Comparison of the best ~2 liter N/A engines ever produced

[chulooz]

Everything can screw up, bent valves already happen during engine failures so its something we can foresee, though their computer is no slouch.

Energy lost? You mean the energy you spent to make those gears and cams turn? The air system doesnt have that. Did you watch it through, it can become a near perpetual system.

I really hope that technology gets widely applied, crazy factory/aftermarket tuning implications.

[serialk11r]

Originally Posted by chulooz

Energy lost? You mean the energy you spent to make those gears and cams turn? The air system doesnt have that. Did you watch it through, it can become a near perpetual system.

I really hope that technology gets widely applied, crazy factory/aftermarket tuning implications.

The losses in a cam driven valve are all frictional, with modern materials this loss is reasonably small, only reason they are one of the lossier things in an engine is because they can't really run under hydrodynamic lubrication so you're dealing with coefficient of friction in the 0.1ish range.

The air system has to push the valve against the spring, loading the spring takes energy. When that valve bounces back there's no good way to capture the energy so it's dissipated into some kind of shock absorbing system. Pumping air or hydraulic fluid to push the valve can be even lossier than the mechanical friction of a cam; The cam loses some percentage of the energy you put in to friction (but the forces are greater when the cam surface is at an angle), but the air pump and valving is likely to see very low efficiency.

One possible solution is an electromagnetic actuator with additional hydraulic damping of some sort, but the challenge is of course getting a magnetic field that is strong enough to apply significant force to the tiny valve.

[regal]

Originally Posted by chrisl

the car comes to about 3k pounds total, you would have to be going up a 12.3 degree incline to be not accelerating at all (and to have all of the power going to maintaining speed up the incline). Besides, if you really have to accelerate that much, why not downshift (or hold it in second longer)? That same speed should only be about 6krpm in 2nd, so you definitely still have some room before redline...

A long >12.3 degree incline is very common on back roads across this country not talking highways.

Why not downshift? Well this is a 2012 build date, no 01C calibration available for these cars.

Just examples of why the Fa20 is not on my list of the best 2L engines ever produced. Though I think that it has potential via the aftermarket long term.

[chulooz]

No wasting energy on turning the gears and cams themselves. Theyve Already proved it to be over 20% more efficient than conventional motors and the tuning potential is nearly limitless when you dont have to be bound to a cam profile

[WolfpackS2k]

Originally Posted by chulooz

Everything can screw up, bent valves already happen during engine failures so its something we can foresee, though their computer is no slouch.

Energy lost? You mean the energy you spent to make those gears and cams turn? The air system doesnt have that. Did you watch it through, it can become a near perpetual system.

I really hope that technology gets widely applied, crazy factory/aftermarket tuning implications.

F1 teams have been testing and developing these systems for over a decade. But who knows when/if it'll make it to the average grocery getter.

[chrisl]

Originally Posted by regal

A long >12.3 degree incline is very common on back roads across this country not talking highways.

I doubt that very much, especially any road you would be going ~50mph on (since many cars would be completely unable to maintain speed up such a slope at that speed). I would believe that there are quite a few 12% grades, but that's a lot shallower (since 12.3 degrees is a 22% grade).

(Feel free to list a specific road though - it's easy enough to verify slope with Google Earth)

[WolfpackS2k]

lol, 12% grade is ridiculously steep, especially for a heavily traveled road. I'm doubtful of this. I don't think I've ever encountered anything over 5% when driving in the mountains.

[serialk11r]

Originally Posted by chulooz

No wasting energy on turning the gears and cams themselves. Theyve Already proved it to be over 20% more efficient than conventional motors and the tuning potential is nearly limitless when you dont have to be bound to a cam profile

It's not the gears and cams that wastes the energy, it's the extremely suboptimal valve operation (as in the way it lets gases in and out) that kills efficiency. The reason no one is doing fully camless valves is because the power consumption of the valvetrain eats up most of the benefit.

Essentially though, you only need to vary either lift and duration together to get most of the benefit, and with roller followers or whatever they're called the friction is reasonably low, so I would bet on some kind of cleverer hydraulic lift adjustment system supplanting the current ones.

Originally Posted by WolfpackS2k

F1 teams have been testing and developing these systems for over a decade. But who knows when/if it'll make it to the average grocery getter.

F1 has used pneumatic springs, but they still have cams. In fact, a fixed cam. Stupid regulations killing innovation and progress.

[regal]

Originally Posted by WolfpackS2k

lol, 12% grade is ridiculously steep, especially for a heavily traveled road. I'm doubtful of this. I don't think I've ever encountered anything over 5% when driving in the mountains.

You guys need to get out more. This is just cities listed below, in the country these 300 year old PA roads are very steep and my FRS won't pull past 4200rpm up the hill up toward my house in 3rd (no I'm not posting where I live and yes its got a 20 mph speed limit, not proud of that.) :

Below is a listing of at least some of the streets in the US which are steeper than the steepest San Francisco streets. 1. Honokaa-Waipio Road (near Waipio, HI, maximum grade 45%)*
2. Canton Avenue (between Coast and Hampshire, Pittsburgh, PA, 37%)
3. 28th Street (between Gaffey and Peck, Los Angeles, CA, 33.3%)
4. Eldred Street (west of Avenue 48, Los Angeles, CA, 33%)
5. Baxter Street (between Alvarado and Allesandro, Los Angeles, CA, 32%)
5. Fargo Street (between Alvarado and Allesandro, Los Angeles, CA, 32%)
5. Maria Avenue (north of Chestnut, Spring Valley (near San Diego), CA, 32%)
8. Dornbush Street (between Bricelyn and Vidette, Pittsburgh, PA, 31.98%)

http://www.geographylists.com/list17y.html


JMHO but either the FA20 is lacking a little or the FRS weighs too much. I honestly think they designed this engine around a 2500 lb curb weight but when the chassis ended up over target and the engine ended up under target it was too late, just a guess.

[chulooz]

Originally Posted by serialk11r

It's not the gears and cams that wastes the energy, it's the extremely suboptimal valve operation (as in the way it lets gases in and out) that kills efficiency. The reason no one is doing fully camless valves is because the power consumption of the valvetrain eats up most of the benefit.

Essentially though, you only need to vary either lift and duration together to get most of the benefit, and with roller followers or whatever they're called the friction is reasonably low, so I would bet on some kind of cleverer hydraulic lift adjustment system supplanting the current ones.

You arent recognizing the drivetrain wasting power on making the cams spin, there would be no need for a cam chain with this innovation among dozens of other associated parts. (Its design makes the engine much smaller too) Why do you keep talking about power consumption, did you watch the video? It costs the system next to nothing to use the air.

Rollers are physically bound to keep repeating the same lift and duration upon every rotation, with their air system both of those conditions can be changed hundreds of times in a single second with no need to follow the shape of a physical roller. The reason no one is doing it yet is the same reason no one was doing hybrids in the 90's, the technology is still just too fresh.

[chulooz]

Originally Posted by regal

You guys need to get out more. This is just cities listed below, in the country these 300 year old PA roads are very steep and my FRS won't pull past 4200rpm up the hill up toward my house in 3rd (no I'm not posting where I live and yes its got a 20 mph speed limit, not proud of that.) :

Drop a gear, problem solved.

[serialk11r]

Originally Posted by chulooz

You arent recognizing the drivetrain wasting power on making the cams spin, there would be no need for a cam chain with this innovation among dozens of other associated parts. (Its design makes the engine much smaller too) Why do you keep talking about power consumption, did you watch the video? It costs the system next to nothing to use the air.

That's not true. Compressing air to be used like this is inefficient in itself, and you need the same spring pressures to prevent valve float as before so you do need a significant amount of energy to open the valve. At low engine speeds you can open the valve less which does represent energy savings but you still lose 100% of the energy going into opening the valves.

I've watched the video. How do you know that thing isn't using a lot of power? You don't. You can't tell from watching the video because there's no power meter anywhere. Poppet valves represent a significant amount of reciprocating mass in an engine, they have a lot of kinetic energy since they move so quickly, and a pneumatic actuator has no means of recovering any of that. Cams only have frictional losses, if you can control the friction then you don't lose that much power.

Again, this system is definitely better in every single way except power consumption. At high engine speed cams have extremely significant friction losses, but at low engine speeds the acceleration of the valves is much lower, and it's likely that these pneumatic valves are consuming more power. At higher torque levels as well, increasing lift means compressing valve springs more and thus losing more power. In a typical car where you don't use high load or high speed often cams probably use less energy (but make the engine run worse, so you'd have to compare specific engines to be able to say which system works better).

[regal]

Originally Posted by chulooz

Drop a gear, problem solved.

Not recommended to drive up a hill over 6k rpm with a 2012 build date FRZ, I found out the hard way.

Anyway its just odd to require a downshift over 4k rpm in a sports car. Regardless quirks like these keep the FA20 off the best 2L ever produced list. Not a bad engine but not on a best of all time list. Times are tough with corp goals to meet current and upcoming emission/economy regs, sacrifices were made imho.

But hopefully tuning and catless headers can undo these sacrifices.

[ZDan]

Originally Posted by serialk11r

Couple issues:
1. Computer screws up, smashes valve into the piston = bent valves. No cam profile can possibly do that.

Obviously this method will have to be made reliable enough that this doesn't often happen. Valves smashing into pistons does also happen with normal valvetrains!

2. All the kinetic energy you give the spring is lost, whereas with cams you get most of it back. This is quite a lot since you still have to open valves at part load.

With a normal valvetrain, you only get some of the energy used to compress the valvespring back at lowish rpm. The higher you rev, the less you get back. Approaching rev limit, you get practically none of it back, as the spring is doing all it can just to close the valve. At that point it isn't pushing on the closing ramp of the cam lobe much at all. On a related note, at higher revs the energy lost to accelerating the valve on the opening ramp is much greater, and you get none of that back either. Minimizing valve mass is a big deal for these reasons!

Power required to drive a conventional valvetrain at, say, 7000rpm is not going to be insignificant...