New concept variable displacement??

[justme1969]

Originally Posted by raylit20

Unfortunately this thought moves in the opposite direction of the KISS mentality. While simple in theory, this is far too complex a design in reality to be implemented into the late stages of a fully matured technology.

Yes it would be far from the simple ideal that is truth but It seems like something ICE will end up with in 10 -20 years, since rotary and turbine are still scoffed at too.

[Frank Lee]

Originally Posted by expert1

There is absolutely nothing more annoying (well ok maybe a few things), than sitting down after a never ending day with your family to enjoy a home cooked meal only to be interrupted before your first bite can even hit your lips by a robocall from a telemarketer likely using a predictive or auto dialer. While these calls can be useful to inform the public about newly launched promotions, without any garnered interest from the intended person picking up the inbound call, it can be nothing more than frustrating.
intercloud9.com

Well, I don't know, spam from morons is right up there too.

[user removed]

Better to have very high cpmpression ratio with reductions made by valve timing and or lift-overlap. I think that is what Mazda is doing with the skyactiv engines. 14 to 1 on pump gas. Probably only 14 to 1 rarely, but 7 to 1 at MAPs of 50% of atmospheric pressure. Add a turbo to that compression ratio! One of the keys to their design is the 5 separate injection pulses in every combustion stroke, occuring after TDC with no posssibility of pre-ignition since the fuel is not there to ignite prematurely.

regards
Mech

[user removed]

Originally Posted by expert1

There is absolutely nothing more annoying (well ok maybe a few things), than sitting down after a never ending day with your family to enjoy a home cooked meal only to be interrupted before your first bite can even hit your lips by a robocall from a telemarketer likely using a predictive or auto dialer. While these calls can be useful to inform the public about newly launched promotions, without any garnered interest from the intended person picking up the inbound call, it can be nothing more than frustrating.
intercloud9.com

Caller ID! In our case on the TV screen and the phone.

regards
Mech

[payne171]

Another one I always wondered about was using valvetrain trickery, fuel and spark cut to turn the engine into a 6 or 8 stroke engine. I think Cadillac's Northstars did something like this to manage overheating, although the valves stayed open so there were still pumping losses.

[Cortez]

Originally Posted by justme1969

I know there must be at least 5 automotive engineers monitoring our threads here so here is a thought for you.
Honda I believe sucessfully breached the electronic valve issue delving into variable valve timing.
Has there been an atempt to get this next step of variable engine displacement?
An example would be a 90 degree V6 where 2 cylinders are 4" and 4 are 2.5".
utilizing cylinder cut out and injector deactivation with all cylinders @ same stroke length The torque could be doubled for acceleration then dropped for cruising speeds and economy.
couple that to a hybrid with regen and electric boosters like formula one uses.
It could teach todays sports cars a nasty little lesson while providing 50+mpg???????
Not magic power just better utilization of it, with much less waste!

Cadillac did it back in 1981. It was a disaster and almost put the company out of business. The engine was a 368 cid. At the time they called it modulated displacement or the V8-6-4. They actually run smooth......when the valve activation and deactivation works correctly....that's not often but it was the computer. It ran a basic TBI fuel delivery system and solenoids that would lock valves under certain conditions. They didn't have any balancing problems but then again the family tree that those engines came from were beast.

A lot of the problem with those engines was when the valves would open. Since it was fogging the manifold with fuel when cylinders reactivated it would deliver fuel very unevenly causing bogging...bucking..

With modern technology you could iron out the problems. They put out a prototype a couple of years ago called the Cadillac Sixteen that used it. Don't think they are putting out a sixteen cylinder engine anytime soon.

[pete c]

Originally Posted by payne171

Boy, maybe I am missing something on the variable displacement, but why not have a couple (or few) of v-twins connected by a clutch? It can't imagine balancing issues could be any worse than the current crop of cylinder deactivation autos. Valve shutoff is moot. The clutch should last quite a while. You could even make one of the engines a lot simpler than the other because it wouldn't have a very big affect on emissions because it would only run during acceleration.

I've wondered this as well. A pair of 90 degree V twins connected by clutch.

Such a system would undoubtedly be more efficient, but, I do see a few potential issues.

1. It's more expensive. It needs two separate ignition systems, and ECUs. Probably two exhaust systems as well.

2. Possible NVH issues. Even though 90 degree twins are inherently balanced, two of them running right next to one another might sound like crap when out of phase with each other. Perhaps this could be dealt with with some engine control wizardry.

3. Emissions. I suspect these would need separate exhaust systems which means one of them kicking in and running cold/dirty frequently.

[darcane]

Originally Posted by Cortez

Cadillac did it back in 1981. It was a disaster and almost put the company out of business. The engine was a 368 cid. At the time they called it modulated displacement or the V8-6-4. They actually run smooth......when the valve activation and deactivation works correctly....that's not often but it was the computer. It ran a basic TBI fuel delivery system and solenoids that would lock valves under certain conditions. They didn't have any balancing problems but then again the family tree that those engines came from were beast.

A lot of the problem with those engines was when the valves would open. Since it was fogging the manifold with fuel when cylinders reactivated it would deliver fuel very unevenly causing bogging...bucking..

With modern technology you could iron out the problems. They put out a prototype a couple of years ago called the Cadillac Sixteen that used it. Don't think they are putting out a sixteen cylinder engine anytime soon.

Um... there are lots of engines now with cylinder deactivation. The current methods for cutting cylinders works much better than the old Cadillac system. GM learned that lesson, and Active Fuel Management (AFM) has been readily accepted since about 2005 IIRC. Dodge has it on their new "Hemi", Honda has it on some V6s.

The new thing Justme was suggesting is to have different bores on certain cylinders.

[darcane]

Originally Posted by pete c

I've wondered this as well. A pair of 90 degree V twins connected by clutch.

Such a system would undoubtedly be more efficient, but, I do see a few potential issues.

This is a case where 1 + 1 != 2.

Coupling engines together is done somewhat regularly in land speed racing. Inevitably, they get less power to the ground than one engine with the same power as the two engines combined, even with a solid shaft coupling the cranks together. So, you might have two 100hp V-twins that only gets 160hp to the transmission.

It would save fuel when running as a 2 cylinder, but it would be less efficient than a conventional 4 cylinder when the power is needed.

[payne171]

I don't know that a land speed record vehicle is really applicable to a fuel economy technology. They are building those for brutal conditionsand 10+ times the horsepower. A passenger car simply needs low NVH levels and less than one tenth the torque handling. Cold startup is irrelevant because the coolant would run through both blocks, thus heating both engines. I don't see why one ECU/ignition system couldn't handle both engines. It is still making four cylinders fire. It would just have to be a little more complicated to program. Of course it would be more complicated/expensive. So are hybrids and diesels, yet they are building plenty of those. Hybrids are also why I think this will work. They have made planetary transmissions and others (Accord hybrid, for instance, used a four speed auto) receive torque from two sources without massive losses.

Of course, when I think of what seems like a good idea, I usually refer back to this question, "If x is such a good idea, why didn't somebody smarter than me do it already?" The pessimist in me thinks that maybe it was dismissed because its image wasn't green enough. You and I both know hybrids have taken of so fast in large part due to their green image, when much of the technology in hybrids (like active radiator blocks, aero, etc.) could have been put on cars long before hybrids hit the market. But a green image wasn't as valuable to car makers then. Still, it is likely that there are other problems.