Why hasn't VTEC been adapted to pushrod engines?
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Originally Posted by Jon B.
Considering the fact that the FIA rules ALSO dictate the material used in construction. I find that hard to believe.
Jon
Jon
There was JUST a big controversy because the slot between the two elements of the Ferrari cars' rear wings was opening and closing based on the speed of the car. People were saying it should be illegal because it does the same thing as a variably controlled wing.
Ferrari's response was that you can only make wings so stiff and it's only natural that it bends.
Hell, even in the Grand Prix of Europe this past weekend there was more talk about it because one of the Renault's front wing was flexing.
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Joined: Jun 2002
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From: Upstate NY
Originally Posted by Ballistic Jello
Yes, and VVT-i.
The rubber lobe idea sounds wicked, I gotta read about that. Did you or your friends ever actually try that, Old SStroker? What did you mean by it didn't work too well?
The rubber lobe idea sounds wicked, I gotta read about that. Did you or your friends ever actually try that, Old SStroker? What did you mean by it didn't work too well?
Finally we decided to just street race for pinks with one run for all the marbles. That was a better deal. Many years later we got some network folks to make a TV show out of racing for pinks. They screwed us out of the idea without paying us much, so now I just hang out on car forums.
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Guys, it's a joke! Don't take me seriously.
Originally Posted by Zeus
Have you ever even WATCHED F1 before?
There was JUST a big controversy because the slot between the two elements of the Ferrari cars' rear wings was opening and closing based on the speed of the car. People were saying it should be illegal because it does the same thing as a variably controlled wing.
Ferrari's response was that you can only make wings so stiff and it's only natural that it bends.
Hell, even in the Grand Prix of Europe this past weekend there was more talk about it because one of the Renault's front wing was flexing.
There was JUST a big controversy because the slot between the two elements of the Ferrari cars' rear wings was opening and closing based on the speed of the car. People were saying it should be illegal because it does the same thing as a variably controlled wing.
Ferrari's response was that you can only make wings so stiff and it's only natural that it bends.
Hell, even in the Grand Prix of Europe this past weekend there was more talk about it because one of the Renault's front wing was flexing.
Jon
Staging Lane
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From: Chicago, IL
Originally Posted by swearitsstock
Although it is nice for a street car, and saves on gas, gives anice ride at low rpms, its just too difficult to deal with when your tuning a car to make big power
The reason a lot of the higher power Hondas lose the VTEC is oil pressure fluctuation and valvetrain weight. The cars that lose it are pure race cars though and have terrible low end power (worse than before
).As far as VVT being a joke and not needed, just watch this:
http://www.youtube.com/watch?v=iRQuO66mYxc
I believe that system only controled cam timing and it created noticible gains. You really think a V8 could NOT benefit from that?
note: i hope that's the right video (that shows the Mine's skyline with and without the VVT system). I'm on dialup right now so i can't watch it
On The Tree
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From: Iowa
Originally Posted by njn63
note: i hope that's the right video (that shows the Mine's skyline with and without the VVT system). I'm on dialup right now so i can't watch it
This topic is great, I'm learning a ton.
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From: Blackwood, NJ
Actually, anything that would let you spin a motor faster would create the potential for more horsepower. Getting an LSx to hold 400lb.ft. of torqe from say 3k to 9k (about where the R34 was) would be beneficial. Period. Actually doing so is easier said than done, though. It's all in the tune.
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From: Anna, OH
Originally Posted by Jon B.
Considering the fact that the FIA rules ALSO dictate the material used in construction. I find that hard to believe.
The only way I think you could give a pushrod engine a secondary cam like VTEC would be if you were able to create a cam lobe made out of multiple pieces and create some device that would make the lobe "grow" in relation to the base lobe slightly thereby giving it additional lift and duration. I just can't think of how to activate the secondary mode... maybe by centrifugal force or something?
I still like the thought of running a stock cam up until 4500 RPM and afterwards running something ridiculous like a Trex up until redline. But it just adds complications, costs, and more difficulty tuning.
These engine do so well with heads/cam or boost we really don't need any of those cool little tricks.
I still like the thought of running a stock cam up until 4500 RPM and afterwards running something ridiculous like a Trex up until redline. But it just adds complications, costs, and more difficulty tuning.
These engine do so well with heads/cam or boost we really don't need any of those cool little tricks.
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Originally Posted by joecar
The most versatile would be PCM controlled bi-directional solenoids operating the valves, pushing them open and pulling them shut.
I don't know the issues, but heat was mentioned, and I imagine that the solenoid must be able to move the valve mass to the open/shut extremes at the max operating frequency without floating;
at 6000 RPM the max operating frequency would be 50 Hz, but now since the valve train is eliminated you could spin faster, so the max freq. could well be 100 Hz;
to move the valve mass at those freq's requires a hefty push-pull solenoid (or 2 opposed solenoids) with sufficient cooling;
I like the idea of being able to tune it from a laptop, but it can be scary.
I don't know the issues, but heat was mentioned, and I imagine that the solenoid must be able to move the valve mass to the open/shut extremes at the max operating frequency without floating;
at 6000 RPM the max operating frequency would be 50 Hz, but now since the valve train is eliminated you could spin faster, so the max freq. could well be 100 Hz;
to move the valve mass at those freq's requires a hefty push-pull solenoid (or 2 opposed solenoids) with sufficient cooling;
I like the idea of being able to tune it from a laptop, but it can be scary.
Originally Posted by cantdrv65
Hmmm. Why have to push or pull a valve at all. Let the solenoid and valve become ONE assembly (integrated in the head), like an industrial solenoid valve. Im sure a cooling system could be made for the valve actuator. I think you have to think outside the box, and redesign the head.
why in the world do you want a valve that obstructs the airflow when "open"?? if you could design some kind of valve thats fully open, and seals properly, takes the heat, miles, ect..... then you would have a massive increase in efficiency, power, ect... and while you're at it, it could be designed to be controlled with a variable timing system from the start...
of course, theres alot of obstacles to overcome...namely a valve design that works and lasts..... and thats why we're not all doing it at the moment.
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From: So.Cal.
Originally Posted by cantdrv65
Hmmm. Why have to push or pull a valve at all. Let the solenoid and valve become ONE assembly (integrated in the head), like an industrial solenoid valve. Im sure a cooling system could be made for the valve actuator. I think you have to think outside the box, and redesign the head.
Originally Posted by MrDude_1
one of the problems i have with all modern engines, is the design of the valve.
why in the world do you want a valve that obstructs the airflow when "open"?? if you could design some kind of valve thats fully open, and seals properly, takes the heat, miles, ect..... then you would have a massive increase in efficiency, power, ect... and while you're at it, it could be designed to be controlled with a variable timing system from the start...
of course, theres alot of obstacles to overcome...namely a valve design that works and lasts..... and thats why we're not all doing it at the moment.
why in the world do you want a valve that obstructs the airflow when "open"?? if you could design some kind of valve thats fully open, and seals properly, takes the heat, miles, ect..... then you would have a massive increase in efficiency, power, ect... and while you're at it, it could be designed to be controlled with a variable timing system from the start...
of course, theres alot of obstacles to overcome...namely a valve design that works and lasts..... and thats why we're not all doing it at the moment.
But to get something going asap with minimal changes requires keeping the good-known-working aspects and avoiding major design changes (for now)...
the one advantage of the current valve shape (that has made it successful for 100 years) is that combustion pressure pushes on the valve helping it to seal.
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From: Blackwood, NJ
Originally Posted by joecar
I agree with you both...
But to get something going asap with minimal changes requires keeping the good-known-working aspects and avoiding major design changes (for now)...
the one advantage of the current valve shape (that has made it successful for 100 years) is that combustion pressure pushes on the valve helping it to seal.
But to get something going asap with minimal changes requires keeping the good-known-working aspects and avoiding major design changes (for now)...
the one advantage of the current valve shape (that has made it successful for 100 years) is that combustion pressure pushes on the valve helping it to seal.
Another Idea would be to make the valves themselves the throttle bodies. It would be prettymuch the same thing as ITB but instead, the valves themselves would be the t/b. Of coarse, that would be rediculously complicated, if not impossible. With how fast the plates will be opening and closing, you'd probably see some flex in the plate after a few hundred miles. I think my hinged valves are a much better idea.
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From: Upstate NY
Originally Posted by MrDude_1
one of the problems i have with all modern engines, is the design of the valve.
why in the world do you want a valve that obstructs the airflow when "open"?? if you could design some kind of valve thats fully open, and seals properly, takes the heat, miles, ect..... then you would have a massive increase in efficiency, power, ect... and while you're at it, it could be designed to be controlled with a variable timing system from the start...
of course, theres alot of obstacles to overcome...namely a valve design that works and lasts..... and thats why we're not all doing it at the moment.
why in the world do you want a valve that obstructs the airflow when "open"?? if you could design some kind of valve thats fully open, and seals properly, takes the heat, miles, ect..... then you would have a massive increase in efficiency, power, ect... and while you're at it, it could be designed to be controlled with a variable timing system from the start...
of course, theres alot of obstacles to overcome...namely a valve design that works and lasts..... and thats why we're not all doing it at the moment.
You might do some more research on this. Smokey Yunick discussed it 20+ years ago, David Vizard has some good info on it also.
Try this link:
http://speedtalk.com/forum/viewtopic.php?t=757
You might also look deeper into the "Coanda effect".
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Originally Posted by Third Gear
The only way I think you could give a pushrod engine a secondary cam like VTEC would be if you were able to create a cam lobe made out of multiple pieces and create some device that would make the lobe "grow" in relation to the base lobe slightly thereby giving it additional lift and duration. I just can't think of how to activate the secondary mode... maybe by centrifugal force or something?...
It would be possible to reverse the lobes to enable the roller element to operate on the high speed lobe, but I suspect an OEM application would choose to garner the fuel economy benefit of the low friction roller in the low speed mode.
Launching!
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From: shasta lake, north cali
Originally Posted by Third Gear
Teching In
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From: Longmont, CO
I can't possibly see how any sort of multi-profile lobe could ever work out in the long run. You could never have enough contact surface between the lifter and lobe for any sort of durability unless the engine was 4 feet long. I would be shocked to see any kind of VTEC, etc. on a pushrod engine.
However, the concept of retro-fitting an electric/pneumatic valvetrain would be the greatest thing since overhead valves. The tuning possibilities of an infinitely adjustable valvetrain would be limitless. I read a magazine article a few years ago (Hot Rod?) about how Siemens was developing something like this. I never heard any more about it though. Somebody's gotta do this...
However, the concept of retro-fitting an electric/pneumatic valvetrain would be the greatest thing since overhead valves. The tuning possibilities of an infinitely adjustable valvetrain would be limitless. I read a magazine article a few years ago (Hot Rod?) about how Siemens was developing something like this. I never heard any more about it though. Somebody's gotta do this...
On The Tree
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From: Edmonton, Alberta
Originally Posted by drivefastgto
I can't possibly see how any sort of multi-profile lobe could ever work out in the long run. You could never have enough contact surface between the lifter and lobe for any sort of durability unless the engine was 4 feet long.
Solenoid/air/hydraulic valves cant be that far off from being developed in street engine. A ton of extreme duty and very reliable designs are already in service in different industries. Yes, it will change the game.