nitsudls1

iTrader: (1)

I've looked at several web sites that talk about expirimental engines with
silinoids operating the valves. I'm gessing the computer can change
the "cam" specs(valve events) as the motor is runing. The problem seems
to be that the silinoids go out after about 1000 hours. What if you would
use a butterfly valve for intake and exaust rather than a push/pull valve.
My thought is that you could get mutch better flow because there wouldn't
be a head on the valve. Also I'm wandering if you would have less weight moving around because the valve would simply flip rather than move back and forth.

Adrenaline_Z

It would be easier to control a butterfly style valve, however, it would be
a large task to maintain a closed position under combustion pressures (~ 1000 PSI).

Having a positive seal would also be a trick with a butterfly style valve. I would
imagine all sorts of blow-by into the ports.

There have been several concepts of rotary valves and electic valve trains,
but none have been promising in a large scale production vehicle.

lt1s10

iTrader: (2)

1000psi??

lt1s10

iTrader: (2)

1000psi??

Adrenaline_Z

Where you expecting higher or lower ?

chuntington101

lotus are loooking into electro-hydrolic valve train. it gives all the advantages of the one you mentioned but will run for longer

i think it takes something like 5kw (about 6.67bhp) to run the solinoids on a 4 cyclinder engine!!!

thanks Chris.

digitalsolo

iTrader: (24)

A good question would be how much HP does it take to turn a camshaft against the springs on a typical 4 Cylinder; I would expect it's not too far off of that number.

Adrenaline_Z

I read a post about Spintron users testing V8 camshafts at high RPM (I think
8000 RPM?).

If I recall correctly, the power to turn the camshaft with xxx lbs of spring pressure
was 22.5 HP.

I think it was OldSStroker that posted this info, I'll try a search.

Nine Ball

iTrader: (38)

fixed thread title. Solenoid

gun5l1ng3r

So I am not the only one who does little nit-picky things like that

Was that for a OHV, or a DOHC race motor?

Generic0

I dont rember what company it is but they have rotary valve heads for a coupple diffrent engines. They make a v-twin that you dont have to change the oil in for like 100,000 miles.

Adrenaline_Z

Very certain it was an OHV engine. Still can't find the info; maybe it was another board.

nitsudls1

iTrader: (1)

A dude that go's to our chuch has one of them hit and miss engines and it
only has a cam for the exaust valve. The intake valve is opened by the piston
vacume. I don't think it would work on high rpm situations like were talking though.

Another question is.....If variable valve timeing ONLY helps to broaden the
power band then what good would a 6 speed trans mission do. Seems to me
the ls7 could sacrafice a few gears. After all my 3800 pound 69 1/2 ton had
a 3 speed in it. I allways wanted an overdrive for the stock motor(307)
but now with the ls1 do I need the 4 speed(4l60e). I'd like to cruse at lower
rpm so I got an over drive but would a 3 speed work good if I put taller gears
in it.

chuntington101

i think you need to remember that it the torque you put to the road that does the accelerating, not what the engine makes!!!!! thats why you accelerate harder in lower gears, cos (aslong as you have traction) the whole drivetrain (inc engine) is making more torque!

the reason they are serching for a wider spread of power is to make the car easier to drive! it makes the engine "feel" like you have more cubic inch than you really do! also its area under the curve that makes a car quick!

i see where your coming from but i realy dont see the point (unless you are saving a **** load of monet) going that route!

thanks Chris.

nitsudls1

iTrader: (1)

So you should keep the motor as close to peek torque as you can while accelorating. I'm not shure I agree....................I've been thinking horse power is how mutch work the engine can do(regardless of rpm).And Ive been thinking torque is the ability to maintain rpm.......


My point is this.......If a drivetrain(trans/gears/tires) can hold an engine in a short power band(will just say that you shift at 6000 and the rpms drop to 4500)than it doesn't matter what kind of power it makes at 2000 rpm because the motor never hits that rpm accept on the initial take off(maybe not even then.)

so if you had infinitly variable valve timing and could get a good power band(say idle-8000 rpm) we rev up to 8000 then shift ........volah when we shift we drop back down to 6500rpm and then who cares how mutch power we can make from idle-6500 or above 8000rpms

nitsudls1

iTrader: (1)

I think were discussing about 20 or 30 subjects under this thread...........I do realize there is a lot of things that determin what gets a car down the track in no time........and those things might and might not be ideal for a production street car.

chuntington101

i agree!

i was thinking more about production (where VVT is manly used). for a car made for the track things would be alot more like what you said!

another thing you guys might want to think aobut. most VVT systems are ditched when people start modding cars! people go for fixed cams.

thanks Chris.

GuitsBoy

iTrader: (4)

HP being a function of torque vs. rpm is actually what you should base your shifting on. If a ficticious motor had a torque curve that looked like a plateau, reaching 300 ft lbs at 3000 rpm and staying at 300 ft lbs all the way to 6000 rpm, you would certainly be doing twice as much work at 6000 rpm, which means you could now gear twice as low and double the ammount of applied torque to the road.

Now for what its worth, a rolling punch will throw you back into you chair more if you punch it at torque peak as opposed to HP peak. Past that, acceleration happens quicker at HP peak.

Cop Car

iTrader: (14)

BMWs V10s in their M5s and M6s have no cams, they are solenoid activated valves. my guess is they last more than 1000 hours

rubin

wow this is 100% FALSE
http://www.rsportscars.com/eng/artic...gine_award.asp

It probably has double vandos. which is able to alter the valve timing and lift almost infinetly but theres still a cam.