Improving Engine Efficiency & Performance

[Bones]

pumping losses are 10hp at 7k and frictional is 56hp.

OK, you got me there. When volumetric efficieny is high, pumping losses are going to be low.

I'm not saying reducing friction isn't important, just that engine efficiency isn't going to suddenly jump 50% by reducing friction.

[SappySE107]

Its not going to be the total answer, but that would simply their design when its actually doing more than just reducing friction. You are using 1 combustion event to power 2 pistons. The power is divided to 2 cranks per piston but the cranks are all connected together, which brings the power to 1 output shaft. You can have a lot more stroke without any rod angularity and side wall friction. With the reduced size of the components and the power potential, your RPM could be much greater as well.

I am not the greatest at explaining things but the design made sense to me.

[Bones]

You are using 1 combustion event to power 2 pistons.

This is the part that lead me to call it a gimmic. The best way I can come up with to explain it is if you stuck a plate in the middle of the cylinder and divided the incoming charge between both halves the engine would not perform any differently than if the two cylinders were side-by-side. The plate would always have the same presure on both sides and it would be like it was never there.

[pocket-rocket]

Well one part that made sense to me was that our compression ratios of today aren't what they could be. One of the weak links to engines is the cylinder head according to that guy. Remove it and put 2 pistons going at each other and you get a much greater compression ratio. I checked the compression on a 97 Tahoe w/ a 350 Vortec. The pressures were all right around 200psi. IIRC, that guy said the pressure at TDC in that engine approached 4k. That sounds like a really high compression ratio to me. Turbos normally run what, around 15 psi if you know what you are doing? I don't know all the math on it, but I doubt after the piston hits TDC in an engine running 15psi of boost it is going to be anywhere around 4k psi. I don't see that tiny engine making 900 hp though. Even with 4 cranks to absorb the hp, I don't see them taking 225 hp each because they all looked like they were about 1" diameter. If I watched you try to shove 225 hp to a 1" crank to catch... Lets just say I won't be staying in the room with you :P

[torq455]

Actually in the mid 70s when the emissions situation hit, compression ratios took a nosedive. Back in the muscle car era it was nothing to have a compression ratio in the double digits up until the switch to unleaded gas. I read about a Camaro that came with 12.0:1 compression stock. Cars today stock haven't hit that mark either. Not the 08 Z06, Viper, or the Enzo.

True about the muscle cars and high compression. Though they did have 100 octane rating which would allow a poorly low tech IRON head engine run safely.

[torq455]

Maybe I can't do it by hand, but the electric starter motor doesn't have any trouble doing it, and it's only a couple horsepower, maybe 5 at the most.

Maybe, though don't forget about the little gear that turns a much, much larger gear.

[pocket-rocket]

True about the muscle cars and high compression. Though they did have 100 octane rating which would allow a poorly low tech IRON head engine run safely.

I don't remember my dad putting leaded gas in his truck, so that was before my time. Man I grew up in the wrong time era

[torq455]

i remember my dad putting leaded gas in his GTO. pretty sure we still had that in the early 80's still.

just confirmed it was phased out by 1986.

[Bones]

Getting back on topic....

I don't see a TURBO on you list of areas to improve A senicible (read: small) turbo with a proper camshaft (short duration, negetive overlap) can actually improve fuel econemy, not to mention give you lots of extra torque. The small turbo will choke the motor so you won't be able to turn a lot of RPMs, and the whole thing is likely to cost you more than you'll save on gas, but hey....TURBO! haha

[SappySE107]

Anything off vacuum will improve efficiency a great deal. Less work for the motor and it gets over 100% volumetric efficiency.

When you combine a larger compression with 2 pistons, its not a gimmick. What you are saying, is the design itself doesn't allow for any more energy to be used. You said that you need to use more of the heat...well doubling your stroke on 1 cylinder by using 2 pistons instead of one does that. It uses more of the energy from that one combustion event than a single piston would.

[Bones]

When you combine a larger compression with 2 pistons, its not a gimmick. What you are saying, is the design itself doesn't allow for any more energy to be used. You said that you need to use more of the heat...well doubling your stroke on 1 cylinder by using 2 pistons instead of one does that. It uses more of the energy from that one combustion event than a single piston would.

Not sure I'm following you... I think compression ratio in current diesel engines is already optimal. More compression creates more heat and not much else, at least that's my understanding. The only possible advantage I'm seeing is that not having any heads reduces the surface area of the cylinder so they'd dissipate less heat, which could lead to a significant improvement, but still nowhere near the "80% efficiency" that they claim. It would take testing to see if there are worth-while improvements. Plus you'd have to develop some kind of valves to work in the cylinder walls (unless we're talking about a 2-stroke diesel which I gather are much less efficient due to having to run a big blower along with port timing compramises)

I don't think that the results would be a very big improvement, and I'd rather see development go into one of the 6-stroke designs, but that's just my opinion. Without a lot of testing there's no way to know for sure.

[Canyonero]

With the gas prices on the rise and not wanting to spend money on another vehicle, I am brainstorming ways to make the 3400 and 60*V6 engines in general more efficient.

I think the physics talk was much less of a digression than this line on theoretical internal combustion engine design.

[Rhedalert]

It's my understanding that pumping losses are very high at part throttle and cruise speeds vs WOT and high RPM. That can be observed based on engine vacuum readings. Since we're talking engine efficiency improvements and for people looking for that extra MPG, we have to assume most of the driving is done under part-throttle, be it city and/or highway environments. So in order to reduce pumping losses, generally you want the throttle to be "more open" without adding additional load, and still maintain a given speed. This can be accomplished by (in theory)

- Dropping the drive ratio. If you need, say, 50 hp to maintain 65mph on the highway, you could achieve this at 15% throttle at 2500 rpm, or 25% throttle at 1500 rpm. The 1500 rpm/25% throttle has the advantage of less frictional loss due to spinning slower, and theoretically lower pumping losses due to the wider open throttle. Just throwing some numbers out there but obviously we'd need a dyno chart showing real values, to see if the engine would be within the powerband.

- Smaller engine. This wouldn't be an answer here but for arguments sake, a larger engine may only need 10% throttle at 2500 rpm while a smaller but otherwise equal engine would need 20% throttle at 2500 rpm to maintain the same speed. This would be a pumping loss reduction.

- Variable displacement, same reason as above. One might even suggest injecting larger amounts of inert (exhaust gases) into the combustion chamber to effectively "reduce displacement"





The only part of that video I disagreed with is how he seemed to explain the internal combustion engine inefficiency was due to "unburned fuel out the tailpipe". At least as far as gasoline engines go, I can't see this being the major cause. How much more BTU energy is lost from the cooling system vs the BTU content of this supposed unburned fuel? It seems to me with modern engines, this can't be the case, since the air/fuel ratio is precisely controlled at stoich under normal conditions.

[merlot566jka]

op engines are fairly comon in the navy used to generate electrical power and propulsion.

opposed piston engines are made by fairbank-morse. they are manufactured in virginia. they sound odd, vibrate and are very complex.

what does this have to do with this thread? things tend to get off topic here and thats when the good info comes out.

to help the 3x00 you need to increase VE....thats about all you can do with the engine untill you start getting into areas that would require extreme modifications. those modifications would almost render the engine a completely different animal.

[onefastV6]

I think the design improvements in the 3500 heads may help... part of the reason I think when I was running the 3500 top end, that I was getting better mileage.

The attached excel spread sheet shows the stock 3400 VE table for a 02 Grand Am compared to a stock 3500 VE table for a 04 malibu.