Why DOHC and not SOHC ??

[YelloRolla]

I actually thought that F1 were still using cams. The followers and valves though are pneumatically controlled.

[ViPeR_NiPPleX]

i was under that impression also....

[Nim]

Damn You Salazaaarrr!!!

[tricky]

Yeah, you are probably right... I was recently reading some developement articles, they just hadn't mentioned whether the covered technologies had been implemented yet. But its getting incredibly close!!

[fuzz!]

here's a paper on an electromagnetic valve actuator..

it makes so much sense in theory, computer controlled lift and duration without the friction of head gear. and this article says that a group in the EU has "successfully designed, produced and tested an improved electromagnetic valve actuation system for car engines".

[Nim]

here's a paper on an electromagnetic valve actuator..

it makes so much sense in theory, computer controlled lift and duration without the friction of head gear. and this article says that a group in the EU has "successfully designed, produced and tested an improved electromagnetic valve actuation system for car engines".

Yeah, when I first started reading up on cams n stuff I thought "why not just open each valve with hydraulics or something?". Then I found out others had thought the same thing.

[ViPeR_NiPPleX]

its the next logical progression in internal combustion engine technology i think atleast.... have a computer with maps for the most efficient 'profile'... however how could you make the system failsafe?? thats my concern

[fuzz!]

however how could you make the system failsafe??

there's no such thing, whether you decide on mechanical or computer controlled valve actuation there's not bulletproof guarantee that it won't f*ck up. i seriously don't think it would be any more or less reliable than a timing chain/belt. it would be still be a case of impact or non-impact when a valve sticks.

[Nim]

there's no such thing, whether you decide on mechanical or computer controlled valve actuation there's not bulletproof guarantee that it won't f*ck up. i seriously don't think it would be any more or less reliable than a timing chain/belt. it would be still be a case of impact or non-impact when a valve sticks.

It is less reliable.

What is likely to go wrong now:
- Belt snap
- Err... can't think of much else that's likely to go wrong...

What can go wrong with the new system:
- Computer shut down
- Power surge causing incorrect signals to be sent
- Acuator malfuction causing it to jam open
- crank angle sensor manfunction
- ECU malfuction

[fuzz!]

- Computer shut down
- Power surge causing incorrect signals to be sent
- Acuator malfuction causing it to jam open
- crank angle sensor manfunction
- ECU malfuction

yeah okay, sensor or computer malfunction.. probably more likely than timing gear wear/failure.

all i mean is, i honestly don't think it's a huge concern.

[ViPeR_NiPPleX]

how often does a modern day ecu or injector malfunction? i think wear items will still be wear items...

[oldcorollas]

Yeah, when I first started reading up on cams n stuff I thought "why not just open each valve with hydraulics or something?". Then I found out others had thought the same thing.

you don't know why?

maybe you could do a bit of google research on these topics, eletro/hyd operated valves, and pneumatic springs etc.. there are pictures available around the place of F1 "springs"

such as.....


but i'll give you a hint.... nah fuggit, i'll just tell you

it won't make it to production engines because of the POWER it take to drive it compared to springs. look at the pressure required to operate pneumatic springs at that speed.

as for electromagnetic, that won't happen until cars are running at higher voltages, like 4-500V.... and even then, the power draw will be considerable (you, if you wanted to be resourceful, could calculate the 'work' and 'power' required to be done by the electrical system in terms of joules and watts to open and close each valve at sayyy, a sinusoidal rate, knowing the rpm and the rough length of time valve is open and the lift, and see how many amps that will take..)
pull finger

[oldcorollas]

look, you can even buy some
http://www.delwestusa.com/manufactur...tic_valves.asp

and (from atlas F1)

gt5816v 20-Dec-02 18:25 8
One of the chaps at the US location got back to me late yesterday afternoon. Very helpful and had lots of info. Unfortunately the pnuematic valvetrains are about $100,000.00 US I'm sure they're well worth it but that's double our entire R&D budget for this project........ I was expecting 1/10th that amount.... Anyway he also said the website was a few weeks out.

Joshua Murray
Matrix Engineeering

oh, and if you look around, you'll see that an F1-like engine was made with a rotary valve, but was not followed up due to ongoing sealing issues and wear (even in short term)

[fuzz!]

as for electromagnetic, that won't happen until cars are running at higher voltages, like 4-500V.... and even then, the power draw will be considerable (you, if you wanted to be resourceful, could calculate the 'work' and 'power' required to be done by the electrical system in terms of joules and watts to open and close each valve at sayyy, a sinusoidal rate, knowing the rpm and the rough length of time valve is open and the lift, and see how many amps that will take..)
pull finger

yeah the article talked about a new 42v standard making possible the case for electromagnetic actuation. and of course it takes power, as does every other method. bill sherwoods article mentioned a 20hp motor being required to drive head gear for testing.

i think a big question is precision.. i mean, you can make a mechanical camshaft pretty precise. can electromagnetic actuators be controlled to an equal (or better) resolution?

[myne]

I can see a rather obvious improvement to the cam over bucket design just by looking at it.
Make the bucket with a dual loop OVER the cam(like handles), but slightly to either side of the lobe. Then create 2 small closing lobes on either side of the main lobe.
Assuming the bucket can be affixed to the valve or collets, it'd work, I'd say fairly well if it could be made strong enough.
Lash might be a pain to worry about, but perhaps inertia will help out with the last few thou.

I'm just going to assume someone's thought of it, so why isnt it used?