Does anyone have an actual confirmed amount by which VTC moves your camshafts when it engages ?

Pretty sure its a 20 degree advance when activated.

At idle the intake cam is in the same position as above 4600 rpm.

Above idle the oil pressure advance the intake cam to 20 BTDC degrees and increase overlap from 8 degrees to 28 degrees until the oil pressure is cut by ecu.

A low to mid rpm torque enhancing method and a way to have a smooth idle with a 28 degree overlap.

The exhaust cam doesn't change and set the upper rpm limit of efficiency as it only closes at 8 ATDC with 248 degrees of duration [same as intake] on 90-95 Q45 engines

Q45tech wrote:At idle the intake cam is in the same position as above 4600 rpm.

Above idle the oil pressure advance the intake cam to 20 BTDC degrees and increase overlap from 8 degrees to 28 degrees until the oil pressure is cut by ecu.

A low to mid rpm torque enhancing method and a way to have a smooth idle with a 28 degree overlap.

The exhaust cam doesn't change and set the upper rpm limit of efficiency as it only closes at 8 ATDC with 248 degrees of duration [same as intake] on 90-95 Q45 engines

So why does the factory service manual's proceedure have a method of testing the VTC solenoid by grounding pin 104 at the ECU under an idle condition to check for "irregular idle".

If what you're saying is true, the VTC solenoid opening at idle should do nothing since there is insufficient oil pressure to change the timing of the cam.

Maybe I'm just not understanding the mechanical functionality of the VTC system.

Does the VTC solenoid being engaged relieve the oil pressure in the VTC system or cause it to build?

Q45tech wrote:The exhaust cam doesn't change and set the upper rpm limit of efficiency as it only closes at 8 ATDC with 248 degrees of duration [same as intake] on 90-95 Q45 engines

Would there be much benefit to have VTC on the exhaust cams to match the intakes?

Hell yes! The dynamics of airflow change with the RPM & throttle position, infinitely variable valve lift and timing on every valve would be the ideal scenario!

I'm thinking that the future holds electrically actuated valves via solenoids. Call my silly but I don't know why this hasn't happened by now. Quite simple actually and the valves can even be of the "butterfly" or "gate" type. Get on it engineers.

That's what BMW is playing with.

I was thinking about that the other day, using oil pressure controlled opening & closing of valves, and having solenoid valves controlling the opening/closing of gates to get the oil into the chambers.

Dunno whether this, or even the electronic solenoids, actually give enough speed to provide true mechanical reliability & perfect function though.

The sum of the electrical draw at idle in winter when lights, rear defroster, heater fan on high, radio, injectors, coils, misc precludes having solenoids for valve control until the shift to 42 volt electrical systems.

BMW already has to use a water cooled 160 ampere alternator to feed all the gadgets.

THe normal idle hot oil pressure is above 14 psi worst case [warm up idle oil pressure goes from 70 > 14 depending on viscosity] which is enough to control cam advance unless the VVT system is old and sticky/varnished was my point.

One of the new BMW engines, think it may be the new Mini does not have a throttle plate but varies valve lift instead. Interesting development of VANOS

I could see high current draw from electric solenoids but...

If you take away the entire upper valve drivetrain, chains, cams, valves, springs... then there is all of the power that you would need to run a secondary alternator in whatever voltage you like.

Reliability isn't an issue if you think about it because your fuel injectors are merely solenoids that run thousands of rpm's a minitue for hundreds of thousands of miles. If you have a gate type valve and the solenoid fails then you will have zero head damage.

With straight intake and exhaust tracts, unlimited compression capability, unlimited duration basically to TDC and BDC and maybe adding direct injection like a diesel, there is mad potential in such an engine.

There would be no valves to hit so the piston could come to tdc before the valve is closed expelling 99% of exhaust gases.

Then again, we should all be using a Wankel anyways. Pistons are so ghetto.

Weigh the fuel injection pintle and compare it to an engine valve plus you have 32 valves and only 8 injectors.

I doubt the entire parasitic loss of the cams, light springs, HLA, followers, and chain friction is 5 horsepower under WC rpms.

A fuel injector draws 1.0 ampere, a valve solenoid would comsume 10 times that amount due to valve weight or 320 amperes [during over lap] in total plus the valve duty cycle is significant vs idle/cruise injection time.

Study the saturation of a solenoid and the magnetic field build up you will see it is extremely difficult to emulate a cam curve..........might be good or bad.

If you used a 42 volt system it would be much more likely to work past a 500 mile race.If a solenoid fails/sticks it bends the valve against the piston.

T45 wrote:I'm thinking that the future holds electrically actuated valves via solenoids. Call my silly but I don't know why this hasn't happened by now. Quite simple actually and the valves can even be of the "butterfly" or "gate" type. Get on it engineers.

I think GM is working on this too...

Psh... valves... http://www.coatesengine.com/technology.html There's one out there that I think looks a little better than those but I can't find the link yet.

Qtech... Forget typical valve design. Forget the current head, throw the entire upper half of the combustion engine out the window.

If one were to go to solenoids there would be no need for the current valve design or springs. The intake tracts could be opened and closed by a gate or "guilletine" type valve. Like on motorcycle flat slide carbs. If one used this type of valve there would be no need for springs as the solenoid would handle the movement, both open and closed.

If this "gate" valve were positioned paralell to the top of the piston there would be nothing for the piston to hit at all. Compression could be limitless.

Throw typical cam duration and curve out the window too. With almost instant valve action the valve could open immediately after the piston starts it's downward travel and close as the piston nears BDC. Your typical cam curve does not allow for as much valve duration due to cam curve and also the valve clearance with the piston.

As far as what affects this much duration would have on an engine I have no idea. I think you know a lot more about engines than I or most anyone in here. Common sense tells me that one could never have too much valve duration and that the ultimate duration is 100% of the piston travel, top to bottom for intake and bottom to top for exhaust.

This is all theory though and just some wacky idea that I had. As far as the true design of the valve and solenoid and all that I am also clueless. I just think outside the box i suppose.

The valve doesn't even have to be round. One could make half of the combustion chamber one valve. As long as both ends of the valve opening are symmetrical then the guilletine valve could be 2 parts opening like a set of doors at wal-mart or something. The engineering possibilities are limitless.

Honda once used oval pistions in one of their engines. There are no rules.

T45 wrote:Qtech... Forget typical valve design. Forget the current head, throw the entire upper half of the combustion engine out the window.

If one were to go to solenoids there would be no need for the current valve design or springs. The intake tracts could be opened and closed by a gate or "guilletine" type valve. Like on motorcycle flat slide carbs. If one used this type of valve there would be no need for springs as the solenoid would handle the movement, both open and closed.

If this "gate" valve were positioned paralell to the top of the piston there would be nothing for the piston to hit at all. Compression could be limitless.

Throw typical cam duration and curve out the window too. With almost instant valve action the valve could open immediately after the piston starts it's downward travel and close as the piston nears BDC. Your typical cam curve does not allow for as much valve duration due to cam curve and also the valve clearance with the piston.

As far as what affects this much duration would have on an engine I have no idea. I think you know a lot more about engines than I or most anyone in here. Common sense tells me that one could never have too much valve duration and that the ultimate duration is 100% of the piston travel, top to bottom for intake and bottom to top for exhaust.

This is all theory though and just some wacky idea that I had. As far as the true design of the valve and solenoid and all that I am also clueless. I just think outside the box i suppose.

The valve doesn't even have to be round. One could make half of the combustion chamber one valve. As long as both ends of the valve opening are symmetrical then the guilletine valve could be 2 parts opening like a set of doors at wal-mart or something. The engineering possibilities are limitless.

Honda once used oval pistions in one of their engines. There are no rules.

Trust me, it's all been thought about before.

One thing youre neglecting is the abuse that combustion and compression put on any sort of airflow controlling device in a combustion chamber. Any sort of valve that will actually be in contact with the combustion chamber will need to withstand 1000+psi and intense thermal loads, all while always being able to seal properly. This pretty much means the valve has to be round so it will still form a seal on the seat even when it has expanded a lot....

Another nice thing about the tappet valve is the pressures of combustion place more seat pressure on the valve, helping to make an even better seal.

There is the Coates/rotary valve design, but it has serious sealing issues, and anything like a slide throttle style intake or butterfly valve will be blown through the ports the first time the fuel mixture ignites. The next best thing to tappet valves is probably cylinder ports where the piston itself exposes and closes the intake and exhaust ports (2 stroke style).

There have even been engines where the intake is controlled by a cylinder port, and the exhaust is a single large valve at the top of the combuston chamber (some rotary piston engines from old airplanes)

What about using a single large valve per cylinder, connected to both intake AND exhaust ports.... Then using barrel valves in the ports to switch between intake flow and exhaust flow??? That was an idea of mine a few years back... maybe one day I will see about developing it.....

I understood this has been worked on for years using solenoid type actuators, but the harshness has always been an issue at high rpm, and the valves get a hammering..literrally. I think some truck manufacturers use them already. Doesnt F1 cars do a similar thing? If so I wonder how they make things survive at 16+000 rpm

So anyway, can anyone confirm how many degrees your intake cam is moved by VTC ? This is an important piece of information, as it'll determine what I can do for cams.

20 degrees!

Ah right... *makes retarded face* >_<

lol, yeah i'm sure there isn't a reason for doing somethng different in the head design. If it were easy it would have already been done right?

I'mma go play with my wankel...