > The gain come form the overlap and IVC
> > modifications.
> 
> So other than the VVT changing the advance or both
> cams, nothing else between the cars is different (save
> for fuel mapping)?  Same intake, same exhaust, same
> cams?  If so, I suppose they must have deliberately
> set the valve timing to give fairly poor performance
> on the base model!

No, I was talking about the same engine with the VVT system
disconnected and connected. Just a wire to disconnect and you
have 2 different engines.

But in fact I'm not very honest in the case of Alfa engine as
the IVC is too late when VVT is disconnected. :-)
The porsche variocam example is better. It really improves
performances at high revs.

And I want control both exhaust and intake :-)

> 
> > Of course I would prefer to also have the variable
> > lift.
> 
> If you really want to get complicated about it, you
> could get a late-model Valvetronic head and control
> system from a BMW, and saw off two cylinders.  :D
> Stranger things have been done!

And not very reliable for now. Toyota's system is simpler and
does the same I believe.
_______________________________________________
diy_efi mailing list
diy_efi at diy-efi.org
http://lists.diy-efi.org/mailman/listinfo/diy_efi